Journal Cover
Journal of Composite Materials
Journal Prestige (SJR): 0.555
Citation Impact (citeScore): 2
Number of Followers: 387  
 
Hybrid Journal Hybrid journal   * Containing 3 Open Access Open Access article(s) in this issue *
ISSN (Print) 0021-9983 - ISSN (Online) 1530-793X
Published by Sage Publications Homepage  [1085 journals]
  • Experimental investigation of a hybrid nickel-carbon black
           polydimethylsiloxane conductive nanocomposite
    • Authors: Sharvari Dhote, Kamran Behdinan, Jan Andrysek, Jia Bian
      Abstract: Journal of Composite Materials, Ahead of Print.
      This paper presents an experimental investigation of single and hybrid carbon black and spiky nickel-filled conductive composite to understand the synergy effect when different types and shapes of fillers are combined in a silicone polymer matrix. The electrical and mechanical properties of the conductive composites are measured under a compressive loading cycle. The results showed that the electrical properties of the hybrid conductive polymer composites have a better repeatability at low filler ratio as compared to the virgin nickel or carbon black composite. The new hybrid composite piezoresistive behavior is similar to a high filler ratio nickel composite. This study provided insights to develop a tailored conductive composite with a low mass-ratio and different morphology of fillers.
      Citation: Journal of Composite Materials
      PubDate: 2019-12-02T04:26:16Z
      DOI: 10.1177/0021998319890406
       
  • Effect of silanized sisal fiber on thermo-mechanical properties of
           reinforced epoxy composites
    • Authors: M Moeez Mughal, M Wasim Akhtar, M Moazam Baloch, Muddassir Ali Memon, Junaid Ali Syed, Jong Seok Kim
      Abstract: Journal of Composite Materials, Ahead of Print.
      An effective method was adopted to improve the thermo-mechanical properties of the epoxy composite by functionalization of the sisal fiber. Initially, a neat sisal fiber was acetylated with molar solution of acidic mixture (0.5:1 of HNO3:H2SO4) that removed the content of lignin and hemicellulose and increased the crystallinity of the sisal fiber. The acetylated sisal (a-sisal) fiber was further treated with 3-aminpropyltriethoxy silane to graft the silanol moieties on sisal fiber. The functionalization of the sisal fiber with 3-aminpropyltriethoxy silane exhibits the strong interaction with epoxy, resulting in homogenous dispersion of the sisal fiber in epoxy. The composite possesses great enhancement in thermal and mechanical properties. The tensile strength in functionalized sisal epoxy composite (CP-f-Sisal) was significantly enhanced up to 23% in comparison to non-functionalized sisal epoxy composite (CP-n-Sisal) by adding 15 wt.% of the sisal fiber. In addition, the functionalized sisal epoxy composite (CP-f-sisal) shows better thermal stability as compared to non-functionalized sisal epoxy composite (CP-n-sisal). Similar results are attributed by investigating the kinetics of thermal stability parameters that include activation energy and integral procedure decomposition temperature.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-29T06:55:04Z
      DOI: 10.1177/0021998319890660
       
  • Continuous ultrasonic welding of thermoplastic composites: Enhancing the
           weld uniformity by changing the energy director

         This is an Open Access Article Open Access Article

    • Authors: Bram Jongbloed, Julie Teuwen, Genevieve Palardy, Irene Fernandez Villegas, Rinze Benedictus
      Abstract: Journal of Composite Materials, Ahead of Print.
      Continuous ultrasonic welding is a high-speed joining method for thermoplastic composites. Currently, a thin film energy director is used to focus the heat generation at the interface. However, areas of intact energy director remain in the welded seam, which significantly lowers the weld strength, and result in a non-uniformly welded seam. To improve the weld uniformity of continuous ultrasonically welded joints, we changed to a more compliant energy director. A woven polymer mesh energy director was found to give a significant improvement in weld quality. The mesh was flattened in between the composite adherends during the welding process. This flattening promoted a good contact between the energy director and the adherends, fully wetting the adherend surfaces, resulting in a more uniformly welded seam without areas of intact energy director.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-29T06:55:03Z
      DOI: 10.1177/0021998319890405
       
  • Effects of ceramic particle size on cell attachment and viability in
           polyurethane-based bone adhesive composites
    • Authors: Meryem Erken, Atakan Tevlek, Pezhman Hosseinian, Bengisu Topuz, Halil Murat Aydin
      Abstract: Journal of Composite Materials, Ahead of Print.
      Millions of people require bone injury treatment and there have been many methods suggested for the stabilization of bone fractures. The need for the development of new methods is obvious since current stabilization methods are inadequate. Here, we described the development of polyurethane-based bone adhesives composites containing β-tricalcium phosphate ceramics in different sizes and ratios. To characterize the proposed materials, Fourier transform infrared spectroscopy, hydrogen-nuclear magnetic resonance, differential scanning calorimetry analyses together with scanning electron microscopy observations, and micro-computerized tomography imaging were examined. Furthermore, in vitro performance of the produced materials was tested by using MG63 human osteosarcoma cell line, and an ex vivo modeling study was conducted to test the mechanical performance of resulting materials using bovine rib bone. All materials were exhibited high porosity (above 90%) and homogeneous distribution of ceramic particles. Polyurethane scaffolds containing 40% (w/w) 1–2 mm β-tricalcium phosphate were shown the highest compressive strength as 1.34 ± 0.10 MPa. In addition, 85.75% cell viability was recorded according to the cytotoxicity analysis and also the cell proliferation was found highest in the same group. Taken into account the obtained results, the prepared polyurethane-based bone adhesive materials containing ceramics has a great potential to transform into a final product and meet a clinically significant medical need.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-28T05:10:31Z
      DOI: 10.1177/0021998319884729
       
  • Prediction of resin pocket geometry around rigid fiber inclusion in
           composite laminate by hot-pressing of prepregs
    • Authors: Yihao Ma, Cheng Xiaoquan, Jikui Zhang, Dafang Zhao, Wenjun Huang
      Abstract: Journal of Composite Materials, Ahead of Print.
      In this paper, two analytic methods are presented to predict the geometry of resin pockets formed around rigid fiber inclusions at the interlayer of unidirectional prepregs. The bending strain energy is calculated on fiber scale in one method, while it is calculated on layer scale in the other method. For the fiber scale method, several fibers in thickness direction are tied together to account for the bending stiffness increase caused by the interaction between fibers. And for the layer scale method, a single ply is divided into several sublayers to account for the bending stiffness decrease caused by the sliding between adjacent fibers. Both analytic methods can provide the closed-form solution for the resin pocket width, and the analytic results agree well with experimental results. The physical consistency of two methods is proved. It is found that the resin pocket size depends mainly on ply angles of the plies close to the inclusion, and the stacking sequence has some effect.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-27T05:54:11Z
      DOI: 10.1177/0021998319889399
       
  • Effect of ceramic preform freeze-casting temperature and melt infiltration
           technique on the mechanical properties of a lamellar metal/ceramic
           composite
    • Authors: Siddhartha Roy, Jan Frohnheiser, Alexander Wanner
      Abstract: Journal of Composite Materials, Ahead of Print.
      Elastic properties, compressive stress–strain behaviour and progressive damage evolution of poly-domain metal/ceramic composite samples fabricated by infiltration of Al12Si melt in freeze-cast alumina preforms are studied. Two different preform freezing temperatures were employed to vary the lamellae size while infiltration was carried out using two different techniques – squeeze-casting and die-casting. Due to the faster cooling kinetics at the lower freezing temperature, the lamellae size in the composites based on these preforms are finer and this results into higher compressive strength and stiffness of this composite along the freezing direction. Among the two techniques employed for melt infiltration, the very fast rate of pressure application in die-casting distorts the lamellar structure of the ceramic along the freezing direction. As a result, in die-cast composite samples, the strength and stiffness along the freezing direction are reduced significantly in comparison to the samples infiltrated by squeeze-casting. In-situ scanning electron microscopy under external compression was used to study the progressive damage mechanism in one poly-domain composite sample infiltrated by squeeze-casting. Transverse cracking of the high-angle ceramic lamellae is identified as the predominant damage mechanism.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-27T05:54:11Z
      DOI: 10.1177/0021998319890661
       
  • Plastic deformation and fracture behaviors in particle-reinforced aluminum
           composites: A numerical approach using an enhanced finite element model
    • Authors: Xiang Gao, Xuexi Zhang, Aibin Li, Lin Geng
      Abstract: Journal of Composite Materials, Ahead of Print.
      A microstructure-based comprehensive finite element model, which incorporated the deformation/fracture of the matrix alloy, fracture of the particle and decohesion of interface, was built to predict the effects of particle size and shape on the plastic deformation and fracture behaviors in particle-reinforced metal matrix composites. The effect of particle size on the yield strength and work hardening rate of the matrix alloy was demonstrated. When the particle diameter is 10 µm. A cohesive zone model was also included in order to predict interfacial failure behavior. It was noted that SiC/Al interface exhibits a high interfacial bonding strength and the interfacial decohesion was caused by crack propagation from the particle to the interface. The simulation results are in good agreement with the experiment tensile test results in the SiCp/6061Al composite.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-26T07:01:57Z
      DOI: 10.1177/0021998319889110
       
  • Sustainable composites: Processing of coir fibres and application in
           hybrid-fibre composites
    • Authors: Lucas Ciccarelli, Frederik Cloppenburg, Sangeetha Ramaswamy, Stepan V Lomov, Aart Van Vuure, Nhan Vo Hong, Truong Chi Thanh, Nguyen Minh Tri, Gries Thomas
      Abstract: Journal of Composite Materials, Ahead of Print.
      Coir fibres, a byproduct of the coconut industry, have high performance qualities but are difficult to process by conventional textile methods. The purpose of the research is to combine the processibility of hemp and flax with the high-performance properties of coir to create a composite product worthy of industrial applications. The evaluation of coir fibre-reinforced composites focuses on the processibility of the coir fibre into a nonwoven, how well it interfaces with polylactic acid and an analysis of how the mechanical properties of the final product change when mixing coir with hemp and flax. The results show that the hybrid samples outperformed most of the researched values for coir composites, despite the reduced properties of control samples as in comparable research. Adding just 10% of either flax or hemp dramatically increased the mechanical properties compared to the pure coir–polylactic acid composite.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-26T07:01:56Z
      DOI: 10.1177/0021998319886108
       
  • Mechanical and thermal properties of polyoxymethylene-matrix composites
           filled with multi-walled carbon nanotubes-coated milled glass fiber
    • Authors: Xu Xiangmin, Hongxiang Zhang, Tong Beibei, Li Binjie, Yudong Zhang
      Abstract: Journal of Composite Materials, Ahead of Print.
      The advanced multifunctional filler has become one of the main challenges in developing high-performance polymer composites. In this study, the acid-treated multiwall carbon nanotubes (MWCNTs) were adhered to the surface of milled glass fiber under the combined effect of 3-aminopropyltriethyloxy silane and tetraethyl orthosilicate to fabricate a hierarchical fiber (MWCNTs-MGF). The morphologies of the hierarchical fibers were characterized using field-emission scanning electron microscope and transmission electron microscope, which showed evidence of a coating layer of MWCNTs on each fiber surface. The MWCNTs-MGF was employed as a multifunctional filler to prepare polyoxymethylene-based composites using a twin-screw extruder by melt blending. The obtained composites exhibited improved mechanical and thermal properties. The composite tensile strength and notched impact strength and Young's modulus increased by 10%, 32%, and 32%, respectively, as the MWCNTs-MGF content varies from 0 to 10 wt.%. Meanwhile, the reinforcing and toughing mechanisms of MWCNTs-MGF were also elaborated by analyzing the interfacial adhesion and fracture morphologies of the composites. Moreover, the study on thermal stability and crystallization behavior indicated that the polyoxymethylene/MWCNTs-MGF composites had higher thermal stability, crystallization temperature, and crystallinity as compared to the polymer matrix. The improvement of thermal stability originates from the unique surface structure of MWCNTs-MGF, while the increase in crystallization temperature and crystallinity is due to the strong heterogeneous nucleation ability of the hierarchical fibers.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-26T07:01:56Z
      DOI: 10.1177/0021998319889117
       
  • Experimental investigation of a method to avoid channel marks during
           vacuum infusion
    • Authors: Arne Hindersmann
      Abstract: Journal of Composite Materials, Ahead of Print.
      Today the impregnation of dry fibre materials is a production method preferred for large composite parts like wind turbine rotor blades or aircraft wing covers. One of the recurring problems of the production process is that the used resin distribution channels leave marks on the surface of the part. The result of the marks in the channel area is a localized deformation of the fibre material, and hence the laminate becomes more prone to shear buckling in this area. The purpose of this paper is to present a report on an unconventional infusion method to avoid channel marks on composite part's surfaces. The channels can be activated by a pressure difference. If the channels are deactivated during a specific process window no channel marks will be left on the part's surface. In order to verify the inexistence of channel marks, three analytical processes are used.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-26T07:01:56Z
      DOI: 10.1177/0021998319889120
       
  • Progressive damage behaviors of the stepped-lap composite joints under
           bending load
    • Authors: Bin Liu, Nongyue Gao, Bosen Tang, Yidi Gao, Peng Jin, Zhixian Lu, Zaiguo Fu
      Abstract: Journal of Composite Materials, Ahead of Print.
      Due to the high connecting strength and excellent load-transferring efficiency, the adhesively stepped-lap composite bonding has been widely used as joints and repairs in advanced aircraft structures. In the service life of composite structures, they frequently subject to bending loads which are rarely reported by the available reference. Hence, in this paper, three-point and four-point bending experiments are performed on composite stepped-lap structures. Typical damage mode of adhesive on the stepped surface has been found in experiments. And the failure of composite fiber, matrix, interlamination and adhesive materials appeared as competitive behavior. Furthermore, numerical models of stepped-lap composite joints, which used cohesive zone model and 3D Hashin criteria to simulate the inter- and intralaminar damages, were utilized to predict the bending strength and progressive damage. The FEM model, based on progressive damage method, captured the detailed failure as the loading displacement was increasing. The simulation results of load displacement and damage have good agreement with the experiments.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-22T07:07:19Z
      DOI: 10.1177/0021998319889119
       
  • Analysis of the critical stresses in high-voltage composite winding
           insulations under thermal loads
    • Authors: Harish Kalyan Ram Pothukuchi, Peter Fuchs, Clara Schuecker
      Abstract: Journal of Composite Materials, Ahead of Print.
      Stator bars are the critical components in generators with respect to their lifespan. The winding insulation may be susceptible to damage under excessive alternating temperature loads incurred by a high number of start–stop cycles and heavy overloads. The differences in thermal expansion between the different components in the multi-layered winding insulation lead to thermal stresses. This work deals with the thermo-mechanical characterisation of the individual constituents of the winding insulation and the finite element model of a stator bar, based on the material data obtained from the tests that enable the identification of the thermal stresses leading to delamination over thermal cycles. The out-of-plane and the interfacial shear stress are found to be in the critical range with respect to the relatively low cohesive strength of the included individual mica layers.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-22T07:07:18Z
      DOI: 10.1177/0021998319887779
       
  • Prediction of elastic anisotropic thermo-dependent properties of
           discontinuous fiber-reinforced composites
    • Authors: D Lopez, S Thuillier, Y Grohens
      Abstract: Journal of Composite Materials, Ahead of Print.
      This study focuses on the micromechanical prediction of temperature-dependent elastic properties of a composite made of a polypropylene matrix reinforced with discontinuous glass fibers. Firstly, an experimental investigation of the mechanical behavior is presented. Specimen are cut from injection-molded rectangular plates using a pattern based on fiber orientation. The microstructure is investigated by X-ray tomography at the specimen center and an average orientation tensor is calculated. Tensile tests are performed over a temperature range from ambient temperature to 85℃ and dispersion of mechanical properties is rather low; moreover, they are representative of the ones measured out of an industrial injected part. Then, the evolution of elastic properties with orientation and temperature is analyzed and compared with numerical predictions calculated with Mori–Tanaka homogenization scheme.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-21T06:27:13Z
      DOI: 10.1177/0021998319889397
       
  • Influence of pyrolytic thermal history on olive pruning biochar and
           related epoxy composites mechanical properties
    • Authors: Mattia Bartoli, Muhammad Abid Nasir, Pravin Jagdale, Elisa Passaglia, Roberto Spiniello, Carlo Rosso, Mauro Giorcelli, Massimo Rovere, Alberto Tagliaferro
      Abstract: Journal of Composite Materials, Ahead of Print.
      Olive pruning is waste from olive cultivation and is generally disposed of through incineration. Olive pruning can, however, be salvaged by pyrolysis, which also produces an interesting carbon-based material known as biochar. Biochar has been proved as a suitable filler which improves the mechanical properties of epoxy composites. Despite this, literature has few studied focused on the relationship between biochar thermal history and the properties it induces in related biochar containing composites. In this work, we report a morphological analysis of biochar produced at different pyrolytic high treatment temperatures (400℃, 600℃, 800℃, and 1000℃) using different heating rates (5℃/min, 15℃/min, and 50℃/min). We investigate the effect of different biochar morphology on the biochar epoxy-related composites, proving the tuneability of the mechanical properties of composites according to the thermal history of the biochar employed.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-20T08:00:39Z
      DOI: 10.1177/0021998319888734
       
  • Thermo-mechanical properties of epoxy nanocomposites incorporating amino
           acid and acid functionalized multi-walled carbon nanotubes
    • Authors: Alireza Bagherzade, Masoud Jamshidi
      Abstract: Journal of Composite Materials, Ahead of Print.
      In this study, multi-walled carbon nanotubes (MWCNTs) were functionalized by both sulfuric/nitric acids and amino acids to form COOH and NH2/COOH/OH groups on their surface, respectively. The functionalized MWCNTs were characterized by Fourier Transform Infrared Spectroscopy, titration test, thermal gravimetric analysis, and solvent stability test. The results revealed that in each method, the functional groups were successfully attached to the surface of nanotubes. Acid treatment grafted more oxygen-containing groups compared to commercial carboxylated MWCNTs. The amino acid functionalized MWCNTs indicated improved stability in different solvents compared to raw and acid treated MWCNTs. These functionalized MWCNTs were incorporated into epoxy resin and the properties of the nanocomposites were evaluated by scanning electron microscopy, tensile test, dynamic mechanical thermal analysis, differential scanning calorimetry, and thermogravimetric analysis. The morphology of the nanocomposites revealed that acid and amino acid treated samples had better interaction with the epoxy resin. Compared to epoxy sample contained raw MWCNT (control) and commercial carboxylated MWCNTs, the addition of functionalized MWCNTs to the epoxy resin improved the tensile strength by 39% and 25% (for acid treated) and 46% and 33% (for amino acid treated), respectively. The best tensile properties for acid and amino acid treated samples were reached by MWCNTs acid treated at 110℃ for 15 min and MWCNTs treated in a 50 g/L aqueous solution of amino acid, respectively. Storage modulus of the epoxy samples which contained acid and amino acid treated MWCNTs were 1560 and 1900 MPa, respectively. The glass rubber transition temperature (Tg) of the epoxy samples containing acid and amino acid treated nanotubes were increased by 1.1℃ and 5.9℃, respectively, compared to the control sample. Therefore, based on these mechanical properties, the epoxy samples containing nanotubes functionalized by amino acid exhibited the highest performance in the epoxy nanocomposite. Incorporating acid and amino acid treated MWCNTs accelerated the curing process of epoxy where the curing temperature decreased by 9.1℃ and 13.3℃, respectively. Because of the reaction between amine groups grafted on MWCNTs in the amino acid treatment and epoxide groups of the epoxy resin, this acceleration was more significant in the case of amino acid sample. Note that addition of functionalized MWCNTs to epoxy resin did not lead to increased thermal stability.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-15T05:54:35Z
      DOI: 10.1177/0021998319886631
       
  • Development and characterisation of multi-layered jute fabric-reinforced
           HDPE composites
    • Authors: Abu Sadat Muhammad Sayem, Julfikar Haider, MM Alamgir Sayeed
      Abstract: Journal of Composite Materials, Ahead of Print.
      The bast fibres, a subgroup of natural fibre family, have emerged as a strong competitor of widely used man-made glass fibre for use as fillers or reinforcing materials in certain types of composite materials, which do not require very high mechanical resistance. This paper investigates the manufacturing of multi-layered jute fabric-reinforced thermoplastic composite and its mechanical performance. Hessian jute fabrics in two, four and six layers without any pre-treatment were sandwiched in 0° orientation into seven layers of high-density polyethylene sheets and pressed at high temperature and pressure to form composite laminates having three different structural designs. The laminates with two, four and six layers contain approximately 6.70 wt%, 12.90 wt% and 18.50 wt% of jute fibres, respectively. Mechanical performance of the composite laminates having four and six layers of jute fabric was found to have improved significantly when compared to the pure high-density polyethylene laminates. Within a given sample thickness of 6.5 mm, the laminate with six layers of jute fabric exhibited the best mechanical performance. Optical microscopic analysis revealed that the yarn orientation of the fabrics within the composites remained stable, and there was no visible void in the laminate structure. Fracture morphology of the composite investigated by a scanning electron microscope showed good adhesion of the jute fabrics with the high-density polyethylene matrix.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-12T06:20:11Z
      DOI: 10.1177/0021998319885440
       
  • Creep in interlaminar shear of an Hi-Nicalon™/SiC–B4C composite at
           1300℃ in air and in steam
    • Authors: MB Ruggles-Wrenn, TA Wallis
      Abstract: Journal of Composite Materials, Ahead of Print.
      Creep behavior in interlaminar shear of an advanced SiC/SiC composite with a self-healing matrix was investigated at 1300℃ in laboratory air and in steam. The composite was processed via chemical vapor infiltration (CVI). The composite has a self-healing oxidation-inhibited matrix comprising alternating layers of silicon carbide and boron carbide and is reinforced with laminated woven Hi-Nicalon™ fibers. Fiber preforms were coated with pyrolytic carbon followed by a boron carbon overlay. The interlaminar shear properties were evaluated at 1300℃. The creep behavior was examined for interlaminar shear stresses ranging from 13 to 20 MPa in air and in steam. Primary and secondary creep regimes were observed in all tests conducted in air and in steam. Creep run-out (defined as 100 h at creep stress) was achieved at 13 MPa in air and in steam. Presence of steam had little influence on creep strain rates and creep lifetimes. However, larger creep strains were accumulated in steam than in air. The retained properties of all specimens that achieved creep run-out were characterized. Composite microstructure and damage and failure mechanisms were investigated.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-10T08:57:35Z
      DOI: 10.1177/0021998319886621
       
  • Recent developments in the processing of waste carbon fibre for
           thermoplastic composites – A review
    • Authors: Muhammad Furqan Khurshid, Martin Hengstermann, Mir Mohammad Badrul Hasan, Anwar Abdkader, Chokri Cherif
      Abstract: Journal of Composite Materials, Ahead of Print.
      The aim of this paper is to highlight recent developments in the processing of waste carbon fibre for thermoplastic composites. Initially, injection moulding and nonwoven technologies have been used to integrate waste carbon fibres into fibre-reinforced thermoplastic composites. Recently, tape and hybrid yarn spinning technologies have been developed to produce tape and hybrid yarn structures from waste carbon fibre, which are then used to manufacture recycled carbon fibre-reinforced thermoplastics with much higher efficiency. The hybrid yarn spinning technologies enable the development of various fibrous structures with higher fibre orientation, compactness and fibre volume fraction. Therefore, thermoplastic composites manufactured from hybrid yarns possess a good potential for use in load-bearing structural applications. In this paper, a comprehensive review on novel and existing technologies employed for the processing of waste carbon fibre in addition to different quality aspects of waste carbon fibre is presented.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-08T06:04:26Z
      DOI: 10.1177/0021998319886043
       
  • Evaluation of the effects of nanomaterials on durability of engineered
           cementitious composites exposed to the aggressive environment
    • Authors: Alireza Mansoori, Kiachehr Behfarnia
      Abstract: Journal of Composite Materials, Ahead of Print.
      The present study was aimed to evaluate the effect of micro silica, nano silica and carbon nanotube in the engineered cementitious composites made with polyvinyl alcohol fibers. Accordingly, the compressive strength and the modulus of the samples rupture were studied to evaluate the impact of micro silica, nano silica and carbon nanotube in engineered cementitious composite. In addition, different curing conditions were considered to investigate the durability of the mixes. In this regard, the mechanical properties of the samples cured in sulphuric acid and freeze and thaw cycling were compared to those cured in water. The results indicated that the mechanical properties were reduced upon exposure to acid and freeze and thaw cycling. It was also found that the application of micro silica and nano silica made the mixtures compacted and reduced the permeability. The module of rupture was increased significantly by the addition of carbon nanotube. Moreover, the evaluation of the samples cured in the aggressive environment showed that the role of carbon nanotube was significant in increasing the durability of the mixes. Further, the scanning electron microscopy images showed that the crack width was reduced by the addition of carbon nanotube. It was also revealed from the scanning electron microscopy images that the polyvinyl alcohol fibers were completely interacted and connected to the paste.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-08T06:04:25Z
      DOI: 10.1177/0021998319887208
       
  • Investigation of thermal and mechanical properties of styrene–butadiene
           rubber nanocomposites filled with SiO2–polystyrene core–shell
           nanoparticles
    • Authors: Mujahid Khan, Satyendra Mishra, Debdatta Ratna, Shriram Sonawane, Navinchandra Gopal Shimpi
      Abstract: Journal of Composite Materials, Ahead of Print.
      The present study investigates the effect of SiO2–polystyrene core–shell nanoparticles on properties of styrene–butadiene rubber nanocomposites. Meanwhile, SiO2–polystyrene core–shell nanoparticles were synthesized under controlled ultrasound assisted microemulsion technique. Further, as-synthesized SiO2–polystyrene nanoparticles were subjected to various characterization techniques, such as X-ray diffraction, field emission scanning electron microscope, transmission electron microscope, and Fourier transform infrared spectroscopy to know its size, shape, and presence of functional groups. The average diameter of SiO2–polystyrene nanoparticles was found to be ∼45 nm. SiO2–polystyrene nanoparticles were reinforced in styrene–butadiene rubber using two-roll mill and molded on compression molding machine, which then subjected to various testings (X-ray diffraction, field emission scanning electron microscope, thermogravimetric analysis, and universal testing machine). Moreover, the crosslinking density was investigated using solvent sorption technique. The properties of styrene–butadiene rubber nanocomposites were found to be improved with increasing amount of SiO2–polystyrene nanoparticles (2.0 wt%) and decreases subsequently (2.5 wt%). This enhancement in properties was due to uniform dispersion of core–shell nanoparticles with embedded chains of rubber. Also this enhancement in properties was due to smooth surface of core–shell nanoparticles (2.0 wt%) and decreases subsequently at higher amount of loading (2.5 wt%). However, the minimal crosslinkage leads to more solvent sorption, which leads to increase in average molecular weight. This decrement in the crosslinkage density with increase in average molecular weight was due to voids or free volume inside the matrix, which allows the solvent to get penetrated inside the matrix. This effect was not due to styrene–butadiene rubber matrix but due to shell of polystyrene over SiO2.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-08T06:04:24Z
      DOI: 10.1177/0021998319886618
       
  • Temperature dependence of statistical fatigue strengths for unidirectional
           carbon fiber reinforced plastics under tension loading
    • Authors: Masayuki Nakada, Yasushi Miyano
      Abstract: Journal of Composite Materials, Ahead of Print.
      The formulation for time- and temperature-dependent statistical static and fatigue strengths for carbon fiber reinforced plastics laminates is newly proposed based on the physically serious role of resin viscoelasticity as the matrix of carbon fiber reinforced plastics. In this study, this formulation is applied to the tensile strength along the longitudinal direction of unidirectional carbon fiber reinforced plastics constituting the most important data for the reliable design of carbon fiber reinforced plastics structures which are exposed to elevated temperatures for a significant period of their operative life. The statistical distribution of the static and fatigue strengths under tension loading along the longitudinal direction of unidirectional carbon fiber reinforced plastics were measured at various temperatures by using resin-impregnated carbon fiber reinforced plastics strands as specimens. The master curves for the fatigue strength as well as the static strength of carbon fiber reinforced plastics strand were constructed based on the time–temperature superposition principle for the matrix resin viscoelasticity. The long-term fatigue strength of carbon fiber reinforced plastics strand can be predicted by using the master curve of fatigue strength.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-08T06:04:24Z
      DOI: 10.1177/0021998319886629
       
  • Abrasive waterjet machining of Ti/CFRP/Ti laminate and multi-objective
           
    • Authors: Dhiraj Kumar, Suhasini Gururaja
      Abstract: Journal of Composite Materials, Ahead of Print.
      In present work, abrasive waterjet machining has been used to machine adhesively bonded titanium-carbon fiber-reinforced plastics-titanium hybrid laminate with varying traverse speed, jet pressure, and stand-off distance. The effect of varying abrasive waterjet machining parameters on cut quality has been quantified by material removal rate, metal composite interface damage factor, taper ratio (Tr), and surface roughness (Ra). Response surface methodology along with central composite design has been used to analyze the influence of process parameters on output responses. Additionally, analysis of variance was performed to identify the significant parameters on the output responses. For better abrasive waterjet cut quality, the optimal values of process parameters obtained were 200 MPa jet pressure, 237.693 mm/min traverse speed, and 1 mm stand-off distance. The corresponding material removal rate, metal composite interface damage factor, taper ratio, and surface roughness are 5.388 mm3/s, 1.41, 1.16, and 3.827 µm, respectively. Furthermore, validation tests have been performed with obtained optimal parameters that deliver satisfactory outcomes with an error of 5.35%, 3.07%, 2.29%, and 0.39% for material removal rate, metal composite interface damage factor, taper ratio, and surface roughness, respectively.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-06T06:10:17Z
      DOI: 10.1177/0021998319884611
       
  • Fatigue responses of cracked Ti/APC-2 nanocomposite laminates at elevated
           temperature
    • Authors: MHR Jen, GT Kuo, YH Wu, YJ Chen
      Abstract: Journal of Composite Materials, Ahead of Print.
      The mechanical properties and fatigue responses of Ti/APC-2 neat and nanocomposites with inclined single-edged cracks due to tensile and cyclic tests at elevated temperature were investigated. Two types of composite laminates [Ti/(0/90)s/Ti] were fabricated with and without (W/WO) nanoparticles SiO2 of optimal 1 wt.%. The geometry and dimensions of specimens were L × W × t = 240 × 25 × 1.55 mm3. The cracks were of constant length 3 mm and width 0.3 mm. The inclined angles were 0°, 45°, and 60°. Both the tensile and cyclic tests were conducted at elevated temperatures 25℃ (RT), 100℃, 125℃, and 150℃. From the tensile tests we obtained the load vs. displacement curves for both types of laminates with varied inclinations at elevated temperatures. Next, we received the applied load vs. cycles curves for the same laminates with inclined cracks at the corresponding temperature due to cyclic tests. According to the experimental data of both tensile and cyclic tests the mechanical properties, such as strength, stiffness, and life, decreased as the temperature rises. The greater the inclined angles were, the greater the strength and stiffness were. Similarly, the fatigue life was in the same trend. However, the effect of inclined angle on mechanical properties was more strong than those of temperature. The mechanical properties of nanocomposite laminates were higher than those of neat composite laminates, but not significant. The main reason was that the enhancement of spreading nano-powder silica on the laminate interfaces did not effectively eliminate the stress intensity at the crack tip locally.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-06T06:10:16Z
      DOI: 10.1177/0021998319883928
       
  • Temperature variation during continuous laser-assisted adjacent hoop
           winding of type-IV pressure vessels: An experimental analysis

         This is an Open Access Article Open Access Article

    • Authors: Amin Zaami, Martin Schäkel, Ismet Baran, Ton C Bor, Henning Janssen, Remko Akkerman
      Abstract: Journal of Composite Materials, Ahead of Print.
      Laser-assisted tape winding is an automated process to produce tubular or tube-like continuous fiber-reinforced polymer composites by winding a tape around a mandrel or liner. Placing additional layers on a previously heated substrate and variation in material and process parameters causes a variation in the bonding temperature of fiber-reinforced thermoplastic tapes which need to be understood and described well in order to have a reliable manufacturing process. In order to quantify the variation in this critical bonding temperature, a comprehensive temperature analysis of an adjacent hoop winding process of type-IV pressure vessels is performed. A total of five tanks are manufactured in which three glass/HDPE tapes are placed on an HDPE liner. The tape and substrate temperatures, roller force and tape feeding velocity are measured. The coefficient of variation for each round is characterized for the first time. According to the statistical analysis, the coefficient of variation in substrate temperature is found to be approximately 4.8–8.8% which is larger than the coefficient of variation of the tape temperature which is 2.1–7.8%. The coefficient of variations of the substrate temperatures in the third round decrease as compared with the coefficient of variations in the second round mainly due to the change in gap/overlap behavior of the deposited tapes. Fourier and thermographic analysis evince that the geometrical disturbances such as unroundness and eccentricity have a direct effect on the temperature variation. In addition to the temperature feedback control, a real-time object detection technique with deep learning algorithms can be used to mitigate the unwanted temperature variation and to have a more reliable thermal history.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-06T06:10:15Z
      DOI: 10.1177/0021998319884101
       
  • Modeling transverse micro flow in dry fiber placement preforms
    • Authors: Oliver Rimmel, David May
      Abstract: Journal of Composite Materials, Ahead of Print.
      Dry fiber placement has a large potential for manufacturing preforms for primary-load components at minimum scrap rate and fiber crimp. Yet, challenging impregnation behavior due to low permeability of these preforms during liquid composite molding imposes a need for further research to optimize preform structure for higher permeability. For full understanding of flow behavior within these preforms, flow has to be considered on micro scale (in between single fibers), on meso scale (in between single rovings or strands), and on macro scale (on scale of parts to be manufactured). While macro and meso scale can be measured in experiments or derived from filling times in real processes, micro scale is usually not easily assessable and accessible for standard textile materials. Analytical approaches are limited to regular fiber arrangements (square and hexagonal) that are strongly differing from real arrangements. The present work deals with application of a numerical solver to random fiber arrangements to determine micro permeability transverse to the fiber orientation, for later use in meso- and macro-scaled models. As a premise for reliable calculation, guidelines for boundary conditions as well as size and resolution of the representative volume element are elaborated in the course of this work. Calculated out-of-plane micro permeabilities are subsequently compared to real experiments and show good accordance. The influence of binder particles on micro permeability has not yet been conclusively clarified.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-05T07:34:40Z
      DOI: 10.1177/0021998319884612
       
  • The effect of high TiC particle content on the tensile cracking and
           corrosion behavior of Al–5Cu matrix composites
    • Authors: Burak Dikici, Fevzi Bedir, Mehmet Gavgali
      Abstract: Journal of Composite Materials, Ahead of Print.
      The high-TiC particle volume fraction on the mechanical properties and corrosion behavior of the A–5Cu matrix composites were investigated with porosity, hardness, tensile tests, and polarization measurements. The composites reinforced with 18, 27, and 50 vol% TiC particulates were produced successfully by using hot-pressing technique under Ar atmosphere and characterized by scanning electron microscope, electron dispersive spectroscope, and X-ray diffraction. The corrosion susceptibilities of the composites were compared with potentiodynamic scanning technique. It was found that the hardness of the composites increases while the fracture strength decreases with increasing TiC reinforcement content in the matrix. The corrosion susceptibilities of 18 and 27 vol% TiC-reinforced composites are almost the same; the corrosion rate of 50 vol% TiC-reinforced composite was approximately 10 times higher than the composites reinforced with 18 and 27 vol% TiC particles in the 3.5% NaCl. In addition, some preferential corrosion attacks were detected at TiC/matrix interfaces and in TiC clusters during the corrosion process of the composites. Therefore, the porosity content in the composites was almost the same level.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-04T05:02:26Z
      DOI: 10.1177/0021998319884098
       
  • The determination of thermal residual stresses in unidirectional and
           cross-ply titanium matrix composites using an etch removal method
    • Authors: Gerald CR Watt, Andrew D Crocombe, Stephen L Ogin, Stephen Kyle-Henney
      Abstract: Journal of Composite Materials, Ahead of Print.
      Recent work has shown that a simple rule-of-mixtures approach may be used to predict the stress–strain behaviour of a cross-ply metal matrix composite laminate. However, the low-strain behaviour was not predicted accurately, probably because thermal residual stresses are obviously not included in such an approach. To increase the understanding of the limitations of the rule-of-mixtures approach for predicting the stress–strain response, the residual strain-state of the fibre reinforcement has been determined using an etching technique (henceforth referred to as the ‘total etch removal method’), and results have been compared both with finite element modelling and with thermal residual strain measurements derived from stress–strain curves. The results show that the residual strain distribution in a cross-ply composite may be more complex than previously thought, with the fibres in internal 0° plies having considerably higher thermal residual strains than fibres in external plies. The results confirm that the rule-of-mixtures approximation can be used, with some reservations with regard to the low-strain behaviour.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-01T12:02:20Z
      DOI: 10.1177/0021998319883167
       
  • Influence of humidity on the dielectric behaviour of BaTiO3–epoxy
           composites
    • Authors: C Gonzalez Aguilar, M Reboredo, M Castro
      Abstract: Journal of Composite Materials, Ahead of Print.
      Epoxy resin and their particulate composites are widely used in different industries, as aeronautical, automotive, microelectronics and coatings. The water absorption can deteriorate the properties on these materials when they are used in service. Many factors influence in water absorption process, as the quantity of hydroxyls groups, the glass transition temperature of the resin or the presence of a dispersed second phase. Thus, the objective of this work is to determine the dielectric behavior of BaTiO3–epoxy composites in different humid environments (controlled moisture of 80, 50 and 30%) and at room temperature. Results of pure resin samples show that dielectric permittivity increases with the percentage of absorbed water and that this increase is greater for the samples exposed to more humid environments. Interestingly, the addition of ceramic particles not only increases the composite dielectric properties but also reduces the water absorption in all the cases.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-01T12:02:20Z
      DOI: 10.1177/0021998319885008
       
  • Direct numerical simulation of infusion and flow-front tracking in
           
    • Authors: Arthur Levy, James Kratz
      Abstract: Journal of Composite Materials, Ahead of Print.
      This paper explores the use of thin film piezoresistive pressure mapping sensors as a means to improve resin transfer moulding processes. The pressure mapping sensor was located between the preform and mould, giving information regarding the permeability map prior to infusion. The permeability map is used as an input to a direct numerical simulation of the infusion step of a highly variable reclaimed carbon fibre preform. The pressure sensor was also used to track the flow front position in-situ, due to a change in load sharing between the preform and liquid during the infusion experiment. Flow front tracking with the pressure mapping sensor was validated against conventional camera images taken through a transparent mould. The direct numerical simulation was able to account for local permeability variation in the preform, providing improved flow-front prediction than homogeneous permeability only, and could be part of a wider strategy to improve resin transfer moulding process robustness.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-01T12:02:19Z
      DOI: 10.1177/0021998319883931
       
  • Multiscale analysis of interlaminar stresses near a free-edge in a
           [±45/0/90]s laminate
    • Authors: M Keith Ballard, John D Whitcomb
      Abstract: Journal of Composite Materials, Ahead of Print.
      A multiscale model for a [±45/0/90]s tape laminate under uniaxial extension was used to investigate the effect of modeling the heterogeneous microstructure near a free-edge. A random fiber arrangement was used for the 0° and 90° plies and homogenized properties for the 45° and −45° plies. The predicted interlaminar normal stress was compared to the prediction using a classical homogeneous model. When fibers and matrix were modeled discretely, the local stress state was shown to be sensitive to the proximity of fibers, which caused a complex stress distribution along the 0–90 ply interface. Next, the effect of reducing the size of region modeled at the microscale was investigated, since this would significantly reduce the computational effort. Reducing the region modeled at the microscale in the direction normal to the 0–90 ply interface to a size that was 25% and 10% of the ply thickness only changed the peak stresses by 3% and 8%, respectively. Reducing the microscale region in the direction normal to the free-edge to be one and two ply thicknesses in size did not have a significant effect on the predicted interlaminar normal stress at points within 75% of a ply thickness of the free-edge.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-01T12:02:18Z
      DOI: 10.1177/0021998319883918
       
  • Ultrasonically assisted electrophoretic deposition of oxidized graphite
           nanoparticle onto carbon fiber, amending interfacial property of CFRP
    • Authors: Ankush Nandi, Subhankar Das, Sudipta Halder, Anirban Chakraborty, Muhammad A Imam
      Abstract: Journal of Composite Materials, Ahead of Print.
      The performance of fiber-reinforced composites significantly relies on the microstructure and properties of the fiber–matrix interface. Escalating the aspect ratio of the fiber surface by coating with nanoparticles is a proven technique for improving the fiber/matrix adhesion. Subsequently, improved adhesion between epoxy and fiber, which is ascribed due to improved interfacial friction, chemical bonding, and resin toughening would enhance the interfacial strength of such laminated composites. Here, graphite nanoparticles were oxidized, and these charged particles were coated onto the carbon fibers (CFs) surface using ultrasonically assisted direct current electrophoretic deposition. Functionalization of the graphite nanoparticle upon oxidation was confirmed through dispersion analysis, Fourier transformed infrared spectroscope, thermogravimetric analysis, and field emission scanning electron microscope. The CFs fabrics were grafted with different sets of samples prepared by varying voltage and deposition time. The deposition of oxidized graphite nanoparticle over the CFs was authenticated through field emission scanning electron microscope. A transverse fiber bundle test was carried out to assess interfacial strength between CF and epoxy matrix. The transverse fiber bundle test strength is found 113% higher for CF coated with oxidized graphite nanoparticles at 50 V for 5 min compared to that of as-received sized CF composites. Field emission scanning electron microscopy analysis of transverse fiber bundle test fractures samples identified multiple crack propagation zone owing to the presence of graphite nanoparticle on CF.
      Citation: Journal of Composite Materials
      PubDate: 2019-10-26T04:57:54Z
      DOI: 10.1177/0021998319884109
       
  • Experimental study of void evolution in partially impregnated prepregs
    • Authors: Leyla Farhang, Mohammad Mohseni, Navid Zobeiry, Göran Fernlund
      Abstract: Journal of Composite Materials, Ahead of Print.
      Controlling voids to minimize the final porosity level is an important concern when processing advanced composite structures. In this study, the porosity evolution during processing of partially impregnated prepregs is investigated using interrupted cure cycles and optical microscopy. Laminates made of MTM 45-1/5HS carbon/epoxy prepreg subjected to different cure cycles, bagging conditions, and humidity levels were studied. Fiber tow geometry and gas permeability were measured to determine the amount of compaction and the interconnectivity of unsaturated zones in the laminates. Three types of voids were identified: inter-laminar, fiber tow and resin voids, all with different origins and evolution patterns. It is shown that gas transport (both in-plane and through-thickness), fiber bed compaction, and resin infiltration govern void evolution during processing. The results provide insights for development of representative transport models and to optimize processing cycles.
      Citation: Journal of Composite Materials
      PubDate: 2019-10-25T06:07:46Z
      DOI: 10.1177/0021998319883934
       
  • High-velocity perforation behaviour of sandwich panels with Al/SiCp
           composite foam core
    • Authors: M Golestanipour, A Babakhani, S Mojtaba Zebarjad
      Abstract: Journal of Composite Materials, Ahead of Print.
      Aluminium foam core sandwich panels are good energy absorbers for impact protection applications, such as light-weight structural panels, packing materials and energy absorbing devices. In this study, the high-velocity perforation response of a range of sandwich panels with Al A356/SiCp composite foam core and 1100 aluminium face-sheets has been investigated using a conventional gas gun. Impact perforation tests were carried out using a 10-mm diameter conical nosed indenter at velocities up to that required to achieve complete perforation of the target (i.e. 230 m/s). The effects of face-sheet thickness, density and thickness of aluminium composite foam core on the total, specific and extra absorbed energy and also ballistic limit of the panels during impact penetration were experimentally investigated. During test, top face-sheets globally bended and tore into several pieces and so absorbed part of impact energy. Rupture and densification are two deformation modes and energy absorption mechanisms of foam core. Localized indentation and tearing, global bending and delamination were also observed on back face-sheets. Higher foam core density and thickness and also thicker face-sheets resulted in higher absorbed energy and ballistic limit.
      Citation: Journal of Composite Materials
      PubDate: 2019-10-25T05:48:09Z
      DOI: 10.1177/0021998319883331
       
  • Electrical, optical and mechanical properties of chitosan biocomposites
    • Authors: Ömer Bahadır Mergen, Ertan Arda, Gülşen Akın Evingür
      Abstract: Journal of Composite Materials, Ahead of Print.
      In this work, chitosan/graphene nanoplatelets (CS/GNP) and chitosan/multi-walled carbon nanotube (CS/MWCNT) biocomposite films were prepared using a simple, eco-friendly and low-cost method. The electrical, optical and mechanical properties of these composite films were investigated. The optical, mechanical and electrical properties of the biocomposites were significantly improved, which make them promising materials for food packaging, ultraviolet protection and biomedical applications. With the increase of carbon filler content (GNP or MWCNT) in CS biocomposites, the surface conductivity (σ), the scattered light intensity (Isc) and the tensile modulus (E) increased significantly. This behaviour in the electrical, optical and mechanical properties of the CS/carbon filler biocomposites was explained by percolation theory. The electrical percolation thresholds were determined as Rσ = 25.0 wt.% for CS/GNP and Rσ = 10.0 wt.% for CS/MWCNT biocomposites, while the optical percolation thresholds were found as Rop =12.0 wt.% for CS/GNP and Rop = 2.0 wt.% for CS/MWCNT biocomposites. Conversely, the mechanical percolation thresholds for both CS/GNP and CS/MWCNT biocomposites were found to be negligibly small (Rm = 0.0 wt.%). The electrical (βσ), optical (βop) and mechanical (βm) critical exponents were calculated for both CS/carbon filler biocomposites and found compatible with the applied percolation theory.
      Citation: Journal of Composite Materials
      PubDate: 2019-10-25T05:48:09Z
      DOI: 10.1177/0021998319883916
       
  • Structural study and thermal behavior of composites: Polyamide 66/glass
           
    • Authors: Azzedine Makhlouf, Abdelheq Layachi, Imane Kouadri, Ahmed Belaadi, Hamid Satha
      Abstract: Journal of Composite Materials, Ahead of Print.
      The present research aims at studying the kinetics of non-isothermal crystallization of the polyamide 66 matrix and its composites with the presence of a glass fiber load. To achieve that goal, the non-isothermal crystallization of polyamide 66 has been studied by means of DSC. The ratio of tested reinforcement varies from 7% to 50% of glass fiber in mass. The modeling, by the theories of Jeziorny and those of Mo, has allowed us to study the influence of adding this reinforcement, as well as the variation of the rate of cooling, on the kinetics of crystallization of the composites in question, which has been manifested by a remarkable change in the nucleation mechanism of the polyamide 66 matrix. Regarding the reinforcement effect, the incorporation of the glass fibers load into the polyamide 66 matrix has caused the appearance of exothermic peaks in a higher temperature range and that for all the working materials. Finally, the results showed that the Mo model is the most suitable for the study of polyamide 66/glass fiber crystallization kinetics.
      Citation: Journal of Composite Materials
      PubDate: 2019-10-24T05:58:34Z
      DOI: 10.1177/0021998319883913
       
  • Tensile properties of ultra-high-molecular-weight polyethylene single
           yarns at different strain rates
    • Authors: Hongxu Wang, Paul J Hazell, Krishna Shankar, Evgeny V Morozov, Zlatko Jovanoski, Andrew D Brown, Zongjun Li, Juan P Escobedo-Diaz
      Abstract: Journal of Composite Materials, Ahead of Print.
      This paper presents the details of experimental work on characterising the tensile properties of UHMWPE (Spectra® 1000) single yarns at different strain rates from 3.3 × 10−5 to 400/s. According to the measured stress–strain curves, there was a transition from ductile to brittle behaviour as the strain rate increased from 3.3 × 10−5 to 0.33/s; the tensile properties were highly sensitive to strain rate in this range. Specifically, the tensile strength and Young’s modulus increased distinctly with increasing strain rate while the failure strain and toughness decreased. However, these tensile properties were not dependent on strain rate over the range from 0.33 to 400/s. The results showed that the measured tensile strength, failure strain and Young’s modulus were independent of the tested gauge lengths (25 and 50 mm). Moreover, yarn type (warp and weft) had a noticeable effect on tensile strength, but the effect of yarn type on failure strain and Young’s modulus was negligible. The microscopic examination of fractured fibres’ ends revealed that fibrillation and axial splitting were the dominant fracture modes at low strain rates, while the fibres failed in a more brittle manner with little fibrillation at high strain rates.
      Citation: Journal of Composite Materials
      PubDate: 2019-10-23T06:36:19Z
      DOI: 10.1177/0021998319883416
       
  • The influence of fiber surface profile and roughness to fiber–matrix
           interfacial properties
    • Authors: Ichsan Setya Putra, Bentang Arief Budiman, Poetro Lebdo Sambegoro, Sigit Puji Santosa, Andi Isra Mahyuddin, Kikuo Kishimoto, Kazuaki Inaba
      Abstract: Journal of Composite Materials, Ahead of Print.
      This work investigates the influence of fiber surface profile and roughness to fiber–matrix interfacial properties. A series of the push-out test is performed using specimens with different fiber surface profile and roughness. Numerical simulation is then carried out by employing a finite element method to fit the experimental data. The model contains an indenter which pushes in a single fiber from the matrix, while the cohesive zone model is applied to represent the interface resulting in force–displacement curves. Our results suggest that continuous cavities formed in graphite-based fiber may not be beneficial to interfacial properties since it can accelerate a debonding process along with the interface. In contrast, scattered cavities on the fiber surface create strong mechanical locking, which increases the interfacial strength. These results broaden the understanding of the surface profile, which would shed light on a new perspective in designing composite structures.
      Citation: Journal of Composite Materials
      PubDate: 2019-10-22T05:44:38Z
      DOI: 10.1177/0021998319883418
       
  • Assessment of the load carrying performance of composite cross joints
    • Authors: Liyang Liu, Mengfei Cai, Xiaoliang Geng, Peiyan Wang, Zhufeng Yue
      Abstract: Journal of Composite Materials, Ahead of Print.
      Composite cross joints are common structures in an airframe. When this type of joint is used on an air inlet stiffened structure, it will undertake large bending moment, especially under overpressure of the engine. In this paper, two types of cross joints are tested experimentally and simulated to investigate the load bearing characteristics and make comparative remarks. Four-point bending tests are conducted and the load deflection curves are obtained; besides, the damage pattern of the joints is reported. Based on composite progressive damage model, the numerical simulations have a good agreement with experimental results, revealing the joint failure mechanism and fastener force feature of various joints. The comparative assessment of two types of joints is summarized.
      Citation: Journal of Composite Materials
      PubDate: 2019-10-21T05:05:40Z
      DOI: 10.1177/0021998319881486
       
  • Influence of machining damage generated during trimming of CFRP composite
           on the compressive strength
    • Authors: N Nguyen-Dinh, C Bouvet, R Zitoune
      Abstract: Journal of Composite Materials, Ahead of Print.
      Machining of composite materials is a challenging task due to the heterogeneity and anisotropy of composite structures. The induced defects reduce integrity of the machined surface as well as the loading capacity of the composite structure in service. Therefore, it is necessary to quantify the damage induced during trimming and correlate the quality of the machined surface to mechanical properties. The correlation of the surface roughness criteria, widely used in literature, to the mechanical behavior raise several contradictions. For this reason, new parameters for the characterization of the machined surface are proposed and correlated to the mechanical behavior under compressive loading. In this context, carbon fiber-reinforced plastic laminates are conventionally trimmed, and the machining damage is characterized using scanning electron microscope observations, X-ray tomography, and 3D optical topography. The results reveal that crater volume and maximum depth of damage quantify the machining damage more realistic compared to the classical surface roughness criteria.
      Citation: Journal of Composite Materials
      PubDate: 2019-10-18T06:53:19Z
      DOI: 10.1177/0021998319883335
       
  • Morphological, physical, and mechanical properties of silanized
           wood-polymer composite
    • Authors: Maryam Ghorbani, Najmeh Poorzahed, S Mojtaba Amininasab
      Abstract: Journal of Composite Materials, Ahead of Print.
      For investigation on the effect of silane compound on practical properties of poplar wood polymer composite, samples were impregnated using vacuum/pressure method with 3-trimethoxysilyl propyl methacrylate, and subsequently with styrene, methyl methacrylate, and mixtures of styrene/methyl methacrylate. Field emission scanning electron microscopy observations and Fourier transform infrared analysis indicated that styrene/methyl methacrylate copolymerized with 3-trimethoxysilyl propyl methacrylate and the resultant polymer tightly contacted to the wood cell walls without noticeable gaps. Impregnation with styrene resulted in a higher density of wood polymer composite compared to methyl methacrylate, which was more obvious in the presence of 3-trimethoxysilyl propyl methacrylate. Mechanical strength of the wood polymer composites improved and the highest strength was obtained for the 3-trimethoxysilyl propyl methacrylate/styrene/methyl methacrylate-modified samples. Maximum hardness was found in 3-trimethoxysilyl propyl methacrylate/styrene/methyl methacrylate-modified samples due to the cross-link formation between modified cell wall and polymer.
      Citation: Journal of Composite Materials
      PubDate: 2019-10-16T06:06:52Z
      DOI: 10.1177/0021998319881493
       
  • Evaluation of the environmental aging of the glass fiber-reinforced
           polymer composite when in contact with the effluent of a treatment plant
    • Authors: Yldeney Silva Domingos, Renata Carla Tavares dos Santos Felipe, Raimundo Nonato Barbosa Felipe, Glauber José Turolla Fernandes
      Abstract: Journal of Composite Materials, Ahead of Print.
      This paper presents an evaluation of the mechanical and physical behavior of the type E glass fiber-reinforced polymeric composite when exposed to environmental aging agents in an effluent treatment plant. The composite was made by the hand layup process, and the test bodies were made according to the American Society for Testing and Materials standards D3039-14 and D790-10 for the uniaxial tensile and three-point bending tests, respectively, where they were exposed for a period of eight months, conditioned above and immersed in the effluent of the treatment plant. The physicochemical characterization of the effluent was evaluated considering the following parameters: pH, conductivity, sulfate, alkalinity, acidity, sulfide, and temperature, aiming to characterize the effluent conditions in direct and indirect contact with the composite. After the exposure period, tests were carried out for morphological evaluation, structural integrity evaluation, mechanical performance evaluation, and fracture characterization of the polymer composite, thereby leading to a comparison of the mechanical characteristics in the original state to that of the aged state (after exposure in the effluent treatment plant). The polymeric composite studied was stable after the aging period, with little mass variation, less than 0.5%, and slight changes in color. The mechanical properties evaluated also did not change significantly during the study period. Variations in uniaxial tensile strength were less than 1.4% and for three-point bending less than 10%, thus showing that the type E glass fiber-reinforced polymer composite has potential for use in harsh environments such as in effluent treatment plants.
      Citation: Journal of Composite Materials
      PubDate: 2019-10-11T01:21:34Z
      DOI: 10.1177/0021998319878766
       
  • Use of a chain extender as a dispersing agent of the CaCO3 into PBAT
           matrix
    • Authors: Edilene de CD Nunes, Alana G de Souza, Derval dos S Rosa
      Abstract: Journal of Composite Materials, Ahead of Print.
      This paper investigates the effect of the incorporation of chain extender on the poly(butylene adipate-co-terephthalate) (PBAT) and their mixture with calcium carbonate (CaCO3) composites. Chain extender (ADR) was used to enhance the compatibility between PBAT and CaCO3, which have poor interfacial adhesion. Mechanical, thermal, and morphological properties of PBAT, PBAT/chain extender, and their composites were studied. The incorporation of the chain extender enhanced Young’s modulus and elongation at break of the neat PBAT, which is an indicator of the interaction between both materials. These results were confirmed by 1H NMR and 13C NMR (proton – hydrogen and carbon nuclear magnetic resonance, respectively). The chain extender acted by dispersing the CaCO3 particles; however, with an increase in the filler content, there is a decrease in the mechanical properties. Thermogravimetric analysis showed that chain extender has no influence on neat PBAT thermal behavior and their composites containing CaCO3. Differential scanning calorimetric analysis showed a decrease in crystallinity values of the PBAT and its composites, which is due to the physical impediment in the organization of polymer chains. Photomicrographs, obtained by scanning electron microscopy, showed that chain extender does not influence PBAT morphology. However, in the composites, chain extender enhanced the dispersion on CaCO3 particles.
      Citation: Journal of Composite Materials
      PubDate: 2019-10-09T05:31:31Z
      DOI: 10.1177/0021998319880282
       
  • Characterization of applied tensile stress to carbon epoxy composites by
           measuring the variation of transverse thermal conductivity using
           transmission thermography
    • Authors: M Bayat, MS Safizadeh
      Abstract: Journal of Composite Materials, Ahead of Print.
      Using the method of step heating thermography, this study seeks to detect and characterize the existence of stress in a beam sample of carbon epoxy composite with the stacking sequence of [08] aided by empirical and simulation approaches. The applied stress in the longitudinal direction of sample, while considering the Poisson’s ratio, changes the lateral dimensions of sample. Furthermore, it is shown that the thermal conductivity along the sample thickness varies as a result of stress existence. Accordingly, to obtain a relation between transverse thermal conductivity and longitudinal tensile stress, one should calculate and eliminate the effect of lateral deformation caused by stress. To this end, by combining the experimental and simulation results of composite sample under the action of different tensile loads, an equation describing the variation of thermal conductivity along the sample thickness with respect to applied stress is developed. Using the relation of transverse thermal conductivity variation in terms of applied stress, the finite element modeling is again carried out by rectifying the values of thermal conductivity. Simulation results are compared with experimental ones, indicating very good agreement between the two approaches.
      Citation: Journal of Composite Materials
      PubDate: 2019-10-09T05:31:30Z
      DOI: 10.1177/0021998319880596
       
  • Hot-stamping technology for carbon fiber reinforced thermoplastic plates
           based on electrical resistance heating
    • Authors: Mitsuhiro Okayasu, Masaya Sato
      Abstract: Journal of Composite Materials, Ahead of Print.
      In the present work, a hot-stamping system for carbon fiber reinforced thermoplastic (CFRTP) plates based on electrical resistance heating was developed, where CFRTP consisted of polyphenylene and polyacrylonitrile. With the hot-stamping process, a simple hat-shaped sample was made. The heating rate and maximum sample temperature varied depending on the electrical resistance of the CFRTP plate. Moreover, the contact conditions between the electrodes and the CFRTP plate also affected the sample temperature owing to their influence on the electrical resistance, which was determined by the amount of exposed carbon fiber (CF) on the sample surface. Temperature measurements performed using samples with various amounts of exposed CF (20%–95% CF) revealed that approximately 65% CF afforded the highest sample temperature and fastest heating rate. The CFRTP plate underwent non-uniform heating, especially during the early stages, e.g. less than 10 s. Sample heating to 150℃ resulted in permanent deformation of the hat-shaped CFRTP samples with less springback, whereas heating to higher temperatures above the melting point led to meandering of the samples. In contrast, CFRTP samples subjected to hot-stamping at lower temperatures, such as 110℃, exhibited rough surfaces. In addition to the sample temperature, the formability of CFRTP during hot-stamping was affected by the holding time. When hot-stamping was performed without a holding time, even at high temperatures of 150℃ and above, low-quality samples with dented surfaces and irregular sample thickness were obtained. The results of this study indicate that a temperature of 150℃ and a holding time of 10 s are optimal for fabricating high-quality hot-stamped CFRTP with smooth surfaces and uniform thickness.
      Citation: Journal of Composite Materials
      PubDate: 2019-10-02T04:16:18Z
      DOI: 10.1177/0021998319877559
       
  • Mechanical properties of nano-silica and nano-clay composites of phenol
           formaldehyde short carbon fibers
    • Authors: Ali Asghar Jahangiri, Yasser Rostamiyan
      Abstract: Journal of Composite Materials, Ahead of Print.
      The mechanical properties of phenol formaldehyde (phenolic novolac) and short carbon fiber T300 polymer-based nano-composites-reinforced with nano-silica and nano-clay particles have been studied experimentally. By increasing the weight percentage of the short carbon fiber in the phenol formaldehyde, the strength of the composite increases, but its plastic deformation is severely limited. Also, in the case of composite reinforced with nano-silica particles, the tensile and flexural strength of the composite with the increase in the weight percentage of the nano-silica increase by 1% to 3%, whereas with the nano-clay particles, the tensile and flexural strength of the composite decrease by 1% to 3%. It is composite with 1% weight percentage of the nano-clay particle which has the highest strength in comparison to the other samples. Regardless of the type of corrosive solution, the composite strength decreases significantly over 25 days. However, with an increase in the duration from 25 days to 45 days, a slight change has been observed. The outcomes indicate that the corrosion of PF/CF40% composites and the composite reinforced with silica nanoparticles are higher corrosion rate in acid than in salt solution. In contrast, the nano-clay composite has more corrosion in salt solution. Furthermore, the analysis of the fracture surface of samples done by SEM microscopy shows reduction of the porosity in the case of using nanoparticles.
      Citation: Journal of Composite Materials
      PubDate: 2019-09-26T05:33:47Z
      DOI: 10.1177/0021998319877225
       
  • Evaluation of the protective performance of hydrophobic coatings applied
           on carbon-fibre epoxy composites
    • Authors: Heather O'Connor, Denis P Dowling
      Abstract: Journal of Composite Materials, Ahead of Print.
      Carbon–fibre epoxy composites are widely used for high-performance structural applications, where they are often exposed to harsh environments. The result of moisture ingress has been extensively studied, causing significant deterioration in the mechanical properties of these composites. This study evaluates the performance of five commercial hydrophobic coatings as protective layers, to inhibit moisture ingress into the composite. The coatings evaluated were NeverWet, HydroBead, SHC, Aculon and LiquidGlass. These coatings were characterised and compared in terms of hydrophobicity, surface energy, roughness and chemical composition. This study also evaluated two atmospheric plasma pre-treatments as a means of enhancing the adhesion performance of these coatings. The pre-treatments involved the use of an air plasma for the activation of the epoxy, as well as the plasma deposition of a nanometre thick SiOx interlayer coating. The durability and protective performance of the coatings, with and without the pre-treatments were then compared using an abrasion test as well as a water immersion study.The use of both plasma pre-treatments was found to enhance the adhesion and the abrasion performance of four out of the five coatings. Of the coatings and pre-treatments investigated, the LiquidGlass in conjunction with a SiOx-coating interlayer was found to exhibit the highest abrasion resistance. This was followed by the composite, which was plasma activated prior to the application of the Aculon coating. Only minor differences were observed when comparing the total moisture ingress (M%) of the epoxy, coated with the different hydrophobic layers. The composite coated with the Aculon and SiOx interlayer exhibited the least amount of moisture ingress, at 0.90%, compared to 1.08% of the uncoated specimen. The shear strength of epoxy composite, coated with the LiquidGlass, NeverWet and the activated Aculon combination, were within the range of the uncoated specimens, therefore the moisture ingress was reversible upon heating and no permanent damage to the epoxy–fibre interface was observed. It is concluded that, of the five coatings investigated, both the Aculon coating and LiquidGlass in combination with a SiOx interlayer coating, exhibit the greatest potential as protective layers for carbon fibre epoxy composites.
      Citation: Journal of Composite Materials
      PubDate: 2019-09-26T05:33:47Z
      DOI: 10.1177/0021998319877454
       
  • Temperature rise caused by adiabatic shear failure in 3D braided composite
           tube subjected to axial impact compression
    • Authors: Zhongxiang Pan, Xianyan Wu, Liwei Wu
      Abstract: Journal of Composite Materials, Ahead of Print.
      Previous investigation on the crashworthiness of braided composite tubes did not take the relationship between adiabatic shear failure and temperature rise into account during dynamic loading. In this study, transient temperature rise caused by adiabatic effect was detected and captured for the three-dimensional braided carbon/epoxy composite specimens during axial impact compression under 600–800/s. A mesostructure model was established based on three-dimensional braided tube architecture to numerically characterize the mechanical and thermal response in material. Based on the results, non-uniform temperature distribution shows good correlation with adiabatic shear failure in the material. Key scientific issues are discovered including the position, morphology, time sequence, and response process of the temperature rise. The catastrophic shear behavior with accelerated temperature rise occurs after the peak force and accompanies the progressive failure process. Nodes having room temperature in the adiabatic shear zone indicates that some positions in plastic zone may still behave as elastic state. There exists different plastic slip distances due to shear instability in the path along or crossing the adiabatic shear band. Through this investigation, the model considering the adiabatic effect was able to show the dynamic shear mechanism involving the fracture position, morphology, and progressive thermo-mechanical response of the temperature rise, which cannot be revealed by experimental testing.
      Citation: Journal of Composite Materials
      PubDate: 2019-09-26T05:33:46Z
      DOI: 10.1177/0021998319877558
       
  • Improvement of fracture toughness and thermo-mechanical properties of
           carbon fiber/epoxy composites using polyhedral oligomeric silsesquioxane
    • Authors: Kunal Mishra, Libin K Babu, Ranji Vaidyanathan
      Abstract: Journal of Composite Materials, Ahead of Print.
      The influence of polyhedral oligomeric silsesquioxanes–polyvinylpyrrolidone on the interlaminar fracture toughness of carbon fiber-reinforced composites (CFRPs) is investigated in this study. Baseline composite material is fabricated using novolac epoxy-infused carbon fiber prepreg. Glycidyl isobutyl polyhedral oligomeric silsesquioxanes (GI) is introduced in the CFRP at loading of 1, 3, 5, and 10 wt.% with respect to polyvinylpyrrolidone used as a compatibilizer. Results of the double cantilever beam test indicate an increase of 70% in interlaminar fracture toughness for 5 wt.% GI-POSS loading compared to the baseline composite. Scanning electron microscopy shows polyhedral oligomeric silsesquioxanes enhanced the adhesion between fiber and the resin that leads to the fiber pull-out. Dynamic mechanical analysis result captures the reduction in the storage modulus with addition of polyvinylpyrrolidone due to the plasticization effect. Nonetheless, the introduction of polyhedral oligomeric silsesquioxanes increases the storage modulus for the GI/PVP composite. Additionally, an increase in the glass transition temperature with the reinforcement of polyhedral oligomeric silsesquioxanes is observed.
      Citation: Journal of Composite Materials
      PubDate: 2019-09-25T01:24:24Z
      DOI: 10.1177/0021998319876339
       
  • Energy absorption capacity of composite thin-wall circular tubes under
           axial crushing with different trigger initiations
    • Authors: JE Chambe, C Bouvet, O Dorival, JF Ferrero
      Abstract: Journal of Composite Materials, Ahead of Print.
      The purpose of this study is to evaluate and compare the ability of various composite structures to dissipate the energy generated during a crash. To this end, circular composite tubes were tested in compression in order to identify their behavior and determine their absorbing capabilities using the specific energy absorption (energy absorbed per unit weight). Several composite tubular structures with different materials and architectures were tested, including hybrid composition of carbon–aramid and hybrid configuration of 0/90 UD with woven or braided fabric. Several inventive and experimental trigger systems have been tested to try and enhance the absorption capabilities of the tested structures. Specific energy absorption values up to 140 kJ.kg−1 were obtained, achieving better than most instances from the literature, reaching around 80 kJ.kg−1. Specimens with 0°-oriented fibers coincidental with the direction of compression reached the highest specific energy absorption values while those with no fiber oriented in this direction performed poorly. Moreover, it has consequently been established that in quasi-static loading, a unidirectional laminate oriented at 0° and stabilized by woven plies strongly meets the expectations in terms of energy dissipation. Incidentally, an inner constrained containment is more effective in most cases, reducing the initial peak load without drastically reducing the specific energy absorption value.
      Citation: Journal of Composite Materials
      PubDate: 2019-09-25T01:24:22Z
      DOI: 10.1177/0021998319877221
       
  • Fabrication and investigation on the properties of ilmenite (FeTiO3)-based
           Al composite by accumulative roll bonding
    • Authors: Medhat Elwan, A Fathy, A Wagih, A R S Essa, A Abu-Oqail, Ahmed E EL-Nikhaily
      Abstract: Journal of Composite Materials, Ahead of Print.
      In the present study, the aluminum (Al) 1050–FeTiO3 composite was fabricated through accumulative roll bonding process, and the resultant mechanical properties were evaluated at different deformation cycles at ambient temperature. The effect of the addition of FeTiO3 particle on the microstructural evolution and mechanical properties of the composite during accumulative roll bonding was investigated. The Al–2, 4, and 8 vol.% FeTiO3 composites were produced by accumulative roll bonding at room temperature. The results showed improvement in the dispersions of the particles with the increase in the number of the rolling cycles. In order to study the mechanical properties, tensile and hardness tests were applied. It was observed that hardness and tensile strength improve with increasing accumulative roll bonding cycles. The microhardness and tensile strength of the final composites are significantly improved as compared to those of original raw material Al 1050 and increase with increasing volume fraction of FeTiO3, reaching a maximum of ∼75 HV and ∼169 MPa for Al–8 vol.% FeTiO3 at seventh cycle, respectively.
      Citation: Journal of Composite Materials
      PubDate: 2019-09-24T05:22:56Z
      DOI: 10.1177/0021998319876684
       
  • Effective shear modulus of a damaged ply in laminate stiffness analysis:
           Determination and validation
    • Authors: Mohamed Sahbi Loukil, Janis Varna
      Abstract: Journal of Composite Materials, Ahead of Print.
      The concept of the “effective stiffness” for plies in laminates containing intralaminar cracks is revisited presenting rather accurate fitting expressions for the effective stiffness dependence on crack density in the ply. In this article, the effective stiffness at certain crack density is back-calculated from the stiffness difference between the undamaged and damaged laminate. Earlier finite element method analysis of laminates with cracked 90-plies showed that the effective longitudinal modulus and Poisson’s ratio of the ply do not change during cracking, whereas the transverse modulus reduction can be described by a simple crack density dependent function. In this article, focus is on the remaining effective constant: in-plane shear modulus. Finite element method parametric analysis shows that the dependence on crack density is exponential and the fitting function is almost independent of geometrical and elastic parameters of the surrounding plies. The above independence justifies using the effective ply stiffness in expressions of the classical laminate theory to predict the intralaminar cracking caused stiffness reduction in laminates with off-axis plies. Results are in a very good agreement with (a) finite element method calculations; (b) experimental data, and (c) with the GLOB-LOC model, which gives a very accurate solution in cases where the crack face opening and sliding displacements are accurately described.
      Citation: Journal of Composite Materials
      PubDate: 2019-09-24T05:22:54Z
      DOI: 10.1177/0021998319874369
       
  • Dielectric characterization of white birch–activated biochar composites:
           A sustainable alternative to radar-absorbing materials
    • Authors: Alan FN Boss, Flavia L Braghiroli, Gisele Amaral-Labat, Ariane AT Souza, Mauricio R Baldan, Hassine Bouafif, Ahmed Koubaa, Guilherme FB Lenz e Silva
      Abstract: Journal of Composite Materials, Ahead of Print.
      Sustainability can be defined as the ability of meet presents needs without compromise the ability of future generations to find their own needs. In this matter, scientists have been warning about natural resource scarcity, and now several researchers are aiming their efforts to develop sustainable technologies. Here, we focus on finding novel uses to biochar, a carbon rich material made from biomass that is usually applied on soil amendment. To expand its applications, biochars were activated using two different methods: a physical activation using CO2; and a chemical one using KOH. We investigate here the dielectric properties of composites made with both activated biochars from white birch, where composites were made using silicone rubber matrix. It was also investigated the influence of composites made with biochar in powder and in flakes. All samples were characterized over the X-band frequency range. Composites made with powder presented a linear permittivity over the frequency range, while composites made with flakes presented oscillations on different frequencies. These oscillations are related to the composite surface, which induces reflection effects because of flakes arrangement in the top surface. Such effects widen opportunities to engineer new materials to be explored as radar-absorbing materials.
      Citation: Journal of Composite Materials
      PubDate: 2019-09-24T05:22:54Z
      DOI: 10.1177/0021998319877493
       
  • Experimental investigation of seismic strengthening of reinforced concrete
           short columns using externally bonded reinforcement, near surface mounted,
           and hybrid techniques
    • Authors: A Kargaran, A Kheyroddin
      Abstract: Journal of Composite Materials, Ahead of Print.
      Nowadays, the existence of short columns is a major factor in the failure and collapse of structures during the earthquake. In this article, 10 reinforced concrete short columns are prepared and experimentally investigated under cyclic lateral displacements. Since failure in short columns under earthquake was in the form of diagonal cracks and shear rupture, two new techniques are proposed to strengthen short columns against seismic loads. These techniques include externally bonded reinforcement with carbon fiber-reinforced polymer sheets and near surface mounted with glass fiber-reinforced polymer bars in the form of transverse, diagonal, and hybrid strengthening techniques. The experimental results demonstrated that the above-mentioned strengthening techniques in short columns lead to a change in the type of failure from shear to flexural, and the change of crack patterns and columns failure. The mentioned strengthening methods lead to an increase of ductility, increase of load carrying capacity and increase of dissipated energy.
      Citation: Journal of Composite Materials
      PubDate: 2019-09-24T05:22:53Z
      DOI: 10.1177/0021998319874499
       
  • Experimental analysis of adhesively bonded joints in synthetic- and
           natural fibre-reinforced polymer composites
    • Authors: HFM de Queiroz, MD Banea, DKK Cavalcanti
      Abstract: Journal of Composite Materials, Ahead of Print.
      The application of adhesively bonded joints in automotive industry has increased significantly in recent years mainly because of the potential for lighter weight vehicles, fuel savings and reduced emissions. The use of composites in making automotive body components to achieve a reduced vehicle mass has also continuously increased. Natural fibre composites have recently attracted a great deal of attention by the automotive industry due to their many attractive benefits (e.g. high strength-to-weight ratio, sustainable characteristics and low cost). However, the literature on natural fibre-reinforced polymer composite adhesive joints is scarce and needs further investigation. The main objective of this study was to evaluate and compare the mechanical performance of adhesively bonded joints made of synthetic- and natural fibre-reinforced polymer composites. Similar and dissimilar single lap joints bonded with a modern tough structural adhesive used in the automotive industry, as well as the epoxy resin AR260 (the same resin used in composite fabrication) were tested. It was found that the average failure loads varied significantly with adhesive material strength and adherend stiffness. Furthermore, it was also observed that failure mode has a significant effect in failure load. The jute-based natural fibre composites joints, both hybrid and purely natural, were superior in strength compared to the sisal-based natural composites joints.
      Citation: Journal of Composite Materials
      PubDate: 2019-09-24T05:22:53Z
      DOI: 10.1177/0021998319876979
       
  • The influence of variability and defects on the mechanical performance of
           tailorable composites
    • Authors: James M Finley, Joël Henry, Milo SP Shaffer, Soraia Pimenta
      Abstract: Journal of Composite Materials, Ahead of Print.
      Aligned hybrid-fibre discontinuous composites offer the ability to tailor their mechanical response through careful microstructural design. However, with tailorability comes microstructural complexity, which in turn leads to many sources of variability and defects. A virtual testing framework was further extended to investigate the influence of variability and defects on the mechanical performance of various aligned discontinuous composite material systems. This approach identified the most critical sources of variability as (i) fibre strength, (ii) the distance between fibre ends, or (iii) the level of fibre-type intermingling, depending on the material system. Fibre vacancy defects were shown to have the most significant influence on the strength and ductility of aligned discontinuous composites, although this sensitivity can be reduced through hybridisation of the fibre types.
      Citation: Journal of Composite Materials
      PubDate: 2019-09-24T05:22:51Z
      DOI: 10.1177/0021998319862855
       
  • Experimental and numerical analyses of stiffened composite panels with
           delamination under a compressive load
    • Authors: Yujiao Bai, Zhonghai Xu, Jieren Song, Linlin Miao, Chaocan Cai, Fan Yang, Rongguo Wang, Xiaodong He, Yi Hong, Xulun Dong
      Abstract: Journal of Composite Materials, Ahead of Print.
      L-shaped stiffened composite panels provide an efficient structure for engineering applications. However, they often produce delamination in the preparation and service process due to a series of factors. To study the effect of different types of delamination on the compressive strength of stiffened composite panels, ABAQUS finite element software was used in combine with the progressive damage subroutine user-defined field variable (USDFLD), and the finite element model was established based on cohesive theory to realize the prediction of the progressive failure process and strength of the stiffened composite panels. The results showed that the delamination of a stringer had a greater impact on the strength of the stiffened composite panels than did the debonding between the skin panel and a stringer and the delamination of the skin panel. The debonding delamination and delamination of a stringer exhibited delamination growth near the damage position during static compression, but delamination of the skin panel exhibited no delamination growth. The experimental results were in good agreement with the finite element simulation results, which verified the validity of the finite element model.
      Citation: Journal of Composite Materials
      PubDate: 2019-09-24T05:22:51Z
      DOI: 10.1177/0021998319875209
       
  • Bending strength and notched-sample fatigue life of hBN/TiC-reinforced
           steel 316 L: A numerical and experimental analysis
    • Authors: Ali Sadooghi, Gholamhassan Payganeh, Mahdi Tajdari, Amir Dehghan Ghadikolaei, Amir H Roohi
      Abstract: Journal of Composite Materials, Ahead of Print.
      Mechanical failure under cyclic and dynamic loading has always been a concern in engineering applications. Many different properties can be achieved by adding different materials to the metal matrix nanocomposites. In this study, steel 316 L is selected as the matrix, and the additive materials of titanium carbide and hexagonal boron nitride in 3.5 wt% for each one are added as the reinforcement particles. The samples are fabricated by powder metallurgy, compacted in pressure of 410 MPa, and sintered in temperature of 1375℃ for 4 h. In addition, some pure steel 316 L samples were provided for comparison purposes. Numerical simulation of bending strength and fatigue life of the notched samples were conducted and verified with experimental tests on the mechanical parts. It appeared that the nanocomposite specimens present a higher mechanical reliability relative to the pure 316 L as a result of adding nanoparticles. Steel 316 L S–N curves of the notched samples are also obtained from numerical analysis.
      Citation: Journal of Composite Materials
      PubDate: 2019-09-24T05:22:50Z
      DOI: 10.1177/0021998319875211
       
  • Porosity analysis of carbon fibre-reinforced polymer laminates
           manufactured using automated fibre placement
    • Authors: Ebrahim Oromiehie, Ulf Garbe, B Gangadhara Prusty
      Abstract: Journal of Composite Materials, Ahead of Print.
      Automated fibre placement-based manufacturing technology is increasingly being used in several engineering applications. Manufacture of carbon fibre-reinforced plastic’s small/large structures have been made possible due to its remarkable capabilities like productivity and accuracy. Nevertheless, making high-quality composite laminate using automated fibre placement relies on the proper selection of critical processing variables to avoid internal flaws during the fibre placement process. Consequently, a reliable non-destructive inspection technique is required for quality assurance and structural integrity of fabricated laminates. Neutron radiography/tomography offers unique imaging capabilities over a wide range of applications including fibre-reinforced polymer composites. The application of this technique towards tomographic reconstruction of automated fibre placement-made thermoplastic composites is presented in this paper. It is shown that the porosity analysis using neutron imaging technique provides reliable information. Additionally, using such technique valuable data regarding the size and the location of the voids in the laminate can be acquired and informed. This will assist the composite structural analysts and designers to select the appropriate processing parameters towards a defect free automated fibre placement part manufacture.
      Citation: Journal of Composite Materials
      PubDate: 2019-09-24T05:22:50Z
      DOI: 10.1177/0021998319875491
       
  • Experimental and numerical investigation of stiffener effects on buckling
           strength of composite laminates with circular cutout
    • Authors: T Shojaee, B Mohammadi, R Madoliat
      Abstract: Journal of Composite Materials, Ahead of Print.
      In the notched structures, to achieve maximum buckling resistance in comparison with structural weight, the optimal design of a stiffener is very important. In this research, after a review of the existing literature, nonlinear buckling behavior of composite plates containing the cutout with three different designs of stringer was investigated. The considered stiffeners are planer, longitudinal, and ring types. The buckling experiments were carried out on the stiffened plates containing a circular notch. Moreover, to achieve an efficient prediction of the buckling in the stiffened laminate with the hole, a finite strip method is developed based on the Airy stress function and von Karman’s large deformation equations. Studies show that there is a good agreement between the postbuckling behaviors derived from developed finite strip method with experimental results. Fast convergence of the considered finite strip method compared with the finite element results shows its efficiency for prediction of buckling behavior in laminated composites. The results show that the buckling load-bearing capacities of perforated plates with a longitudinal and planer stiffener are higher compared with the other stiffener, respectively. The detailed parametric study on the effects of thickness of the plate and stiffener and opening diameter on buckling behavior was performed using experiments and modeling.
      Citation: Journal of Composite Materials
      PubDate: 2019-09-24T05:22:46Z
      DOI: 10.1177/0021998319874101
       
  • Structure and mechanical properties of Ni/Ti multilayered composites
           produced by accumulative roll-bonding process
    • Authors: Mohammad Mokhles, Morteza Hosseini, Seyed Mojtaba Zebarjad, Habib Danesh-Manesh
      Abstract: Journal of Composite Materials, Ahead of Print.
      This research studies the structure and mechanical properties of Ni/Ti multilayered composites produced from commercial pure Ni and Ti foils by accumulative roll-bonding technique. To investigate these properties, scanning electron microscopy, Vickers microhardness, and uniaxial tensile tests were conducted at different processing cycles. Studies showed that in terms of structure, Ni and Ti layers maintain their continuity even up to 10 cycles of accumulative roll-bonding. Moreover, the energy-dispersive spectroscopy in scanning electron microscopy detected no deformation induced diffusion or reactive interfacial zones. It was found that by increasing the accumulative roll-bonding cycles, tensile and yield strengths as well as the hardness of the composite enhance and the total elongation reduces continuously.
      Citation: Journal of Composite Materials
      PubDate: 2019-09-23T06:06:18Z
      DOI: 10.1177/0021998319874391
       
  • Analytic solution of angle-ply laminated plates under extension, bending,
           and torsion
    • Authors: Shen-Haw Ju, Wen-Yu Liang, Hsin-Hsiang Hsu, Jiann-Quo Tarn
      Abstract: Journal of Composite Materials, Ahead of Print.
      This paper develops a Hamiltonian state space approach for analytic determination of deformation and stress fields in multilayered monoclinic angle-ply laminates under the combined action of extension, bending, and torsion. The present solution satisfies the equations of anisotropic elasticity, the end conditions, the traction-free boundary conditions on the four edge surfaces of the rectangular section, and the interfacial continuity conditions in multilayered laminates. The proposed method only requires the solutions of matrix and eigen equations, regardless of the number or lamination of the layers. The finite element analyses are used to validate the accuracy of the analysis. The analytical solution and the numerical solutions are in excellent agreement.
      Citation: Journal of Composite Materials
      PubDate: 2019-09-10T01:49:38Z
      DOI: 10.1177/0021998319873025
       
  • Fabrication of Al5083 surface hybrid nanocomposite reinforced by CNTs and
           Al2O3 nanoparticles using friction stir processing
    • Authors: Farhad Ostovan, Sattar Amanollah, Meysam Toozandehjani, Ehsan Shafiei
      Abstract: Journal of Composite Materials, Ahead of Print.
      In the present study, friction stir processing was adopted for surface treatment of Al5083 by incorporation of CNT and Al2O3 nanoparticles. Microstructural, mechanical and tribological properties of the surface of Al5083/CNT, Al5083/Al2O3 and hybrid Al5083/CNT/Al2O3 nanocomposite were investigated and compared. The friction stir processing yielded a nearly uniform dispersion of CNTs and Al2O3 nanoparticles, irrespective of nanoparticle reinforcements and their weight fraction. Microstructural observations revealed that Al2O3 nanoparticles have dispersed in different zones including intra-grain and grain boundary zones while, CNTs are pinned into grain boundaries during friction stir processing. From mechanical point of view, hybridization of CNT/Al2O3 enhances the hardness (126 HV at stirred zone), strength (UTS of ∼487 MPa) and also wear resistance of Al5083/CNT/Al2O3 nanocomposites. The enhancement is attributed to the presence and combination of features of both CNT and Al2O3 nanoparticles which are different in nature; one spherical oxide and one nanotube.
      Citation: Journal of Composite Materials
      PubDate: 2019-09-10T01:49:38Z
      DOI: 10.1177/0021998319874849
       
  • Single-walled carbon nanotubes–polyaniline composites: Synthesis and
           field-emission analysis
    • Authors: Nagma Ansari, Shumaila, Mohd Yaseen Lone, Javid Ali, M Husain, Samina Husain
      Abstract: Journal of Composite Materials, Ahead of Print.
      In this article, we report a facile synthesis and comparative analysis of field emission behavior of polyaniline (PANI)-coated as-received and annealed single-walled carbon nanotube (SWCNT) films by in-situ polymerization and ex-situ synthesis routes, respectively. Amongst all the samples, the sample prepared by in-situ polymerization method with more fraction of annealed SWCNTs in the composite gave an enhanced field emission characteristics with Eto = 3 V/μm and β = 1.2 × 104 probably because of good formation of pi-pi non-covalent bonds between the SWCNTs and PANI represented by pi-pi interaction between the quinoid rings of PANI and π bond of the SWCNTs lattice. A significant increase in the threshold field is observed after annealing and doping of nanocomposite films. Field emission behavior of as-prepared nanocomposite samples are also analyzed and discussed with two PANI forms: micro-PANI particles and PANI nanofibers. It is also speculated that PANI may have helped in lowering the overall work function of the composite structure which gave an enhanced field emission. The stability of all the samples are also presented and it is analyzed that nanocomposite sample films synthesized by in-situ polymerization method showed a stability for at least 8 h. The surface morphology analysis by field emission scanning electron microscopy of nanocomposite sample films reveal an increase in SWCNTs diameter upon PANI wrapping. The high-resolution transmission electron microscopy and Raman spectra and X-ray diffraction analysis are also presented.
      Citation: Journal of Composite Materials
      PubDate: 2019-09-10T01:49:37Z
      DOI: 10.1177/0021998319870571
       
  • A numerical investigation on ultrasonic bulk wave propagation features in
           functionally graded plates
    • Authors: Saeed Farahmand, Mohammad Hossein Soorgee
      Abstract: Journal of Composite Materials, Ahead of Print.
      The goal of this research is to numerically look for a proper feature for functionally graded materials mechanical property distribution function evaluation based on through transmitted ultrasonic bulk wave amplitude variation. A numerical approximation called homogenous layers approximation is introduced and employed for wave propagation formulation in functionally graded plate, followed by finite element utilization for verification. As the amplitude of the propagated ultrasonic wave is affected by acoustic impedance and wave divergence angle variation in the functionally graded material plate thickness, while neglecting the attenuation phenomenon, numerical investigation has been performed in order to quantify the contribution of each mechanism on the wave amplitude behavior. One-dimensional investigations, using homogenous layers approximation and finite element method, show that the final value of the wave amplitude is the same for all functionally graded material property distribution function power index, while two-dimensional results, obtained from finite element method, provide a suitable amplitude variation manner based on the wave divergence angle variation in functionally graded material thickness direction. The final results shows that it is possible to calibrate the received wave amplitude distribution on the receiving side of the plate, in a through transmission test, for the material property distribution function power index evaluation. Moreover, the concept of functionally graded material ultrasonic shoe is introduced, suitable for beam focusing applications instead of expensive phased array systems.
      Citation: Journal of Composite Materials
      PubDate: 2019-09-06T01:38:44Z
      DOI: 10.1177/0021998319874104
       
  • Micromechanics-based analyses of short fiber-reinforced composites with
           functionally graded interphases
    • Authors: Yang Yang, Qi He, Hong-Liang Dai, Jian Pang, Liang Yang, Xing-Quan Li, Yan-Ni Rao, Ting Dai
      Abstract: Journal of Composite Materials, Ahead of Print.
      A micromechanical model for short fiber-reinforced composites (SFRCs) with functionally graded interphases and a systematic prediction scheme to determine the effective properties are presented. The matrix and the fibers are regarded to be linear elastic, isotropic, and homogeneous. Fibers are assumed to be ellipsoids coated perfectly by functionally graded interphases, which is supposed to be formed chemically or physically by the constituents near the interface. First, to analyze the grading interphase effect, layer-wise concept is followed to divide the functionally graded interphases into multi-homogeneous sub-layers. Next, to take the effect of functionally graded interphases into account, a combination of multi-inclusion method and Mori–Tanaka method is applied to predict effective elastic properties of this unidirectional SFRCs with respect to the content and aspect ratio of the inclusions. By employing coordinate transformation, spatially elastic moduli are obtained. Finally, Voigt homogenization scheme is used to obtain the overall, averaged, symmetrical elastic properties of the SFRCs. Numerical examples and analyses demonstrate the applicability of the proposed method and indicate the influences of graded interphase, orientation, and aspect ratio of inclusions as well as properties and contents of the constituents on the overall properties of SFRCs.
      Citation: Journal of Composite Materials
      PubDate: 2019-09-02T02:55:50Z
      DOI: 10.1177/0021998319873033
       
  • Investigation of composite fabric impregnated with non-Newtonian fluid for
           protective textiles
    • Authors: Danmei Sun, Fuyou Zhu, George K Stylios
      Abstract: Journal of Composite Materials, Ahead of Print.
      Commercial high-performance fibre materials for body armour have very low surface friction and this has become an issue in the effectiveness of ballistic impact energy absorption. Also, the incidence of sports injuries in high contact sports is high. The severity of injuries of police and sportsman can be reduced by wearing enhanced protective clothing that have the ability to absorb the shocks. In this study, a type of non-Newtonian fluid has been developed. It became hardened upon a shock impact which was observed through a drop-on-weight test. The non-Newtonian fluid was successfully applied on to a traditional plain weave body armour fabric made of Twaron®. The treated fabric was studied by scanning electron microscopy and a yarn pulling-out test. It shows that the force to pull out a yarn from the non-Newtonian fluid treated fabric is four times higher than that of the untreated one. The flexibility of the non-Newtonian polymer treated fabric remains unchanged. The polymer can be used for applications where impact protection can be a highly desirable property.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-30T01:48:28Z
      DOI: 10.1177/0021998319873067
       
  • Electrical and thermal conductivities of the Cu–CF composite
    • Authors: J Koráb, S Krcho, P Štefánik, J Kováčik
      Abstract: Journal of Composite Materials, Ahead of Print.
      The paper presents a new approach in the field of metal–matrix composite characterisation where an electrical conductivity measurement was used to calculate the electron part of composite thermal conductivity by using the Wiedemann–Franz law. The electrical and thermal conductivities of the composite were characterised and their relationship was analysed. Results showed that in comparison with simple analytical models, this method can also be used for predicting the thermal conductivity of the copper matrix–continuous carbon fibre composite in a transverse direction. The unidirectional composite was produced by diffusion bonding and contained 40–60 vol.% of unidirectional fibres. Experiments were performed in directions parallel and normal to the fibre orientation and showed that with an increasing ratio of fibre volume, both thermal and electrical conductivities decreased from 221.6 W/m·K to 38.7 W/m·K and from 35.8 MS/m to 5.3 MS/m, respectively.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-30T01:48:27Z
      DOI: 10.1177/0021998319872261
       
  • Microstructure characterization and evaluation of mechanical properties of
           stir rheocast AA2024/TiB2 composite
    • Authors: Semegn Cheneke, D Benny Karunakar
      Abstract: Journal of Composite Materials, Ahead of Print.
      In this research, microstructure and mechanical properties of stir rheocast AA2024/TiB2 metal matrix composite have been investigated. The working temperature was 640℃, which was the selected semisolid temperature that corresponds to 40% of the solid fraction. Two weight percentage, 4 wt%, and 6 wt% of the TiB2 reinforcements were added to the matrix. The field emission scanning electron microscope micrographs of the developed composites showed a uniform distribution of the particles in the case of the 2 wt% and 4 wt% of the reinforcements. However, the particles agglomerated as the weight percentages of the reinforcement increases to 6%. The optical microscope of the liquid cast sample showed the dendritic structure, whereas the rheocast samples showed a globular structure. The X-ray diffraction analysis confirmed the distribution of the reinforcements in the matrix and the formation of some intermetallic compounds. Mechanical properties significantly improved by the addition of the reinforcements in the matrix. An increase in tensile strength of 13.3%, 40%, 28%, and 5% was achieved for the unreinforced rheocast sample, 2 wt%, 4 wt%, and 6 wt% reinforced rheocast samples respectively, compared to the liquid cast sample. An increase in 20% of hardness was attained for the composite with 2 wt% TiB2 compared to the liquid cast sample. According to the fractography analysis, small dimples were observed on the fractured surface of the unreinforced rheocast sample, whereas small and large voids were dominant on the fractured surface of the 2 wt% composite, which shows the ductile fracture mode.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-28T04:30:06Z
      DOI: 10.1177/0021998319871693
       
  • Investigation of interlayer hybridization effect on burst pressure
           performance of composite overwrapped pressure vessels with load-sharing
           metallic liner
    • Authors: Serkan Kangal, Osman Kartav, Metin Tanoğlu, Engin Aktaş, H Seçil Artem
      Abstract: Journal of Composite Materials, Ahead of Print.
      In this study, multi-layered composite overwrapped pressure vessels for high-pressure gaseous storage were designed, modeled by finite element method and manufactured by filament winding technique. 34CrMo4 steel was selected as a load-sharing metallic liner. Glass and carbon filaments were overwrapped on the liner with a winding angle of [±11°/90°2]3 to obtain fully overwrapped composite reinforced vessel with non-identical front and back dome endings. The vessels were loaded with increasing internal pressure up to the burst pressure level. The mechanical performances of pressure vessels, (i) fully overwrapped with glass fibers and (ii) with additional two carbon hoop layers on the cylindrical section, were investigated by both experimental and numerical approaches. In numerical approaches, finite element analysis was performed featuring a simple progressive damage model available in ANSYS software package for the composite section. The metal liner was modeled as elastic–plastic material. The results reveal that the finite element model provides a good correlation between experimental and numerical strain results for the vessels, together with the indication of the positive effect on radial deformation of the COPVs due to the composite interlayer hybridization. The constructed model was also able to predict experimental burst pressures within a range of 8%. However, the experimental and finite element analysis results showed that hybridization of hoop layers did not have any significant impact on the burst pressure performance of the vessels. This finding was attributed to the change of load-sharing capacity of composite layers due to the stiffness difference of carbon and glass fibers.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-28T04:30:05Z
      DOI: 10.1177/0021998319870588
       
  • Impact of silane treatment on the dielectric properties of pineapple
           leaf/kenaf fiber reinforced phenolic composites
    • Authors: F Agrebi, H Hammami, M Asim, M Jawaid, A Kallel
      Abstract: Journal of Composite Materials, Ahead of Print.
      This work deals with the dielectric properties of silane treated pineapple leaf fiber and kenaf fiber reinforced phenolic hybrid composites. The aim of the present paper is to investigate the effect of silane treatment on the pineapple leaf fiber–kenaf fiber/matrix interfacial adhesion using the dielectric relaxation spectroscopy in the frequency range from 0.1 Hz to 1 MHz and temperature range from 50 to 180℃. Our hybrid composites were fabricated by hand lay-up method at 50% total fiber loading. All the results obtained were discussed in terms of dynamic molecular and interfacial process. Two interfacial polarizations identified as the Maxwell–Wagner–Sillars effect are observed. We note that silane treatment improved the interfacial adhesion between pineapple leaf fiber/kenaf fiber and phenolic resin and it will help to develop high performance kenaf fiber/pineapple leaf fiber reinforced polymer composites for industrial applications. In fact, as known, the silane treatment developed hydrophobic nature in pineapple leaf fiber and kenaf fiber which is very positive for fiber/matrix compatibility.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-27T06:23:53Z
      DOI: 10.1177/0021998319871351
       
  • Transverse Young's modulus of carbon/glass hybrid fiber composites
    • Authors: Ganesh Venkatesan, Maximilian J Ripepi, Charles E Bakis
      Abstract: Journal of Composite Materials, Ahead of Print.
      Hybrid fiber composites offer designers a means of tailoring the stress–strain behavior of lightweight materials used in high-performance structures. While the longitudinal stress–strain behavior of unidirectional hybrid fiber composites has been thoroughly evaluated experimentally and analytically, relatively little information is available on the transverse behavior. The objective of the current investigation is to present data on the transverse modulus of elasticity of unidirectional composites with five different ratios of carbon and glass fiber and to compare the data with predictive and fitted models. The transverse modulus increases monotonically with the proportion of glass fiber in the composite. Finite element analysis was used to evaluate different ways to model voids in the matrix and allowed the unknown transverse properties of the carbon fibers to be backed out using experimental data from the all-carbon composite. The finite element results show that the transverse modulus can be accurately modeled if voids are modeled explicitly in the matrix region and if modulus is calculated based on stress applied along the minimum interfiber distance path between adjacent fibers arranged in a rectangular array. The transverse modulus was under-predicted by the iso-stress model and was well predicted by a modified iso-stress model and a modified Halpin–Tsai model.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-27T06:23:53Z
      DOI: 10.1177/0021998319871689
       
  • Cellulose nanofibrils and nano-scaled titanium dioxide-reinforced
           biopolymer nanocomposites: Selecting the best nanocomposites with
           multicriteria decision-making methods
    • Authors: Havva Gumus, Deniz Aydemir, Ertugrul Altuntas, Rıfat Kurt, Erol Imren
      Abstract: Journal of Composite Materials, Ahead of Print.
      The aim of the paper is to determine the effects of nano fillers such as cellulose nanofibrils and nano-scaled titanium dioxide on some properties of polyhydroxybutyrate and polylactic acid biopolymers; it also determined the selection of biopolymer nanocomposites with the optimum properties by using multicriteria decision-making methods such as multi-attribute utility theory, simple additive weighting, and weighted aggregated sum product assessment. Test results showed that the mechanical properties of the biopolymer nanocomposites generally increased with the addition of the cellulose nanofibrils and nano-scaled titanium dioxide. However, the addition of nano-scaled titanium dioxide decreased the tensile modulus. The addition of the cellulose nanofibrils had a higher effect on the tensile and flexure modulus of elasticity than the addition of the nano-scaled titanium dioxide. Thermal properties were generally found to improve with the addition of the cellulose nanofibrils and nano-scaled titanium dioxide. Melting temperature (Tm) generally decreased with the addition of the nano fillers. The scanning electron microscopic images showed that the nano fillers were dispersed as white dots in the biopolymer matrix. After accelerated weathering and decay test, outdoor performance of the biopolymer nanocomposites was found to be improved with the addition of the nano fillers. Multicriteria decision-making methods were conducted to determine the biopolymer nanocomposites having the optimum properties, and all the methods showed that the best biopolymer nanocomposites was polylactic acid with 1% cellulose nanofibrils.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-23T05:06:52Z
      DOI: 10.1177/0021998319870842
       
  • The role of electrical anisotropy and effective conducting thickness in
           understanding and interpreting static resistance measurements in CFRP
           composite laminates
    • Authors: Robert J Hart, OI Zhupanska
      Abstract: Journal of Composite Materials, Ahead of Print.
      This study is focused on (i) the experimental characterization of the anisotropic electrical resistivity of carbon fiber reinforced polymer (CFRP) composites and (ii) the development and experimental validation of predictive finite element (FE) models of the electrical response in CFRP laminates based on the concept of the effective conducting thickness. Two experimental methods have been developed to characterize the anisotropic electrical resistivities in three principle directions for the CFRP composite laminates using a direct current source. One method utilizes a traditional 6-probe resistance scheme and the alternative point-type 4-probe method is based on a handheld probe device similar to the JIS K7194 standard for homogenous plastics. An extensive experimental study has been conducted to characterize the anisotropic electrical resistivities of 16-ply unidirectional and 16-ply symmetric cross-ply IM7/977-2 and 32-ply unidirectional IM7/977-3 composites using the developed methods. Exploiting the concept of the effective conducting thickness, which describes the effective depth of current penetration through the thickness of an electrically anisotropic material, a unique methodology is developed for constructing FE models of these highly anisotropic CFRP materials. The concept of effective conducting thickness was identified as a critical component in achieving accuracy of the FE results as well as recovery of experimental resistivity from the alternative point-type 4-probe method. The FE models have been validated using the experimental results on the CFRP specimens of varying layup and thickness, and the techniques developed in this work may lead to advancements in non-destructive techniques in the areas of electrical characterization and damage sensing.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-21T05:27:33Z
      DOI: 10.1177/0021998319870860
       
  • Preparation of fluorescent calcium carbonate and visualization of its
           dispersion states in polypropylene
    • Authors: Xiangmeng Lv, Ming Kang, Kexu Chen, Lu Yuan, Simin Shen, Rong Sun, Lixian Song
      Abstract: Journal of Composite Materials, Ahead of Print.
      The dispersion states of fillers in the polymer matrix is an important factor to determine the properties of the polymer composites. Mastering the dispersion structure of inorganic minerals such as calcium carbonate in the polymer matrix is of great significance for the design of high performant polymer composites. Currently, due to the limitations of conventional electron microscope imaging capabilities, it is difficult to understand the internal dispersion structure of fillers in polymer composites comprehensively, regionally and stereoscopically. Here, we successfully embed the rare earth complex into the silica of the calcium carbonate surface to realize the fluorescent labeling of the calcium carbonate fillers. The fluorescent calcium carbonate exhibited broad excitation band ranging from 220 nm to 440 nm and showed bright red under ultraviolet light (365 nm). The two-dimensional dispersion states of the fillers at different depths in the polymer composite were obtained by the fluorescent imaging ability of laser scanning confocal microscope; these two-dimensional confocal images were further three-dimensionally reconstructed through Avizo Fire VSG software, and the spatial distribution of fillers in polymer composite was obtained without damage. This characterization method provides a new noninvasive method for studying the dispersion structure of fillers in polymers.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-21T05:27:32Z
      DOI: 10.1177/0021998319869822
       
  • Development of N-doped bamboo-shaped carbon nanotube/magnesium oxide
           nanocomposites
    • Authors: László Vanyorek, Ádám Prekob, Emőke Sikora, Gábor Muránszky, Bilal El Mrabate, Mahitha Udayakumar, Péter Pekker, Béla Viskolcz, Zoltán Németh
      Abstract: Journal of Composite Materials, Ahead of Print.
      Nitrogen-doped bamboo-shaped carbon nanotubes/magnesium oxide composites were prepared using a simple impregnation method. Magnesium oxide nanoparticles with different crystal morphologies were obtained using magnesium oxide powder and stearic acid precursors. The calcination of bamboo-shaped carbon nanotubes/magnesium stearate mixture in a 1:1 ratio with different temperatures (300 and 400℃) in an inert atmosphere was carried out. The prepared composites were further analyzed by X-ray powder diffraction, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, specific surface area measurement, Fourier transform infrared spectroscopy, transmission and scanning electron microscopy and thermogravimetric analysis techniques. Results revealed that the characteristic morphology and the crystal structure of the composites rely primarily on the heat treatment temperature chosen. To obtain a proper crystalline magnesium oxide, at least 400℃ is required. As-prepared bamboo-shaped carbon nanotube-based composites would be an ideal candidate as a catalyst or a membrane additive material for water purification technology.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-21T05:27:32Z
      DOI: 10.1177/0021998319870843
       
  • Overall buckling prediction model for fibre reinforced plastic laminated
           tubes with balanced off-axis ply orientations based on Puck failure
           criteria
    • Authors: Ruoyu Li, Ruijie Zhu, Feng Li
      Abstract: Journal of Composite Materials, Ahead of Print.
      Fibre reinforced plastic tubes with balanced off-axis ply orientation exhibit excellent mechanical properties and are widely used in various types of structures. In this study, a theoretical prediction model was proposed to determine the overall buckling load and the failure mode of fibre reinforced plastic laminated tubes with off-axis ply orientation under axial compression. This model considers the transverse shear effect and adopts Puck failure criteria to perform an analysis based on deduced three-dimensional stress and strain fields. A series of carbon fibre reinforced plastics tubes with varying off-axis ply orientations and lengths were designed and prepared. Axial compression tests with effective end-reinforcement and hinge support were performed to validate the proposed prediction model. The results indicated that the predicted model results were in good agreement with the test results, with respect to ultimate loads, failure modes, and locations of failure. Parametric analysis on the influence of transverse shear effect was also conducted, which further explained the influencing degree of transverse shear effect considering different tube lengths, ply sequences, and initial deflection.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-21T05:27:32Z
      DOI: 10.1177/0021998319871086
       
  • Neurofuzzy modelling of moisture absorption kinetics and its effect on the
           mechanical properties of pineapple fibre-reinforced polypropylene
           composite
    • Authors: J Lilly Mercy, R Velmurugan, T Sasipraba, Chrystella Jacob
      Abstract: Journal of Composite Materials, Ahead of Print.
      Natural fibres possess low density, less abrasiveness, good strength and sound absorption capacity and its significance lies in being renewable and biodegradable. The mechanical characteristics and moisture absorption of pineapple fibres reinforced with polypropylene resin are focused in this study. Chopped fibres and unidirectional fibre mats of pineapple were reinforced with polypropylene resin to make pineapple fibre/polypropylene composites. The length of the pineapple fibres and the orientation of the layup of the fibre mats are varied to make composite specimens and the mechanical properties are tested. Moisture absorption studies were carried out and it was confirmed to follow Fickian diffusion. A total of 384 samples were tested and it was observed that all the samples reached its saturation in moisture absorption before 720 h and the strength was inversely proportional to the moisture absorbed. Specimens reinforced with unidirectional fibre mats of alternate orientation possessed high strength irrespective of the moisture absorbed when compared to the specimens reinforced with chopped fibres of random orientation. Neuro fuzzy modelling using ANFIS tool box in MATLAB was used to correlate the static mechanical properties of pineapple fibre-reinforced polymer under different moisture conditions, fibre orientations, fibre volume percentage, fibre size, etc.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-21T05:27:31Z
      DOI: 10.1177/0021998319870581
       
  • Experimental investigation on impact, sound, and vibration response of
           natural-based composite sandwich made of flax and agglomerated cork
    • Authors: S Prabhakaran, V Krishnaraj, Krishna Shankar, M Senthilkumar, R Zitoune
      Abstract: Journal of Composite Materials, Ahead of Print.
      In recent years, material scientists have been focusing on the utilization of materials from natural resources due to environmental concerns. In the same context, the aim of this work is to evaluate impact response, sound absorption behavior, and vibration damping characteristics of natural-based composite sandwich made of flax as skin reinforcement and agglomerated cork as core. Vacuum bagging method was used for manufacturing composite sandwiches with different cork densities of 240, 280, and 340 kg/m3. Composite sandwiches have also been manufactured by using glass as skin reinforcement for comparison. Low velocity impact test was conducted and found that glass fiber reinforced composite sandwich required 73–77% more energy to perforate when compared to the flax fiber reinforced composite sandwich irrespective of core density. Flax fiber reinforced composite sandwich has 45–96% higher sound absorption capacity and 27–32% higher vibration damping ratio than glass fiber reinforced composite sandwich irrespective of core density. This is due to multiscale structure and cellular nature of the flax fiber and the cork materials, respectively. These enhancements in sound and vibration are accomplished with just little forfeits in perforation energy. This study recommends that, if optimized, the natural-based composite sandwich could be an ecologically appealing answer for automobile and construction applications, where impact behavior is important, along with sound and vibration properties.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-21T04:35:33Z
      DOI: 10.1177/0021998319871354
       
  • Electrical impedance analysis of carbon nanotube/epoxy nanocomposite-based
           piezoresistive strain sensors under uniaxial cyclic static tensile loading
           
    • Authors: Abdulkadir Sanli, Olfa Kanoun
      Abstract: Journal of Composite Materials, Ahead of Print.
      Carbon nanotubes-based nanocomposites have gained a great amount of attraction and play a key role in the realization of strain sensors owing to their remarkable physical properties. In this study, the piezoresistivity of multi-walled carbon nanotubes (MWCNTs)/epoxy-based nanocomposite-based strain sensor under static tensile load is examined using electrochemical impedance spectroscopy. Morphological examinations show that MWCNTs are randomly and homogeneously distributed in the epoxy polymer matrix. A simplified resistance constant phase element model is proposed and validated by impedance spectrum to fit the impedance spectra and the equivalent circuit parameters are extracted under uniaxial static load. Impedance results suggest that depending on the frequency regions, the sensor exhibits different responses under loading. Moreover, the proposed sensor gives high sensitivity, linearity and low hysteresis under cyclic quasi-static loading and unloading that makes the sensor a promising candidate for practical strain sensor applications.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-19T05:55:36Z
      DOI: 10.1177/0021998319870592
       
  • Fastening composite structures using braided thermoplastic composite
           rivets
    • Authors: Vincent Fortier, Jean-E Brunel, Louis L Lebel
      Abstract: Journal of Composite Materials, Ahead of Print.
      Aerospace composite material components are currently joined using heavy titanium bolts. This joining method is not ideal when considering its weight, thermal expansion, electrical conductivity, and risk of unbalanced load distribution. We propose here an innovative fastening technology using thermoplastic composite rivets. A rivet blank is heated above its melting temperature using Joule heating and is formed directly in the composite laminates by an automated process. Carbon fiber and polyamide blanks were used with two fiber architecture: 2D braid and unidirectional. The braided architecture showed superior manufacturing performance and repeatability. Joints were riveted in less than 40 s per rivet. The temperature measured in the riveted composite laminate in the vicinity of formed rivet reached only 136℃ during riveting. Double fastener lap shear testing showed breaking load of 6146 N per fastener. This joint strength is higher than comparable aluminum-riveted joints, and the specific joint strength is higher than titanium-bolted joints. With these advantages, the technology could be developed and used in the next generations of lighter, cleaner, and safer aircraft.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-15T06:42:23Z
      DOI: 10.1177/0021998319867375
       
  • Design and finite element assessment of fully uncoupled multi-directional
           layups for delamination tests
    • Authors: Torquato Garulli, Anita Catapano, Daniele Fanteria, Julien Jumel, Eric Martin
      Abstract: Journal of Composite Materials, Ahead of Print.
      In this paper, a procedure to obtain fully uncoupled multi-directional stacking sequences for delamination specimens is outlined. For such sequences, in-plane, membrane-bending and torsion–bending coupling terms are null (in closed-form solution in the framework of classical laminated plate theory) for the entire stack and for both its halves, which form two arms in the pre-cracked region of a typical delamination specimen. This is achieved exploiting the superposition of quasi-trivial quasi-homogeneous stacking sequences, according to appropriate rules. Any pair of orientations of the plies embedding the delamination plane can be obtained. To assess the effectiveness of the proposed approach, a fully uncoupled multi-directional sequence is designed and compared to other relevant sequences proposed in the literature. Finite element simulations of double cantilever beam test are performed using classic virtual crack closure technique and a revised state-of-the-art virtual crack closure technique formulation too. Some interesting conclusions regarding proper design of multidirectional stacks for delamination tests are drawn. Moreover, the results confirm the suitability of fully uncoupled multi-directional sequences for delamination tests. Thanks to their properties, these sequences might lay the foundations for the development of standard test procedures for delamination in angle-ply interfaces.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-15T06:42:23Z
      DOI: 10.1177/0021998319868293
       
  • Development of a methodology for characterizing reaction kinetics,
           rheology, and in situ compaction of polyimide prepregs during cure
    • Authors: James Magato, Donald Klosterman
      Abstract: Journal of Composite Materials, Ahead of Print.
      PMR-type polyimide prepregs are challenging to fabricate into high quality composites due to volatiles that are generated and must be removed in situ during processing. The current work was conducted to develop accurate, reliable, and practical characterization techniques of the prepreg rheology, volatile generation, and subsequent volatile removal from the prepreg during composite fabrication. Thermal analysis was used to characterize volatile generation, reaction rates, and rheology. A novel approach was used to measure the thickness of the prepreg in situ during vacuum bag/oven processing using a high-temperature LVDT. Experimental results are presented for the commercially available RM-1100 polyimide/carbon prepreg system, including the reaction rate, rheology, and panel thickness results for a series of heating rates and ply counts. The results show the key interrelationships in these coupled phenomena and how that information can be used to select the optimum temperature of pressure application to minimize the final void content.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-15T06:42:22Z
      DOI: 10.1177/0021998319869433
       
  • Micromechanical evaluation of failure models for unidirectional
           fiber-reinforced composites
    • Authors: Azam Arefi, Frans P van der Meer, Mohammad Reza Forouzan, Mohammad Silani, Mahmoud Salimi
      Abstract: Journal of Composite Materials, Ahead of Print.
      In this paper, micromechanical simulations are employed to evaluate the performance of the Tsai–Wu and Hashin failure criteria for fiber-reinforced composites, especially in stress states whose experimental reproduction is complicated. Micromechanical responses are generated using a finite element model of a representative volume element, in which only the matrix material experiences damage and the fibers are assumed to be elastic. Micromechanical simulations of basic load cases are used to calibrate macrolevel criteria. Finally, the response of the micromodel and macromodels is compared for various load combinations. Despite a good agreement between Tsai–Wu criterion predictions and micromodel results in a wide range of stress states, some stress combinations are highlighted for which the strength is not predicted accurately. Additionally, accuracy of the Hashin criterion suffers from ignoring the influence of stress in fiber direction on matrix failure.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-15T06:42:21Z
      DOI: 10.1177/0021998319867470
       
  • HAp/TiO2 nanocomposites: Influence of TiO2 on microstructure and
           mechanical properties
    • Authors: Ajay Kumar Vemulapalli, Rama Murty Raju Penmetsa, Ramanaiah Nallu, Rajesh Siriyala
      Abstract: Journal of Composite Materials, Ahead of Print.
      Hydroxyapatite is a very attractive material for artificial implants and human tissue restorations because they accelerate bone growth around the implant. The hydroxyapatite nanocomposites (HAp/TiO2) were produced by using high energy ball milling. X-ray diffraction studies revealed the formation of HAp and TiO2 composites. Cubic-like crystals with boundary morphologies were observed; it was also found that the grain size gradually increased with the increase in TiO2 content. It was found that the mechanical properties (hardness, Young's modulus, fracture toughness, flexural strength, and compression strength)of the composites significantly improved with the addition of TiO2, which was sintered at 1200℃. These properties were then also correlated with the microstructure of the composites. This paper investigates the effect of titania (TiO2 = 0, 5, 10, 15, 20, and 25 wt%) addition on the microstructure and mechanical properties of hydroxyapatite (Ca10(PO4)6(OH)2) nanocomposites.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-12T04:47:11Z
      DOI: 10.1177/0021998319868517
       
  • Nonlinear interphase effects on plastic hardening of nylon 6/clay
           nanocomposites: A computational stochastic analysis
    • Authors: Vahid Yaghoubi, Mohammad Silani, Hossein Zolfaghari, Mostafa Jamshidian, Timon Rabczuk
      Abstract: Journal of Composite Materials, Ahead of Print.
      In this paper, the nonlinear effect of interphase properties on the macroscopic plastic response of nylon 6/clay nanocomposites is investigated by applying a stochastic analysis on a multiscale computational model of nanocomposites. The mechanical behavior of interphase is described with respect to that of the matrix by a weakening coefficient. The interphase thickness and properties are considered as the stochastic inputs and the hardening modulus and hardening exponent describing the plastic hardening characteristics of the nanocomposite are the random outputs. The stochastic analysis consists of three procedures including (i) model selection using Akaike information criterion, (ii) uncertainty propagation using Latin Hypercube sampling in conjunction with chi-square test, and (iii) sensitivity analysis using Sobol indices. The results indicate that the exponential hardening model best describes the flow stress–plastic strain response of the nanocomposite. It is also shown that increasing the clay content generally increases the plastic hardening rate of the nanocomposite up to 4% clay content. Besides, the hardening characteristics of the nanocomposite are more sensitive to the weakening coefficient than the interphase thickness.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-12T04:47:11Z
      DOI: 10.1177/0021998319868523
       
  • Electromagnetic analysis of composite structures subjected to transient
           magnetic fields
    • Authors: Jerome T Tzeng, Kou-Ta Hsieh
      Abstract: Journal of Composite Materials, Ahead of Print.
      When carbon composites are exposed to a transient electromagnetic field, a rapid temperature increase can be observed due to joule heating from magnetic induction. The electromagnetic induction heating and heat transfer in the composite are anisotropic and concentrated upon the carbon fiber orientation and distribution. In addition, the strength and frequency of transient electromagnetic fields have great influence on the final quality of the composite. A computational model has been developed by solving coupled Maxwell’s and heat transfer equations. The analysis accounts for the three-dimensional transient electromagnetic field and electrical conductivity of the composite material. This paper will illustrate the derived formulation and numerical solution based on finite element methods. The developed code is validated with a 2D closed-form solution. Numerical simulations of a cylinder and a flat laminated plate are conducted to illustrate the computational capability. The induction heating for composite manufacture is also discussed for current Army’s applications.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-10T05:55:54Z
      DOI: 10.1177/0021998319868005
       
  • Effect of different stacking sequences on hybrid carbon/glass/epoxy
           composites laminate: Thermal, dynamic mechanical and long-term behavior
    • Authors: Dielly Cavalcanti da Silva Monte Vidal, Heitor L Ornaghi, Felipe Gustavo Ornaghi, Francisco Maciel Monticeli, Herman Jacobus Cornelis Voorwald, Maria Odila Hilário Cioffi
      Abstract: Journal of Composite Materials, Ahead of Print.
      In the present study, different stacking sequences on hybrid carbon/glass/epoxy composites laminate were examined in relation to thermal, dynamic mechanical and long-term behavior. A positive hybrid effect was found for both hybrid composites (interleaved-Hybrid 1 and in block-Hybrid 2) showing that in some cases hybrid composites can properly replace carbon or glass composites. The composite containing all glass fiber in the middle (Hybrid 2) presented similar thermal behavior when compared to glass fiber composite. All hybrid composites presented higher storage modulus when compared to glass composite. Dynamic mechanical analysis showed that both hybrids can satisfactorily perform the requirement in a wide temperature range. The long-term prediction was successfully applied for all composites, showing to be highly temperature-dependent. Hence, depending on the application requirement, both hybrids can be used, saving weight and cost.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-07T12:59:58Z
      DOI: 10.1177/0021998319868512
       
  • Interfacial characterization of functionalized graphene-epoxy composites
    • Authors: Liliana S Melro, Lars R Jensen
      Abstract: Journal of Composite Materials, Ahead of Print.
      The interface of graphene/epoxy was studied using molecular dynamics simulations by calculating the work of separation and traction-separation responses in the normal mode. The influence of functionalization of the graphene layers on the traction-separation behaviour was also examined by grafting hydroxyl, carboxyl, and carbonyl groups. It is shown that the magnitude of the maximum traction is clearly larger for functionalized graphene/epoxy systems as compared to pristine graphene. The work of adhesion also shows a clear difference in the interface behaviour of functionalized graphene/epoxy and pristine/epoxy systems with the presence of functional groups generating higher values of work of separation.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-07T12:59:57Z
      DOI: 10.1177/0021998319866252
       
  • Microstructure and mechanical characterizations of graphene
           nanoplatelets-reinforced Mg–Sr–Ca alloy as a novel composite in
           structural and biomedical applications
    • Authors: S Ramezanzade, GR Ebrahimi, M Torabi Parizi, HR Ezatpour
      Abstract: Journal of Composite Materials, Ahead of Print.
      In this study, the novel composites were fabricated by the introduction of Mg-0.3Sr-0.3Ca alloy as the matrix and addition of different amounts of graphene nanoplatelets (0.1, 0.2, and 0.4 wt.%) as reinforcement using a stir casting technique followed by homogenization and extrusion in order to improve the mechanical properties of the base alloy. Optimum weight percent of adding graphene nanoplatelets was 0.2 wt.%. The addition of 0.2 wt.% graphene nanoplatelets in the extruded Mg–Sr–Ca alloy led to the grain refinement (∼36%), the decrease of anisotropy (∼14%) and the lowest twin formation. Moreover, the tensile and compressive yield strengths and tensile and compressive fracture strains of extruded Mg-0.3Sr-0.3Ca/0.2GNP composite were enhanced by 22.8%, 66.7%, 43.1% and 28%, respectively. The load transfer was significant strengthening mechanism. The uniform dispersion of graphene nanoplatelets followed by the increase of non-basal slip and grain refinement improved tensile fracture strain. In addition to maintained factors, the increase of compressive fracture strain in the extruded Mg-0.3Sr-0.3Ca/0.2GNP composite was affected by local stresses caused by twins which resulted non-basal slip and conserved basal slip due to presence of twins. Simultaneously, enhancement of the strengthening and elongation efficiencies in both tensile and compressive tests was achieved in Mg-0.3Ca-0.3Sr/0.2GNP. The biocorrosion behavior of extruded Mg-0.3Sr-0.3Ca/0.2GNP composite was promoted by 11% compared with Mg-0.3Sr-0.3Ca alloy. Comparative plots indicated that the fabricated materials can be introduced as a new class of composites for the purpose of structural as well as biomedical applications.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-07T12:59:57Z
      DOI: 10.1177/0021998319867464
       
  • Developments in the aluminum metal matrix composites reinforced by
           micro/nano particles – A review
    • Authors: Neeraj K Bhoi, Harpreet Singh, Saurabh Pratap
      Abstract: Journal of Composite Materials, Ahead of Print.
      ‘The micro/nano reinforced particle’ aluminum metal matrix composites (Al-MMCs) are widely used in manufacturing sector due to light-weight, superior strength-to-weight ratio, better fracture toughness, improved fatigue, and tensile property, enhanced corrosion resistance to harsh environment, etc. This article provides an overview of the manufacturing processes and different reinforcing elements used during the synthesis of Al-MMCs. Generally, the reinforced particles like carbides, nitrides, and compounds of oxides are used. Different organic, inorganic, industrial and agricultural waste which can be used for reinforcement in the aluminum matrix is highlighted with their feasible applications. The common mechanical properties (i.e. hardness, tensile and compressive strength, etc.) reported by different researchers are thoroughly discussed with the aim to highlight the amount of reinforcement and improvement occurred during processing. The formation and methodology for mixing condition and sintering behaviour of Al-MMCs are discussed to impart knowledge about the processing circumstances in powder metallurgical route. The affecting conditions during operating and responsible factor for the tribological behaviour are deliberated in a precise manner to recognize the potentiality of reinforcing particles in Al-MMCs. Finally, the different shortcomings and future prospects of the Al-MMCs are given to encourage the future research directions.
      Citation: Journal of Composite Materials
      PubDate: 2019-07-30T01:46:30Z
      DOI: 10.1177/0021998319865307
       
  • Nanocomposite coatings on steel for enhancing the corrosion resistance: A
           review
    • Authors: AV Radhamani, Hon Chung Lau, S Ramakrishna
      Abstract: Journal of Composite Materials, Ahead of Print.
      Steel is known for its low cost of fabrication, high mechanical strength and hence is extensively used for drilling equipment, pipelines, ship building and offshore structures. Corrosion of steel is a costly problem in many applications especially in oilfield and marine environments which are known for the high temperature, high pressure and corrosive conditions. In this paper, nanocomposite coating is being explored as the preferred strategy to improve corrosion resistance for steel. Here, we will give details on the various coating materials, deposition techniques and the challenges involved in realising the most suitable coating on steel based on results of recent research. In addition, we also detail the filler specifications for getting high performance nanocomposites.
      Citation: Journal of Composite Materials
      PubDate: 2019-07-30T01:46:29Z
      DOI: 10.1177/0021998319857807
       
  • Simultaneous effects of strain rate and temperature on mechanical response
           of fabricated Mg–SiC nanocomposite
    • Authors: K Rahmani, GH Majzoobi, A Atrian
      Abstract: Journal of Composite Materials, Ahead of Print.
      Mg–SiC nanocomposite samples were fabricated using split Hopkinson pressure bar for different SiC volume fractions and under different temperature conditions. The microstructures and mechanical properties of the samples including microhardness and stress–strain curves were captured from quasi-static and dynamic tests carried out using Instron and split Hopkinson pressure bar, respectively. Nanocomposites were produced by hot and high-rate compaction method using split Hopkinson pressure bar. Temperature also significantly affects relative density and can lead to 2.5% increase in density. Adding SiC-reinforcing particles to samples increased their Vickers microhardness from 46 VH to 68 VH (45% increase) depending on the compaction temperature. X-ray diffraction analysis showed that by increasing temperature from 25℃ to 450℃, the Mg crystallite size increases from 37 nm to 72 nm and decreases the lattice strain from 45% to 30%. In quasi-static tests, the ultimate compressive strength for the compaction temperature of 450℃ was improved from 123% for Mg–0 vol.% SiC to 200% for the Mg–10 vol.% SiC samples compared with those of the compaction at room temperature. In dynamic tests, the ultimate strength for Mg–10 vol.% SiC sample compacted at high strain rate increased remarkably by 110% compared with that for Mg–0 vol.% SiC sample compacted at low strain rate.
      Citation: Journal of Composite Materials
      PubDate: 2019-07-26T08:50:22Z
      DOI: 10.1177/0021998319864629
       
  • Comparison between different non-destructive techniques methods to detect
           and characterize impact damage on composite laminates
    • Authors: I Papa, MR Ricciardi, V Antonucci, A Langella, J Tirillò, F Sarasini, V Pagliarulo, P Ferraro, V Lopresto
      Abstract: Journal of Composite Materials, Ahead of Print.
      This paper aims to investigate the ability of ultrasonic and electronic speckle pattern interferometry to analyse the low-velocity impact internal damage mechanisms on basalt composite laminates and to provide information on the shape and the extent of the delamination in non-destructive way.Basalt/epoxy composites with different thicknesses have been realised and characterised by mechanical tests to investigate both fibre-dominated (tensile and flexural behaviour) and matrix-dominated properties (interlaminar shear strength). Specimens were impacted at penetration and at increasing energy values, to explore the damage onset and propagation. The results showed that the damage was concentrated under the impactor–material contact point and that the composite with intermediate thickness had the best balance between the different kinds of impact damages: delamination and indentation. Further, a good agreement was found between the overall data obtained by the two non-destructive techniques, confirming the capability of both techniques to examine the composite impact damage.
      Citation: Journal of Composite Materials
      PubDate: 2019-07-23T09:41:29Z
      DOI: 10.1177/0021998319864411
       
  • Effects of material and process parameters on void evolution in
           unidirectional prepreg during vacuum bag-only cure
    • Authors: Wei Hu, Timotei Centea, Steven Nutt
      Abstract: Journal of Composite Materials, Ahead of Print.
      Void reduction during composites manufacturing is critical for successful processing. In this study, we perform a parametric study to determine the mechanisms of interply void evolution in unidirectional prepregs during vacuum bag-only cure and to identify the key factors that affect interply air removal. We employ an in situ visualization setup for direct, real-time observation of air removal for prepregs during cure. Results showed that super-ambient dwell at 50℃ effectively promoted interply air removal in unidirectional prepregs, reduced vacuum quality (80% vacuum) had negligible effects on part quality, and that an increase in moisture content of the laminate notably increased void content. Prepreg moisture content was tracked by the inspection of laminate water content at different times during the cure cycle, and the data was combined with a diffusion-based analytical model to predict void size and to improve the understanding of void evolution mechanisms. Results indicated that moisture content of the laminate decreased markedly as cure progressed, providing insights into bubble behavior (expansion and shrinkage) observed during cure. The modified model predictions aligned with experimental data, especially during the second stage, confirming that the observed void growth results from moisture diffusion.
      Citation: Journal of Composite Materials
      PubDate: 2019-07-23T09:41:28Z
      DOI: 10.1177/0021998319864420
       
  • Fabrication and characterization of hollow glass beads-filled
           thermoplastic composite filament developed for material extrusion additive
           manufacturing
    • Authors: Jung Sub Kim, Chang Su Lee, Sang Won Lee, Sung-Min Kim, Jae Hyuk Choi, Haseung Chung, Pil-Ho Lee
      Abstract: Journal of Composite Materials, Ahead of Print.
      This paper explores the characteristics of a new lightweight thermoplastic composite filament filled with hollow glass beads developed for material extrusion additive manufacturing. Compounding experiments, which mix hollow glass beads with neat acrylonitrile butadiene styrene matrix, were conducted using a twin-screw extruder to prepare composite filaments. Two different types of hollow glass beads were selected as the fillers of composite filament due to their varying densities. In order to characterize the final components produced using composite filament, various specimens were fabricated by a material extrusion additive manufacturing process. In order to characterize the physical properties of the specimens, measurements of density and flexural testing were performed. To identify the thermomechanical effects of hollow glass beads on the neat acrylonitrile butadiene styrene matrix, thermal diffusivity and specific heat were obtained. Consequently, the thermal conductivity of the specimen was derived from its density, thermal diffusivity, and specific heat capacity. The microstructures of the fractured interfaces of the specimens were also observed by scanning electron microscopy. The experimental results revealed that most of the hollow glass beads survived, thus bringing about lighter weight (lower density) and thermal insulation (lower thermal conductivity), which can be useful for numerous potential applications.
      Citation: Journal of Composite Materials
      PubDate: 2019-07-23T04:57:33Z
      DOI: 10.1177/0021998319863836
       
  • Study on the fracture toughness and deformation micro-mechanisms of
           PP/EPDM/SiO2 ternary blend-nanocomposites
    • Authors: S Hajibabazadeh, MK Razavi Aghjeh, M Palahang
      Abstract: Journal of Composite Materials, Ahead of Print.
      A detailed fracture analysis of polypropylene/ethylene–propylene–diene monomer rubber/nano-silica (PP/EPDM/SiO2) ternary blend-nanocomposites was conducted through using both Izod impact and quasi-static fracture tests. The phase morphology and the fractured surfaces were evaluated using scanning electron microscopy. Morphological observations revealed that the SiO2 nanoparticles were mainly located either around the EPDM particles or at the PP/EPDM interface. A synergistic effect was observed between the soft EPDM rubber particles and rigid SiO2 filler on activation of different toughening micro-mechanisms, so that the impact strength of the ternary systems was significantly higher than that of corresponding binary blends. This effect was much more significant for percolated morphologies. The concept of the essential work of fracture (EWF) was used to analyze the fracture behavior and toughening/deformation mechanisms of the samples. The percolated structure of the EPDM particles and the SiO2 nanoparticles exhibited superior fracture resistance under EWF fracture tests. Formation of multiple void-fibrillar structures dissipated further energy and significantly improved fracture resistance under EWF tests. It was demonstrated that the toughness and stiffness could successfully be balanced via controlling the microstructure of the ternary systems.
      Citation: Journal of Composite Materials
      PubDate: 2019-07-23T04:57:32Z
      DOI: 10.1177/0021998319863475
       
  • Additive manufacturing of composites made of epoxy resin with magnetite
           particles fabricated with the direct ink writing technique
    • Authors: Jose J Restrepo, Henry A Colorado
      Abstract: Journal of Composite Materials, Ahead of Print.
      In this investigation, particulate composites materials made of epoxy resin matrix with magnetite particles were fabricated via additive manufacturing with the direct ink writing technique. Magnetite is an inexpensive material and the direct ink writing process is not only inexpensive but also easy to adapt to any material. A total of eight formulations were investigated, from which only four were feasible for the printing process: 32.6, 33.6, 35.4 and 41 wt.% of particles. The composites were characterized by scanning electron microscopy, compressive strength, particle size distribution, density, and ductility. Results showed that composites exhibit very competitive mechanical properties even though the process was not vacuum assisted, therefore enabling them to be used in large scale and in other structural applications. Composite can be used in electromagnetic shielding.
      Citation: Journal of Composite Materials
      PubDate: 2019-07-23T04:57:32Z
      DOI: 10.1177/0021998319865019
       
  • Corrigendum: Evaluation of mechanical properties and microstructure of
           Al/Al–12%Si multilayer via warm accumulative roll bonding process
    • Abstract: Journal of Composite Materials, Ahead of Print.

      Citation: Journal of Composite Materials
      PubDate: 2019-05-14T05:45:51Z
      DOI: 10.1177/0021998319851993
       
  • Synthesis and characterization of Sr-doped HAp-incorporated polyether
           ether ketone composite
    • Authors: Anindya Pal, Bhabatosh Biswas, Ankita Das, Arindam Chakraborty, Pallab Datta, Amit Roy Chowdhury, Arijit Sinha
      First page: 287
      Abstract: Journal of Composite Materials, Ahead of Print.
      Hydrothermally synthesized undoped and Sr-doped hydroxyapatite-dispersed polyether ether ketone composites has been fabricated by using hot isostatic pressing technique with 5, 10, 15, and 20 wt.% as the dispersoids content. The detailed structural investigation of the fabricated composites has been performed by scanning electron microscope, high-resolution transmission electron microscope, and X-ray diffraction technique that confirmed the uniform dispersion of the dispersoids with the polyether ether ketone matrix. The microindentation measurements show that the mechanical properties of the polyether ether ketone matrix improved remarkably with incorporation of the hydroxyapatite (HAp) particles. The nondestructively evaluated elastic modulus so obtained for the matrix and composites were further validated through finite element analysis. Moreover, the in vitro cytotoxic of the fabricated nanocomposites were also evaluated to assess its potential as a bioactive material.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-19T07:33:26Z
      DOI: 10.1177/0021998319888006
       
  • Modeling the effect of uniaxial deformation on electrical conductivity for
           composite materials with extreme filler segregation
    • Authors: Oleg V Lebedev, Sergey G Abaimov, Alexander N Ozerin
      First page: 299
      Abstract: Journal of Composite Materials, Ahead of Print.
      In this work, the correlation between electrical conductivity and uniaxial deformation of a material with highly segregated distribution of conductive filler is studied. Multi-walled carbon nanotubes are used as a model filler. A numerical model that can be used to predict changes in conductive microstructure made of multi-walled carbon nanotubes in response to uniaxial deformation of material is proposed. The model takes into account the ability of nanotubes to assume various conformations and orientations during deformation. Numerical simulations are conducted for uniformly distributed multi-walled carbon nanotubes providing confinement of the filler in a two-dimensional film structure with high volume fraction of the filler. The embedded element method to conduct realistic and computationally efficient simulation of multi-walled carbon nanotube behavior during deformation of the composite material is implemented. Finally, the results of numerical simulations of changes in electrical conductivity of composite during deformation are compared with the experimental data to prove the correctness of assumptions used in the model.
      Citation: Journal of Composite Materials
      PubDate: 2019-07-11T05:38:58Z
      DOI: 10.1177/0021998319862045
       
  • Short-beam shear of nanoprepreg/nanostitched three-dimensional
           carbon/epoxy multiwall carbon nanotube composites
    • Authors: Kadir Bilisik, Nesrin Karaduman, Erdal Sapanci
      First page: 311
      Abstract: Journal of Composite Materials, Ahead of Print.
      The effect of out-of-plane stitching and the addition of multiwalled carbon nanotubes on the short-beam shear properties of carbon/epoxy composites were investigated. Stitching influenced the short-beam strength of carbon satin and twill fabric composites, where the stitched satin carbon/epoxy composites showed improved short-beam properties compared with the unstitched satin carbon/epoxy composites. In general, stitching and MWCNTs addition enhanced the short-beam strength of the composite. The fracture of the composites generally exhibited as a combination of lateral total matrix cracking, warp fiber breakage and interlayer opening. In addition, all the structures experienced angularly sheared catastrophic through-the-thickness layer breakage. It was also shown that delamination was largely restricted in stitched and nano-added composites when compared to the unstitched samples. It can be concluded that nanostitching could be considered for improving short-beam strength properties of the composite.
      Citation: Journal of Composite Materials
      PubDate: 2019-07-16T05:57:14Z
      DOI: 10.1177/0021998319863472
       
  • Effect of modified nano zinc oxide on physico-chemical and antimicrobial
           properties of gamma-irradiated sawdust/epoxy composites
    • Authors: Hoda A. Abdel-Rahman, Eman H. Awad, Rasha M. Fathy
      First page: 331
      Abstract: Journal of Composite Materials, Ahead of Print.
      The present study aims to investigate the influence of modified zinc oxide nanoparticles content on the physico-chemical properties of sawdust/epoxy composite specimens. The results show an improvement in the mechanical properties in terms of flexural strength, impact strength, and hardness with increasing the modified zinc oxide nanoparticles content up to 5%, while the physical properties such as water absorption and thickness swelling percentages are decreased directly with increasing the content of modified zinc oxide. In addition, the behavior of irradiated composite specimens containing 5% modified zinc oxide nanoparticles at different gamma-irradiation doses, 10, 30, and 50 kGy, has been studied. The results indicate that the irradiated composite specimens at 10 kGy have better physico-chemical properties as compared to the unirradiated specimens. Furthermore, the antimicrobial properties of composite specimens containing 5% modified zinc oxide at 0 kGy and 10 kGy against different plant pathogenic fungi and bacteria are also discussed. The results demonstrate that the growth activity of fungi and bacteria on the composite specimens are reduced to a great extent as compared to the control composite specimens (0% of zinc oxide nanoparticles). Thermal behavior and morphology of the prepared specimens are detected using thermogravimetric analysis and scanning electron microscopy technique.
      Citation: Journal of Composite Materials
      PubDate: 2019-07-18T05:10:24Z
      DOI: 10.1177/0021998319863835
       
  • Nylon 612/TiO2 composites by anionic copolymerization-molding process:
           Comparative evaluation of thermal and mechanical performance
    • Authors: Elena Rusu
      First page: 345
      Abstract: Journal of Composite Materials, Ahead of Print.
      This study describes the changes in some properties of two series of nylon 612/TiO2 composites by varying filler type (untreated and treated) and content (up 8.0 wt.%). The samples preparation by simultaneous anionic copolymerization-molding process ensures a good dispersion of the filler in matrix. Differential scanning calorimetry, thermogravimetrical analysis, static mechanical testing, dynamic mechanical analysis and scanning electron microscopy allowed to investigate the effects of filler loading on the mechanical, thermal and morphological characteristics of the samples and revealed the importance of filler treatment on the composites behaviour. The semicrystalline character has been proved by differential scanning calorimetry (only a single melting peak is present) and wide-angle X-ray diffraction (two reflexion plane with d-spacing of 0.4311 and 0.3817 nm appear). At the same filler content, the difference ΔHm1–ΔHc was higher for the samples with treated filler. The lower Tm,α(2) in comparison with Tm,α(1) revealed a modification of the nucleation process during crystallization. The main mass loss of the samples occurred between 277 and 550℃. The addition of the filler leads to the improvement of flexural strength and flexural modulus in comparison with neat copolymer. Incorporating 8.0 wt.% treated filler, the Tg value increases by about 11.0%, reaching 61.0℃.
      Citation: Journal of Composite Materials
      PubDate: 2019-07-18T05:14:12Z
      DOI: 10.1177/0021998319862345
       
  • Modeling and optimization of electrospinning conditions of PVB nanofiber
           by RSM and PSO-LSSVM models for improved interlaminar fracture toughness
           of laminated composites
    • Authors: Hossein Ipakchi, Amir Masoud Rezadoust, Masoud Esfandeh, Hamed Mirshekar
      First page: 363
      Abstract: Journal of Composite Materials, Ahead of Print.
      In this study, the diameter of polyvinyl butyral nanofibers was modeled using response surface method based on three variables, at three levels of central composite design and particle swarm optimization-least squares support vector machine. Under optimal conditions, the measured mean diameter of the nanofibers was 175 nm. Sensitivity analysis in both models showed that polyvinyl butyral concentration in the solution was found to be the most effective parameter on the nanofiber diameter. The voltage is placed in the next. Fracture toughness under Mode I condition shows that the use of electrospun nanowebs as an interlayer in the structure of multi-layers composite has a positive effect on the GIc which values for the oriented and random nanofibers modified samples increased by 60% and 55%, respectively. According to SEM images, the main mechanism of fracture toughness in these samples was crack deflection and nanofibers crack bridging.
      Citation: Journal of Composite Materials
      PubDate: 2019-07-18T05:14:11Z
      DOI: 10.1177/0021998319863126
       
  • Fibre architecture modification to improve the tensile properties of
           flax-reinforced composites
    • Authors: Rishad Rayyaan, William Richard Kennon, Prasad Potluri, Mahmudul Akonda
      First page: 379
      Abstract: Journal of Composite Materials, Ahead of Print.
      As far as the tensile properties of natural fibres as reinforcements for composites are concerned, flax fibres will stay at the top-end. However, an efficient conversion of fibre properties into their corresponding composite properties has been a challenge, due to the fibre damages through the conventional textile methods utilised to process flax. These techniques impart disadvantageous features onto fibres at both micro- and meso-scale level, which in turn degrade the mechanical performances of flax fibre-reinforced composites (FFRC). Undulation of fibre is one of those detrimental features, which occurs during traditional fibre extraction from plant and fabric manufacturing routes. The undulation or waviness causes micro-compressive defects or ‘kink-bands’ in elementary flax fibres, which significantly undermines the performances of FFRC. Manufacturing flax fabric with minimal undulation could diminish the micro-compressive defects up to a substantial extent. In this research, nonwoven flax tapes of highly aligned flax fibres, blended with a small proportion of polylactic acid have been manufactured deploying a novel technique. Composites reinforced from those nonwoven tapes have been compared with composites reinforced with woven Hopsack fabrics and warp knitted unidirectional fabrics from flax, comprising undulating fibres. The composites reinforced with the highly aligned tapes have shown 33% higher fibre-bundle strength, and 57% higher fibre-bundle stiffness in comparison with the composites reinforced with Hopsack fabric. The results have been discussed in the light of fibre undulation, elementary fibre individualisation, homogeneity of fibre distribution, extent of resin rich areas and impregnation of the fibre lumens.
      Citation: Journal of Composite Materials
      PubDate: 2019-07-18T05:14:10Z
      DOI: 10.1177/0021998319863156
       
  • Influence of filler loading on the mechanical and morphological properties
           
    • Authors: Uchechi C Mark, Innocent C Madufor, Henry C Obasi, Udochukwu Mark
      First page: 397
      Abstract: Journal of Composite Materials, Ahead of Print.
      The high cost of mineral-based fillers and their processing difficulties have necessitated the search for alternative and cheaper filler materials, usually agro-waste materials such as coconut shells. The coconut shells were carbonized, pulverized, and sieved into four particles sizes, namely; 63 μm, 150 μm, 300 μm, and 425 μm. The carbonized coconut shell particles of each particle size were used as fillers in the preparation of polypropylene-filled composites at filler loadings of 0, 10, 20, 30, and 40 wt. %. The control was the neat polypropylene of 0% filler addition. The polypropylene/carbonized coconut shell particles composites were prepared via melt blending of polypropylene and the filler in an injection molding machine to obtain composite sheets. The influence of filler loading on the mechanical properties was evaluated. The addition of fillers was found to improve the yield strength, tensile strength, tensile modulus, flexural strength, flexural modulus, and hardness of polypropylene as these mechanical properties increased with increase in filler loading. The elongation at break and modulus of resilience of the prepared polypropylene/carbonized coconut shell particles composites were, however, observed to decline with an increase in the filler loading. Compared with the neat polypropylene, the filler showed enhanced mechanical properties in the prepared composites. SEM revealed good filler–matrix interaction because of good interfacial adhesion. The incorporation of more filler resulted in the formation of more spherulite-producing nuclei, reduction of pore sizes, and enhanced particle size distribution with improved mechanical properties. Experimental data modeling showed the addition of more than 48% carbonized coconut shell particles to polypropylene would compromise property enhancement.
      Citation: Journal of Composite Materials
      PubDate: 2019-07-19T04:49:40Z
      DOI: 10.1177/0021998319856070
       
  • Analytical modeling and experimental validation of the low-velocity impact
           response of hemp and hemp/glass thermoset composites
    • Authors: Simonetta Boria, Carlo Santulli, Elena Raponi, Fabrizio Sarasini, Jacopo Tirillò
      First page: 409
      Abstract: Journal of Composite Materials, Ahead of Print.
      Natural fiber composites have the potential to be widely applied as an alternative to or in combination with glass fiber composites in sustainable energy-absorbing structures. This study investigates the behavior of hemp fiber-reinforced vinylester composites when subjected to low-velocity impact loading by using an instrumented falling weight impact equipment. Different stacking sequences are tested, including a hybrid pattern resulting from a combination of natural and traditional glass fibers. Both penetration and indentation tests are performed. In the light of an increase in safety of green composite components and systems subjected to low-velocity impacts, next to the numerical models, the development of theoretical models is also useful and low time-consuming. Therefore, analytical models, available in the literature for traditional fiber-reinforced plastics and aimed at predicting the critical load of delamination onset, the indentation as a function of absorbed energy, as well as the approximation of the load–displacement curve, are used and implemented in this work. Good agreement was found between the theoretical predictions and experimental results.
      Citation: Journal of Composite Materials
      PubDate: 2019-07-20T02:18:37Z
      DOI: 10.1177/0021998319862856
       
  • Highly sensitive and stretchable strain sensors based on chopped carbon
           fibers sandwiched between silicone rubber layers for human motion
           detections
    • Authors: MB Azizkhani, Sh Rastgordani, A. Pourkamali Anaraki, J Kadkhodapour, B Shirkavand Hadavand
      First page: 423
      Abstract: Journal of Composite Materials, Ahead of Print.
      Tuning the electromechanical performance in piezoresistive composite strain sensors is primarily attained through appropriately employing the materials system and the fabrication process. High sensitivity along with flexibility in the strain sensing devices needs to be met according to the application (e.g. human motion detection, health and sports monitoring). In this paper, a highly stretchable and sensitive strain sensor with a low-cost fabrication is proposed which is acquired by embedding the chopped carbon fibers sandwiched in between silicone rubber layers. The electrical and mechanical features of the sensor were characterized through stretch/release loading tests where a considerably high sensitivity (the gauge factor about 100) was observed with very low hysteresis. This implies high strain reversibility (i.e. full recovery in each cycle) over 700 loading cycles. Moreover, the sensors exhibited ultra-high stretchability (up to ∼300% elongation) in addition to a low stiffness meaning minimal mechanical effects induced by the sensor for sensitive human motion monitoring applications including large and small deformations. The results suggest the promising capability of the present sensor in reflecting the human body motion detection.
      Citation: Journal of Composite Materials
      PubDate: 2019-07-16T05:57:16Z
      DOI: 10.1177/0021998319855758
       
  • Special issue on “Impact and Dynamic Response” in the Journal
           of Composite Materials
    • Authors: KT Tan, Leslie Lamberson, Hyonny Kim
      First page: 437
      Abstract: Journal of Composite Materials, Ahead of Print.

      Citation: Journal of Composite Materials
      PubDate: 2019-11-15T05:54:35Z
      DOI: 10.1177/0021998319888090
       
  • Dynamic response and validation of a flexible matrix composite
    • Authors: Daniel Whisler, Rafael G Consarnau, Ezequiel Buenrostro
      First page: 439
      Abstract: Journal of Composite Materials, Ahead of Print.
      Testing and predicting the dynamic response of flexible matrix composites in impact loading condition face two primary challenges: (i) experimentally, existing techniques using existing instruments do not always provide high fidelity material data under simultaneous high strain and high strain rate loading conditions; and (ii) finite element simulations of a highly flexible material require many material parameters and complex mathematical formulations. To address these limitations, this research investigation presents a technique originally developed in-house for modeling and validating hyper-viscoelastic materials and applies it toward the flexible matrix composite. Results from a simple low-velocity impact (2 m/s) test on a 75 × 75 mm2 flexible matrix composite indicate that the critical material properties for the low strength, highly deformable matrix in conjunction with an updated constitutive model can accurately predict the dynamic behavior within 10% with respect to the force time history response using MATLAB and ABAQUS/Explicit. Finite element interrogation also shows full field stress response within the composite specimen not easily measured via sensors and deformation matching the behavior observed via high-speed camera. Finally, on-going research in this arena indicates that the technique can be applied to higher rate loading mechanisms, such as a gas gun and Hopkinson bar apparatus, in order to obtain material parameters for even more devastating impact loading strain rates.
      Citation: Journal of Composite Materials
      PubDate: 2019-04-26T06:28:50Z
      DOI: 10.1177/0021998319845431
       
  • A three-dimensional progressive damage model for drop-weight impact and
           compression after impact
    • Authors: Dinh Chi Pham, Jim Lua, Haotian Sun, Dianyun Zhang
      First page: 449
      Abstract: Journal of Composite Materials, Ahead of Print.
      In this paper, an enhanced three-dimensional continuum damage mechanics model is applied to predict the drop-weight impact response and compression after impact failure of a fiber-reinforced polymer composite specimen. The three-dimensional progressive damage model incorporates a three-dimensional maximum stress criterion to predict the intra-ply damage initiation, followed by a fracture-energy-based smeared crack model to capture the post-peak softening behavior. Driven by the dominant through-the-thickness failure under impact loading, a three-dimensional continuum damage model is implemented for the three-dimensional solid element via its explicit material model for Abaqus (VUMAT) to capture the effect of three-dimensional stress state and the interaction of matrix cracking and delamination. Abaqus’ restart analysis capability is used to activate the compression after impact analysis using the final damage state from the dynamic impact analysis. Both the dynamic failure and the compression after impact are demonstrated via a suite of verification examples followed by the sensitivity analysis using distinct impact configurations. The predictive capability of the proposed three-dimensional damage model is first verified using a static open-hole tension test. Applications of the damage model are then demonstrated for simulations of the dynamic drop-weight tests and compression after impact tests. A comparative study on the developed method is performed using the results predicted from the open-source CompDam. A sensitivity study is also performed to demonstrate the impact energy-dependent failure mode. The proposed model has shown its advantages in performing a quick assessment of impact damage and its effects on the residual compressive strength.
      Citation: Journal of Composite Materials
      PubDate: 2019-06-29T04:46:56Z
      DOI: 10.1177/0021998319859050
       
  • Implementing deformation, damage, and failure in an orthotropic plastic
           material model
    • Authors: Loukham Shyamsunder, Bilal Khaled, Subramaniam D Rajan, Robert K Goldberg, Kelly S Carney, Paul DuBois, Gunther Blankenhorn
      First page: 463
      Abstract: Journal of Composite Materials, Ahead of Print.
      Theoretical and implementation details of an orthotropic plasticity model are presented. The model is comprised of three sub-models dealing with elastic and inelastic deformations, damage, and failure. The input to the three sub-models involves tabulated data that can be obtained from laboratory and/or virtual testing. In this article, the focus is on the development of the failure sub-model and its links to the other components. Details of how the user-selected failure criterion is used, and what steps are implemented post-failure are presented. The well-known Puck failure criterion is used in the numerical examples. Three validation tests are used to illustrate the strengths and weaknesses of the failure sub-model—10°, 15°, and 30° off-axis tests, a stacked-ply test carried out at room temperature under quasi-static loading, and finally, a high-speed impact test. Results indicate that while the deformation and damage sub-models give reasonably accurate results, the failure predictions are a huge challenge especially for high-speed impact tests.
      Citation: Journal of Composite Materials
      PubDate: 2019-07-26T08:50:19Z
      DOI: 10.1177/0021998319865006
       
  • Modeling and simulation of carbon composite ballistic and blast behavior
    • Authors: Chian-Fong Yen, Bob Kaste, Charles Chih-Tsai Chen, Nelson Carey
      First page: 485
      Abstract: Journal of Composite Materials, Ahead of Print.
      The design of the next generation of aeronautical vehicles is driven by the vastly increased cost of fuel and the resultant imperative for greater fuel efficiency. Carbon fiber composites have been used in aeronautical structures to lower weight due to their superior stiffness and strength-to-weight properties. However, carbon composite material behavior under dynamic ballistic impact and blast loading conditions is relatively unknown. For aviation safety consideration, a computational constitutive model has been used to characterize the progressive failure behavior of carbon laminated composite plates subjected to ballistic impact and blast loading conditions. Using a meso-mechanics approach, a laminated composite is represented by a collection of selected numbers of representative unidirectional layers with proper layup configurations. The damage progression in a unidirectional layer is assumed to be governed by the strain-rate-dependent layer progressive failure model using the continuum damage mechanics approach. The composite failure model has been successfully implemented within LS-DYNA® as a user-defined material subroutine. In this paper, the ballistic limit velocity (V50) was first established for a series of laminates by ballistic impact testing. Correlation of the predicted and measured V50 values has been conducted to validate the accuracy of the ballistic modeling approach for the selected carbon composite material. A series of close-in shock hole blast tests on carbon composite panels were then tested and simulated using the LS-DYNA® Arbitrary-Lagrangian-Eulerian (ALE) method integrated with the Army Research Laboratory (ARL) progressive failure composite model. The computational constitutive model has been validated to characterize the progressive failure behavior in carbon laminates subjected to close-in blast loading conditions with reasonable accuracy. The availability of this modeling tool will greatly facilitate the development of carbon composite structures with enhanced ballistic impact and blast survivability.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-09T04:54:16Z
      DOI: 10.1177/0021998319866902
       
  • Rate effects on fiber–matrix interfacial transverse debonding
           behavior
    • Authors: Jou-Mei Chu, Benjamin Claus, Boon Him Lim, Daniel O’Brien, Tao Sun, Kamel Fezzaa, Wayne Chen
      First page: 501
      Abstract: Journal of Composite Materials, Ahead of Print.
      The rate effect of fiber–matrix interfacial debonding behavior of SC-15 epoxy with S-2 glass and aramid fiber reinforcements was studied via in-situ visualization of the transverse debonding event. In this study, the debonding force history, debonding initiation, debonding crack velocity, and crack geometry were characterized using a quasi-static load frame and a modified tension Kolsky bar at loading velocities of 0.25 mm/s and 2.5 m/s. Cruciform-shaped specimens were used for interfacial transverse debonding between SC-15 epoxy matrix and two types of fiber reinforcements. The load history and high-speed images of the debonding event were simultaneously recorded. A major increase was observed for the average peak debonding force and a minor increase was observed for the average crack velocity with increasing loading velocity. The crack geometry of the cruciform specimens under both loading velocities was also tracked. Scanning electron microscopy of the recovered specimens revealed the debonding direction along the fiber–matrix interface through angled patterns on the failure surface.
      Citation: Journal of Composite Materials
      PubDate: 2019-10-04T12:39:43Z
      DOI: 10.1177/0021998319866904
       
  • Failure behavior of woven fiberglass composites under combined compressive
           and environmental loading
    • Authors: Ariana Paradiso, Isabella Mendoza, Amanda Bellafato, Leslie Lamberson
      First page: 519
      Abstract: Journal of Composite Materials, Ahead of Print.
      The purpose of this study is to quantitatively characterize the compressive and damage behavior of a woven fiberglass composite under combined environmental loading. Cuboidal samples of a commercially available woven fiberglass epoxy resin composite, garolite G10, are examined under uniaxial compressive loading perpendicular to the plies at quasi-static (10−3 s−1) and dynamic (103 s−1) strain rates using a standard load frame and Kolsky (split-Hopkinson) bar. In order to simulate environmental conditions, a subset of samples were soaked in either distilled or ASTM standard seawater prior to loading. Two time periods of environmental conditioning were investigated: short term at two weeks and long term at four months. Results demonstrate that, on average, the dynamic compressive strength of the fiberglass increased 35% from the quasi-static. Moreover, environmentally treated samples generally experienced a decrease strain to failure, and composites exposed to water for only short periods exhibited signs of the absorbed water sustaining additional load under quasi-static rates. Ultra-high-speed photography combined with digital image correlation, a full-field surface kinematic measurement technique, is used to map 2D strains on the sample during loading. In all cases, a clear shear failure mechanism from local instabilities appears, and a Mohr–Coulomb failure criterion is used to extract a mesoscale cohesive shear stress and coefficient of internal friction.
      Citation: Journal of Composite Materials
      PubDate: 2019-10-09T08:14:40Z
      DOI: 10.1177/0021998319878771
       
  • Dynamic impact behavior of syntactic foam core sandwich composites
    • Authors: P Breunig, V Damodaran, K Shahapurkar, S Waddar, M Doddamani, P Jeyaraj, P Prabhakar
      First page: 535
      Abstract: Journal of Composite Materials, Ahead of Print.
      Sandwich composites and syntactic foams independently have been used in many engineering applications. However, there has been minimal effort towards taking advantage of the weight saving ability of syntactic foams in the cores of sandwich composites, especially with respect to the impact response of structures. To that end, the goal of this study is to investigate the mechanical response and damage mechanisms associated with syntactic foam core sandwich composites subjected to dynamic impact loading. In particular, this study investigates the influence of varying cenosphere volume fraction in syntactic foam core sandwich composites subjected to varying dynamic impact loading and further elucidates the extent and diversity of corresponding damage mechanisms. The syntactic foam cores are first fabricated using epoxy resin as the matrix and cenospheres as the reinforcement with four cenosphere volume fractions of 0% (pure epoxy), 20%, 40%, and 60%. The sandwich composite panels are then manufactured using the vacuum assisted resin transfer molding process with carbon fiber/vinyl ester facesheets. Dynamic impact tests are performed on the sandwich composite specimens at two energy levels of 80 J and 160 J, upon which the data are post-processed to gain a quantitative understanding of the impact response and damage mechanisms incurred by the specimens. A qualitative understanding is obtained through micro-computed tomography scanning of the impacted specimens. In addition, a finite element model is developed to investigate the causes for different damage mechanisms observed in specimens with different volume fractions.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-10T08:57:36Z
      DOI: 10.1177/0021998319885000
       
  • Shadowed delamination area estimation in ultrasonic C-scans of impacted
           composites validated by X-ray CT
    • Authors: Andrew Ellison, Hyonny Kim
      First page: 549
      Abstract: Journal of Composite Materials, Ahead of Print.
      Although ultrasonic pulse-echo C-scanning is a mature non-destructive evaluation technique for imaging internal damage in composite structures, a major impediment of obtaining a full characterization of the internal damage state is delamination shadowing effects. Specifically, shadowing refers to regions of interest that are behind other delamination planes or discontinuities with respect to the scanning surface. The delamination planes block ultrasonic wave transmission and the regions of interest are thus hidden (i.e. shadowed) from the scan. A methodology has been developed to expand ultrasonic scan data of impacted composites by utilizing damage morphology information that is well established in the composite impact research community, such as matrix cracks bounding delaminations, to estimate shadowed delamination information and matrix cracking. First, impacted flat composite plates were C-scanned by pulse-echo ultrasonic and the results were segmented by depth of damage to establish interface-by-interface delamination information. These delaminations were then fit by bounding lines representing the fiber/matrix crack directions defined by the orientations of plies adjacent to each interface to estimate the shadowed portion of the delamination results. The area inside this boundary was added to the original ultrasonic delamination area to create an estimation of the full delamination state at each shadowed interface. Additionally, because this extension method is based on the interactions between delaminations and matrix cracking, this extension method provides an approximation of the matrix cracking of adjacent plies. Results were compared with X-ray computed tomography scans to assess the effectiveness of the extension method.
      Citation: Journal of Composite Materials
      PubDate: 2019-07-27T09:06:39Z
      DOI: 10.1177/0021998319865311
       
  • Towards sustainable copper matrix composites: Manufacturing routes with
           structural, mechanical, electrical and corrosion behaviour
    • Authors: Anbesh Jamwal, Prateek Mittal, Rajeev Agrawal, Sumit Gupta, Devendra Kumar, Kishor Kumar Sadasivuni, Pallav Gupta
      Abstract: Journal of Composite Materials, Ahead of Print.
      In the last few decades, man has become more innovative in discovering new materials to make his life more sustainable. Copper metal matrix composite is the most promising material for many engineering applications where the higher temperature resistance and good microstructural stability is required. The sustainable development of copper metal matrix composite is based on the use of ceramics as reinforcements. The choice of reinforcement material is highly influenced by their mechanical properties such as hardness, wear resistance, cost advantage, availability in market and refractory nature. In the current scenario, copper and its alloy are gaining popularity due to their high sustainability, high conductivity and good corrosion resistance. However, the relatively low wear resistance and high temperature strength restrict the use of copper in many applications. Recent developments in metal matrix composites have provided new means to produce high sustainable copper metal matrix composite materials with high wear resistance and high strength materials. It has been found that the wear resistance and strength of materials can be improved by adding hard ceramic particles such as Al2O3, SiC, TiC and ZrO2 into the metal matrix. The aim of the present study is to summarise the research work carried out in the field of sustainable copper metal matrix composites. It also reports the various manufacturing routes along with the structural, mechanical, electrical and corrosion properties. It is found that copper metal matrix composites are preferred over the conventional composites. Sustainability issues around the globe has forced the industries to adopt the eco-friendly materials with their fabrication and machining routes, which results in less carbon emission and also has less affect to the environment. Fabrication of eco-friendly composites is an emerging research area, which has made several research scopes in production of sustainable composites. It is expected that this study can be beneficial for the researcher to decide their research direction in the field of sustainable material production.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998319900655
       
  • Experimental analysis on tribo-performance of aluminum composites
    • Authors: Santanu Sardar, Susanta K Pradhan, Santanu K Karmakar, Debdulal Das
      Abstract: Journal of Composite Materials, Ahead of Print.
      Two-body abrasion is of critical interest in engineering applications due to the severity of material and dimensional loss. In the present work, composites were manufactured through advanced stir-casting route by reinforcing Al-Zn-Mg-Cu alloy with 0 to 20 wt.% alumina particles. Microstructures of the developed materials were characterized through optical and field emission scanning electron microscopic examinations along with energy dispersive spectroscopy analyses besides measurements of porosity and Vickers hardness. Experimentation on two-body abrasion was carried out over a wide range of loads (20–80 N) and sliding velocities (0.125–1.50 m s−1) against silicon carbide abrasive medium. Tribological performances of base alloy and composites were assessed via evaluation of wear rate and coefficient of friction (COF) in addition to the estimation of surface roughness (SR) of abraded specimens. Composites exhibited higher SR, but lower wear rate and COF than alloy; the extents of those increased with raising reinforcement quantity. With rise in load, wear rate and abraded SR of the developed materials rose but COF decreased. Influence of sliding velocity was nominal on material loss for composites unlike base alloy, whereas SR was found to increase considerably and COF diminished slightly at higher velocities for all materials. Influences of various in-situ and ex-situ parameters on observed tribo-responses were explained through identification of different wear micromechanisms which were established via extensive postwear analyses of surface topography, worn surface, debris, and abraded paper.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998319900524
       
  • Strength characterization of glass/epoxy plain weave composite under
           different biaxial loading ratios
    • Authors: A Kobeissi, P Rahme, L Leotoing, D Guines
      Abstract: Journal of Composite Materials, Ahead of Print.
      Over the past years, various studies have been investigated in order to characterize the behavior of composite materials under different multi-axial loading conditions. One of the most used biaxial techniques is the in-plane biaxial test on cruciform specimens. To achieve reliable biaxial failure results, the design of the cruciform specimen presents a crucial part. Previous studies show that there is no well-adapted cruciform geometry for the composite biaxial tests. In this paper, an optimal cruciform specimen has been defined numerically for the composite characterization test. The specimen is composed of two aluminum tabs glued on top and bottom side of the plain-weave glass/epoxy composite. Finite element simulations have been carried out in order to study the influence of the aluminum grade and thickness on the stress distribution in the composite. An experimental validation confirms the failure of the specimen in the central zone under three different biaxial tensile ratios. The experimental strains were evaluated using the digital image correlation method. The traction/traction quadrant of the failure envelop was obtained and compared with different failure criteria. The maximum strain criterion shows a good agreement with the experimental results.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998319899135
       
  • The effect of loading rate on the compression properties of carbon
           fibre-reinforced epoxy honeycomb structures
    • Authors: Alia R A, J Zhou, ZW Guan, Q Qin, Y Duan, WJ Cantwell
      Abstract: Journal of Composite Materials, Ahead of Print.
      The effect of varying strain rate on the compression strength and energy absorption characteristics of a carbon fibre-reinforced plastic honeycomb core has been investigated over a wide range of loading rates. The honeycombs were manufactured by infusing an epoxy resin through a carbon fibre fabric positioned in a dismountable honeycomb mould. The vacuum-assisted resin transfer moulding technique yielded honeycomb cores of a high quality with few defects. Compression tests were undertaken on single and multiple cells and representative volumes removed from the cores in order to assess how the compression strength and specific energy absorption vary with test rate. Crushing tests over the range of strain rates considered highlighted the impressive strength and energy-absorbing response of the honeycomb cores. At quasi-static rates of loading, the compression strength and specific energy absorption characteristics of the unidirectional samples exceeded those of the multidirectional cores. Here, extensive longitudinal splitting and fibre fracture were the predominant failure mechanisms in the cores. For all three stacking sequences, the single-cell samples offer higher compression strength than their five-cell counterparts. In contrast, the specific energy absorption values were found to be slightly higher in the five-cell cores. The experiments highlighted a trend of increased compression strength with loading rate in the multidirectional samples, whereas the strength of the [0°]4 samples was relatively insensitive to strain rate. Finally, the energy absorbing capacity of all structures studied was found to be reasonably constant at increasing rates of strain.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998319900364
       
  • Microstructure and thermal properties of nickel-coated carbon
           fibers/aluminum composites
    • Authors: Li-Fu Yi, Takashi Yamamoto, Tetsuhiko Onda, Zhong-Chun Chen
      Abstract: Journal of Composite Materials, Ahead of Print.
      Electroless nickel-coated carbon fibers/aluminum composites were prepared by spark plasma sintering, and the effect of nickel coating on microstructure and thermal properties of the composites has been investigated. Nickel coating on carbon fibers resulted in more homogeneous distributions of carbon fibers in aluminum matrix, higher relative density of carbon fibers/aluminum composites, and stronger interfacial bonding between carbon fibers and aluminum. Microstructural observations exhibited that the majority of carbon fibers were randomly distributed on the sections (X-Y direction) perpendicular to spark plasma sintering pressing direction (Z direction), thus leading to an anisotropic behavior in thermal conductivity of the composites. The thermal conductivity values in the X-Y direction of the carbon fibers/aluminum composites were much higher than those in the Z direction. As a result, the nickel-coated carbon fibers/aluminum composites with a nickel-coating thickness of ∼0.2 µm showed higher thermal conductivity and lower coefficient of thermal expansion values in comparison with those of the uncoated carbon fibers/aluminum samples.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998319899154
       
  • Orthogonal cutting of UD-CFRP using multiscale analysis: Finite element
           modeling
    • Authors: Amira Hassouna, Slah Mzali, Farhat Zemzemi, Salah Mezlini
      Abstract: Journal of Composite Materials, Ahead of Print.
      Unsuitable surface quality is frequently observed in the machining of composites due to their heterogeneity and anisotropic properties. Thus, minimizing the machining damages requires a thorough understanding of the machining process. In this study, two different finite element models were developed using Abaqus/Explicit to simulate the cutting process of unidirectional carbon fiber-reinforced polymer: (i) a macromechanical model based on the homogenization approach and (ii) a micromechanical model in which the composite constituents were treated separately. The effects of CFRP mechanical properties, the energy of breaking and hourglass control were analyzed using a macromechanical model. The results revealed that CFRP properties and the numerical parameters highly influenced the cutting process. A comparative study was also performed between the macromechanical and the micromechanical models to study the mechanisms of chip formation. It was demonstrated that the material removal mechanisms for both models are in good agreement with the experimental observations for different fiber orientation angles.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998319899129
       
  • A stress-relaxation approach to determine onset of delamination in angle
           ply laminates
    • Authors: Yi Xiao, Jiaxin Lv, P-Y Ben Jar
      Abstract: Journal of Composite Materials, Ahead of Print.
      A new test method, named multi-relaxation test, is proposed for detecting on-set of delamination in fibre-reinforced polymers. Multi-relaxation test is based on the principle that uses change of stress relaxation behaviour of fibre-reinforced polymer to detect the occurrence of delamination. In this study, angle-ply laminated fibre-reinforced polymer (APL-FRP) is used to demonstrate and evaluate multi-relaxation test for detection of the delamination occurrence. The stress relaxation behaviour is characterized using a standard, three-element viscoelastic model in which the Eyring’s law is used to govern the time-dependent stress response to deformation. Results suggest a high possibility of using the trend line change of viscous stress at the beginning of stress relaxation to determine the critical stroke for the onset of delamination. The results also suggest that value for the corresponding static stress is very close to the value reported in the literature for APL-FRP of the same fibre lay-up. The major advantage of multi-relaxation test over other tests for the same purpose is that multi-relaxation test is able to detect delamination without relying on ancillary information such as acoustic signals. Therefore, multi-relaxation test can be used to characterize critical loading and deformation in fibre-reinforced polymer structures of any size and geometry, even when subjected to a loading mode that mimics the in-service loading.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998319899131
       
  • Mechanical modeling of textile composites using fiber-reinforced voxel
           models
    • Authors: Jun-bo Xie, Chong Liu, Zhi Yang, Wei Jiao, Yi-fan Zhang, Xiao-ming Chen, Li Chen
      Abstract: Journal of Composite Materials, Ahead of Print.
      The fiber-reinforced voxel modeling technique is proposed to analyze the stress field and predict stiffness properties of textile composites. The textile reinforcements and matrix materials are modeled by virtual fibers and 3D voxel elements separately. Then the virtual fibers are “inserted” into the background voxel elements to construct the fiber-reinforced voxel elements. Stiffness properties of each fiber-reinforced voxel element are determined using volume average method based on the volume fraction and orientation of the virtual fibers it occupies. Geometry modeling and meshing of the complex reinforcements and matrix regions are avoided. As the reinforcements are generated in quasi-fiber scale, contact interactions and compaction deformations of the yarns can be modeled with high fidelity. A composite model containing one crimped yarn is used to verify the proposed method by comparing the calculating results of the fiber-reinforced voxel and traditional meso-scale models. The effect of voxel meshing density and virtual fiber radius on the simulation accuracy is also analyzed. Mechanical modeling of a multiply plain weave composite is performed by this model. Influence of nesting and compaction of the plies on the stress field can be fully characterized.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998319899134
       
  • An accurate zigzag theory for bending and buckling analysis of thick
           laminated sandwich plates with soft core
    • Authors: Qilin Jin, Weian Yao
      Abstract: Journal of Composite Materials, Ahead of Print.
      An accurate and computationally attractive zigzag theory is developed for bending and buckling analysis of thick laminated soft core sandwich plates. The kinematic assumptions of the proposed zigzag theory are obtained by superimposing a nonlinear zigzag function on the first-order shear deformation theory. In order to obtain the accurate transverse shear stresses, a preprocessing approach based on the three-dimensional equilibrium equations and the Reissner mixed variational theorem is used. It is significant that the second-order derivatives of in-plane displacement variables have been removed from the transverse shear stresses, such that the finite element implementation is greatly simplified. Thus, based on the proposed zigzag model, a computationally efficient four-node C0 quadrilateral plate element with linear interpolation function is proposed for bending and buckling analysis of soft core sandwich plates. The advantage of the present formulation is that no post-processing approach is needed to calculate the transverse shear stresses while maintaining the computational accuracy of a linear plate element. Moreover, the accurate transverse shear stresses can be involved in the strain energy which can actively improve the accuracy of critical loads. Performance of the proposed model is assessed by comparing with several benchmark solutions. Agreement between the present results and the reference solutions is very good, and the proposed model only includes the seven displacement variables which can demonstrate the accuracy and effectiveness of the proposed model.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998319899138
       
  • Performance of polylactide against UV irradiation: Synergism of an organic
           UV absorber with micron and nano-sized TiO2
    • Authors: Ulas Can, Cevdet Kaynak
      Abstract: Journal of Composite Materials, Ahead of Print.
      The main purpose of this study was to investigate mechanical and thermal performance of polylactide specimens against UV irradiation; first when only adding benzotriazole benzotriazole-based organic UV absorber (UVA), micro (200 nm) and nano (50 nm) sized titania (TiO2) particles alone, and then to reveal possible synergism when they are added together. Compounds were prepared by twin-screw extruder melt mixing, while the 2 mm thick specimens were shaped by compression molding. Specimens were exposed to UV irradiation under fluorescent lamps (UVB-313) with 0.50 W/m2 for the periods of 12 and 24 days. Changes in the performance of UV irradiated specimens were evaluated in terms of % weight loss, changes in color and chemical structure, including the decreases in the mechanical and thermal properties. Various tests and analysis revealed that synergistic benefits of using micro and nano TiO2 particles together with benzotriazole-type UVA were not only due to the effective stiffening, strengthening and toughening actions of titania particles, but also due to their very significant “UV screening” actions absorbing the photons of the UV irradiation, thus decreasing the degree of the detrimental photodegradation reactions leading to chain scissions in their PLA matrix.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998319899140
       
  • A new theoretical creep model of an epoxy-graphene composite based on
           experimental investigation: effect of graphene content
    • Authors: Ata Khabaz-Aghdam, Bashir Behjat, Lucas F M da Silva, E A S Marques
      Abstract: Journal of Composite Materials, Ahead of Print.
      In this paper, the creep behavior of an epoxy-based adhesive reinforced with different weight fractions of graphene up to 0.5 wt% was studied. Creep tests were performed in three stress levels, using the ultimate strength of the neat epoxy as a reference. Results indicated that the presence of graphene up to 0.5 wt% reduces the creep strain and strain rate of the epoxy. However, the dominant behavior in the creep of epoxy–graphene composites is the creep pattern of the neat epoxy. These experimental observations led to development of theoretical creep models to an appropriate creep model for graphene-reinforced composites by introducing a new function of the graphene weight ratio. A scanning electron microscopy analysis indicated that the strong bond between the graphene surface and epoxy matrix limits the mobility of the molecular chains of the neat epoxy and therefore reduces the creep strain.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998319895806
       
  • Will a buried composite pipeline system fail at its joints under the
           effects of overburden soil, pipe operating pressurization, and traffic
           loads'
    • Authors: Kwong Ming Tse, William Toh, Long Bin Tan, Heow Pueh Lee, Vincent Beng Chye Tan
      Abstract: Journal of Composite Materials, Ahead of Print.
      In real world applications, buried pipelines span across great lengths. It is inevitable that certain sections of a buried pipeline experience external loads in addition to top soil overburden, such as weights of aboveground buildings and traffic loads located directly above these sections. The present study investigated the effects of overburden soil, pipe internal pressurization, and traffic loads on fiber-reinforced plastic pipelines at various pipe sections with particular emphasis on pipe joints using finite element method. This study includes realistic modeling of traffic loading on service road running across a buried pipeline system, consisting of straight, bent, and joint sections. Our results also revealed that surcharge loading might not be a predominant factor in pipe failure or leakage issues as compared to the cyclic pipe internal pressurization. Moreover, it was also confirmed in our study that the pipe joint remained as the most critical region for pipe failure or leakage issues.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998319897138
       
  • Electrical, mechanical, and optical changes in MWCNT-doped PMMA composite
           films
    • Authors: Ömer Bahadır Mergen, Ertan Arda, Gülşen Akın Evingür
      Abstract: Journal of Composite Materials, Ahead of Print.
      In this study, we report the preparation of poly (methyl methacrylate)/multi-walled carbon nanotube (MWCNT) composite thin films by simple and efficient solution mixing and ultrasonic method and the electrical, optical, and mechanical characterizations. Scattered light intensity (Isc), tensile modulus (E), and surface conductivity (σ) of these composites have increased with the addition of MWCNT into the composite. The observed behavior in electrical, optical, and mechanical properties of the poly (methyl methacrylate)/MWCNT composites was interpreted by site and classical percolation theory. The optical mechanical and electrical percolation thresholds of poly (methyl methacrylate)/MWCNT composites were determined as φop = 3 wt%, φm = 0 wt%, and φσ = 5 wt%, respectively. The optical (top), mechanical (tm), and electrical (tσ) critical exponents were calculated as 2.23, 0.43, and 0.11, respectively. Both the tensile modulus and tensile strength of poly (methyl methacrylate)/MWCNT composites were increased with increasing MWCNT content until it reaches to 10 wt%. However, above φ = 10 wt%, the mechanical properties of the composites were decreased due to the aggregation of MWCNTs, while the toughness does not show a significant change until φ = 10 wt% MWCNT content, whereas it was decreased above this value.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998319898507
       
  • Bi-tubular corrugated composite conical–cylindrical tube for energy
           absorption in axial and oblique loading: Analysis and optimization
    • Authors: Amirreza Sadighi, Mahshid Mahbod, Masoud Asgari
      Abstract: Journal of Composite Materials, Ahead of Print.
      In this paper, a new bi-tubular corrugated composite tube, consisting of inner and outer cylindrical and conical tubes is proposed. Different models with various geometrical parameters including the radius of curvatures and their numbers are considered and studied numerically in axial and oblique crushing in order to achieve favorable crashworthiness parameters. Moreover, quasi-static compression tests have been conducted to obtain results in order to validate the finite element model. There has been a sensible agreement between the numerical results and experimental data. Finite element models are also validated using the analytical solutions for both straight and corrugated composite tubes. Regardless of the number and radius of curvatures, as the crashworthiness of bi-tubular corrugated structures both in axial and oblique crushing is investigated and compared with their single-wall and bi-tubular straight peers, a considerable improvement is achieved in all crashworthiness parameters, including desirable increase in specific energy absorption, favorable reduction in peak force, and consequently a beneficial rise in crushing force efficiency. In addition, an optimization study using a suitable multi-objective function is done to choose the best model among the existing models, in addition to finding an optimum model via genetic algorithm. In the next step, a parametric study is conducted on the best model to inspect how well it undergoes oblique crushing at different angles. Finally, this best model and two other candidates have been chosen to investigate the effect of using foams and then the energy absorption capability of the empty and foam-filled tubes has been compared.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998319897407
       
  • Static and fatigue behavior of basalt fiber-reinforced thermoplastic epoxy
           composites
    • Authors: Xin Wang, Xing Zhao, Siqi Chen, Zhishen Wu
      Abstract: Journal of Composite Materials, Ahead of Print.
      The static, fatigue properties and their damage mechanism of basalt fiber-reinforced thermoplastic epoxy polymer composites are investigated. The stress–life curves and stiffness degradation under long-term cyclic loading were tested for basalt fiber-reinforced thermoplastic epoxy polymer. An advanced fatigue loading equipment combined with in situ scanning electron microscopy was used in the tests to track the damage propagations and analysis the fracture surfaces of all specimens. Results were also compared with those of thermosetting epoxy-based basalt fiber-reinforced polymer composites. The results show that the basalt fiber-reinforced thermoplastic epoxy polymer has good interface properties between the fiber and new thermoplastic epoxy, which results in high tensile strength and ductility. Different degradation rates of low- and high-cycle fatigue loads are observed for the basalt fiber-reinforced thermoplastic epoxy polymer composites. Under high fatigue stress levels, a high degradation rate of the fatigue life is found because the dominating damage pattern showed fiber fractures. At low and medium fatigue stress levels, the damage pattern is dominated by matrix cracking and interface debonding, which results in a low degradation rate of the fatigue life. A bilinear phenomenological fatigue model has a higher accuracy for fitting the stress–life data than linear fatigue models. In addition, 80–90% stiffness degradations are observed before failure for all stress levels at a stress ratio of 0.8. Furthermore, compared with thermosetting epoxy-based basalt fiber-reinforced thermoplastic epoxy polymer, the basalt fiber-reinforced thermoplastic epoxy polymer has similar static strength and similar fatigue life at high-stress levels. However, at low-stress levels, the fatigue life of the this polymer is much higher than that of thermosetting one.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998319896842
       
  • Properties improvement of multiwall carbon nanotubes-reinforced
           cement-based composites
    • Authors: Baomin Wang, Bo Pang
      Abstract: Journal of Composite Materials, Ahead of Print.
      Multiwall carbon nanotubes with extraordinary mechanical properties have been widely used as effective nano-reinforcer of cement-based composites. In this research, multiwall carbon nanotubes were dispersed uniformly in aqueous solution using N,N-dimethylformamide as dispersant with ultrasonication. The structure and micromorphology of multiwall carbon nanotubes were characterized via X-ray photoelectron spectroscopy and transmission electron microscopy. The effect of N,N-dimethylformamide on multiwall carbon nanotubes dispersion was better than that of previous dispersants. The multiwall carbon nanotubes/cement composites with different multiwall carbon nanotubes contents were prepared and the mechanical performances of multiwall carbon nanotubes/cement composites were researched. Results showed that the flexural strength growth rate of multiwall carbon nanotubes/cement composites was 21.7% and the compressive strength growth rate of the multiwall carbon nanotubes/cement composites was 2.9% incorporating with 0.04 wt% multiwall carbon nanotubes at 28 days. The ratio of compressive strength to flexural strength of decline rate of multiwall carbon nanotubes/cement composites was 15.9% with 0.04 wt% multiwall carbon nanotubes at 28 days. The isothermal calorimetry (TAM Air) showed that multiwall carbon nanotubes could accelerate the hydration reaction. The X-ray diffraction and thermal gravity analysis (TG/DTG) suggested that multiwall carbon nanotubes could improve the hydration process and increase the number of hydration products. The mercury intrusion porosimetry revealed the porosity of multiwall carbon nanotubes/cement composites was decreased. There is an effect of multiwall carbon nanotubes on inhibiting the extension of cracks and promoting the degree of compactibility of the cement-based composites. The micromorphology of multiwall carbon nanotubes/cement composites was observed through scanning electron microscope.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998319896835
       
  • Rheological and mechanical properties of tape-casted zirconia-toughened
           alumina composite thick films reinforced with multiwalled carbon nanotubes
           
    • Authors: SH Mussavi Rizi, M Ghatee
      Abstract: Journal of Composite Materials, Ahead of Print.
      This paper reports the effects of adding carbon nanotubes on the mechanical properties of zirconia-toughened alumina thick films prepared by tape casting. Polyvinylpyrrolidone, polyvinyl alcohol, and glycerin were used as dispersant, binder, and plasticizer, respectively. The microstructure and phase content of the samples were studied using scanning electron microscopy and X-ray diffraction methods, respectively. Mechanical properties of thick composite films were investigated by microhardness and nanoindentation methods. It was determined that polyvinylpyrrolidone can be used as a dispersant for carbon nanotube, alumina, and zirconia particles; tape casting can produce thick films with homogeneous phase distribution, and that adding up to 0.01 wt.% carbon nanotube enhanced the zirconia-toughened alumina hardness by more than 30%, and fracture toughness about 40%. Increasing carbon nanotube content over 0.01 wt.% up to 0.1 wt.% increases microhardness and nanohardness but does not affect fracture toughness significantly.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998319897741
       
  • Experimental and numerical investigation of the transition zone of locally
           steel-reinforced joining areas under combined tension–bending loading

         This is an Open Access Article Open Access Article

    • Authors: E Petersen, J Koord, O Völkerink, D Stefaniak, C Hühne
      Abstract: Journal of Composite Materials, Ahead of Print.
      In modern lightweight structures, the use of fasteners is preferred to other joining techniques. An approach to increase the bearing strength is the local metal hybridisation, where carbon fibre-reinforced plastics layers are substituted locally by metal foils of the same thickness. The local replacement leads to a transition zone between the hybrid region and the pure carbon fibre-reinforced plastics region. The present work deals with the investigation of different transition zone patterns of carbon fibre-reinforced plastics-steel hybrid specimens in combined tension–bending tests and accompanying non-linear static simulation. The simulation includes delamination and intralaminar damage with the use of a cohesive zone model and Cuntze’s failure mode concept. Furthermore, residual thermal stresses are considered. A satisfying agreement of test and simulation is achieved, which allows the identification of beneficial transition zone configurations and also validates the numerical model for further parametric studies.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998319893729
       
  • A study on microstructural effect and mechanical behaviour of
           Al6061–5%SiC–TiB2 particulates reinforced hybrid metal matrix
           composites
    • Authors: Justin Maria Hillary J, Ramamoorthi R, Dixon Jim Joseph J, Samson Jerold Samuel C
      Abstract: Journal of Composite Materials, Ahead of Print.
      In this present work, an attempt is made to prepare Al6061–5%SiC–TiB2 hybrid composites using stir casting process by considering optimal process parameters such as stirring temperature, stirring speed, stirring time, preheating temperature, grain size and wt% of particulate reinforcement and examine their metallurgical effect and mechanical behaviour. The metal composite samples were prepared using stir casting process in which the amount of reinforcement of 5%SiC is kept constant, and second reinforcement of TiB2 is varied by its weight fraction of 2, 4, 6, 8 and 10%. The prepared dual particulates reinforced hybrid composites are characterised, and their microstructural, mechanical properties and fractograpy were evaluated as per the standards. Strong interfacial bonding between matrix and reinforcements which are the significance of improved wettability is due to Potassium Hexafluorotitanate salt addition, and preheating of particles of SiC at 800℃ and TiB2 at 250℃ is made before adding into the melt. The results revealed that the increase in addition of TiB2 increases the tensile strength, flexural strength, impact strength and hardness by decreasing their weight density, and also the influence of SiC increases the hardness of the material of newly developed composite. Also, fracture morphology of tensile failure has been studied to examine micro-mechanisms of failure, and the mode of failure of the composites was found to be ductile.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998319894666
       
  • The effect of particle size on microstructure, relative density and
           indentation load of Mg-B4C composites fabricated at different loading
           rates
    • Authors: K Rahmani, GH Majzoobi
      Abstract: Journal of Composite Materials, Ahead of Print.
      The effect of reinforcing particle size on microstructure, relative density and indentation of Mg reinforced by 0, 1.5, 3, 5 and 10% volume fractions of nano- and micro-sized B4C was investigated. The composites were fabricated through powder compaction technique at strain rates of 1.6 × 103 s−1, 8 × 102 s−1 and 8×103 s−1 using split Hopkinson bar, drop hammer and Instron, respectively. The results indicated that the size of B4C and loading rate had significant effect on relative density. For example, the relative density of Mg-10 vol.% B4C nanocomposite was around 2.5% higher than that of its corresponding microcomposites. The relative density of the samples produced at high rate of loading was in average 1.2% higher than that of the samples fabricated quasi-statically. The results of indentation tests on the produced nanocomposite and microcomposite samples also revealed that loading rate and B4C particle size had significant effect on strength of specimens. For example, for Mg-5 vol.% B4C, the maximum load in load–depth curve of the specimens produced by split Hopkinson bar increased from 530 N for micron-sized B4C to 780 N for nano-sized B4C, around 45% improvement. Moreover, nanocomposites had better indentation resistance compared to similar micro composites fabricated using the three methods.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998319896009
       
  • Calibration of the material parameters of a CFRP laminate for numerical
           simulations
    • Authors: A Gilioli, A Manes, M Giglio
      Abstract: Journal of Composite Materials, Ahead of Print.
      The aim of present paper is to show a procedure to calibrate mechanical properties to be used in a finite element model for a carbon fibre-reinforced plastic laminate that use solid elements. A reduced experimental programme including tensile test, tensile test on specimen with a central hole, three-point bending test and three-point bending test on short beam test were carried out. Every test was numerically reproduced by means of an explicit solver. Properties are determined from the tensile test and unmodified for the other load scenarios which are used as validation benchmarks. Finally, it is demonstrated that the properties determined with the simple tensile tests can guarantee accurate results when adopted to simulate much more complicated stress patterns.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998319896015
       
  • Void characteristics and mechanical strength of cementitious mortars
           containing multi-walled carbon nanotubes
    • Authors: Arash Sedaghatdoost, Kiachehr Behfarnia, Ali Hendi, Mohammad Bayati
      Abstract: Journal of Composite Materials, Ahead of Print.
      In this paper, the relationship between mechanical strength and void characteristics including porosity, the mean area of voids (MAV), and circularity was determined for the first time by analyzing the petrographic images of some cement mortars containing multi-walled carbon nanotubes (MWCNTs). The results showed that the compressive, tensile, and flexural strength for specimens containing 0.1% MWCNTs (optimum dosage of MWCNT) were 21, 12.5, and 9.5% more than that of the control samples, respectively. Also, it was shown that the application of MWCNTs can change the shape and the amount of voids, thereby imposing a significant impact on the mortar behavior. For the optimum dosage of MWCNTs, the porosity and MAV decreased about 63 and 71%, respectively, while the circularity enhanced 23% in comparison with the ordinary mortar samples. The void shape is one of the reasons for the enhanced properties of the MWCNT mortars. The image processing of the petrographic specimens and probability theorization revealed that the circularity of the voids had a significant impact on the flexural strength of the mortars, while the compressive strength was mostly affected by only the amount of porosity.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998319896016
       
  • Temperature effect on the mechanical properties and damage mechanisms of a
           glass/thermoplastic laminate
    • Authors: L Cadieu, J B Kopp, J Jumel, J Bega, C Froustey
      Abstract: Journal of Composite Materials, Ahead of Print.
      The aim of this study is to evaluate the temperature effect on the mechanical properties and damage mechanisms of a Glass/Elium 150 laminate composite. Quasi-static indentation tests are carried out at different temperatures to highlight the temperature dependency of different parameters of the samples (stiffness, maximum load, stored elastic energy, and applied energy). The different damage mechanisms involved in the collapse of the composite are observed at the macro-, meso-, and micro-scopic scales using optical and scanning electron microscopy. The influence of temperature on these damage mechanisms is discussed based on post-mortem observations. It has been highlighted that the kind and the severity of damage are strongly temperature dependent. Below 20℃, fiber breakage, strand failure, intra- and inter-laminar crack propagation are identified. At 60℃, plastic flow of the polymer matrix is observed, which modifies micro-crack propagation at the fiber/matrix interface. Above 90℃, only intra-laminar micro-cracking occurs. To conclude, based on all these observations the kinetics of damage appearance are discussed.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998319894383
       
  • The effect of radiation exposure on carbon fiber-reinforced Rohacell®
           core laminate structural composites
    • Authors: Rafael J Zaldivar, D Marques, C Barrie, D Patel
      Abstract: Journal of Composite Materials, Ahead of Print.
      Two equivalent density foams with identical shear strengths were used to manufacture carbon-fiber reinforced composite sandwich structures. One foam core system (Rohacell® 71 WF) has a cell diameter of 1117 µm and a wall thickness of 29 µm, while the second one (Rohacell® 71 HERO) has cell diameter of 146 µm and a wall thickness of 3 µm. A 60Co source was used to expose composites from 0 to 12 Mrads of radiation. Tests were used to evaluate the effect of radiation on the core shear strength and failure mechanism for both types of composites. The WF composites experienced a 75% decrease in core shear strength, while the HERO only exhibited an 8% decrease. The fracture behavior of the WF composites changed from a more compliant to a brittle fracture path with increased radiation. The fracture modes for the HERO were similar and did not change characteristics, even with maximum radiation dosage. Thermal analysis also showed that even after composite thermal processing, the WF foam retained a lower Tg in comparison to the HERO foam. Dynamic mechanical analyzer also indicated a faster rate of Tg degradation for the WF foam composites as a function of radiation, suggesting a lower degree of crosslinking which resulted in fragmentation of the network. Thermal gravimetric analysis and size exclusion chromatography also exhibited an earlier onset of thermal degradation for the WF foams with radiation. This investigation suggests that changes in composite mechanical properties with radiation are related to both foam macrostructure and the degree of crosslinking of the polymer foam. Careful evaluation must be performed to establish proper selection of the composite core material based on end of life environmental exposure.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998319893009
       
  • Improving mechanical and thermal properties of graphite–aluminium
           composite using Si, SiC and eggshell particles
    • Authors: MO Durowoju, TB Asafa, ER Sadiku, S Diouf, MB Shongwe, PA Olubambi, KO Oladosu, A Ogbemudia, MM Babalola, MT Ajala
      Abstract: Journal of Composite Materials, Ahead of Print.
      Graphite–aluminium (Gr–Al) composites are being used for diverse engineering applications because of their light weight, good electrical conductivity and thermal properties. However, their applications are limited by high coefficient of thermal expansion and low microhardness values which can be enhanced by adding cheap and efficient fillers. This paper reports the effect of addition of eggshell (ES) particles on the properties of sintered Gr–Al-based composites. Five different composites (Gr–Al, Gr–Al  +  20 wt.%Si, Gr–Al + 20 wt.%SiC, Gr–Al + 20Si wt.% + 20 wt.%ES and Gr–Al + 20SiC wt.% + 20 wt.%ES) were sintered at a temperature of 540 ℃, holding time of 10 min, heating rate of 52 ℃/min and pressure of 50 MPa using spark plasma sintering system. The sintered samples were characterized based on morphology, microhardness, relative density, coefficient of thermal expansion and electrical conductivity. Based on SEM images, graphite particles of flake-like structure were largely undeformed while Al particles were smaller, round and irregular in shape and fairly uniformly distributed in the composites. The microhardness value of sintered Gr–Al + 20 wt.%SiC + 20 wt.%ES composite was 39.55 HV compared to 30.46 HV for Gr–Al, the least of the samples. The Gr–Al + 20 wt.%SiC + 20 wt.%ES composite also has a very low thermal expansion coefficient (0.98 × 10−5/K) but lowest electrical conductivity at temperature beyond 150 ℃. Highest densification and minimum relative density (94%) were obtained in Gr–Al + 20 wt.%Si + 20 wt.%ES composite. These enhanced performances are largely due to the incorporation of ES particles. This study therefore demonstrated that ESs particles enhanced microhardness and lowered thermal expansion of Gr–Al-based composites which have promising applications in industries especially for thermal management.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998319892058
       
  • High-temperature effect on the mechanical performance of screwed
           CFRPI–TC4 alloy joints repaired with metal inserts
    • Authors: Yun-Tao Zhu, Jun-Jiang Xiong
      Abstract: Journal of Composite Materials, Ahead of Print.
      This paper seeks to study high-temperature effect on mechanical performance of screwed single-lap carbon fiber-reinforced polyimide–TC4 titanium alloy joints repaired with metal inserts. Quasi-static tension tests were conducted at room temperature (RT) and 250℃ to determine the joint strength and stiffness of repaired joints with metal inserts. Based on the experimental results, high-temperature effect on joint strength and stiffness and insert repair efficiency were analyzed and discussed. A new analytical model was established to evaluate the effect of high temperature on joint stiffness. It is concluded that (1) joint strength and stiffness for all configurations are lower at 250℃ than that at RT, showing the expected detrimental effect of high temperature on joint strength and stiffness. The reductions in joint strength and stiffness depend on the joint configuration; (2) the repair efficiencies of embedded conical nut for joint strengths of protruding and countersunk head screw joints decrease, but those for joint stiffness increase at 250℃ as against at RT. Unlike the repair efficiencies of embedded conical nut, the repair efficiency of bushing for joint strength is slightly greater, but that for joint stiffness is less at 250℃ than at RT; and (3) the developed analytical model is capable of predicting the displacement of screwed single-lap carbon fiber-reinforced polyimide–TC4 joints at RT and high temperature, and there is good agreement between the experimental data and the predicted curves.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998319893749
       
  • Low-velocity impact behavior of glass fiber epoxy composites modified with
           nanoceramic particles
    • Authors: Harish Kallagunta, Jitendra S Tate
      Abstract: Journal of Composite Materials, Ahead of Print.
      The introduction of new type of nanomaterials has provided challenges in a deeper level understanding of mechanical behavior and failure mechanisms of fiber-reinforced composites. In this study, a comparison of low-velocity impact behavior of E-Glass epoxy composites modified with 10 wt% nanosilica and 2.5 wt% Nafen™ alumina nanofibers manufactured using vacuum-assisted resin transfer molding is reported. Low-velocity impact tests at three impact energies of 29 J, 39 J, and 50 J are conducted and impact responses, such as impact strength, absorbed energy, and damage area are determined and compared for the two nanoparticles. The damage sustained by composite samples is evaluated by optical microscopy and infrared thermography. Nanosilica-incorporated composites showed rigid behavior, whereas alumina nanofiber-modified composites showed increased stiffness at increased energy of impact as observed from the initial stiffness and deflection of samples. The degree of damage in case of 10 wt% nanosilica-modified composites is reduced by 7.04%, 3.96%, and 7.92% for energy levels of 29 J, 39 J, and 50 J respectively when compared to nonmodified composites, whereas 2.5 wt% alumina nanofiber-modified composites showed 1.66%, −7.35%, and 26.39% for energy levels of 29 J, 39 J, and 50 J, respectively.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998319893435
       
  • Dielectric strength and mechanical properties of epoxy resin filled with
           self-propagating high-temperature synthesized Al2O3/SiC nanoparticles
    • Authors: M Hoseini, G Dini, M Bahadori
      Abstract: Journal of Composite Materials, Ahead of Print.
      In this study, the rice husk as a source of silica was used to synthesize the Al2O3/SiC composite via the self-propagation high-temperature synthesis (SHS) process. Then, the particle size of the synthesized product was reduced to the nanoscale using a planetary ball mill. Finally, different amounts (5, 10, and 15 wt.%) of Al2O3/SiC nanoparticles were incorporated into an epoxy resin in order to improve the mechanical properties and the dielectric strength of fabricated epoxy-based composites. The results indicated that the Al2O3/SiC composite was successfully synthesized by the SHS process from a mixture of the rice husk ash, Al, and carbon black powders as starting materials. The average size of the synthesized Al2O3/SiC particles decreased to 80 nm after 12-h ball milling. Also, the mechanical properties of the fabricated epoxy-based composite samples were improved with the addition of Al2O3/SiC nanoparticles in the investigated range in comparison with the pure epoxy sample. Additionally, the overall dielectric strength of the fabricated epoxy-based composites containing 5–15 wt.% of Al2O3/SiC nanoparticles was higher than that of the pure epoxy. These results were interpreted in terms of the synthesis mechanism of Al2O3/SiC composite via the SHS process, the rice husk ash structure, the interfacial bonding between the polymer chains and the surface of nanoparticles, and the insulation nature of the synthesized nanoparticles.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998319891202
       
  • Effects of EVA-g-MA and EVACO compatibilizers/tougheners on morphological
           and mechanical properties of PP/EVA/HNT blend polymer nanocomposites
    • Authors: Salih Doğu, Emre Tekay, Sinan Şen
      Abstract: Journal of Composite Materials, Ahead of Print.
      A series of polypropylene (PP)/poly(ethylene-co-vinyl acetate) (EVA) blend nanocomposites was produced by utilizing different amounts of organophilic halloysite nanotube (Org-HNT) and EVA-based compatibilizers/tougheners. They were prepared by using either only EVA elastomer or using EVA with the compatibilizers which are maleic anhydride grafted EVA (EVA-g-MA) and poly(ethylene-vinyl acetate-carbon monoxide) (EVACO) as well as maleic anhydride grafted PP (PP-g-MA). The morphology–mechanical property relationship was investigated as a function of nature of the compatibilizer and the amount of aluminosilicate nanotube/compatibilizer. The composites prepared without using the EVA-based compatibilizers in all nanotube loading degrees (1%, 3%, 5%) exhibited nanotube aggregates as evidenced by scanning electron microscope analyses. On the other hand, EVA-g-MA and EVACO provided a good dispersion of HNTs at both PP–EVA interface and in the PP matrix. The use of compatibilizers together with 3% Org-HNT resulted in PP/EVA blend nanocomposites with higher tensile modulus and toughness when compared to PP/EVA blend. Particularly, EVACO compatibilizer having highly polar carbonyl group at its backbone provided the highest toughness and Young’s modulus as well as impact resistance for the 3% Org-HNT loaded nanocomposite while retaining the yield strength as an indication of a good balance between stiffness/toughness.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998319893423
       
  • Applying the Hashin–Shtrikman bounds to predict stiffness of
           multicomponent 3D printed structures: Towards regenerative orthopaedic
           medicine
    • Authors: Georgio A Katsifis, David R McKenzie, Natalka Suchowerska
      Abstract: Journal of Composite Materials, Ahead of Print.
      Customised orthopaedic implants made from polymer materials would have advantages over metallic implants, if the mechanical properties could be matched more closely to bone. Here, the Hashin–Shtrikman bounds for isotropic composites are used to examine the feasibility of using scaffolds made from 3D printed polyether–etherketone (PEEK) that may adequate modulus immediately after printing, but when integrated and mineralised could approach the modulus of bone. The ability to predict the mechanical properties of 3D printed objects is essential for skeletal implants that require both immediate and long-term strength, such as the mandible and the femur. However, there is no method for predicting the change in mechanical properties due to the effect of ossification of bone scaffolds. Our aim was to calculate the upper and lower limits of the elastic moduli of polymer composites using the Hashin–Shtrikman bounds for isotropic composite solids and use them to compare the pre- and post-ossification properties for a range of scaffolds. We describe 3D printed PEEK as a composite of fully dense PEEK and air, water or bone. We confirm, by mechanically testing three designs, that our 3D printed scaffolds lie within the Hashin–Shtrikman bounds for PEEK–air composites. Improvements in strength achieved by integrating the PEEK scaffold with bone are predicted by calculating the Hashin–Shtrikman bounds for a three-phase composite and show the feasability of reaching bone equivalence. These predictions can be implemented for orthopaedic applications, customising the implant such that it can provide the appropriate immediate and long-term mechanical support for a specific implant size.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998319891201
       
  • Numerical study of GFRP joints bearing strength reduction due to
           drilling-induced delamination
    • Authors: M Safarabadi, M Sardar
      Abstract: Journal of Composite Materials, Ahead of Print.
      Delamination is one of the most common defects caused by drilling, which can have negative effect on the joint performance. This study investigates the effect of delamination on the bearing strength of [0/90]2s, [15/−75]2s, [30/−60]2s and [45/−45]2s GFRP layers numerically. Cohesive zone method and virtual crack closure technique have been used for delamination modeling and the results of these two methods have been compared. FEM results show good agreement with available experimental data. Results demonstrated that delamination reduces the bearing strength. Among four different stacking sequences, delamination has the most effect on the laminate with the stacking sequence of [0/90]2s. In both delaminated and non-delaminated models, [0/90]2s and [45/−45]2s stacking sequences have the most and the least bearing strength, respectively. By increasing the radius of delaminated zone from 3 mm to 15 mm, bearing strength does not change a lot. As the delaminated zone reaches the edge of the specimen, bearing strength reduces strongly because the layers separate completely and the load-carrying capacity reduces. A parametric study was also conducted to examine the effects of different factors. The results of parametric study showed that by increasing the volume fraction of the fiber as well as the use of carbon fiber instead of glass fiber, the bearing strength increases.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998319893075
       
  • Effects of honeycomb core damage on the performance of composite sandwich
           structures
    • Authors: William T King, William E Guin, J Brian Jordon, Mark E Barkey, Paul G Allison
      Abstract: Journal of Composite Materials, Ahead of Print.
      This work presents an experimental and numerical investigation of the effects of pre-existing core damage on aluminum honeycomb core composite sandwich structures. Quasi static flexural and compression experiments were performed, where the effects of core damage on the shear modulus and Young's modulus were quantified. In addition, finite element analysis was performed on the sandwich structures to elucidate the effects of the core damage on the structural response. Comparisons of experimental and finite element responses are presented for sandwich structures consisting of carbon fiber facesheets and an aluminum honeycomb core. The pre-existing core damage is observed to cause up to an 8% reduction in shear modulus and a 9% reduction in elastic modulus. It is also determined that the presence of pre-existing core damage results in an asymmetrical compressive load distribution in the composite structures.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998319890656
       
  • Gate optimization for resin transfer molding in dual-scale porous media:
           Numerical simulation and experiment measurement
    • Authors: Yutaka Oya, Tsubasa Matsumiya, Akira Ito, Ryosuke Matsuzaki, Tomonaga Okabe
      Abstract: Journal of Composite Materials, Ahead of Print.
      For resin transfer molding in a woven fabric, this study developed a novel framework for optimization by combining a multi-objective genetic algorithm and mold-filling simulation including a void-formation model, which gives us not only the spatial distribution of the mesoscopic and microscopic voids but also the correlations between molding characteristics such as fill time, total amount of void, weld line, and wasted resin. Our experiment observation of one-point radial injection successfully captured the anisotropic distribution of mesoscopic voids, which qualitatively validates the simulated result. As a result of multi-objective optimization for an arrangement of two injection positions, we found the trade-off relations of weld line with the other characteristics, which also have positive correlation with each other. Furthermore, visualization techniques such as self-organizing maps and parallel coordinate maps extracted the design rule of the arrangement. For example, a diagonal gate arrangement with an appropriate distance is required for reducing the both total amount of voids, fill time, and wasted resin; however, the total area of the weld line becomes relatively large. Our framework and the knowledge obtained from this study will enable us to determine the appropriate mold design for resin transfer molding.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998319890122
       
  • Micro/nanoscale structural, mechanical and tribological characterization
           of ZA-27/SiC nanocomposites
    • Authors: Miroslav Babic, Blaza Stojanovic, Dragan Dzunic, Marko Pantic
      Abstract: Journal of Composite Materials, Ahead of Print.
      The structural, mechanical and tribological properties of ZA-27/SiC nanocomposites were investigated at micro/nanoscale. The nanocomposites with different volume fractions of nano-sized SiC particles were produced using the compocasting technique. The microstructure of nanocomposites was characterized with formation of SiC nano agglomerates, which were relatively uniformly distributed. The increase in SiC content contributed to the uniformity of their distribution. Also, the phenomenon of particle segregation in the form of particle-rich clusters, as well as particle-porosity clusters, was identified. The density level of composites decreased with the increase of the SiC content. The porosity followed a reverse trend. The tendency for formation of local particle-porosity clusters was the highest in ZA-27/1% SiC nanocomposite, causing the highest level of porosity. Increasing percentage of SiC content was followed by the increase in micro/nanohardness of the composites. The results of micro/nanoscale tribotests revealed that the reinforcing with SiC nanoparticles significantly improved wear and friction behavior of ZA-27 matrix alloy. The rate of improvement increased with the increase of SiC nanoparticle content, load, and sliding speed. The highest degree of changes corresponded to the change of the SiC nanoparticle content from 0 to 1 wt%. The further decrease of wear with SiC content (from 1 to 5 wt%) was almost linear. The different tribological behavior of tested ZA-27 matrix and ZA-27/SiC nanocomposites was influenced by differences of intensity of adhesion resulted in transferred layers of matrix material onto worn surfaces of Al2O3 ball counterpart. The intensity of adhesion significantly decreased with the increase of SiC nanoparticle content.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998319891766
       
  • Influence of carbon nanotubes on the properties of friction composite
           materials
    • Authors: Emad F EL-kashif, Shaimaa A Esmail, Omayma AM Elkady, BS Azzam, Ali A Khattab
      Abstract: Journal of Composite Materials, Ahead of Print.
      Carbon nanotubes have a lot of applications in mechanical fields. This is because nanomaterials have many superior mechanical properties such as very high strength-to-weight ratio, high modulus-to-weight ratio, high corrosion resistance, and super intelligence properties, which make them as smart materials. One of these attractive applications is the use of carbon nanotubes in vehicle brake friction material. Therefore, the fabrication and testing processes of these nanomaterials should be performed carefully to evaluate their mechanical, tribological, and noise properties. In this paper, friction material mixed with carbon nanotubes have been fabricated with different carbon nanotube contents and the same fabrication parameters. The carbon nanotubes have been produced using the conventional submerged arc discharge technique. The produced friction materials have been cut into pieces with standard sizes and then tested mechanically and tribologically. The results of tests have illustrated that the addition of carbon nanotubes into the friction materials could improve their mechanical properties (hardness, strength, and modulus) and also could enhance their tribological properties (wear rate and friction coefficient). Moreover, the tests showed that the presence of carbon nanotubes in friction materials could reduce the noise, vibration of the friction materials, and reduce the temperature rise due to the effect of friction, which means that the carbon nanotubes could raise the thermal conductivity of friction material, while the friction coefficient has stayed within the allowable standard limits (0.35–0.45). Surface morphology shows that the presence of carbon nanotubes in the friction materials could help to avoid surface friction cracks or fins within the normal operating conditions. The good combination of mechanical and tribological properties was obtained at 0.5% carbon nanotubes.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998319891772
       
  • Flexural, pull-out, and fractured surface characterization for
           multi-material 3D printed functionally graded prototype
    • Authors: Sudhir Kumar, Rupinder Singh, TP Singh, Ajay Batish
      Abstract: Journal of Composite Materials, Ahead of Print.
      This paper reports the flexural, pull-out, and fractured surface characterization for multi-material three-dimensional printed functionally graded prototypes, which is prepared on fused deposition modeling setup. The work is an extension of previously reported study in which different thermoplastic matrices of polylactic acid blended with polyvinyl chloride, wood dust, and Fe3O4 powder (as multiple blended feedstock filaments) have been prepared separately with twin screw extrusion for possible three-dimensional printing. Finally, functionally graded prototypes with alternative layers of polylactic acid (01 layer), polylactic acid + polyvinyl chloride (01 layer), polylactic acid + wood dust (02 layers), and polylactic acid + Fe3O4 (02 layers) were three-dimensional printed on fused deposition modeling for flexural samples as per ASTM D790. With regard to process parameters of fused deposition modeling (in this case study), infill density of 100%, infill angle of 45°, and infill speed of 50 mm/s were the optimized processing conditions. The results of study suggest that maximum flexural strength 26.92 MPa and pull-out strength 18.11 MPa were observed for functionally graded multi-material three-dimensional printed prototypes. From fractured surface analysis and hardness result, it has been ascertained that higher infill density and lower infill angle lead to better diffusion of material in layer-by-layer fashion resulting into less void formation and better flexural and pull-out performances. The novelty of this work lies in accessing the behavior of three-dimensional printed prototypes having different functional ability for each layer, with a potential to replace hybrid blend-based prototypes.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998319892067
       
  • Atomic force microscopy-based nanomechanical characterization of kenaf
           fiber
    • Authors: M Subbir Parvej, Xinnan Wang, Joseph Fehrenbach, Chad A Ulven
      Abstract: Journal of Composite Materials, Ahead of Print.
      Kenaf (Hibiscus cannabinus L.) fiber is being extensively used as a reinforcement material in composites due to its excellent mechanical properties. To use this fiber more efficiently, it is necessary to understand its mechanical properties at micro/nano meter scale. Despite the evidence of some past studies to determine the elastic modulus of kenaf fiber, most of them were performed on fiber bundles. Bundle-based method to find the elastic moduli has some obvious issues of foreign materials being present, incorrect gauge length, and sample diameter due to void spaces. These issues pose as obvious hurdles to determine the elastic modulus accurately. In this study, individual kenaf micro fiber was used to find elastic modulus in the radial direction. The radial elastic modulus of the fiber was characterized by atomic force microscopy-based nanoindentation. To determine the radial elastic modulus from the force versus sample deformation data, the extended Johnson–Kendall–Roberts model was used which considered adhesion force from the fiber surface. The radial elastic modulus of the kenaf fiber was found to be 2.3 GPa.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998319892073
       
  • Analytical and numerical investigation on the mechanical behavior of
           subsurface damage during orthogonal cutting of carbon fiber reinforced
           polymer composites
    • Authors: Jun-Wei Yin, Fu-Ji Wang, Chong Zhang, Chen Chen
      Abstract: Journal of Composite Materials, Ahead of Print.
      Rejection of parts at the assembly stage due to poor machining quality is major problems in the manufacturing of structural components from carbon fiber reinforced polymer composites. On-line monitor of the multi-scale failure modes during machining to reveal the damage formation mechanisms is a great challenge for industries. Therefore, there is a great need for multi-scale mechanical modeling method. This study will address this problem through a combined analytical–numerical method. A microscale analytical model considering the cutting edge of tool is established to clarify the effect of cutting edge radius on the fiber deformation and failure mechanism. In addition to the analytical model, a user-defined subroutine based on maximum stiffness degradation model of composite is implemented into the two-dimensional macroscopic anisotropic finite element code to characterize the dynamic processes of subsurface damage initiation and propagation. It is found that the extent of uncut fibers increases as the cutting edge radius increases when the fiber orientation is less than 90°. The subsurface damage is relatively serious when the fiber orientation is greater than 90°, and the cutting edge radius has no obvious effect, while the tool rake angle has a significant impact. The results provide theoretical basis for the development of new tools and new technologies to the composite machining.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998318812177
       
  • Evaluation of mechanical properties and microstructure of Al/Al–12%Si
           multilayer via warm accumulative roll bonding process
    • Authors: N El Mahallawy, A Fathy, M Hassan, W Abdelaziem
      Abstract: Journal of Composite Materials, Ahead of Print.
      In this study, accumulative roll bonding (ARB) process was used to produce Al/Al–12%Si multilayered composites at 300℃. Microstructure and mechanical properties of the composites were studied during various ARB cycles by field emission scanning electron microscope (FE-SEM), tensile test, and the Vickers microhardness test. The FE-SEM results revealed that, as the ARB cycle increases the thickness of individual Al and Al–12%Si sheets decreased. After the 5th cycle, Al–12%Si layers were necked, fractured and dispersed in the aluminum matrix. A new intermetallic phase Al3.21Si0.47 was formed at the Al/Al–12%Si interface, indicating that the ARB process could result in a metallurgical bonding. It was observed that the tensile strength of composites improved by increasing the ARB passes, i.e. the tensile strength of the Al/Al–12%Si composite was measured to be about 5.52 and 2.17 times that of the primary 1050-Al and Al–12%Si sheets, respectively. Observations reveal that the failure mode in ARB-processed composites is of the shear ductile rupture type. The microhardness of the Al and Al–12%Si alloys were raised to 110 HV and 121 HV after five cycles.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998317692141
       
  • Influence of electric field direction of terahertz radiation on composite
           materials
    • Authors: Kwang-Hee Im, Je-Woong Park, In-Young Yang, David Kuei Hsu
      Abstract: Journal of Composite Materials, Ahead of Print.
      Terahertz waves (T-ray) for the non-destructive evaluation were investigated on composite materials. The modalities of the T-ray radiation used were time domain spectroscopy and continuous wave for composites. The composite materials are composed of non-conducting polymeric composites and carbon fiber composites. T-ray signals in the time domain spectroscopy mode resembles that of ultrasound; however, unlike ultrasound, T-ray pulse can detect a crack hidden behind a larger crack (shadow effect). Thick glass fiber reinforced polymer laminates containing double-saw slots was demonstrated. Also, in carbon composites the penetration of T-ray waves was investigated in order to detect flaws is strongly affected by the angle between the electric field vector of the terahertz waves and the intervening fiber directions. Other composites tested in this study include both solid laminates and honeycomb sandwiches. The defects and anomalies investigated by T-ray were foreign material inclusions, simulated disbond and delamination, mechanical impact damage, heat damage, and water or hydraulic fluid ingression. The intensive characterization of T-ray for the non-destructive evaluation of composites are being discussed.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998316688592
       
  • The development of a modified bi-axial composite test specimen
    • Authors: Anthony S. Torres, Arup K. Maji
      Abstract: Journal of Composite Materials, Ahead of Print.
      The significance of biaxial testing is increasing with the use of composites in more complex applications and the advent of new manufacturing techniques. Existing failure theories have not been proven to be accurate for predicting failure for laminated composites and very limited test data are available for woven composites. It is believed that the fabrication process used to make composite biaxial specimens induces initial damage into the specimen. Two different methods were developed to reduce the amount of damage induced into a biaxial tests specimen. In addition, the effect of stress concentration due to a center hole added to a composite biaxial specimen is also studied.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998311427768
       
  • Molecular dynamics simulation of carbon nanotube reinforced polyethylene
           composites
    • Authors: Rahul Anjana, Sumit Sharma, Amit Bansal
      Abstract: Journal of Composite Materials, Ahead of Print.
      This article is an attempt to identify the topics that are most relevant to carbon nanotube/polymer materials. Publications, in which mechanical properties like stiffness and damping have been predicted, are reviewed. The effects of volume fraction (Vf) and aspect ratio (l/d) on the mechanical properties of composites reinforced with single-walled carbon nanotubes have been studied using molecular dynamics simulations. Results showed that the longitudinal Young’s modulus of the composite is strongly dependent on l/d and carbon nanotube Vf. Analytical models have been compared with the simulation results.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998316674264
       
  • Micromechanical behavior of β-Al3Mg2-dispersed aluminum composite
           prepared by high-energy ball milling and hot pressing
    • Authors: Shubhadeep Maity, Sumit Chabri, Subhranshu Chatterjee, Supriya Bera, Arijit Sinha
      Abstract: Journal of Composite Materials, Ahead of Print.
      The present investigation deals with the ball milling of Al–Mg, which results in the formation of metastable fcc solid solutions after 100 h that transform into more stable β-Al3Mg2 phase during subsequent annealing treatment. Powder metallurgy route was successfully employed to synthesize different weight fractions of low density β-Al3Mg2 dispersed Al matrix composites. Maximum hardness was achieved for 15 wt% β-Al3Mg2-dispersed Al composites. Compacted composites display lower hardness for higher percentage (20 wt%) of dispersing phase due to possible agglomeration. Nanomechanical properties as obtained from nanoindentation and nanoscratch measurements substantiate the results obtained from the microhardness measurements. Moreover, the significant hardening of the Al matrix was successfully achieved by incorporation of low density β-Al3Mg2 phase.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998316673705
       
  • Porous mullite/alumina-layered composites with a graded porosity
           fabricated by camphene-based freeze casting
    • Authors: KH Kim, DH Kim, SC Ryu, SY Yoon, HC Park
      Abstract: Journal of Composite Materials, Ahead of Print.
      A freeze casting technique was processed to fabricate porous mullite/alumina-layered composite with a gradient in porosity and pore size. In this work, a camphene/coal fly ash slurry system with an appropriate addition of Al2O3 was used. The pore channels with circular-shaped cross-sections were aligned along the solidification direction of molten camphene and connected with each other. The pore morphology was influenced by the starting solids loading and sintering temperature. The compressive strength of monolithic specimen greatly decreased when the porosity increased. However, the layered composites with a graded porosity exhibited improved compressive strength with minor decrease in porosity, probably due to the formation of residual compressive stress and relatively dense glass phase in the outer layer.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998316636460
       
  • Numerical simulation of mold filling and particulate flow of A356/SiCp
           indirect squeeze casting
    • Authors: Qiyao Hu, Haidong Zhao, Han Long, Puyun Dong, Gang Zhu
      Abstract: Journal of Composite Materials, Ahead of Print.
      In this investigation, a mathematical model based on the dispersed phase model and multiphase flow principle was introduced, and applied to simulate the mold filling and particulate flow of particulate reinforced metal matrix composites casting. Experiments of spiral-square shaped indirect squeeze castings of A356/50 µm SiCp were conducted to validate the established model. The SiCp fractions in the casting different locations were quantitatively measured with micro digital image analysis system and were compared with the simulation results. It was found that particulate fractions and distribution patterns at different locations were quite different along the filling distance. The experimental and simulated results about the SiCp distribution in the castings show acceptable agreement. Further, the effect of fluid flow and particulate trajectories on the particulate distribution was analyzed and discussed. The research has shown the validity of application of the model for practical particulate reinforced Al-based composites casting.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998316644855
       
  • Investigation on repairable damage tolerance for structural design of
           aircraft composite structure
    • Authors: Hyunbum Park
      Abstract: Journal of Composite Materials, Ahead of Print.
      The aircraft composite structure has a disadvantage which is very weak against impact damages. A repair technique using external patch is recognized as an effective method to recover the service life of damaged structures. This work is focusing on the impact damage evaluation and the external patch repair techniques of the aircraft sandwich composite structure. The impact damages of the carbon/epoxy fabric face sheets–honeycomb core sandwich laminate are simulated by the drop-weight type impact test equipment. The damaged specimens are repaired using the external patch repair method after removing the damaged area. The compressive strength test and analysis results of the repaired impact damaged specimens are compared with the results of the undamaged specimens. Finally, the strength recovery capability after repairing is investigated.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998316643579
       
  • Bearing strength of interference-fit pin joined glass fiber reinforced
           plastic composites
    • Authors: Sang-Young Kim, Bin He, Dave (Dae-Wook) Kim, Chun Sik Shim, Ha Cheol Song
      Abstract: Journal of Composite Materials, Ahead of Print.
      Glass fiber reinforced plastic structures are mostly used in mid-sized marine vessels due to high strength and stiffness to weight ratio, corrosion resistance, and total life cost reductions. Mechanical joints using metallic bolts, screws, and pins are commonly used for joining thick glass fiber reinforced plastic laminates. Interference-fit pin connections provide beneficial effects such as fatigue enhancement and/or prevention of moisture intrusion to the fiber reinforced composites. This numerical and experimental study aims to investigate the effect of interference-fit on the bearing stiffness and strength of pin joined glass fiber reinforced plastic. The stress and strain distributions have been investigated for bearing loading through experiments as well as a nonlinear three dimensional finite element analysis. The quasi-static properties of the pin-loaded composites with interference-fit (0.6% and 1%) are compared with the samples with transition-fit (0% of interference-fit). The radial and the tangential strains on the vicinity of the hole obtained from the FE simulation were verified with the experimental results. The radial strains on the interference-fit pin joined glass fiber reinforced plastic coupons are lower than those on the transition-fit pin joined glass fiber reinforced plastic coupons at the consistent pin displacement, resulting in enhancement of the joint stiffness per unit bearing area by interference-fit.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998316636462
       
  • Mechanical properties of 3D-woven composites with guide sleeves
    • Authors: Xiaochuan Wu, Zhongde Shan, Feng Liu, Yuan Wang
      Abstract: Journal of Composite Materials, Ahead of Print.
      In this study, the preforms of 3D woven composite materials were made by a flexible oriented 3D composite woven process. The vacuum-assisted resin infusion (VARI) process was used to impregnate the preforms. The short-beam shear test, the compression test, and SEM were used to investigate the interlaminar shear performance and the compression behavior of the 3D woven composite with guide sleeves, and the effect of the guide sleeves on the above properties. It is indicated that the interlaminar shear behavior of 3D woven composites with guide sleeves showed the typical fracture characteristics of a pseudoplastic material. And the fracture modes of interlaminar shear mainly include interlaminar shear fracture and tensile fracture of fibers at the bottom. The interlaminar shear strength of materials increased with the diameter and interval of guide sleeves decreasing. Furthermore, the loss of in-plane compression properties of the materials brought by guide sleeves could be effectively avoided by reasonable control of the diameter and the volume fracture of guide sleeves.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998316636461
       
  • Surfactant-aided sol-gel synthesis of TiO2–MgO nanocomposite and their
           photocatalytic azo dye degradation activity
    • Authors: Ajit K Sharma, Byeong-Kyu Lee
      Abstract: Journal of Composite Materials, Ahead of Print.
      In this work, a surfactant-aided TiO2–MgO nanocomposite (Ti-M-S) was successfully synthesized by a sol-gel process with the aid of sodium dodecyl sulfate as a structure-directing anionic surfactant. The results demonstrated the effectiveness of this approach for controlling both the amount and the distribution of MgO nanoparticles within the TiO2 framework after calcination. The photocatalytic activity of the synthesized nanocomposite for degradation of methyl orange (MO) and methylene blue (MB) dyes used as a model wastewater contaminant was investigated under visible light irradiation. The synthesized nanocomposite was systematically characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy/energy-dispersive X-ray (SEM/EDX) analysis. The decolorization results revealed that the Ti-M-S1 (with an anionic surfactant: sodium dodecyl sulfate) and Ti-M-S2 (with a non-ionic surfactant: Triton X-100) nanocomposites showed much more photocatalytic activity than the pure TiO2 did under visible light. MB and MO dye removal efficiencies of 82.4% and 77.8 %, respectively, were achieved by Ti-M-S1 (1%) within about 120 min and no further changes in the uptake were observed up to 24 h. This confirmed the suitability of the synthesized nanocomposite for use as a photocatalyst under visible light with the added advantage of increasing the versatility of potential applications for TiO2 photocatalysts.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998316636464
       
  • A study on mechanical properties of Al5052/CFRP/Al5052 composite through
           three-point bending tests and shear lap tests according to surface
           roughness
    • Authors: MS Lee, SJ Kim, OD Lim, CG Kang
      Abstract: Journal of Composite Materials, Ahead of Print.
      In this study, aluminum samples with various microsurface roughness values were produced by sandblasting to investigate the effect of the Ra (Surface roughness) value on the samples’ mechanical properties. Toward this end, a carbon fiber reinforced plastic/Al5052 hybrid sample was produced, and its mechanical properties were investigated through a tensile test, three-point bending test, and shear lap test. The theoretical and experimental tensile strength values of the hybrid composite were compared. During the bending test, CFRP and AI5052 separated in untreated specimens. A side-view examination revealed that the adhesion was best when the surface roughness was greatest (Ra = 1.2 µm). Furthermore, shear load increased with the surface roughness. Therefore, the surface treatment was a crucial factor in making the specimen surface even and in increasing the roughness and therefore improving adhesion.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998316636458
       
  • Analytical model of the stress–strain state of multilayer composite
           plates under the influence of different load types with asymmetrical
           boundary conditions
    • Authors: Olga Bitkina, Jang-Ho Lee, Ki-Weon Kang, Elena Darlington
      Abstract: Journal of Composite Materials, Ahead of Print.
      Composite structure design experience has demonstrated that use of the finite element method during the first stage of the design process is unfounded and that analytical methods to determine the stress–strain state are needed for more accurate calculations. Therefore, an analytical model of the stress–strain state of multilayer composite plates under the influence of temperature, technological, and power loads with different boundary conditions around four boundaries of a rectangular plate was developed. This model enables the solution of more than 240 different boundary value problems with a combination of the following boundary conditions: fixed, moving, hinged, and free edge. In the derivation of this mathematical analytic model, the Kirchhoff hypothesis was applied to the entire body of the anisotropic medium for the interconnected deflection and bending in the plate plane. The resulting equation is an octic linear partial differential equation to express the generalized function of movements.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998316636463
       
  • Molecular dynamics simulation of functionalized SWCNT–polymer
           composites
    • Authors: Sumit Sharma, Rakesh Chandra, Pramod Kumar, Navin Kumar
      Abstract: Journal of Composite Materials, Ahead of Print.
      The analysis of the influence of functionalization on the mechanical properties of the carbon nanotubes (CNTs) has been poorly addressed, especially when compared with the extensive amount of work on pristine CNTs. This article analyzes the effect of carboxylic (COOH), ester (COOCH3), silane (COSiCH3), and vinyl (CH = CH2) groups attached on the surface of single-walled carbon nanotube (SWCNT) on elastic properties of polypropylene (PP) composites reinforced with functionalized SWCNTs along the axial direction of the CNTs by using MD approach. Effect of CNT aspect ratio and volume fraction on the elastic moduli has also been studied. The results show that although chemical functionalization of SWCNTs has been considered as a means to increase the load-transfer efficiency in a nanotube–polymer composite, this functionalization has, in fact, degraded most of the macroscopic elastic stiffness components of the composite materials considered in this study. The decrease in longitudinal modulus of functionalized SWCNT–PP composite with respect to pristine SWCNT reinforced PP composite is largest for COOH functionalized SWCNT–PP composites. The values of transverse moduli are approximately one-tenth the corresponding values of longitudinal modulus.
      Citation: Journal of Composite Materials
      DOI: 10.1177/0021998316628973
       
 
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