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Journal of Composite Materials
Journal Prestige (SJR): 0.555
Citation Impact (citeScore): 2
Number of Followers: 386  
 
Hybrid Journal Hybrid journal   * Containing 1 Open Access Open Access article(s) in this issue *
ISSN (Print) 0021-9983 - ISSN (Online) 1530-793X
Published by Sage Publications Homepage  [1079 journals]
  • Retraction Notice
    • Abstract: Journal of Composite Materials, Ahead of Print.

      Citation: Journal of Composite Materials
      PubDate: 2019-09-13T10:07:13Z
      DOI: 10.1177/0021998319875285
       
  • 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
       
  • Modeling and simulation of carbon composite ballistic and blast behavior
    • Authors: Chian-Fong Yen, Bob Kaste, Charles Chih-Tsai Chen, Nelson Carey
      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
       
  • 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
       
  • Shadowed delamination area estimation in ultrasonic C-scans of impacted
           composites validated by X-ray CT
    • Authors: Andrew Ellison, Hyonny Kim
      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
       
  • 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
       
  • 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
      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
       
  • 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
       
  • 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
      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
       
  • Influence of filler loading on the mechanical and morphological properties
           
    • Authors: Uchechi C Mark, Innocent C Madufor, Henry C Obasi, Udochukwu Mark
      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
       
  • Nylon 612/TiO2 composites by anionic copolymerization-molding process:
           Comparative evaluation of thermal and mechanical performance
    • Authors: Elena Rusu
      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
      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
      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
       
  • 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
      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
       
  • 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
      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
       
  • Short-beam shear of nanoprepreg/nanostitched three-dimensional
           carbon/epoxy multiwall carbon nanotube composites
    • Authors: Kadir Bilisik, Nesrin Karaduman, Erdal Sapanci
      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
       
  • Water resistance, mechanical, and morphological characteristics in
           polyamide-6/zirconium phosphate nanocomposites
    • Authors: Daniela de França da Silva Freitas, Luis Claudio Mendes
      Abstract: Journal of Composite Materials, Ahead of Print.
      Polyamide-6/organointercalated zirconium phosphate nanocomposites (PA-6/ZrPOct) were prepared by melt extrusion. The synthesized lamellar ZrP was expanded with octadecylamine at different amine:phosphate ratio, and its influence was evaluated by tensile test, melt flow rate, water absorption, rheology, scanning electron microscopy, and wide-angle X-ray diffraction. For all nanocomposites, the increase of modulus and decrease of elongation at rupture were observed. The decrease in water uptake was observed as the amine/phosphate increase, indicating that the presence of the amine reduces the hydrophilic nature of PA-6. Rheology revealed by pseudoplasticity indices that the nanofillers dispersion was homogeneous in all nanocomposites. Wide-angle X-ray diffractometry analysis showed that the characteristic basal spacing peak of pristine ZrP was absent for ZrOct 1:1 and 2:1. Also a high decrease in crystallinity was observed for PA-6/ZrOct 2:1 sample, which would be associated to plasticizing effect of octadecylamine avoiding crystallites formation. Evidences showed that structures with different degrees of intercalation and/or exfoliation could have been achieved.
      Citation: Journal of Composite Materials
      PubDate: 2019-07-11T05:39:05Z
      DOI: 10.1177/0021998319857120
       
  • Performance of composite sandwich structures under thermal cycling
    • Authors: Sandesh Rathnavarma Hegde, Mehdi Hojjati
      Abstract: Journal of Composite Materials, Ahead of Print.
      Effect of thermally induced microcracks on mechanical performance of a space grade laminated sandwich panel is investigated. A simple non-contact setup using liquid nitrogen is developed to subject the material to low temperature of −170℃ with cooling rate of 24℃/min. Then the samples are exposed to the elevated temperature of 150℃ inside oven. Microcracks formation and propagation are monitored through microscopic observation of cross-section during the cycling. Flatwise tensile test is performed after a number of cycles. A correlation is made between number of cycles and flatwise mechanical strength after quantifying the microcracks. It is observed that the crack formation gets saturated at about 40 cycles, avoiding the need to conduct more thermal cycles. Microcrack formation both at the free edge and middle of laminate was observed. The crack density at the middle was comparatively less than the ones found on the free edges. Results for non-contact cooling are compared with samples from direct nitrogen contact cooling. Microscopic inspection and flatwise test show differences between contact and non-contact cooled samples. Flatwise tensile strength for non-contact cooled samples shows 15% reduction, while the contact cooled samples have about 30% decrease in bond strength. A 3D finite element analysis is conducted to qualitatively identify the location of stress concentration which can be possible sites of crack formation. Good agreement is observed between the model and experimental results.
      Citation: Journal of Composite Materials
      PubDate: 2019-07-11T05:39:05Z
      DOI: 10.1177/0021998319862324
       
  • 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
      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
       
  • Macroscale bending large-deformation and microbuckling behavior of a
           unidirectional fiber-reinforced soft composite
    • Authors: Xin Lan, Sida Hao, Liwu Liu, Yanju Liu, Jinsong Leng
      Abstract: Journal of Composite Materials, Ahead of Print.
      Due to microscale fiber microbuckling, a fiber-reinforced soft composite demonstrates large macroscale bending deformation (e.g. 10% reversible macroscale compressive strain), which is larger than that of a convenient fiber-reinforced plastics (e.g. 1.5–2% elongation/compression at break). To investigate the deformation behavior, a normalized average energy density of a fiber-reinforced soft composite laminate was derived. By using a self-consistent approach according to the minimum energy principle, a series of analytical expressions were derived by a simplified theoretical method through solving simplified partial differential equations of average energy density. Furthermore, an improved numerical calculation method was developed using the full four terms of partial differential equations of average energy density by employing the results of simplified theoretical method as initial calculating values. The dimensionless results demonstrated that the trend correlated well between those two methods, and the improved numerical method obtained more accurate results than those of the simplified theoretical method. Analytical and numerical results in normalized expressions systematically descripted the bending large-deformation behavior including position of neutral surface and critical buckling, wavelength, amplitude, shearing strain, macroscale compressive/tensile strain, buckled fiber strain, and actuation moment. To design a fiber-reinforced soft composite for use in engineering, the simplified theoretical method is used to predict trend and obtain approximate results for preliminary design, and the improved numerical method is further used to check and obtain more accurate results on detailed design stage.
      Citation: Journal of Composite Materials
      PubDate: 2019-07-07T12:35:19Z
      DOI: 10.1177/0021998319854145
       
  • Quasi-static indentation damage and residual compressive failure analysis
           of carbon fiber composites using acoustic emission and micro-computed
           tomography
    • Authors: Yan-nan Zhang, Wei Zhou, Peng-fei Zhang
      Abstract: Journal of Composite Materials, Ahead of Print.
      In present research, the internal damage evolution and failure characteristics of carbon fiber woven composites under indentation and residual compressive loads were studied by using acoustic emission technology and X-ray micro-computed tomography. Real-time acoustic emission signals originating from internal damage of composites under applied loads were obtained and analyzed by the k-means clustering algorithm. Moreover, the internal damage characteristics were observed by the reconstructed three-dimensional model and the slice images of composite specimens. The results showed that the higher the indentation force reading, the more acoustic emission signals with high amplitude and frequency (over 300 kHz) are generated. Furthermore, the early acoustic emission signals with high-frequency were observed under residual compressive loads. It can be attributed to serious failures of fibers with the increase of static indentation loads. In addition, the internal damages such as delamination, debonding, crack and fiber breakage can be clearly characterized by micro-computed tomography and scanning electron microscopy observation. The complementary technology combing acoustic emission with micro-computed tomography can provide a better understanding of internal damages and evolution behaviors of the composites.
      Citation: Journal of Composite Materials
      PubDate: 2019-07-05T05:34:55Z
      DOI: 10.1177/0021998319861140
       
  • Evaluation of boron nitride nanoparticles on delamination in drilling
           carbon fiber epoxy nanocomposite materials
    • Authors: Halil Burak Kaybal, Ali Unuvar, Yusuf Kaynak, Ahmet Avcı
      Abstract: Journal of Composite Materials, Ahead of Print.
      The reinforcements of nanoparticles have an important role in improving the machinability of nanocomposite materials. Except for the known nanoparticles such as carbon nanotube, graphene, nanoclay, etc., the effect of boron nitride reinforcement on the machinability of composite materials are a recent research topic. In this study, boron nitride nanoparticle was introduced to the matrix resin that brings about additional strength and enhancement in thermal and mechanical properties of the composite. Though it was confirmed that this composition enhances the focused properties, it is necessary to investigate drilling performance of these composite and identify the effects of this boron nitride nanoparticle on machinability of carbon fiber epoxy nanocomposite considering thrust force, delamination factor, etc. Accordingly, while the thrust force is increased by reinforcement of the boron nitride nanoparticles, on the contrary of literature, delamination factor is tend to reduce as compared with reference composite. This experimental study shows the addition of boron nitride nanoparticles help to reduce delamination factor of carbon fiber epoxy nanocomposite. In addition, hole surfaces and drilling mechanism analyzed with optical and scanning electron microscope about damage estimation.
      Citation: Journal of Composite Materials
      PubDate: 2019-07-04T03:47:58Z
      DOI: 10.1177/0021998319860245
       
  • Impact damage assessment of carbon fiber reinforced composite with
           different stacking sequence
    • Authors: Rahul S Sikarwar, R Velmurugan
      Abstract: Journal of Composite Materials, Ahead of Print.
      This work examines the experimental and analytical investigation of impact on the carbon/epoxy laminates of various stacking sequence. The impact tests were carried out by using gas gun equipped with high-speed camera. Projectile velocities selected were 80 m/s and 30 m/s where 80 m/s was above ballistic limit velocity and 30 m/s was below ballistic limit velocity. The impact process was recorded with high-speed camera which facilitated to identify different energy absorbing mechanisms. High-speed images were also used to measure pre-impact and post-impact velocities of the projectile accompanied by photo diode and aluminum foil method. Total energy absorbed by the laminates, which is the difference between pre-impact and post-impact kinetic energy of the projectile, was calculated for the laminates with different stacking sequences. Damage extent in the laminates of different stacking sequences were also assessed by C-Scan of the laminates. Then effect of stacking sequences on damage extent and energy absorbing capacity was established. An analytical model was proposed to predict the residual velocity of the projectile at above ballistic limit velocity, which was based on the total energy absorbed by different energy absorption mechanisms. The analytical model was validated with experimental results for different stacking sequences. Additionally, effect of fiber orientation on damage shape at below ballistic limit velocity was also studied.
      Citation: Journal of Composite Materials
      PubDate: 2019-07-04T03:47:57Z
      DOI: 10.1177/0021998319859934
       
  • Thermally stimulated depolarization current characteristic of
           EVA–conductive PPy composites
    • Authors: F. S. Thabet, A. M. AbdElbary, G. M. Nasr
      Abstract: Journal of Composite Materials, Ahead of Print.
      Thermally stimulated depolarization current in pure poly(ethylene-co-vinyl acetate) and poly(ethylene-co-vinyl acetate) composites with different amounts of polypyrrole/carbon nanoparticles (of various weight ratios, 100:0, 95:5, 90:10, 85:15, 80:20, and 70:30) have been investigated at poling temperature 363 K using different polarizing voltage. Thermograms of pure and composite samples have two or three peaks over all temperature ranges depending on the polarizing voltage. The decrease in peak height with increased polarized voltage is observed in pure poly(ethylene-co-vinyl acetate) samples loaded with 5%, 10%, 15%, and 30% polypyrrole due to the detrapping of the large amounts of charge results in electrode blocking and decrease in thermally stimulated depolarization current in those samples. The molecular parameters, such as activation energy E, charge released Q, and relaxation times τ0 and τm for thermally stimulated depolarization current peaks have been estimated.
      Citation: Journal of Composite Materials
      PubDate: 2019-07-04T03:47:56Z
      DOI: 10.1177/0021998319860891
       
  • Effects of environmental exposures on carbon fiber epoxy composites
           protected by metallic thin films
    • Authors: Arash Afshar, Dorina Mihut, Pengyu Chen
      Abstract: Journal of Composite Materials, Ahead of Print.
      Carbon fiber epoxy composites have a wide range of applications in aerospace, construction, and automotive industries due to their good mechanical properties and lightweight characteristics. Carbon fiber epoxy composite structures are typically intended for service in corrosive and hostile environmental conditions. Therefore, development of coatings which are able to protect carbon fiber epoxy composite laminates against prolonged and harsh environmental conditions such as ultraviolet radiation and moisture deems critical. This paper offers a novel method for environmental protection of fiber-reinforced polymer composites by applying thin metallic films on composites' surface as coating materials. In order to investigate the protective properties of metallic thin films, copper and aluminum coatings were deposited on the surface of carbon fiber epoxy specimens by using direct current magnetron-sputtering technique, and then mechanical properties and surface morphology of specimens were monitored during the course of accelerated environmental exposure. Both metallic coatings showed good adhesion to carbon fiber epoxy samples during environmental aging and provided protection for the specimens' surface against environmental degradation. The correlation between flexural properties and surface morphology of carbon fiber epoxy specimens is also presented.
      Citation: Journal of Composite Materials
      PubDate: 2019-07-02T06:43:03Z
      DOI: 10.1177/0021998319859051
       
  • Numerical investigation of the effect of thermal gradients on curing
           performance of autoclaved laminates
    • Authors: Qing Wang, Lingyun Wang, Weidong Zhu, Qiang Xu, Yinglin Ke
      Abstract: Journal of Composite Materials, Ahead of Print.
      Autoclave curing process is one of the most frequently used manufacturing techniques of thermosetting composite materials. An efficient curing process requires good understanding of the thermal behavior of molds and composites during autoclave processing. In this paper, the effect of thermal gradients on curing performance of laminates is investigated through numerical approaches. In the first section, a computational fluid dynamics–finite element method numerical model is established to simulate the temperature field and the process-induced deformation of laminates. Then, a curved composite part with two different structures of mold is introduced to exhibit different temperature and degree of cure gradients during the autoclave process. Furthermore, by analyzing the position errors of measurement points, the deformation of the composite parts in different molds is evaluated. The results suggested that more synchronous curing process and less deformation of the composite part can be achieved by reducing the thermal gradients. In this specific case of a curved part, the range of position errors in X direction (the length direction) is reduced by 86.9% with the redesigned mold.
      Citation: Journal of Composite Materials
      PubDate: 2019-07-02T04:24:13Z
      DOI: 10.1177/0021998319859061
       
  • Influence of TiC content on mechanical, wear and corrosion properties of
           hot-pressed AZ91/TiC composites
    • Authors: Fatih Aydin, Yavuz Sun, M Emre Turan
      Abstract: Journal of Composite Materials, Ahead of Print.
      This study aims to investigate the mechanical, wear and corrosion performances of TiC reinforced AZ91 matrix composites. AZ91 alloy and AZ91/TiC composites with different weight fractions of 10, 20 and 30 (wt%) were fabricated by powder metallurgy incorporating hot pressing. Microstructure characterization shows that partial agglomeration of particles is present especially in AZ91/30 wt% TiC composite. The addition of TiC led to significant improvement in hardness and wear resistance. Observed wear mechanism is abrasive. As compared with AZ91, compressive yield strength and ultimate compressive strength of the composites were also significantly improved. On the other hand, corrosion rate increased with the addition of TiC particles by virtue of presence of the galvanic reactions.
      Citation: Journal of Composite Materials
      PubDate: 2019-07-02T04:24:13Z
      DOI: 10.1177/0021998319860570
       
  • A multidirectional damage model for fiber-reinforced plastic laminates
           under static load
    • Authors: Wenxuan Qi, Weixing Yao, Haojie Shen
      Abstract: Journal of Composite Materials, Ahead of Print.
      A multidirectional damage model based on continuum damage mechanics for fiber-reinforced composite laminates is proposed in this paper. The influence of three main damage mechanisms, including transverse matrix cracking, local delamination, and fiber breakage, on the multidirectional stiffness properties of composite laminates is analyzed by introducing macro phenomenological damage variables. Then the mechanical behavior of elementary ply in laminates is modeled based on these damage variables. Besides, relations between micro-level damage variables and macro-level damage variables are established. Damage evolution laws of the three damage mechanisms are proposed to predict the degradation of multidirectional stiffness and failure strength of composite laminates under quasi-static loading. The experiment of cross-ply glass fiber-reinforced plastic laminates is carried out, and the prediction results show good agreement with the experimental results.
      Citation: Journal of Composite Materials
      PubDate: 2019-07-02T04:24:12Z
      DOI: 10.1177/0021998319854148
       
  • Design of the ultrahigh molecular weight polyethylene composites with
           multiple nanoparticles: An artificial intelligence approach
    • Authors: A Vinoth, Shubhabrata Datta
      Abstract: Journal of Composite Materials, Ahead of Print.
      This study proposes a suitable composite material for acetabular cup replacements in hip joint that involves ultrahigh molecular weight polyethylene, a clinically proven material, as the matrix. To design new ultrahigh molecular weight polyethylene composites with multiple reinforcements for the improvement in mechanical and tribological performance, artificial neural network and genetic algorithm, the two artificial intelligence techniques, are employed. Published reports on the use of ultrahigh molecular weight polyethylene reinforced with multi-walled carbon nanotube and graphene are used as database to develop two artificial neural network models for Young's modulus and tensile strength. The optimum solutions are obtained using genetic algorithm, where the artificial neural network models are used as the objective functions. Two different composites, derived from the optimum solutions, are made reinforcing both multi-walled carbon nanotube and graphene. Tensile and wear tests show significant enhancement in the properties. The structures of the composites are also characterized, and wear mechanisms are discussed.
      Citation: Journal of Composite Materials
      PubDate: 2019-07-02T04:24:11Z
      DOI: 10.1177/0021998319859924
       
  • Eco-friendly castor oil-based UV-curable urethane acrylate zinc oxide
           nanocomposites: Synthesis and viscoelastic behavior
    • Authors: Abbas Madhi, Behzad S Hadavand
      Abstract: Journal of Composite Materials, Ahead of Print.
      Attention to environmental problems and the importance of maintaining it have caused the researchers to pay more attention in this regard. The production of polymers and resins has increased in recent years and has affected by environmental pollution due to their long-term degradation. An appropriate solution to this problem is the synthesis of degradable and environmentally friendly polymers and resins. Using natural materials in the synthesis of polymers and resins can help them to be environmentally friendly. The purpose of this research is to synthesize urethane acrylate resins using natural resources. For this purpose, the urethane acrylate pre-polymer was synthesized with castor oil. Then, using modified zinc oxide nanoparticles with 1, 3 and 5 wt% urethane acrylate zinc oxide nanocomposites were produced. The use of castor oil as a degradable part and lack of organic solvent in radiation systems led to the creation of an environmentally friendly resin. Subsequently, the viscoelastic behavior of the prepared nanocomposite was evaluated. Spectrometry results confirm the synthesized resin structure. The morphology of nanocomposites confirmed the proper particle size distribution in a 3 wt.% sample. The results of the dynamic mechanical thermal analysis test showed that increasing the amount of modified nano ZnO could increase the glass transition temperature, and the maximum value was observed in 5 wt.% modified nano ZnO (69.7℃).
      Citation: Journal of Composite Materials
      PubDate: 2019-06-29T04:46:57Z
      DOI: 10.1177/0021998319858017
       
  • A three-dimensional progressive damage model for drop-weight impact and
           compression after impact
    • Authors: Dinh Chi Pham, Jim Lua, Haotian Sun, Dianyun Zhang
      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
       
  • Evaluation method for lightning damage of carbon fiber reinforced polymers
           subjected to multiple lightning strikes with different combinations of
           current components
    • Authors: Jinru Sun, Xueling Yao, Wenjun Xu, Jingliang Chen, Yi Wu
      Abstract: Journal of Composite Materials, Ahead of Print.
      The aircraft lightning environment consists of four lightning current components with different parameters, which are known as lightning components A, B, C and D. The lightning damage of aeronautic carbon fiber reinforced polymer laminates subjected to multiple continuous sequential lightning current components with different timing combinations was experimentally evaluated. The experimental results indicated that the carbon fiber reinforced polymer laminates suffered serious lightning damage, including carbon fiber fracture, resin pyrolysis and delamination. Through an analysis of the lightning damage properties of carbon fiber reinforced polymers, the influential factors and evaluation methods of the lightning damage in carbon fiber reinforced polymer laminates were studied. Because the lightning damage evaluation method under a single lightning impulse was found to be inapplicable for the multiple continuous lightning strikes, a multi-factor evaluation method was proposed. In the multiple continuous lightning strike test, the damage depth was found to be closely related to lightning components A, B and D and could be estimated based on the amplitudes and rise rates of the applied lightning components. Increases in the damaged area after a lightning strike were driven by lightning component C due to its substantial thermal effects. The damaged area was evaluated on the basis of the parameters of the electrical action integral and the transfer charge. The research on the evaluation methods for carbon fiber reinforced polymer laminate lightning damage presented herein may provide experimental support and a theoretical basis for studying the lightning effect mechanism and optimizing material formulations, manufacturing processes and structural designs to achieve performance improvements for carbon fiber reinforced polymer laminates in the future.
      Citation: Journal of Composite Materials
      PubDate: 2019-06-29T04:46:56Z
      DOI: 10.1177/0021998319860562
       
  • Fabrication of bulk aluminum-graphene nanocomposite through friction stir
           alloying
    • Authors: Abhishek Sharma, Vyas Mani Sharma, Jinu Paul
      Abstract: Journal of Composite Materials, Ahead of Print.
      Friction stir alloying is primarily employed for the fabrication of surface composite to improve surface properties like hardness, wear resistance, and corrosion resistance without significantly affecting the bulk properties of the alloy. The present study demonstrates the novel method for the fabrication of bulk aluminum-graphene nanoplatelets composite by using friction stir alloying. Here, the novelty is shown through the method of graphene nanoplatelets incorporation in the stir zone. For this purpose, a channel is fabricated on the cross-sectional surface of the aluminum plate and filled with graphene nanoplatelets. It is then covered by the cross-sectional surface of another aluminum plate of same dimensions and friction stir alloying is carried out. Reference material (RM) is also fabricated at the same parameters without any graphene nanoplatelet reinforcements for the performance evaluation of the nanocomposite. The microhardness of the fabricated composite increased by ∼57% as compared to the reference material. However, the tensile strength of the fabricated Al-graphene nanoplatelet composites decreased marginally as compared to reference material. The strengthening of the composite is explained systematically by various mechanisms. The results of microhardness and tensile test were corroborated with various characterization methods such as optical micrographs, scanning electron microscopy, atomic force microscope, and X-ray diffraction.
      Citation: Journal of Composite Materials
      PubDate: 2019-06-28T04:56:54Z
      DOI: 10.1177/0021998319859427
       
  • Electrical, optical, and mechanical percolations of multi-walled carbon
           nanotube and carbon mesoporous-doped polystyrene composites
    • Authors: Ömer Bahadır Mergen, Ertan Arda, Gülşen Akın Evingür
      Abstract: Journal of Composite Materials, Ahead of Print.
      In this study, we have investigated and compared electrical, optical, and mechanical properties of polystyrene thin films with added multi-walled carbon nanotube and carbon mesoporous. Surface conductivity (σ), scattered light intensity (Isc), and all the mechanical parameters of these composites have increased with increasing the content of carbon filler (multi-walled carbon nanotube or carbon mesoporous) in the polystyrene composites. This behavior in electrical, mechanical, and optical properties of the polystyrene/carbon fiber composites has been explained by classical and site percolation theory, respectively. The electrical percolation thresholds (Rσ) were determined to be 8.0 wt% for polystyrene/multi-walled carbon nanotube and 25.0 wt% for polystyrene/carbon mesoporous composites. The optical percolation thresholds were found to be Rop = 0.8 wt.% for polystyrene/multi-walled carbon nanotube and Rop = 3.0 wt.% for polystyrene/carbon mesoporous composites. For the polystyrene/carbon mesoporous composite system, it was determined that the mechanical percolation threshold occurred at lower R values than the polystyrene/multi-walled carbon nanotube composite system. The electrical (βσ), optical (βop), and mechanical (βm) critical exponents have been calculated for both of the polystyrene/carbon fiber composites and obtained as compatible with used percolation theory.
      Citation: Journal of Composite Materials
      PubDate: 2019-06-28T04:56:53Z
      DOI: 10.1177/0021998319859053
       
  • Characterization of carbon fiber-reinforced poly(phenylene sulfide)
           composites prepared with various compatibilizers
    • Authors: Bedriye U Durmaz, Ayse Aytac
      Abstract: Journal of Composite Materials, Ahead of Print.
      The aim of this study was to investigate the effects of different compatibilizers on the properties of polyamide-sized carbon fiber-reinforced poly(phenylene sulfide) composites. The composites were prepared by using melt blending and injection molding methods by using three different compatibilizers at various loading levels. The characterization of composites was performed by Fourier transform infrared spectroscopy, tensile test, dynamic mechanical analysis, differential scanning thermometer, thermogravimetric analysis and scanning electron microscope. According to tensile test results, the highest increment in tensile strength and strain at break values of composites was observed with the addition of Joncryl. According to scanning electron microscope and dynamic mechanical analysis results, the best interfacial adhesion between carbon fiber and poly(phenylene sulfide) was obtained by using Joncryl as the compatibilizer.
      Citation: Journal of Composite Materials
      PubDate: 2019-06-28T04:56:53Z
      DOI: 10.1177/0021998319859063
       
  • Strain rate-dependent large deformation inelastic behavior of an epoxy
           resin
    • Authors: Sandeep Tamrakar, Raja Ganesh, Subramani Sockalingam, Bazle Z (Gama) Haque, John W Gillespie
      Abstract: Journal of Composite Materials, Ahead of Print.
      The objective of this paper is to model high strain rate and temperature-dependent response of an epoxy resin (DER 353 and bis(p-aminocyclohexyl) methane (PACM-20)) undergoing large inelastic strains under uniaxial compression. The model is decomposed into two regimes defined by the rate and temperature-dependent yield stress. Prior to yield, the model accounts for viscoelastic behavior. Post yield inelastic response incorporates the effects of strain rate and temperature including thermal softening caused by internal heat generation. The yield stress is dependent on both temperature and strain rate and is described by the Ree–Erying equation. Key experiments over the strain rate range of 0.001–12,000/s are conducted using an Instron testing machine and a split Hopkinson pressure bar. The effects of temperature (25–120 ℃) on yield stress are studied at low strain rates (0.001–0.1/s). Stress-relaxation tests are also carried out under various applied strain rates and temperatures to obtain characteristic relaxation time and equilibrium stress. The model is in excellent agreement over a wide range of strain rates and temperatures including temperature in the range of the glass transition. Case studies for a wide range of monotonic and varying strain rates and large strains are included to illustrate the capabilities of the model.
      Citation: Journal of Composite Materials
      PubDate: 2019-06-28T04:56:52Z
      DOI: 10.1177/0021998319859054
       
  • Experimental investigation on the influence of carbon-based nanoparticle
           coating on the heat transfer characteristics of the microprocessor
    • Authors: Tamilarasi Thangamuthu, Rajasekar Rathanasamy, Saminathan Kulandaivelu, Ravichandran Kuttiappan, Mohanraj Thangamuthu, Moganapriya Chinnasamy, Velu Kaliyannan Gobinath
      Abstract: Journal of Composite Materials, Ahead of Print.
      In the current scenario, thermal management plays a vital role in electronic system design. The temperature of the electronic components should not exceed manufacturer-specified temperature levels in order to maintain safe operating range and service life. The reduction in heat build-up will certainly enhance the component life and reliability of the system. The aim of this research work is to analyze the effect of multi-walled carbon nanotube and graphene coating on the heat transfer capacity of a microprocessor used in personal computers. The performance of coating materials was investigated at three different usages of central processing unit. Multi-walled carbon nanotube-coated and graphene-coated microprocessors showed better enhancement in heat transfer as compared with uncoated microprocessors. Maximum decrease in heat build-up of 7 and 9℃ was achieved for multi-walled carbon nanotube-coated and graphene-coated microprocessors compared to pure substrate. From the results, graphene has been proven to be a suitable candidate for effective heat transfer compared to with multi-walled carbon nanotubes due to high thermal conductivity characteristics of the former compared to the latter.
      Citation: Journal of Composite Materials
      PubDate: 2019-06-28T04:56:52Z
      DOI: 10.1177/0021998319859926
       
  • Experimental study on the bond behavior of the CFRP-steel interface under
           the freeze–thaw cycles
    • Authors: Yu-Yang Pang, Gang Wu, Hai-Tao Wang, Zhi-Long Su, Xiao-Yuan He
      Abstract: Journal of Composite Materials, Ahead of Print.
      The bond–slip degradation relationship between carbon fiber-reinforced polymer and steel in a freeze–thaw environment is crucial to evaluate the long-term service performance of steel structures strengthened with carbon fiber-reinforced polymer plates. However, limited studies on the durability and long-term performance of the carbon fiber-reinforced polymer-steel-bonded interface are the major obstacle for the application of carbon fiber-reinforced polymer plates in strengthening steel structures. This paper reports an experimental study to investigate the effects of the carbon fiber-reinforced polymer bond length and the freeze–thaw cycles on the bond behavior of the carbon fiber-reinforced polymer-steel-bonded interface. The three-dimensional digital image correlation technique is applied to obtain displacements and strains on the surface of the single-shear specimen. The experimental results present herein include the failure mode, the ultimate load, the carbon fiber-reinforced polymer strain distribution, the displacement distribution, and the bond–slip relationship. The results show that the ultimate load increases with increasing bond length until a certain bond length value is reached, after which the ultimate load remained approximately constant, and the ultimate loads of carbon fiber-reinforced polymer-steel interface decrease gradually under freeze–thaw cycles. The bond–slip parameters degradation models are proposed, and the bond–slip degradation relationship under the freeze–thaw cycles is established. Finally, the bond–slip degradation relationship is confirmed through comparisons with the experimental results.
      Citation: Journal of Composite Materials
      PubDate: 2019-06-27T04:32:27Z
      DOI: 10.1177/0021998319851191
       
  • Comparative analysis of particle size on the mechanical and metallurgical
           characteristics of Al2O3-reinforced sintered and extruded AA2014
           nano-hybrid composite
    • Authors: Senthil Kumar R, K Prabu, G Rajamurugan, P Ponnusamy
      Abstract: Journal of Composite Materials, Ahead of Print.
      Aluminum metal matrix composites (AMCs) are having exotic properties which attract the research community to develop new nano-composite material. The aim of the work is to compare the effect of various weight percentage of alumina particle (micro-size (20–50 μm) and nano-size (50–80 nm)) in the AA2014 hybrid nano-composite by sintering and hot extrusion processes. The prepared composites are subjected to mechanical and metallurgical characterization. A comparative analysis is performed by varying the weight percentages (1–10%) of alumina-reinforced particles. The AA2014 hybrid composite sample-3 (S3) is showing a substantial enhancement in the mechanical characteristics (Ys-255 MPa and UTS-265 MPa) than the other samples. The interfacial bonding between the AA2014 and alumina has observed minimum micro-hardness magnitude (98 VHN) in the sintered samples. The compressive strength of extruded composite S3 (327 MPa) is 1.157 times as high as the sintered sample. The agglomeration and segregation of Al2O3-reinforced nano-particles is identified in the AA2014 hybrid composite by using SEM analysis. The conical and equiaxed dimple failure in the AA2014 matrix and the circular cavities are observed through fractography analysis.
      Citation: Journal of Composite Materials
      PubDate: 2019-06-26T01:58:03Z
      DOI: 10.1177/0021998319856676
       
  • Effect of secondary bending and bolt load on damage and strength of
           composite single-lap interference-fit bolted structures
    • Authors: Kaifu Zhang, Junshan Hu, Peng Zou, Yi Cheng, Bing Luo, Hui Cheng
      Abstract: Journal of Composite Materials, Ahead of Print.
      The single-lap interference-fit bolted joint is widely used in composite structures. In order to get an accurate prediction of bearing strength, secondary bending and bolt load effects are studied in the present research via combination of experimental and numerical methods. The joint specimens with four levels of interference-fit size (I) and bolt torque (T) were tested according to ASTM standard D5961 to evaluate the bearing behavior and joint stiffness. Meanwhile, a finite element model considering the shear nonlinearity is built to simulate the bearing strength and evolution of intralaminar damage and delamination. Results show that the bearing behavior of composite joints is more sensitive to bolt load than interference-fit size, and the optimal pattern is I = 0.4% and T = 8 N-m, which can effectively improve bearing performance and alleviate secondary bending effect. Matrix failure and fiber–matrix shear-out failure accompanied with delamination are commonly observed and localized on the bearing side of joint-holes, indicating the desired non-catastrophic failure modes.
      Citation: Journal of Composite Materials
      PubDate: 2019-06-26T01:40:30Z
      DOI: 10.1177/0021998319857463
       
  • The effects of voids in quasi-static indentation of resin-infused
           reinforced polymers
    • Authors: SM Sisodia, DJ Bull, AR George, EK Gamstedt, MN Mavrogordato, DT Fullwood, SM Spearing
      Abstract: Journal of Composite Materials, Ahead of Print.
      The focus of this study is the influence of voids on the damage behaviour in quasi-static loading of resin-infused carbon fibre-reinforced polymers. Experimental results are presented for quasi-static loading in combination with high-resolution tomographic imaging and statistical analysis (homology of pores or voids and induced cracks). Three distinct mechanisms were observed to control delamination growth in the presence of sharp and blunt voids. Delamination cracks interact with the supporting yarns, especially in combination with air pockets trapped in the resin in the form of long, sharp voids. This resulted in crack growth that coalesces with delamination cracks from neighbouring yarn-voids during increased out-of-plane load–displacement, with almost no presence of intralaminar transverse cracks. This highlights the benefits and drawbacks of the supporting yarn during out-of-plane loading.
      Citation: Journal of Composite Materials
      PubDate: 2019-06-26T01:40:29Z
      DOI: 10.1177/0021998319858024
       
  • Nonwoven polyester interleaving for toughness enhancement in composites
    • Authors: Adnan A Gheryani, David C Fleming, Ronnal P Reichard
      Abstract: Journal of Composite Materials, Ahead of Print.
      Various researchers have developed techniques to control delamination in laminated structures. One of these techniques is “interleaving,” adding high toughness material to key interfaces in a laminate. This paper studies using polyester veil as a low-cost interleaf alternative to other materials and focuses on a nonwoven, polyester spunbond material. Two different interleaf thicknesses, 0.18 mm and 0.74 mm, are primarily used. In addition, fine 4 g/m2 polyester was also compared. Carbon/epoxy composites are manufactured using 2 × 2 Twill 24″–12k carbon fibers embedded in an epoxy resin, with polyester interleaves at key interfaces. Specimens are fabricated using wet hand layup and cured at room temperature in a vacuum bag. Mode I fracture toughness is measured using the double cantilever beam test and Mode II fracture toughness is examined using the end-notched flexure test. Further evaluation is made using static indentation and full penetration impact testing. Toughness is compared, and the resulting fracture surfaces are investigated. Significant improvement is seen in Mode I testing. Up to a factor of 4 increase in propagation energy per unit area resulted from the inclusion of the interleaf material. Smaller improvements were observed in Mode II, with the best cases showing an increase in propagation energy to maximum load by about a factor of 2 compared with control cases. The polyester interleaf significantly influences the fracture morphology observed in static indentation and full penetration tests.
      Citation: Journal of Composite Materials
      PubDate: 2019-06-25T05:08:57Z
      DOI: 10.1177/0021998319857116
       
  • Influence of TiC on dry sliding wear and mechanical properties of in situ
           synthesized AA5052 metal matrix composites
    • Authors: Priya R Samal, Pandu R Vundavilli, Arabinda Meher, Manas Mohan Mahapatra
      Abstract: Journal of Composite Materials, Ahead of Print.
      In this paper, aluminium metal matrix composites were synthesized through in situ process in which aluminium alloy 5052 (AA5052) and titanium carbide were used as matrix and reinforcement materials, respectively. The microstructural characterization and formation of stable TiC phases were analyzed with the help of field emission scanning electron microscope, X-ray diffraction analysis, respectively. The 9% TiC-reinforced MMCs had shown a considerable improvement, i.e. 32% increase in hardness, 78% in ultimate tensile strength and 116% increase in yield strength when compared with the base alloy. The tensile fracture of the specimens shows dimples, voids, cracks, and ridges indicating the brittle nature. Further, the dry sliding wear properties of the composites were studied with the help of a pin-on-disc wear testing machine. The composite with 9% TiC exhibited a decrease in volumetric wear loss by 24% when compared with the base alloy at a load of 30 N. With increase in the TiC content and applied load, the COF values decreased linearly for the composites. The 9% TiC-reinforced composites show an abrasive mode of wear mechanism as a result of formation of deep grooves with no plastic deformation. With the improvement obtained in the wear properties, this metal matrix composite can be considered as a replacement for the conventional brake disc material used in the automobile industry.
      Citation: Journal of Composite Materials
      PubDate: 2019-06-19T05:40:52Z
      DOI: 10.1177/0021998319857124
       
  • Understanding the influence of laminate stacking sequence on strain/stress
           concentrations in thin laminates at repair holes with large scarf angles
    • Authors: Mahdi Damghani, Jerzy Bakunowicz, Adrian Murphy
      Abstract: Journal of Composite Materials, Ahead of Print.
      Scarf repair is widely used in the restoration of structural performance of damaged aircraft secondary structures. Such repairs result in reduced thickness sections which are significantly larger than those associated with typical fastener holes. Significant literature exists on the distribution of strain/stress concentration in fastener hole geometries, both straight sided and countersunk, but is lacking for the geometries associated with shallow scarf angles and thin laminates. Hence, herein three-dimensional finite element models are developed to understand the influence of stacking sequence and scarf angle on strain/stress concentrations. The results demonstrate and quantify for the first time that strain concentrations are not only dependant on the laminate membrane stiffness but also on laminate bending stiffness, due to the anisotropy created as a result of scarfing angle, hole geometry and laminate thickness. Scarfing is demonstrated, for typical repair geometry associated with foreign object damage (hole diameter 20 mm, scarf angles 3° to 7°), to elevate strains by up to 2.5 times when compared to equivalent diameter straight-sided holes in laminates of thickness ≈1 mm.
      Citation: Journal of Composite Materials
      PubDate: 2019-06-19T05:40:51Z
      DOI: 10.1177/0021998319855772
       
  • Metal matrix composite material reinforced with metal wire and produced
           with gas metal arc welding
    • Authors: Roberta Cristina Silva Moreira, Oksana Kovalenko, Daniel Souza, Ruham Pablo Reis
      Abstract: Journal of Composite Materials, Ahead of Print.
      In the search for high-performance parts and structures, especially for the aviation and aerospace industry, metal matrix composites appear with prominence. However, despite exhibiting high levels of mechanical properties and low densities, these materials are still very expensive, mainly due to complex production. Thus, this work aims to present and evaluate a novel way of manufacturing metal matrix composites, with relative low cost and complexity: by using low-energy fusion welding to deposit the matrix material on top of continuous metal wire reinforcement. For proof of concept, Al alloy was used as matrix material, a single Ti alloy wire as reinforcement, and gas metal arc welding CMT-Pulse® as the process for material deposition. The simplified Al–Ti composite was evaluated in terms of impact resistance and tensile strength and stiffness. Overall, the mechanical performance of the composite was around 23% higher than that of the matrix material itself (Al), this with only about 2% of reinforcement volume and just over 3% of increase in weight. Analyses of the Al–Ti composite fractures and cross-sections and of chemical composition and hardness of the matrix–reinforcement transition interface indicated the preservation (no melting) of the Ti wire and the existence of a fine contour of bonding between matrix and reinforcement. At the end, a brief discussion on the dynamics of the wire reinforcement preservation is carried out based on high-speed filming.
      Citation: Journal of Composite Materials
      PubDate: 2019-06-19T05:40:51Z
      DOI: 10.1177/0021998319857920
       
  • Performance of FRP confined and unconfined engineered cementitious
           composite exposed to seawater
    • Authors: Alaa Mohammedameen, Abdulkadir Çevik, Radhwan Alzeebaree, Anıl Niş, Mehmet Eren Gülşan
      Abstract: Journal of Composite Materials, Ahead of Print.
      Conventional concrete suffers from brittle failures under mechanical behaviour, and lack of ductility results in the loss of human life and property in earthquake zones. Therefore, the degree of ductility becomes significant in seismic regions. This paper investigates the influence of poly-vinyl alcohol fibers, basalt fiber-reinforced polymer (BFRP) and carbon fiber-reinforced polymer (CFRP) fabrics on the ductility and mechanical performance of low (LCFA) and high (HCFA) calcium fly ash-based engineered cementitious composite concrete. The study also focuses on the mechanical behaviour of the CFRP and BFRP materials using different matrix types exposed to 3.5% seawater environment. Cyclic loading and scanning electron microscopy observations were also performed to see the effect of chloride attack on mechanical performance and ductility of the specimens. In addition, utilization of CFRP and BFRP fabrics as a retrofit material is also evaluated. Results indicated that the degree of ductility and mechanical performance were found to be superior for the CFRP-engineered cementitious composite hybrid specimens under ambient environment, while LCFA-CFRP hybrid specimens showed better performance under seawater environment. The effect of matrix type was also found significant when engineered cementitious composite is used together with fiber-reinforced polymer materials. In addition, both fiber-reinforced polymer materials can be used as a retrofit material under seawater environment.
      Citation: Journal of Composite Materials
      PubDate: 2019-06-19T05:40:50Z
      DOI: 10.1177/0021998319857110
       
  • Preparation and characterization of
           poly(3-glycidoxypropyltrimethoxysilane) nanocomposite using organophilic
           montmorillonite clay (Mag-cetyltrimethylammonium)
    • Authors: Nadia Embarek, Nabahat Sahli, Mohammed Belbachir
      Abstract: Journal of Composite Materials, Ahead of Print.
      Nanocomposites of linear poly(3-glycidoxypropyltrimethoxysilane) based on Algerian natural organophilic clay: montmorillonite–cetyltrimethylammonium named Maghnite-CTA were prepared by enhancing the dispersion of the matrix polymer in sheets of the organoclay. The effect of the organoclay, used with different amounts (3, 5, and 7% by weight) and the preparation method were studied in order to determine and evaluate their structural, morphological and thermal properties. X-ray diffraction analysis of obtained nanocomposites showed a significant change in the distance interlayer of montmorillonite–cetyltrimethylammonium. Therefore, interlayer expansion and exfoliation of linear poly(3-glycidoxypropyltrimethoxysilane) between layers of montmorillonite–cetyltrimethylammonium were observed. The thermal properties of the prepared nanocomposites were given by thermogravimetric analysis. The structure and morphology of the obtained materials were determined respectively by Fourier transform infrared spectroscopy and scanning electronic microscopy. The results obtained have approved the privilege of the intercalation of linear poly(3-glycidoxypropyltrimethoxysilane) in the interface of montmorillonite–cetyltrimethylammonium and the best quantity of organoclay required to prepare nanocomposite with a high thermal stability is 5% (by weight).
      Citation: Journal of Composite Materials
      PubDate: 2019-06-19T05:40:50Z
      DOI: 10.1177/0021998319857112
       
  • Micromechanical modelling of carbon nanotube reinforced composite
           materials with a functionally graded interphase
    • Authors: Vahidullah Taç, Ercan Gürses
      Abstract: Journal of Composite Materials, Ahead of Print.
      This paper introduces a new method of determining the mechanical properties of carbon nanotube-polymer composites using a multi-inclusion micromechanical model with functionally graded phases. The nanocomposite was divided into four regions of distinct mechanical properties; the carbon nanotube, the interface, the interphase and bulk polymer. The carbon nanotube and the interface were later combined into one effective fiber using a finite element model. The interphase was modelled in a functionally graded manner to reflect the true nature of the portion of the polymer surrounding the carbon nanotube. The three phases of effective fiber, interphase and bulk polymer were then used in the micromechanical model to arrive at the mechanical properties of the nanocomposite. An orientation averaging integration was then applied on the results to better reflect macroscopic response of nanocomposites with randomly oriented nanotubes. The results were compared to other numerical and experimental findings in the literature.
      Citation: Journal of Composite Materials
      PubDate: 2019-06-19T05:18:01Z
      DOI: 10.1177/0021998319857126
       
  • Numerical simulation for strain rate and temperature dependence of
           transverse tensile failure of unidirectional carbon fiber-reinforced
           plastics
    • Authors: Mio Sato, Sakie Shirai, Jun Koyanagi, Yuichi Ishida, Yasuo Kogo
      Abstract: Journal of Composite Materials, Ahead of Print.
      In the present study, strain-rate and temperature dependence of the transverse tensile failure mode of unidirectional heat-resistant carbon fiber-reinforced plastics is numerically simulated by finite element analyses. In the analyses, interface failure and matrix failure are represented by cohesive zone modeling and continuum damage mechanics, respectively. For the continuum damage mechanics, Christensen's failure criteria of multi-axial stress states for each strain rate are applied to the matrix properties. Interfacial properties which are obtained by microbond test are introduced into cohesive zone modeling. A time-temperature superposition principle approach is applied in order to translate the difference in temperature as the difference in strain rate. The damage initiation depends on strain rate and temperature, while the cohesive zone modeling is assumed to be temperature- and time-independent. The initial damage starting points and the failure mode are predicted in numerical analysis. The transverse tensile strengths in analysis results are compared with the three-point bending testing results.
      Citation: Journal of Composite Materials
      PubDate: 2019-06-19T05:17:59Z
      DOI: 10.1177/0021998319857111
       
  • Compression after ballistic impact response of pseudoelastic shape memory
           alloy embedded hybrid unsymmetrical patch repaired glass-fiber reinforced
           polymer composites
    • Authors: Luv Verma, Srinivasan M Sivakumar, Jefferson J Andrew, G Balaganesan, A Arockirajan, S Vedantam
      Abstract: Journal of Composite Materials, Ahead of Print.
      This paper investigated the influence of embedding pseudoelastic shape memory alloy within the external bonded patch made up of glass fibers on the compression after impact response of adhesively bonded external patch repaired glass/epoxy composite laminates. Unsymmetrical patch repair was employed in the current studies. Three innovative pseudoelastic shape memory alloy configurations (straight wired, meshed and anchored) were embedded inside the patch and the changes in high-velocity impact response and damage tolerance at four impact velocities (70, 85, 95, 105 m/s) were compared with the conventional glass/epoxy (glass fiber-reinforced polymer) patch. Anchored specimens showed the best response by improving the compressive strength by 25% under non-impacted conditions and restoring it by 88%, 77%, 29%, and 28% at the impact velocity of 70, 85, 95, and 105 m/s, respectively, in comparison to the conventional normal specimens.
      Citation: Journal of Composite Materials
      PubDate: 2019-06-18T06:15:50Z
      DOI: 10.1177/0021998319856426
       
  • Mode-II toughness of nanostitched carbon/epoxy multiwall carbon nanotubes
           prepreg composites: Experimental investigation by using end notched
           flexure
    • Authors: Kadir Bilisik, Gulhan Erdogan, Erdal Sapanci, Sila Gungor
      Abstract: Journal of Composite Materials, Ahead of Print.
      The mode-II interlaminar fracture toughness properties following the end notched flexure method of nanostitched carbon/epoxy nanoprepreg composites were studied. The fracture toughness (GIIC) of the nanostitched and stitched composites showed 3.4 fold and 2.7 fold increase compared to the control, respectively. Thus, the nanostitching improved the mode-II toughness of all the carbon/epoxy composites with regard to the nano, and base composites. It was assumed that the type of stitch fiber as well as fabric pattern, in particular prepreg carbon stitching fiber and satin prepreg woven fabric, was effective. The basic mechanism for the enhancement of the GIIC toughness in the nanostitched composite was the interlaminar resin layer failure especially as a form of shear hackle marks where nanostitching arrested the delamination in the stitching zone during crack propagations. Multiwall carbon nanotubes in the matrix and filament also mitigated the stress concentration probably as an outline of debonding/pull-out/stick-slip/friction. Therefore, nanostitched as well as stitched carbon/epoxy woven composites exhibited improved damage tolerance performance with regard to the base composites.
      Citation: Journal of Composite Materials
      PubDate: 2019-06-18T06:15:50Z
      DOI: 10.1177/0021998319857462
       
  • Sustainable mineral coating of alkali-resistant glass fibres in
           textile-reinforced mortar composites for structural purposes
    • Authors: Cesare Signorini, Andrea Nobili, Cristina Siligardi
      Abstract: Journal of Composite Materials, Ahead of Print.
      The mechanical performance of a silica-based mineral nano-coating applied to alkali-resistant glass textile-reinforced composite materials aimed at structural strengthening is investigated experimentally. The silica nano-film is directly applied to the alkali-resistant glass fabric by sol–gel deposition. Two lime mortars are adopted as embedding matrix, which differ by the ultimate compressive strength and elongation. Uni-axial tensile tests of prismatic coupons are carried out according to the ICC AC434 guidelines. Remarkable strength and ductility enhancements could be observed in the silica-coated group, as compared to the uncoated group, for both mortar types. Digital image correlation, electron scanning and optical microscopy provide evidence of improved interphase strength. X-ray diffraction of the anhydrous mortars brings out the role of the mineralogical composition of the embedding media on the overall bonding properties of the composites. Consideration of design limits and energy dissipation capabilities reveals the crucial role of matrix ductility in bringing the contribution of interphase enhancement to full effect. We conclude that best performance requires optimizing the pairing between fabric-to-matrix adhesion and matrix ductility.
      Citation: Journal of Composite Materials
      PubDate: 2019-06-14T05:30:07Z
      DOI: 10.1177/0021998319855765
       
  • Microstructural, mechanical and corrosion behaviour of Al–Si alloy
           reinforced with SiC metal matrix composite
    • Authors: Kapil Bandil, Himanshu Vashisth, Sourav Kumar, Lokesh Verma, Anbesh Jamwal, Devendra Kumar, Neera Singh, Kishor Kumar Sadasivuni, Pallav Gupta
      Abstract: Journal of Composite Materials, Ahead of Print.
      The aim of the present study is to investigate the effect of Si and SiC addition on the microstructure, mechanical, and corrosion properties of Al matrix-based composites. Al–Si (2 wt% fixed) alloy reinforced SiC composites were prepared by stir-casting process using SiC reinforcement contents from 0 to 20 wt% at an interval of 5%. A uniform dispersion of SiC particles in the Al matrix was observed from the scanning electron microscopic analysis. Maximum hardness is found for composites having 15 wt% reinforcement content. Pin-on-disc wear test reveals that SiC particles increase the wear resistance of composites. Corrosion test reveals that composites reinforced with 20% reinforcement content shows the minimum icorr among all the compositions, attributing to the maximum corrosion resistance. Tribological and corrosion behaviour were found to be dependent on the reinforcement content. However, they were not interdependent on each other. It is expected that the present study would be helpful in the development of lightweight composites for aerospace and shipping industries applications.
      Citation: Journal of Composite Materials
      PubDate: 2019-06-14T05:30:07Z
      DOI: 10.1177/0021998319856679
       
  • Experimental and numerical study of the spring-in of angled brackets
           manufactured using different resins and fiber textiles

         This is an Open Access Article Open Access Article

    • Authors: Alexander Bernath, Fabian Groh, Wibke Exner, Christian Hühne, Frank Henning
      Abstract: Journal of Composite Materials, Ahead of Print.
      Process-induced distortion of composite structures often leads to a violation of tolerances, making the assembly of components difficult and expensive. It therefore can inhibit a cost-effective mass production of high-performance composite structures. Process-induced distortion is often introduced by curved regions of a part due to spring-in. Main drivers are chemical shrinkage of the resin and thermal expansion of both fiber and resin during cooling after demolding. Both contribute to residual strains and consequently lead to distortion of the manufactured part. The spring-in phenomenon has been already addressed in many studies. However, variations in manufacturing and specimen properties inhibit a detailed comparison of the results. Hence, it is difficult to isolate major influencing parameters. Here we show spring-in results of specimens that were manufactured using the very same experimental setup and laminate configuration but different resin and fiber types. It is therefore possible to identify the interaction of the curing temperature and the maximum achievable glass transition temperature of the individual resins as a major influencing factor. Furthermore, it is shown that the properties of the investigated resins do not differ largely in terms of thermal expansion and chemical shrinkage. Moreover, the latter was measured using two different techniques to enable a comparison. Numerical spring-in prediction revealed good accuracy throughout the investigated specimen configurations. Limitations found are the influence of the sewing of fiber textiles and the sensitivity of the model to gradual changes of the layup. Moreover, different homogenization techniques are compared with regard to spring-in prediction accuracy.
      Citation: Journal of Composite Materials
      PubDate: 2019-06-13T05:32:03Z
      DOI: 10.1177/0021998319855423
       
  • High-speed edge trimming of carbon fiber-reinforced polymer composites
           using coated router tools
    • Authors: R Prakash, Vijayan Krishnaraj, Jamal Sheikh-Ahmad
      Abstract: Journal of Composite Materials, Ahead of Print.
      During trimming of edges of carbon fiber-reinforced polymer composite parts, issues such as resin degradation, delamination, and poor surface finish at the trimmed edges, and increased tool wear in cutting tools used is common. Therefore, it is essential to carry out investigations on edge trimming of carbon fiber-reinforced polymer to find the effect of cutting forces generated and the cutting tool temperature induced at different high speeds and feeds conditions. In this work, two different-coated router tools of titanium aluminum nitride-coated and diamond-like carbon-coated routers were used for investigating the effect of these coatings on cutting force and cutting tool temperature which affect the surface quality of trimmed carbon fiber-reinforced polymer. From the investigation, it was found that the diamond-like carbon-coated router tool has generated lower cutting forces, cutting tool temperatures, and, in turn, better surface finish even at high-speed conditions when compared to other tools. Due to the complex geometry of the router tool, online tool wear monitoring by acoustic emission technique was employed. Acoustic emission signals were taken as the measuring index of tool wear which shows good correlation with direct tool wear measurements. From the experiments, it was found that the tool performance of the diamond-like carbon-coated router is superior when compared to other tools. In addition, for edge trimming of carbon fiber-reinforced polymer composite parts, the diamond-like carbon router tool performed without much disturbance for a length of machining of around 5.9 m which is about 46% of increase in length of machining when compared to uncoated router tool.
      Citation: Journal of Composite Materials
      PubDate: 2019-06-13T05:32:03Z
      DOI: 10.1177/0021998319856071
       
  • Influence of gripping method on tensile properties of unidirectional
           thermoplastic CFRP – Round-robin activity for international
           standardization in Japan
    • Authors: Tsuyoshi Matsuo, Masaki Hojo, Kazuro Kageyama
      Abstract: Journal of Composite Materials, Ahead of Print.
      For unidirectional thermoplastic composite materials, it is preferable to use tab-less specimens in tensile tests owing to the low adhesive performance between specimens and tabs, as well as considerable warpage in laminates due to compression molding. In this study, round-robin tests are performed for unidirectional laminates in the 0° and 90° directions by two types of thermoplastic composites – carbon/polyamide 6 and carbon/polypropylene. The purpose of the round-robin test is to examine the difference between tab-bonded and tab-less specimens. Statistical analyses determined the degree to which tab-less specimens influenced their evaluation of the mechanical performance. In addition, from the detailed experiments, precisely controlled gripping force, fine roughness of grip surfaces, and a few inserted abrasive papers had significant impact on the 0° tensile strength of tab-less specimens. Based on the results, 0° tab-less strength of the proposed gripping method was shown to be almost equal to that of tab-bonded specimens recommended by the present tensile test standard.
      Citation: Journal of Composite Materials
      PubDate: 2019-06-13T05:32:02Z
      DOI: 10.1177/0021998319855419
       
  • On the Inter-Laminar Shear Strength of Composites Manufactured via a
           Stepped-Concurrent UV Curing and Layering Process
    • Authors: Shiferaw D Beyene, Beshah Ayalew, Srikanth Pilla
      Abstract: Journal of Composite Materials, Ahead of Print.
      In this paper, we set to examine the inter-laminar shear strength of a fiber-reinforced composite part manufactured via a stepped-concurrent ultraviolet curing and layering process. This process was specifically proposed for making epoxy-based thick parts, whereby a layer-by-layer, model-based, optimal layering time and ultraviolet control scheme is set up with the objective of minimizing the degree of cure deviation across the final thick part. We focus on a cationic curing process wherein additional energy savings are possible by switching off the ultraviolet source after initiating the curing reaction with the ultraviolet source at each layer addition. Since the inter-laminar sheer strength of parts made via a layering process is often a concern, we consider the application of in-situ consolidation pressure in the layering process. We then characterize the inter-laminar shear strength by manufacturing samples with application of different in-situ consolidation pressures and measuring the inter-laminar shear strength of each sample by the short-beam shear test. The results showed that the inter-laminar shear strength of composite parts fabricated with the proposed stepped-concurrent curing, and layering process increases with the applied consolidation pressure up to a point. Scanning electron microscopy of samples cured at different in-situ consolidation pressure showed that the sample with optimum consolidation pressure has relatively uniform fiber to resin distribution and hence improved inter-laminar shear strength.
      Citation: Journal of Composite Materials
      PubDate: 2019-06-13T05:32:01Z
      DOI: 10.1177/0021998319846550
       
  • Flexural properties of notched carbon–aramid hybrid composite
           laminates
    • Authors: TA Sebaey, Ahmed Wagih
      Abstract: Journal of Composite Materials, Ahead of Print.
      Hybrid composite laminates are currently receiving researchers’ attention due to their specific advantages in designing laminates with improved specific strength and stiffness. One of the main disadvantages of polymeric laminated composites is their high sensitivity to notches, which cannot be avoided in design. This paper presents a comparison between two common hybridization techniques, namely sandwich and intra-ply hybridization. The study adopts experimental observations to investigate the influence of hybridization method on the flexural properties of notched carbon–aramid hybrid laminates. After four-point bending tests, the results show that the damage nature in both laminates is different. A catastrophic damage is observed for intra-ply hybrid laminates, while sandwich laminates show progressive damage. In terms of the strength, sandwich specimens show 1.3 times higher specific strength, compared to intra-ply specimens. Moreover, the bottom layers of the laminate manufactured in the sandwich fashion show minimal damage due to the high capability of the aramid/epoxy core to absorb the energy in deformation and concentrate the damage at the top layers (the compression side).
      Citation: Journal of Composite Materials
      PubDate: 2019-06-12T04:56:29Z
      DOI: 10.1177/0021998319855773
       
  • Simulation and experiment on the effect of patch shape on adhesive repair
           of composite structures
    • Authors: Cheng Li, Qiaoli Zhao, Junjun Yuan, Yuliang Hou, Ying Tie
      Abstract: Journal of Composite Materials, Ahead of Print.
      In order to investigate the performance of the adhesive bonding repair in composite structures, static tensile test is carried out on the bonding structures numerically and experimentally. The tensile stress–displacement behaviors of T7901 composite adhesive bonding structure is studied under room temperature. Based on the three-dimensional progressive damage theory, the model of adhesive bonding structures with different patch shape has been constructed, and the final failure strength is predicted using APDL language. Moreover, experiment has been performed on each adhesive bonding structure with different patch shape. The results indicate a good agreement with numerical predictions. Furthermore, it is found that the repair effect of the adhesive bonding structure with the square patch is better than others. The final damage pattern and damage range of the patch repair structure are also tested by X-ray machine, which are consistent with the simulation results.
      Citation: Journal of Composite Materials
      PubDate: 2019-06-11T04:47:29Z
      DOI: 10.1177/0021998319853033
       
  • Mechanical and thermal properties of reticulated SiC aerogel composite
           prepared by template method
    • Authors: Xinli Ye, Zhaofeng Chen, Sufen Ai, Junxiong Zhang, Bin Hou, Qianbo Zhou, Fei Wang, Hezhou Liu, Sheng Cui
      Abstract: Journal of Composite Materials, Ahead of Print.
      A novel structure-controllable reticulated silicon carbide (SiC) skeleton-reinforced silica aerogel composites (SiC/aerogel) were fabricated successfully by template method. Three-dimensional SiC skeletons prepared by different deposition time were prepared via the chemical vapor deposition technology, and then the silica aerogel was induced by the sol–gel process. The test results showed that the mechanical properties increased and thermal conductivities decreased remarkably after impregnating reticulated SiC skeleton with silica aerogel. The SiC/aerogel-24 possessed the highest compressive strength of 0.82 MPa with the thermal conductivity of 0.1597 W/(m·K) at 600℃, while the SiC/aerogel-12 exhibited the lowest thermal conductivity of 0.1244 W/(m·K) and its compressive strength was 0.64 MPa. The present work reported a novel method to manufacture the structure-controllable reticulated SiC aerogel composite which could be used as a high-temperature super-thermal insulation material for the potential applications.
      Citation: Journal of Composite Materials
      PubDate: 2019-06-09T11:22:51Z
      DOI: 10.1177/0021998319851190
       
  • In situ real-time 3D observation of porosity growth during composite part
           curing by ultra-fast synchrotron X-ray microtomography
    • Authors: Basile de Parscau du Plessix, Patrice Lefébure, Nicolas Boyard, Steven Le Corre, Nicolas Lefèvre, Frédéric Jacquemin, Vincent Sobotka, Sabine Rolland du Roscoat
      Abstract: Journal of Composite Materials, Ahead of Print.
      The present study reports on an experimental development addressing 3D void growth in epoxy-based carbon fibre-reinforced composites during their curing process. For that purpose and to investigate autoclave condition effects, composites samples were cured according to different curing cycles by using a specially designed device, which was installed on a synchrotron beamline dedicated to ultra-fast X-ray microtomography. Thus, 3D in situ images of the voids evolution could be obtained as a function of time, temperature, pressure, initial water content and resin conversion degree, which are the driving factors of void size evolution during the polymerization cycles. Results confirm the combined roles of humidity and temperature on the porosity growth and highlight the complex shape of the generated bubbles. It is also emphasized that a sharp increase of the applied pressure during the curing cycle instantaneously reduces the pore size. Such results improve the understanding of the cure of composites parts and can finally be used as input data for modelling purpose or for validation of existing models.
      Citation: Journal of Composite Materials
      PubDate: 2019-06-05T09:39:15Z
      DOI: 10.1177/0021998319846260
       
  • Fabrication of graphene-magnetite multi-granule nanocluster composites for
           microwave absorption application
    • Authors: Boo H An, Bum C Park, Hamad A Yassi, Ji S Lee, Jung-Rae Park, Young K Kim, Jong E Ryu, Daniel S Choi
      Abstract: Journal of Composite Materials, Ahead of Print.
      Ferrite multi-granule nanoclusters are fabricated for microwave absorption materials in different sized particles and granules by modified polyol process. Various sizes of ferrite nanoclusters are placed on graphene-based composites and the behavior of their microwave absorbing properties is studied. The absorbing properties are measured using the free-space method with two horn antennas for X-band range (8.2 GHz–12.4 GHz). Relative permittivity and permeability values are calculated in measured frequency domain. The absorption coefficient changes by forming ferrite-graphene composites are presented as well.
      Citation: Journal of Composite Materials
      PubDate: 2019-06-04T07:28:26Z
      DOI: 10.1177/0021998319853032
       
  • Three-dimensional nanoprepreg and nanostitched aramid/phenolic multiwall
           
    • Authors: Kadir Bilisik, Gulhan Erdogan, Erdal Sapanci, Sila Gungor
      Abstract: Journal of Composite Materials, Ahead of Print.
      In-plane shear of nanostitched three-dimensional para-aramid/phenolic composites were experimentally investigated. Adding the nanostitched fiber into nanoprepreg para-aramid fabric preform composites slightly improved their shear strengths. The carbon-stitched composite exhibited comparatively better performance compared to the para-aramid stitched composite probably due to well bonding between carbon fiber and phenolic resin. The stitched nano composites had mainly matrix breakages and micro shear hackles in the matrix; matrix debonding and filament pull-out in the composite interface; fibrillar peeling and stripping on the filaments due to angular deformation. This mechanism probably prohibited extensive interlaminar opening in the nanostitched composites. The result exhibited that the introducing of the nano stitched fiber where multiwall carbon nanotubes were transferred to the out-of-plane of the base structure enhanced its transverse fracture as a form of confined delamination area. Therefore, the damaged tolerance properties of the stitched nano composites were enhanced compared to the base.
      Citation: Journal of Composite Materials
      PubDate: 2019-06-03T05:47:00Z
      DOI: 10.1177/0021998319854211
       
  • Finding the best sequence in flexible and stiff composite laminates
           interleaved by nanofibers
    • Authors: Hamed Saghafi, Seyed R Ghaffarian, Hesam Yademellat, Hossein Heidary
      Abstract: Journal of Composite Materials, Ahead of Print.
      The brittle nature of thermoset-based composite laminates restricts the application of these materials in various industries. One of the most effective methods for resolving this problem is interleaving the laminate by nanofibrous mats. Applying nanofibers between all layers is very costly and time-consuming. Therefore, the efficiency of using nanofibers in half of the layers for various interleaf sequences is investigated in this study. On the other hand, since the damage pattern is different in thick and thin laminates under impact, its effect is also considered. Cohesive parameters are required for impact modeling in ABAQUS, so they were obtained by mode-I and mode-II fracture tests and numerical studies. The results showed that the best position for interleaving the nanofibers is mid-layers and top layers (near impact point) in thin (flexible) and thick (stiff) laminates, respectively. If it is not possible to predict the damage penetration through the thickness, putting nanofibers in the top section of the laminate is suggested.
      Citation: Journal of Composite Materials
      PubDate: 2019-06-02T05:34:28Z
      DOI: 10.1177/0021998319850874
       
  • Micro-computed tomography analysis of natural fiber and bio-matrix
           tubular-braided composites
    • Authors: Brianna M Bruni-Bossio, Garrett W Melenka, Cagri Ayranci, Jason P Carey
      Abstract: Journal of Composite Materials, Ahead of Print.
      There is an increasing demand for the use of “green”-based materials as reinforcement and matrix materials in composites. However, the ability of these natural-based materials to perform as consistently and reliably as conventional materials is still relatively unknown. A key importance in the viability of these materials is the evaluation of the content of voids and imperfections, which may affect the properties of the entire composite. In this study, the microstructure of tubular-braided composites manufactured from cellulose fibers and a partially bio-derived resin was studied with the use of micro-computed tomography. These methods were used to determine the effect of modifying braid angle, resin type, and curing method on fiber volume fraction, void volume, and void distribution. It was determined that the void content increased with the increase in braid angle, and vacuum-bagging reduced the total void content. The sample with the smallest braid angle produced with vacuum-bagged curing contained a void fraction of 1.5%. The results of this study proved that the materials used could be viable for further testing and development and that micro-computed tomography imaging is valuable for identifying how to improve consistency and minimize imperfections to create more accurate and reliable natural fiber-braided composites.
      Citation: Journal of Composite Materials
      PubDate: 2019-05-30T05:49:18Z
      DOI: 10.1177/0021998319853023
       
  • Fabrication of aluminum-carbon nanotube nano-composite using
           aluminum-coated carbon nanotube precursor
    • Authors: Muhammad Mansoor, Shaheed Khan, Amjad Ali, Khalid Mahmood Ghauri
      Abstract: Journal of Composite Materials, Ahead of Print.
      Demand of special combination of different properties of the materials instigated the development of metal matrix composite. The carbon nanotubes being renowned for their excellent physical and mechanical properties are one of the major choices as strengthen material for metal matrix composites. To benefit their properties, the carbon nanotubes should be thoroughly dispersed and have wetting with the matrix. In the present study, a precursor of aluminum-carbon nanotubes was prepared by coating the nanotubes with titanium and used to fabricate the composite by induction melting. The precursor provided easy wetting, while induction melting facilitated dispersion of the nanotubes readily. Consequently, the composite exhibited noticeable augmentations in yield and tensile strength from 64 to 193 MPa and 81 to 227 MPa, respectively.
      Citation: Journal of Composite Materials
      PubDate: 2019-05-30T05:49:18Z
      DOI: 10.1177/0021998319853341
       
  • Studying delamination in composite laminates using shell elements and a
           strain-rate-dependent micro-mechanical model
    • Authors: Sandeep Medikonda, Ala Tabiei
      Abstract: Journal of Composite Materials, Ahead of Print.
      The effectiveness of studying inter-laminar delamination in laminated composites with the help of thickness-stretch shell elements which utilize a 3-D material model sub-routine as compared to the traditional plane-stress shell elements has been investigated using a non-linear finite element solver (LS-DYNA®). A strain-rate-dependent micro-mechanical material model using ply-level progressive failure criteria has been used to simulate the initiation and propagation of delamination. A methodology of assigning physical significance to the choice of damage parameters has been presented. The numerical delamination growth has been qualitatively analyzed against the experimental C-scan images for multiple impact events on different composite plates.
      Citation: Journal of Composite Materials
      PubDate: 2019-05-30T05:49:17Z
      DOI: 10.1177/0021998319853024
       
  • Fabrication and characterization of aluminum hybrid composites reinforced
           with silicon nitride/graphene nanoplatelet binary particles
    • Authors: Mahmut Can Şenel, Mevlüt Gürbüz, Erdem Koç
      Abstract: Journal of Composite Materials, Ahead of Print.
      In this study, pure aluminum was reinforced with pure silicon nitride (varying from 1 to 12 wt%), pure graphene nanoplatelets (changing from 0.1 to 0.5 wt%), and their hybrid form (silicon nitride/graphene nanoplatelets) by using powder metallurgy method. The results show that Vickers hardness increased to 57.5 ± 3 HV (Al-9Si3N4) and 57 ± 2.5 HV (Al-0.1GNPs) from 28 ± 2 HV (pure aluminum). Similarly, ultimate compressive strength of the pure silicon nitride and pure graphene nanoplatelet-reinforced aluminum composite was improved to 268 ± 6 MPa (Al-9Si3N4) and 138 ± 4 MPa (Al-0.5GNPs) from 106 ± 4 MPa (pure aluminum), respectively. Interestingly, the highest Vickers hardness, ultimate compressive strength, and ultimate tensile strength of aluminum-silicon nitride-graphene nanoplatelet hybrid composites were determined as 82 ± 3 HV (Al-9Si3N4-0.5GNPs), 334 ± 9 MPa (Al-9Si3N4-0.1GNPs), and 132 MPa (Al-9Si3N4-0.1GNPs), respectively. The Vickers hardness (for Al-9Si3N4-0.5GNPs), ultimate compressive strength (for Al-9Si3N4-0.1GNPs), and ultimate tensile strength (for Al-9Si3N4-0.1GNPs) improved ∼193%, ∼215%, and ∼47% when compared to pure Al, respectively. Above 9 wt% silicon nitride and 0.1 wt% graphene nanoplatelets content, an adverse effect was observed due to the agglomeration of silicon nitride and graphene nanoplatelets in aluminum matrix composites. Also, energy-dispersive X-ray and scanning electron microphotographs confirmed the presence of both silicon nitride and graphene nanoplatelets and uniformly distributed in the aluminum matrix.
      Citation: Journal of Composite Materials
      PubDate: 2019-05-30T05:49:17Z
      DOI: 10.1177/0021998319853329
       
  • Dielectric analysis as a low-complexity methodology for tracking prepreg
           out-time and its effects on the curing cycle
    • Authors: Olivia de Andrade Raponi, Bárbara Righetti de Souza, José Everardo Baldo Junior, Antonio Carlos Ancelotti Junior, Alessandro Guimarães
      Abstract: Journal of Composite Materials, Ahead of Print.
      The final properties of advanced composite parts manufactured from prepregs are strongly dependent on the combination of raw materials' properties and manufacturing parameters. Therefore, monitoring techniques that can characterize the prepreg cure advancement and the effects of this advancement on the curing process are of great interest to composite industries. In the present work, dielectric analyses were performed using a previously developed simple and low-cost device, as a successful alternative to track prepreg out-time and the specificities of aged prepregs curing process. The findings point out that, despite the temperature and humidity influence in the measurements, models for estimating prepreg out-times can be developed based on dielectric analyses results. Also, the dielectric properties can signalize the necessity of cure parameters adjustments, which might lead to the extension of prepreg out-time limits without significant detriment to the performance of the final part.
      Citation: Journal of Composite Materials
      PubDate: 2019-05-30T05:49:16Z
      DOI: 10.1177/0021998319853325
       
  • Elaboration and mechanical properties analysis of a composite based on
           polyester resin reinforced with natural Alfa fibres
    • Authors: A Boukhoulda, FB Boukhoulda, H Makich, M Nouari, B Haddag
      Abstract: Journal of Composite Materials, Ahead of Print.
      In this paper, the elaboration process of a new composite material based on polyester resin reinforced with long Alfa fibres is described. The used Alfa fibres have been obtained using the chemical method of extraction based on alkali treatment with different percentage of sodium hydroxide (NaOH). The obtained average diameters of fibres treated with 9%, 10%, 11% and 14% NaOH concentrations are about 145 ± 35 µm, 90 ± 15 µm, 83 ± 15 µm and 75 ± 15 µm, respectively. The composite was elaborated with impregnation of the fabric Alfa fibres in polyester resin. Besides, an experimental characterization using tensile tests has been conducted to determine the mechanical properties of the fibres obtained with the different NaOH concentrations. The results show that the composite made of polyester resin reinforced with fibres treated with 9% concentration of NaOH presents the greatest tensile strength.
      Citation: Journal of Composite Materials
      PubDate: 2019-05-29T06:55:14Z
      DOI: 10.1177/0021998319853025
       
  • Mechanical, fire, and smoke behaviour of hybrid composites based on
           polyamide 6 with basalt/carbon fibres
    • Authors: Karolina Mazur, Stanislaw Kuciel, Kamila Salasinska
      Abstract: Journal of Composite Materials, Ahead of Print.
      This paper describes the hybridization of basalt and carbon fibres in polyamide 6 by injection moulding method and the analyses of the mechanical, morphological, fire, and smoke properties of the obtained materials. The content of basalt/carbon fibres in hybrid composites amounted to 5/5 wt%, 7/7 wt%, and 10/10 wt%. The addition of fibres resulted in an increase in mechanical properties of the examined materials, was reflected by the threefold increase of Young modulus for the composites containing 10/10 wt% of fibres. To investigate the aging, the samples were stored in distilled water for 1, 7, 14, 100, and 210 days. After 210 days, a significant decrease in mechanical properties was observed. Interestingly, the addition of fibres caused a 50% reduction in stiffness, whereas, in the case of neat polyamide 6, the decrease was about 78%. Additionally, the addition of fibres reduced water sorption. With the increasing fibre load, the decrease in the maximum average rate of heat emission was observed. In the case of composites containing 10 wt% of basalt fibres and 10 wt% of carbon fibres, it amounted to 207 kW/m2 and was lower by approx. 37% in comparison to the unmodified polymer.
      Citation: Journal of Composite Materials
      PubDate: 2019-05-29T06:55:13Z
      DOI: 10.1177/0021998319853015
       
  • Investigation of mechanical properties of nanostructured Al-SiC composite
           manufactured by accumulative roll bonding
    • Authors: AF Meselhy, MM Reda
      Abstract: Journal of Composite Materials, Ahead of Print.
      To manufacture high-strength, fine dispersed and uniform distribution of Al-5 vol.% SiC composite, accumulative roll bonding process is proposed and applied through this study. The microstructure illustrates and validates a good distribution of SiC reinforced in the Al 1050 matrix. It is found that after eight pass, the mean grain size of the composite sample is 188 nm. It can be concluded from tensile test that by increasing the number of passes the strengths of both Al ARBed and composite samples increase; however, their ductility decreases at the initial accumulative roll bonding pass and then increases. The tensile strength of Al-SiC composite sample is greater than the annealed Al 1050 used as the original raw material by five times. The strengthening of the proposed composite sample occurs due to grain refinement, uniformity, reinforcing role of particles, strain hardening, bonding quality and size of particles. From the hardness test, it is concluded that, after the initial pass, hardness increased quickly, then dwindled and finally saturated by further rolling. Observations discovered that the failure mode in the composite occurs due to the shear fracture. From the experimental investigation, governing equations are derived to describe the effect of the number of accumulative roll bonding passes on the tensile strength and elongation of manufactured metal matrix composite materials. It is found that the tensile strength and elongation can be described as an exponential function of the number of passes. Numerical results from these equations are more consistent with the experimental investigation.
      Citation: Journal of Composite Materials
      PubDate: 2019-05-28T05:55:22Z
      DOI: 10.1177/0021998319851831
       
  • Thermo-mechanical analysis of multilayered composite beams based on a new
           mixed global-local model
    • Authors: Qilin Jin, Ziming Mao, Xiaofei Hu, Weian Yao
      Abstract: Journal of Composite Materials, Ahead of Print.
      An accurate mixed-form global-local higher-order theory including transverse normal thermal deformation is developed for thermo-mechanical analysis of multilayered composite beams. Although transverse normal deformation is considered, the number of displacement parameters is not increased. The proposed mixed-form global-local higher-order theory is derived using the displacement assumptions of global-local higher-order theory in conjunction with the Reissner mixed variational theorem. Moreover, the mixed-form global-local higher-order theory retains a fixed number of displacement variables regardless of the number of layers. In order to obtain the improved transverse shear stresses, the three-dimensional equilibrium equation is used. It is significant that the second-order derivatives of in-plane displacement variables have been eliminated from the transverse shear stress field, such that the finite element implementation is greatly simplified. The benefit of the proposed mixed-form global-local higher-order theory is that no post-processing integration procedure is needed to accurately calculate the transverse shear stresses. The equilibrium equations and analytical solution of the proposed model can be obtained based on the Reissner mixed variational equation. The performance of the proposed model is assessed through different numerical examples, and the results show that the proposed model can better predict the thermo-mechanical responses of multilayered composite beams.
      Citation: Journal of Composite Materials
      PubDate: 2019-05-28T05:55:22Z
      DOI: 10.1177/0021998319851839
       
  • Testing, characterizing, and forming of glass twill fabric/polypropylene
           prepregs
    • Authors: Mingrui Liu, Lidong Wang, Xiongqi Peng
      Abstract: Journal of Composite Materials, Ahead of Print.
      This paper investigates the mechanical behaviors of thermoplastic woven prepregs via testing and forming experiments. Glass twill fabric/polypropylene prepregs are produced by chemical treatment on fabric surface and a hot pressure molding approach. Then, mechanical tests including uniaxial tensile and bias extension of the glass twill fabric and its prepregs are carried out to provide basic data set for material modelling. An anisotropic hyperelastic model based on strain energy decomposition is proposed. And its material parameters are obtained by fitting these experimental data. Hemispherical thermo-stamping experiments are implemented for model verification. Very good agreements between forming simulation results and experimental data including boundary profiles, local shear angles, and forming force magnitude are obtained. The present work provides a complete data set for the model development and verification of thermoplastic woven fabric prepregs.
      Citation: Journal of Composite Materials
      PubDate: 2019-05-24T08:37:54Z
      DOI: 10.1177/0021998319851215
       
  • Characterization and mechanical response of novel Al-(Mg–TiFe–SiC)
           metal matrix composites developed by stir casting technique
    • Authors: Samuel O Akinwamide, Serge M Lemika, Babatunde A Obadele, Ojo J Akinribide, Bolanle T Abe, Peter A Olubambi
      Abstract: Journal of Composite Materials, Ahead of Print.
      This study was conducted to investigate the synthesis, characterization and mechanical properties of aluminium reinforced with ferrotitanium and silicon carbide via stir casting technique. Microstructures of as-cast samples were analysed using optical and scanning electron microscopes equipped with energy-dispersive X-ray spectroscopy. The mechanical properties in terms of hardness, tensile, tribological behaviour and fracture were assessed. Results showed that the homogeneous dispersion of reinforcement was within the metal matrix composite. Tribological study revealed a decrease in frictional coefficient of the composites with lowest frictional coefficient observed in composite with addition of silicon carbide as reinforcement. Morphology of fractured surface displayed a reduction in the size of dimples formed in reinforced aluminium composites when compared with larger dimple sizes observed in as-cast aluminium alloy.
      Citation: Journal of Composite Materials
      PubDate: 2019-05-21T04:20:51Z
      DOI: 10.1177/0021998319851198
       
  • Experimental and molecular dynamics study of boron nitride
           nanotube-reinforced polymethyl methacrylate composites
    • Authors: Sumit Sharma, Prince Setia, Rakesh Chandra, Nitin Thakur
      Abstract: Journal of Composite Materials, Ahead of Print.
      Heat dissipation is very essential for the efficient working of electronic devices. There is a widespread demand for high thermal conductivity materials. Boron nitride nanotubes have high thermal conductivity but due to their poor interfacial adhesion with polymers, their use as heat dissipating material is restricted. In this study, a silane-coupling agent has been used to modify the boron nitride nanotubes. These tubes were then inserted in polymethyl methacrylate matrix. Various properties such as thermal conductivity, storage modulus, and loss factor have been predicted. Molecular dynamics simulations have also been used for accurate prediction of the properties of boron nitride nanotubes/polymethyl methacrylate composites. The boron nitride nanotubes weight percentage was varied from 0% to 70% for studying the effect on thermal conductivity, storage modulus, and loss factor. The experimentally obtained thermal conductivity increased rapidly from 0.6 W/mK at 40 wt.% of boron nitride nanotubes to about 3.8 W/mK at 80 wt.% of boron nitride nanotubes in polymethyl methacrylate matrix (an increase of nearly 533%). A similar trend was obtained using molecular dynamics simulations. The storage modulus increased from 2 GPa (for pure polymethyl methacrylate) to about 5 GPa (for 70 wt.% boron nitride nanotubes). The glass transition temperature of boron nitride nanotubes/polymethyl methacrylate composites shifted to higher temperatures with an increase in boron nitride nanotubes weight percentage.
      Citation: Journal of Composite Materials
      PubDate: 2019-05-16T05:08:29Z
      DOI: 10.1177/0021998319851221
       
  • 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
       
  • Dynamic response and validation of a flexible matrix composite
    • Authors: Daniel Whisler, Rafael G Consarnau, Ezequiel Buenrostro
      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
       
  • Chemical resistance of carbon, basalt, and glass fibers used in FRP
           reinforcing bars
    • Authors: P Cousin, M Hassan, PV Vijay, M Robert, B Benmokrane
      First page: 3651
      Abstract: Journal of Composite Materials, Ahead of Print.
      One of the most important fields of research dealing with the use of carbon-, basalt-, and glass-fiber composites in the civil construction industry is their behavior under various chemical exposure conditions. Fiber-reinforced-polymer composites used as internal and external reinforcement in various structural applications can be subjected to widely differing pH situations. This study investigated the chemical durability of various carbon, basalt and glass fibers. The fibers were immersed in four types of solutions with acid, saline, alkaline, and deionized-water conditioning schemes. The fiber mass loss and surface damage along with changes due to chemical reactions were observed through weight-loss measurements and scanning electron microscopy. A criterion was developed to characterize the performance of fibers as very good, good, fair, and poor. This methodology can also be used by manufacturers as a quick quality-control tool for evaluating the chemical resistance of different fibers prior to large-volume production. The results reveal that the carbon fibers exhibited higher chemical resistance than the basalt and glass fibers based on weight loss and evidence of chemical reactions. Moreover, the determination of the fiber chemical composition before and after conditioning in acid and alkaline solutions clearly shows that the E-glass fibers, which are known to contain boron, were very sensitive to chemical corrosion. The ECR-glass fibers showed excellent chemical durability, even better than the basalt fibers.
      Citation: Journal of Composite Materials
      PubDate: 2019-04-24T06:23:18Z
      DOI: 10.1177/0021998319844306
       
  • Environmental, mechanical and materialistic effects on delamination damage
           of glass fiber composites: Analysis and optimization
    • Authors: Ali Tabatabaeian, Mohammad Baraheni, Saeid Amini, Ahmad R Ghasemi
      First page: 3671
      Abstract: Journal of Composite Materials, Ahead of Print.
      Machining process of glass fiber composites usually induces delamination damage. The presence of delamination may cause changes in the mechanical characteristics of the composite structures. In this research, a comprehensive experimental study is performed to analyze the influence of different parameters such as thermal fatigue, lay-up arrangement, resin type, feed rate and cutting velocity on the delamination of glass fiber composites under different drilling processes. Besides, influence of ultrasonic vibration exerting on the tool as a new and high-tech process is investigated. To follow this aim, different composite specimens with various resin types and lay-up arrangements are fabricated and a thermal fatigue condition is provided. Additionally, the Taguchi method is employed to obtain the optimized damage reduction condition in terms of mentioned parameters. The results indicated that thermal fatigue and unsymmetrical lay-up arrangement result in more delamination damage. It was also established that the influence of mentioned parameters is more considerable in higher cutting velocities. Moreover, ultrasonic vibration application is suggested to have the least delamination damage.
      Citation: Journal of Composite Materials
      PubDate: 2019-04-24T06:23:21Z
      DOI: 10.1177/0021998319844811
       
  • Impact resistance of Z-pin-reinforced sandwich composites
    • Authors: Gaye Kaya, Erdem Selver
      First page: 3681
      Abstract: Journal of Composite Materials, Ahead of Print.
      This study investigates the effect of face materials, Z-pin types and distribution densities on drop-weight impact properties of foam core sandwich composites. The novelty of this study is to eliminate damage of face part by only reinforcing the core part of sandwich structures. Impact test was performed at different energy levels (20–50 J). The addition of Z-pins into the sandwich composites decreased the elasticity and ductility while it increased the stiffness of sandwich composites. The Z-pin reinforcement increased the peak forces, but decreased the peak deformations of the sandwich composites. However, higher energy absorption was only observed at the higher Z-pin distribution density. The results showed that Z-pin distribution density, bonding between the face sheets/pins, and the face sheet material have a great influence on the impact behaviour of the Z-pin-reinforced sandwich composites besides the Z-pin types.
      Citation: Journal of Composite Materials
      PubDate: 2019-04-24T06:23:19Z
      DOI: 10.1177/0021998319845428
       
  • Thermal aging effect on the failure loads of adhesively strap joints
    • Authors: Kadir Turan
      First page: 3701
      Abstract: Journal of Composite Materials, Ahead of Print.
      In this study, the effects of thermal aging on failure loads in adhesively strap joints were investigated. Thermal aging treatment was applied to the woven glass fibre/epoxy composite plates with eight-layered 0° fibre reinforcement angle, epoxy-based adhesive and to the adhesively strap joints produced with these materials. The strength of the adhesively strap joints of single strap and double strap was determined by static tensile tests. Three conditions were analyzed in the thermal aging process. The first group samples were thermally aged at a temperature of 75, 100 and 150℃ with a constant time of 4 h. The second group samples were thermally aged at a constant temperature of 150℃ for 2, 4, 6 and 8 h and the third group samples were kept at room temperature (not aged). The failure loads of samples which are exposed to thermal aging were compared with the failure loads of the non-aged samples. As a result of experimental studies, it has been determined that the failure loads of thermally aged samples have increased by 27.7% to 133.1%.
      Citation: Journal of Composite Materials
      PubDate: 2019-04-27T05:13:25Z
      DOI: 10.1177/0021998319846552
       
  • A preliminary study on the preparation of seamless tubular bacterial
           cellulose-electrospun nanofibers-based nanocomposite fabrics
    • Authors: Muhammad Awais Naeem, Mensah Alfred, Hina Saba, Qasim Siddiqui, Tayyab Naveed, Umar Shahbaz, Qufu Wei
      First page: 3715
      Abstract: Journal of Composite Materials, Ahead of Print.
      Due to various production stages involved, textiles and clothing industry is known for causing carbon dioxide emissions, water pollution, soil erosion and huge waste generation. It is a need of the hour to seek for natural, renewable, and bio-degradable fabrication materials and environmentally friendly production methods. This study proposes an eco-friendly approach to prepare bacterial cellulose/electrospun nanofibers membrane-based hybrid non-woven fabrics using in-situ self-assembly method. This fabrication method enables bacterial cellulose cultivation on nanofibrous membrane support to create custom-made seamless tubular hybrid fabrics in desirable dimensions, to be used for various textile applications with minimized material wastage. As-prepared nano-composite fabric was characterized using SEM, X-ray diffraction, and FTIR. FTIR and X-ray diffraction results confirmed the presence of bacterial cellulose in the composite structure. SEM analysis showed as the bacterial cellulose cultivates, its nanofibrils penetrate and grow into empty voids of membrane's structure, which results in secure binding and interlocking of electrospun nonofibers. Sample thickness and weight gain measurements after the modification were found to be approx. 33.90% and 39.02%, respectively. Reduced surface hydrophobicity, water uptake, and increased tensile strength might contribute towards better fabric performance and comfort. Overall, this study suggests an eco-friendly approach to prepare nano-composite fabrics that might be used for bio-textiles and related applications.
      Citation: Journal of Composite Materials
      PubDate: 2019-04-29T11:48:11Z
      DOI: 10.1177/0021998319842295
       
  • Tensile behaviour of hybrid fibre architectures of randomly oriented
           strands combined with laminate groups
    • Authors: Swaroop B Visweswaraiah, Larry Lessard, Pascal Hubert
      First page: 3725
      Abstract: Journal of Composite Materials, Ahead of Print.
      In this work, the tensile behaviour of co-moulded hybrid fibre architectures of randomly oriented strands (carbon/PEEK) combined with laminate groups (cross-ply, angle-ply and quasi-isotropic) is studied. The effects of varying the thickness of the laminate group relative to that of randomly oriented strands, stacking sequence of the architectures within a hybrid specimen, and the ply stacking sequences within the laminate group are quantified. Processing benefits of hybridization such as reduction in warpage and strand waviness are discussed. The tensile behaviour of hybrid fibre architectures is quantified and compared with that of randomly oriented strand specimens, base laminate groups and aluminum 7075. In addition, tensile failure modes have been investigated. Significant improvements in the mechanical properties of randomly oriented strands are observed with small proportions of laminate groups in the specimen. In addition, hybrid fibre architectures exhibit a positive synergy or a positive deviation from the rule-of-mixtures in the overall stiffness and strength behaviour when stacked in specific configurations, despite the same fundamental fibre type and matrix system.
      Citation: Journal of Composite Materials
      PubDate: 2019-05-03T01:41:58Z
      DOI: 10.1177/0021998319844590
       
  • Effects of processing conditions on solidification characteristics and
           mechanical properties of in situ magnesium metal matrix composites derived
           from polysilazane precursor
    • Authors: Nagaraj M Chelliah, Padaikathan Pambannan, MK Surappa
      First page: 3741
      Abstract: Journal of Composite Materials, Ahead of Print.
      Polymer-derived in situ magnesium metal matrix composites (P-MMMCs) were fabricated by injecting a liquid or cross-linked polysilazane precursor into molten magnesium by a stir-casting method at two different melt temperatures of 700 and 800℃. Microstructural analysis reveals that the composites fabricated at 700℃ exhibit uni-modal grain size distribution having more or less columnar-shaped grain morphology. On the contrary, bi-modal grain size distribution with predominantly dendritic grain morphology occurs in the Mg matrix composites fabricated at 800℃. Such difference in grain morphology can be associated with variation in the availability of heterogeneous nucleation sites, and direction of heat flux during solidification. All of the fabricated composites were investigated for their solidification characteristics, microstructural evolution, micro/nano-hardness and compression properties. This article discusses the correlation between the processing parameters, microstructural evolution and mechanical properties of the as-cast in situ composites fabricated by liquid metallurgical route. Polymer-injection followed by in situ pyrolysis holds the potential of revolutionary processing technologies for producing castings of metal matrix nanocomposites, for example by bubbling the organic liquid with a carrier gas, e.g. nitrogen, into the molten metal by a Bessemer-like process.
      Citation: Journal of Composite Materials
      PubDate: 2019-05-03T01:42:00Z
      DOI: 10.1177/0021998319846546
       
  • An experimental characterization of wrinkling generated during prepreg
           autoclave manufacturing using caul plates
    • Authors: Tobias A Weber, Markus Englhard, Jan-Christoph Arent, Joachim Hausmann
      First page: 3757
      Abstract: Journal of Composite Materials, Ahead of Print.
      Out-of-plane ply wrinkling is a major quality issue for carbon fiber reinforced prepreg parts. Its triggers are numerous and not every influencing parameter is fully understood, yet. The research presented in this paper aims at providing a better insight into ply wrinkling generated during autoclave compaction using caul plates. A detailed description of the experimental set-up and the applied methodology is provided. Statistical analyses of varying influencing factors such as part thickness, geometry, tool–part interaction, and laminate lay-up are presented. This, in turn, generates a better understanding of their impact on fiber wrinkling risk and size. Part geometry and compaction deformation show the most significant influence on wrinkle size. However, for the given manufacturing concept, tool–part interaction also plays a significant role. It influences both the dimension and location of the wrinkles, as well as the existence and size of a critical flange length of the part. A noteworthy effect on wrinkle generation and size can also be observed when adding unidirectional plies to an otherwise fabric laminate.
      Citation: Journal of Composite Materials
      PubDate: 2019-05-03T01:41:59Z
      DOI: 10.1177/0021998319846556
       
  • Enhanced mechanical, electrical and corrosion characteristics of
           Al-CNTs-Nb composite processed via spark plasma sintering for conductor
           core
    • Authors: Chika Ujah, Patricia Popoola, Olawale Popoola, Victor Aigbodion
      First page: 3775
      Abstract: Journal of Composite Materials, Ahead of Print.
      Monolithic aluminium has low density and high conductivity required in transmission conductors. However, it lacks the requisite strength necessary for long space crossing. To augment the strength, it needs to be reinforced with adequate materials. So, this work is focused on spark plasma sintering of Al-CNTs-Nb composite for power transmission conductor core. Spark plasma sintering of the samples was carried out with pre-determined optimum sintering parameters. After the sintering, the density of the sintered samples was calculated using Archimedes principle, while the micro hardness was tested with Vickers hardness tester. The polarisation test was carried out with Autolab (PGSTAT302N), while the electrical conductivity was tested with four-point probe meter. The results gave a 37% improvement in micro hardness and 30% increase in tensile strength with Al-8CNTs-1Nb. Al-1CNTs-4Nb gave the best corrosion characteristics of 51% and 57% improvements in corrosion rates and 443% and 323% improvements in polarisation resistance in NaCl and H2SO4 media, respectively. Electrical conductivity showed a little increase by 2%. In all, it is evident that this composite is a suitable material for power transmission conductor core for upgrading the power grid.
      Citation: Journal of Composite Materials
      PubDate: 2019-05-03T01:41:57Z
      DOI: 10.1177/0021998319848055
       
  • Water-jet guided laser drilling of SiC reinforced aluminium metal matrix
           composites
    • Authors: S Marimuthu, J Dunleavey, Y Liu, B Smith, A Kiely, M Antar
      First page: 3787
      Abstract: Journal of Composite Materials, Ahead of Print.
      Laser drilling of monolithic materials like metals and alloys is a well-established process and used extensively in a wide range of applications in many sectors including aerospace, medical and automotive. However, conventional laser drilling of materials like metal matrix composites is challenging due to the differences in the chemical and physical properties of the hard ceramic reinforcement particles and the soft-metal matrix. The water-jet guided laser process has the potential to machine advanced materials such as an aluminium metal matrix composite reinforced with silicon carbide particles (Al MMC), with exceptional quality. The main objective of this research is to understand the material removal mechanism associated with water-jet guided laser drilling of Al MMCs and compare this with conventional laser drilling of Al MMC. Experimental results showed that the water-jet guided laser process is an excellent technique for drilling holes in composite materials like metal matrix composites. During water-jet guided laser drilling of Al MMC, the material has been removed by cold ablation, without leaving any residual melt layer within the bulk material. Both soft-matrix and hard-particles are removed by the same process of cold ablation, which is completely different to the conventional laser drilling process in which the solid SiC are ejected without melting, along with the molten aluminium.
      Citation: Journal of Composite Materials
      PubDate: 2019-05-03T01:42:00Z
      DOI: 10.1177/0021998319848062
       
  • Synergetic effect of fullerene and graphene oxide nanoparticles on
           mechanical characteristics of cross-linked polyurethanes under static and
           dynamic loading
    • Authors: Alexander E Tarasov, Denis V Anokhin, Yana V Propad, Egor A Bersenev, Sergey V Razorenov, Gennady V Garkushin, Elmira R Badamshina
      First page: 3797
      Abstract: Journal of Composite Materials, Ahead of Print.
      The effect of low concentration of fullerene, graphene oxide and their combinations at an 85/15 ratio as additives on structure and mechanical properties of cross-linked polyurethanes has been studied at static and dynamic loading. Structure of nanocomposites has been determined from X-ray analysis and scanning electron microscopy. It has been shown that the presence of carbon nanoparticles in a composite results in its lower strength under both static and shock-wave loads. The synergetic effect of carbon nanoparticles mixture is revealed to have 1.25 times higher Young's modulus as compared with native polymer.
      Citation: Journal of Composite Materials
      PubDate: 2019-05-03T01:41:58Z
      DOI: 10.1177/0021998319848077
       
  • A novel stress analysis method for composite Z-stiffeners under mechanical
           and thermal loads
    • Authors: WT Lu, S Singh, WS Chan
      First page: 3807
      Abstract: Journal of Composite Materials, Ahead of Print.
      A closed-form analytical solution is developed for analyzing laminated composite beam with asymmetric Z cross-section. The explicit expressions for evaluating sectional properties such as centroid, shear center, equivalent bending/torsional stiffness and warping stiffness are formulated based upon modified lamination theory and taken into consideration of the structural deformation characteristics of beam with narrow section. The ply stresses of flanges and web laminates are computed for composite Z-stiffener under axial, bending, and torsional loads. The present results give excellent agreement with the results from ANSYS™. A parametric study of their centroid and shear center with various layup sequences was performed by using the developed solution. It is found that the sectional properties are not only dependent of structural configuration but also the laminate property. Moreover, these properties are only dependent of structural configuration if the entire Z-stiffener is made of the same family laminates regardless their ply orientation and stacking sequence. It is concluded that the present approach is a viable and efficient method for designing composite Z-stiffener.
      Citation: Journal of Composite Materials
      PubDate: 2019-05-08T07:02:00Z
      DOI: 10.1177/0021998319846947
       
  • Improvement in the mechanical and tribological behavior of epoxy matrix
           with the inclusion of synthesized Ti3AlC2 MAX particles
    • Authors: Rasoul Jamshidi, Akbar Heidarpour, Hamed Aghamohammadi, Reza Eslami-Farsani
      First page: 3819
      Abstract: Journal of Composite Materials, Ahead of Print.
      This study has investigated the mechanical and tribological performance of epoxy composites filled with different contents of Ti3AlC2 MAX phase particles. The Ti3AlC2 particles were synthesized by the mechanical alloying of Ti, Al and C powders. The ultrasonic blending was used for preparing the mixture of Ti3AlC2 and epoxy matrix. The Vickers microhardness and pin on disc tests were carried out to investigate the mechanical and wear properties of samples, respectively. Moreover, the fracture and worn surface of the samples were analyzed by scanning electron microscopy images. Results showed that the microhardness values were increased due to increasing the content of Ti3AlC2 in the epoxy matrix. In this regard, the highest value of 39.24 Hv was achieved for composites containing 0.75 wt.% Ti3AlC2, which corresponds to the 75.4% improvement in microhardness value, compared to neat epoxy. Moreover, wear results demonstrated that the friction coefficient and wear rate values were decreased by the addition of Ti3AlC2 particles in the epoxy matrix.
      Citation: Journal of Composite Materials
      PubDate: 2019-05-08T07:02:01Z
      DOI: 10.1177/0021998319848140
       
  • Creep behaviour of FM906 glass-fibre epoxy as used in heated fibre metal
           laminates
    • Authors: Michiel Hagenbeek, Marcelo M Dias, Jos Sinke, Kaspar Jansen
      First page: 3829
      Abstract: Journal of Composite Materials, Ahead of Print.
      An innovative deicing system for aircraft leading edges has been developed which integrates heater elements into fibre metal laminates. Such an electrical system can lead to weight reductions and more efficient performances compared to conventional bleed air systems. However, the combination of thermal and mechanical loadings also raises new questions on the durability of such a structure, in particular due to the repeated heating to elevated temperature. The linear viscoelastic creep behaviour, including the effects of temperature and ageing, is therefore investigated for manufactured FM906 glass-fibre epoxy composite as used in heated GLARE. A master curve is derived based on the time–temperature and time–age superposition. The effect of physical ageing during loading is included in a long-term creep prediction.
      Citation: Journal of Composite Materials
      PubDate: 2019-05-10T05:16:00Z
      DOI: 10.1177/0021998319845045
       
  • Stress relaxation and strain recovery phenomena during curing and
           thermomechanical loading: Thermorheologically simple viscoelastic analysis
           
    • Authors: Sibin Saseendran, Daniel Berglund, Janis Varna
      First page: 3841
      Abstract: Journal of Composite Materials, Ahead of Print.
      Stress relaxation and strain recovery phenomena during curing and changed thermal conditions are analyzed using a viscoelastic model developed for thermorheologically complex materials (VisCoR). By making several simplifying assumptions regarding the material behavior, the incremental form of the VisCoR model is reformulated to a version describing thermorheologically simple material and presented in one-dimension for simplicity. The model (called VisCoR-simple) is used to analyze material behavior under various conditions, including stress relaxation behavior at varying temperatures and time scales; tensile loading and unloading tests at high temperatures; stress build up and “frozen-in” strains during curing and following cool-down and strain recovery during the next step of heating. Furthermore, the differences between the so-called “path-dependent” model, which is a linear elastic model with different elastic properties in glassy and rubbery regions, and the presented viscoelastic model are studied. The path-dependent model is an extreme case of the viscoelastic model presented. The importance of considering viscoelasticity when considering temperature and curing effects on polymers and the shortcomings of the path-dependent model are revealed and discussed.
      Citation: Journal of Composite Materials
      PubDate: 2019-05-10T05:16:11Z
      DOI: 10.1177/0021998319848818
       
  • Synthesis and characterization of high-performance epoxy/
           Ti3AlC2-reinforced conductive polymer composites
    • Authors: Vijayakumar M.P, Lingappa Rangaraj, Raja S
      First page: 3861
      Abstract: Journal of Composite Materials, Ahead of Print.
      Titanium aluminium carbide powder was reaction synthesized and used as reinforcement in the aircraft grade epoxy matrix (LY556) to develop a high-performance conductive polymer composite. The particle sizes of 4 and 7 µm were employed from 0 to 40 wt.% to improve the mechanical and electrical properties of conductive polymer composites. It was observed that the percolation characteristics were exhibited at a critical threshold of 20 wt.% for both the filler particle sizes. Further, microstructural observations revealed the formation of a conductive network in the conductive polymer composites when the filler content was 20 wt.%. The tensile and flexural properties were increased when the particle size was decreased. Experimental values were then compared with the available analytical models for validation. The mechanical and electrical properties of the conductive polymer composites were optimized by tailoring the filler particle size to 4 µm and particle loading at 20 wt.%. Compared to neat epoxy, the optimized conductive polymer composites have shown a simultaneous increase in strength, stiffness and conductivity performances, which can find applications in aerospace and electronics industries.
      Citation: Journal of Composite Materials
      PubDate: 2019-05-10T05:16:03Z
      DOI: 10.1177/0021998319849250
       
  • Hygrothermal effects on mechanical joints prepared from fiber reinforced
           plastic nanocomposites
    • Authors: Kulwinder Singh, JS Saini, H Bhunia, S Ray Chowdhury
      First page: 3875
      Abstract: Journal of Composite Materials, Ahead of Print.
      The present work deals with the hygrothermal aging of the bolt joints prepared from glass fiber reinforced plastics. To investigate the effect of nanoclay on joint performance, nanoclay content was varied from 0 to 5 wt%, with laminates prepared from 3 wt% of nanoclay content demonstrating the best mechanical properties. Nanoclay acts as a mechanical interlock between the fiber and the epoxy and thus improves the interfacial bonding. A good dispersion of nanoclay also improves moisture barrier properties which in turn reduces the degradation of the composite material hygrothermal conditions. Bolt joints were prepared from woven glass fiber reinforced laminates incorporating 3 wt% of nanoclay content. To design the bolt joint, ASTM D5961 was used and the geometric parameters, i.e. edge distance to hole diameter (E/D) ratio and width to hole diameter (W/D) ratio were fixed to 5 and 6, respectively. Three different temperatures, i.e. 25℃, 50℃ and 75℃ were considered for the aging to three different duration of exposure, i.e. 1, 2 and 3 weeks. The effect of different levels of bolt torque, i.e. 0, 2 and 4 Nm were considered for the failure analysis of the joint. A full factorial design of experiment was conducted on important control factors, i.e. water temperature, exposure time, bolt torque and material variation. It was found that the hygrothermal conditions degraded the material with temperature as the most contributing factor.
      Citation: Journal of Composite Materials
      PubDate: 2019-05-13T04:52:55Z
      DOI: 10.1177/0021998319848479
       
  • Aligned discontinuous carbon fibre tows in hybrid composites and their
           tensile behaviour: An experimental study
    • Authors: Khong Wui Gan, You Wei Ho, Zheng Yang Ow, Haris Ahmad Israr, King Jye Wong
      First page: 3893
      Abstract: Journal of Composite Materials, Ahead of Print.
      The paper aims to explore potential higher value applications of discontinuous carbon fibre tows. A vibration-assisted dry alignment method is presented to align the discontinuous fibre tows between conventional dry reinforcement mats/fabrics to fabricate cost-effective hybrid composites. Its viability is demonstrated by successful fabrication of two hybrid composite panels, where thin layers of aligned 12 mm discontinuous carbon fibre tows were deposited between E-glass chopped strand mats or woven fabrics respectively, via an out-of-autoclave resin infusion process; 54% and 81% of the fibre tows were aligned in the range of ±5° and ±10°, respectively. The tensile test results clearly demonstrate the importance of having the discontinuous fibre tows highly aligned in the hybrid composites, which shows increased stiffness (up to 24.4%) and strength (up to 59.9%) over the non-aligned hybrid composites. The aligned hybrid composites also exhibit a non-linear pseudo-ductile response due to subcritical progressive damage compared to the catastrophic brittle failure of the baseline non-hybrid E-glass and non-aligned hybrid composites, despite the tensile strength knockdown (up to −40.3%) due to premature inter-tow debonding. They also display increased stiffness up to 90%.
      Citation: Journal of Composite Materials
      PubDate: 2019-05-13T04:52:58Z
      DOI: 10.1177/0021998319849697
       
  • Fabrication and characterization of MWCNT/natural Azerbaijani bentonite
           electroconductive ceramic composites
    • Authors: Asgar Huseynov, Aydin Israfilov, Samira Mammadova, Sevda Abdullayeva, Sergey Sokolov, Alexey Goryunkov, Akif Guliyev
      First page: 3909
      Abstract: Journal of Composite Materials, Ahead of Print.
      Multi-walled carbon nanotubes have been synthesized by Aerosol-Chemical Vapor Deposition method. Carbon nanotubes firstly have been used as filler in affordable and prevalent natural Azerbaijani bentonite clays for fabrication electroconductive ceramic composites. In this paper, multi-walled carbon nanotubes/natural Azerbaijani bentonite ceramic composites were prepared by two-factor mechanical method and followed by calcination at 1050℃ in an inert atmosphere. The ceramic composites were characterized by scanning electron microscope, atomic force microscope, X-ray diffraction and thermogravimetric-differential-thermal analysis. X-ray diffraction analysis confirmed the presence of two principal components – multi-walled carbon nanotube and bentonite in composites. From the thermogravimetric-differential-thermal data, it was revealed that multi-walled carbon nanotube/ bentonite ceramic composites demonstrate thermo-oxidative stability up to 580–640℃. Scanning electron microscope images demonstrated a sufficiently high dispersibility of carbon nanotubes and satisfactory homogeneity in the composites. Experimental results demonstrated that by increasing the mass fraction of multi-walled carbon nanotubes from 1% to 8% in multi-walled carbon nanotube/bentonite ceramic composites, the electrical conductivity enhances substantially. The enhancement of electrical conductivity of the composites explained the mass fraction of multi-walled carbon nanotubes, as well as the uniform dispersion of multi-walled carbon nanotubes in the bentonite clays. Compared with other 8% multi-walled carbon nanotubes/bentonite ceramic composites, the electrical conductivity of heptane-multi-walled carbon nanotube/Gobu bentonite (σ = 397 S·m−1) and heptane-multi-walled carbon nanotubes/Atyali (σ = 305 S·m−1) composites is 2–5 times higher than the conductivity of composites obtained with cyclohexane carbon nanotubes- cyclohexane-multi-walled carbon nanotube/Atyali (σ = 78 S·m−1), cyclohexane-multi-walled carbon nanotube/Gobu (σ = 111,5 S·m−1). These results can be explained with the structure, the number of layers, purity and diameter distribution, as well as the type and amount of defects in internal and external layers of Hep-multi-walled carbon nanotubes which cause better dispersion in bentonite clays. Due to the high conductivity and high temperature stability, these composites can be used as promising material for fabrication heating elements, electrodes, substrates for microelectronic devices, etc.
      Citation: Journal of Composite Materials
      PubDate: 2019-05-14T05:45:50Z
      DOI: 10.1177/0021998319848798
       
 
 
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