Journal Cover
Journal of Composite Materials
Journal Prestige (SJR): 0.555
Citation Impact (citeScore): 2
Number of Followers: 384  
 
Hybrid Journal Hybrid journal   * Containing 2 Open Access Open Access article(s) in this issue *
ISSN (Print) 0021-9983 - ISSN (Online) 1530-793X
Published by Sage Publications Homepage  [1087 journals]
  • 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
      Pages: 3929 - 3938
      Abstract: Journal of Composite Materials, Volume 53, Issue 28-30, Page 3929-3938, December 2019.
      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
       
  • Testing, characterizing, and forming of glass twill fabric/polypropylene
           prepregs
    • Authors: Mingrui Liu, Lidong Wang, Xiongqi Peng
      Pages: 3939 - 3950
      Abstract: Journal of Composite Materials, Volume 53, Issue 28-30, Page 3939-3950, December 2019.
      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
       
  • Investigation of mechanical properties of nanostructured Al-SiC composite
           manufactured by accumulative roll bonding
    • Authors: AF Meselhy, MM Reda
      Pages: 3951 - 3961
      Abstract: Journal of Composite Materials, Volume 53, Issue 28-30, Page 3951-3961, December 2019.
      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
      Pages: 3963 - 3978
      Abstract: Journal of Composite Materials, Volume 53, Issue 28-30, Page 3963-3978, December 2019.
      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
       
  • Mechanical, fire, and smoke behaviour of hybrid composites based on
           polyamide 6 with basalt/carbon fibres
    • Authors: Karolina Mazur, Stanislaw Kuciel, Kamila Salasinska
      Pages: 3979 - 3991
      Abstract: Journal of Composite Materials, Volume 53, Issue 28-30, Page 3979-3991, December 2019.
      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
       
  • 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
      Pages: 3993 - 4001
      Abstract: Journal of Composite Materials, Volume 53, Issue 28-30, Page 3993-4001, December 2019.
      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
       
  • 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
      Pages: 4003 - 4013
      Abstract: Journal of Composite Materials, Volume 53, Issue 28-30, Page 4003-4013, December 2019.
      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
       
  • Studying delamination in composite laminates using shell elements and a
           strain-rate-dependent micro-mechanical model
    • Authors: Sandeep Medikonda, Ala Tabiei
      Pages: 4015 - 4034
      Abstract: Journal of Composite Materials, Volume 53, Issue 28-30, Page 4015-4034, December 2019.
      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
       
  • 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
      Pages: 4035 - 4042
      Abstract: Journal of Composite Materials, Volume 53, Issue 28-30, Page 4035-4042, December 2019.
      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
       
  • Fabrication and characterization of aluminum hybrid composites reinforced
           with silicon nitride/graphene nanoplatelet binary particles
    • Authors: Mahmut Can Şenel, Mevlüt Gürbüz, Erdem Koç
      Pages: 4043 - 4054
      Abstract: Journal of Composite Materials, Volume 53, Issue 28-30, Page 4043-4054, December 2019.
      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
       
  • Fabrication of aluminum-carbon nanotube nano-composite using
           aluminum-coated carbon nanotube precursor
    • Authors: Muhammad Mansoor, Shaheed Khan, Amjad Ali, Khalid Mahmood Ghauri
      Pages: 4055 - 4064
      Abstract: Journal of Composite Materials, Volume 53, Issue 28-30, Page 4055-4064, December 2019.
      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
       
  • Finding the best sequence in flexible and stiff composite laminates
           interleaved by nanofibers
    • Authors: Hamed Saghafi, Seyed R Ghaffarian, Hesam Yademellat, Hossein Heidary
      Pages: 4065 - 4076
      Abstract: Journal of Composite Materials, Volume 53, Issue 28-30, Page 4065-4076, December 2019.
      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
       
  • Three-dimensional nanoprepreg and nanostitched aramid/phenolic multiwall
           
    • Authors: Kadir Bilisik, Gulhan Erdogan, Erdal Sapanci, Sila Gungor
      Pages: 4077 - 4096
      Abstract: Journal of Composite Materials, Volume 53, Issue 28-30, Page 4077-4096, December 2019.
      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
       
  • 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
      Pages: 4097 - 4103
      Abstract: Journal of Composite Materials, Volume 53, Issue 28-30, Page 4097-4103, December 2019.
      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
       
  • 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
      Pages: 4105 - 4116
      Abstract: Journal of Composite Materials, Volume 53, Issue 28-30, Page 4105-4116, December 2019.
      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
       
  • 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
      Pages: 4117 - 4124
      Abstract: Journal of Composite Materials, Volume 53, Issue 28-30, Page 4117-4124, December 2019.
      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
       
  • 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
      Pages: 4125 - 4135
      Abstract: Journal of Composite Materials, Volume 53, Issue 28-30, Page 4125-4135, December 2019.
      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
       
  • Flexural properties of notched carbon–aramid hybrid composite
           laminates
    • Authors: TA Sebaey, Ahmed Wagih
      Pages: 4137 - 4148
      Abstract: Journal of Composite Materials, Volume 53, Issue 28-30, Page 4137-4148, December 2019.
      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
       
  • 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
      Pages: 4149 - 4159
      Abstract: Journal of Composite Materials, Volume 53, Issue 28-30, Page 4149-4159, December 2019.
      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
       
  • 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
      Pages: 4161 - 4171
      Abstract: Journal of Composite Materials, Volume 53, Issue 28-30, Page 4161-4171, December 2019.
      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
       
  • 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
      Pages: 4173 - 4188
      Abstract: Journal of Composite Materials, Volume 53, Issue 28-30, Page 4173-4188, December 2019.
      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
      Pages: 4189 - 4202
      Abstract: Journal of Composite Materials, Volume 53, Issue 28-30, Page 4189-4202, December 2019.
      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
       
  • Sustainable mineral coating of alkali-resistant glass fibres in
           textile-reinforced mortar composites for structural purposes
    • Authors: Cesare Signorini, Andrea Nobili, Cristina Siligardi
      Pages: 4203 - 4213
      Abstract: Journal of Composite Materials, Volume 53, Issue 28-30, Page 4203-4213, December 2019.
      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
      Pages: 4215 - 4223
      Abstract: Journal of Composite Materials, Volume 53, Issue 28-30, Page 4215-4223, December 2019.
      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
       
  • 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
      Pages: 4225 - 4247
      Abstract: Journal of Composite Materials, Volume 53, Issue 28-30, Page 4225-4247, December 2019.
      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
      Pages: 4249 - 4271
      Abstract: Journal of Composite Materials, Volume 53, Issue 28-30, Page 4249-4271, December 2019.
      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
       
  • 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
      Pages: 4273 - 4284
      Abstract: Journal of Composite Materials, Volume 53, Issue 28-30, Page 4273-4284, December 2019.
      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
       
  • Performance of FRP confined and unconfined engineered cementitious
           composite exposed to seawater
    • Authors: Alaa Mohammedameen, Abdulkadir Çevik, Radhwan Alzeebaree, Anıl Niş, Mehmet Eren Gülşan
      Pages: 4285 - 4304
      Abstract: Journal of Composite Materials, Volume 53, Issue 28-30, Page 4285-4304, December 2019.
      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
       
  • 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
      Pages: 4305 - 4312
      Abstract: Journal of Composite Materials, Volume 53, Issue 28-30, Page 4305-4312, December 2019.
      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
       
  • Preparation and characterization of
           poly(3-glycidoxypropyltrimethoxysilane) nanocomposite using organophilic
           montmorillonite clay (Mag-cetyltrimethylammonium)
    • Authors: Nadia Embarek, Nabahat Sahli, Mohammed Belbachir
      Pages: 4313 - 4322
      Abstract: Journal of Composite Materials, Volume 53, Issue 28-30, Page 4313-4322, December 2019.
      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
       
  • Influence of TiC on dry sliding wear and mechanical properties of in situ
           synthesized AA5052 metal matrix composites
    • Authors: Priyaranjan Samal, Pandu R Vundavilli, Arabinda Meher, Manas Mohan Mahapatra
      Pages: 4323 - 4336
      Abstract: Journal of Composite Materials, Volume 53, Issue 28-30, Page 4323-4336, December 2019.
      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
       
  • Micromechanical modelling of carbon nanotube reinforced composite
           materials with a functionally graded interphase
    • Authors: Vahidullah Taç, Ercan Gürses
      Pages: 4337 - 4348
      Abstract: Journal of Composite Materials, Volume 53, Issue 28-30, Page 4337-4348, December 2019.
      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
       
  • Nonwoven polyester interleaving for toughness enhancement in composites
    • Authors: Adnan A Gheryani, David C Fleming, Ronnal P Reichard
      Pages: 4349 - 4367
      Abstract: Journal of Composite Materials, Volume 53, Issue 28-30, Page 4349-4367, December 2019.
      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
       
  • 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
      Pages: 4369 - 4384
      Abstract: Journal of Composite Materials, Volume 53, Issue 28-30, Page 4369-4384, December 2019.
      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
      Pages: 4385 - 4398
      Abstract: Journal of Composite Materials, Volume 53, Issue 28-30, Page 4385-4398, December 2019.
      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
      Pages: 4399 - 4410
      Abstract: Journal of Composite Materials, Volume 53, Issue 28-30, Page 4399-4410, December 2019.
      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
       
  • 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
      Pages: 4411 - 4426
      Abstract: Journal of Composite Materials, Volume 53, Issue 28-30, Page 4411-4426, December 2019.
      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
       
  • Retraction Notice
    • Pages: 4427 - 4428
      Abstract: Journal of Composite Materials, Volume 53, Issue 28-30, Page 4427-4428, December 2019.

      Citation: Journal of Composite Materials
      PubDate: 2019-09-13T10:07:13Z
      DOI: 10.1177/0021998319875285
       
  • Development and characterisation of multi-layered jute fabric-reinforced
           HDPE composites
    • Authors: Abu Sadat Muhammad Sayem, Julfikar Haider, MM Alamgir Sayeed
      Abstract: Journal of Composite Materials, Ahead of Print.
      The bast fibres, a subgroup of natural fibre family, have emerged as a strong competitor of widely used man-made glass fibre for use as fillers or reinforcing materials in certain types of composite materials, which do not require very high mechanical resistance. This paper investigates the manufacturing of multi-layered jute fabric-reinforced thermoplastic composite and its mechanical performance. Hessian jute fabrics in two, four and six layers without any pre-treatment were sandwiched in 0° orientation into seven layers of high-density polyethylene sheets and pressed at high temperature and pressure to form composite laminates having three different structural designs. The laminates with two, four and six layers contain approximately 6.70 wt%, 12.90 wt% and 18.50 wt% of jute fibres, respectively. Mechanical performance of the composite laminates having four and six layers of jute fabric was found to have improved significantly when compared to the pure high-density polyethylene laminates. Within a given sample thickness of 6.5 mm, the laminate with six layers of jute fabric exhibited the best mechanical performance. Optical microscopic analysis revealed that the yarn orientation of the fabrics within the composites remained stable, and there was no visible void in the laminate structure. Fracture morphology of the composite investigated by a scanning electron microscope showed good adhesion of the jute fabrics with the high-density polyethylene matrix.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-12T06:20:11Z
      DOI: 10.1177/0021998319885440
       
  • Dynamic impact behavior of syntactic foam core sandwich composites
    • Authors: P Breunig, V Damodaran, K Shahapurkar, S Waddar, M Doddamani, P Jeyaraj, P Prabhakar
      Abstract: Journal of Composite Materials, Ahead of Print.
      Sandwich composites and syntactic foams independently have been used in many engineering applications. However, there has been minimal effort towards taking advantage of the weight saving ability of syntactic foams in the cores of sandwich composites, especially with respect to the impact response of structures. To that end, the goal of this study is to investigate the mechanical response and damage mechanisms associated with syntactic foam core sandwich composites subjected to dynamic impact loading. In particular, this study investigates the influence of varying cenosphere volume fraction in syntactic foam core sandwich composites subjected to varying dynamic impact loading and further elucidates the extent and diversity of corresponding damage mechanisms. The syntactic foam cores are first fabricated using epoxy resin as the matrix and cenospheres as the reinforcement with four cenosphere volume fractions of 0% (pure epoxy), 20%, 40%, and 60%. The sandwich composite panels are then manufactured using the vacuum assisted resin transfer molding process with carbon fiber/vinyl ester facesheets. Dynamic impact tests are performed on the sandwich composite specimens at two energy levels of 80 J and 160 J, upon which the data are post-processed to gain a quantitative understanding of the impact response and damage mechanisms incurred by the specimens. A qualitative understanding is obtained through micro-computed tomography scanning of the impacted specimens. In addition, a finite element model is developed to investigate the causes for different damage mechanisms observed in specimens with different volume fractions.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-10T08:57:36Z
      DOI: 10.1177/0021998319885000
       
  • Creep in interlaminar shear of an Hi-Nicalon™/SiC–B4C composite at
           1300℃ in air and in steam
    • Authors: MB Ruggles-Wrenn, TA Wallis
      Abstract: Journal of Composite Materials, Ahead of Print.
      Creep behavior in interlaminar shear of an advanced SiC/SiC composite with a self-healing matrix was investigated at 1300℃ in laboratory air and in steam. The composite was processed via chemical vapor infiltration (CVI). The composite has a self-healing oxidation-inhibited matrix comprising alternating layers of silicon carbide and boron carbide and is reinforced with laminated woven Hi-Nicalon™ fibers. Fiber preforms were coated with pyrolytic carbon followed by a boron carbon overlay. The interlaminar shear properties were evaluated at 1300℃. The creep behavior was examined for interlaminar shear stresses ranging from 13 to 20 MPa in air and in steam. Primary and secondary creep regimes were observed in all tests conducted in air and in steam. Creep run-out (defined as 100 h at creep stress) was achieved at 13 MPa in air and in steam. Presence of steam had little influence on creep strain rates and creep lifetimes. However, larger creep strains were accumulated in steam than in air. The retained properties of all specimens that achieved creep run-out were characterized. Composite microstructure and damage and failure mechanisms were investigated.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-10T08:57:35Z
      DOI: 10.1177/0021998319886621
       
  • Recent developments in the processing of waste carbon fibre for
           thermoplastic composites – A review
    • Authors: Muhammad Furqan Khurshid, Martin Hengstermann, Mir Mohammad Badrul Hasan, Anwar Abdkader, Chokri Cherif
      Abstract: Journal of Composite Materials, Ahead of Print.
      The aim of this paper is to highlight recent developments in the processing of waste carbon fibre for thermoplastic composites. Initially, injection moulding and nonwoven technologies have been used to integrate waste carbon fibres into fibre-reinforced thermoplastic composites. Recently, tape and hybrid yarn spinning technologies have been developed to produce tape and hybrid yarn structures from waste carbon fibre, which are then used to manufacture recycled carbon fibre-reinforced thermoplastics with much higher efficiency. The hybrid yarn spinning technologies enable the development of various fibrous structures with higher fibre orientation, compactness and fibre volume fraction. Therefore, thermoplastic composites manufactured from hybrid yarns possess a good potential for use in load-bearing structural applications. In this paper, a comprehensive review on novel and existing technologies employed for the processing of waste carbon fibre in addition to different quality aspects of waste carbon fibre is presented.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-08T06:04:26Z
      DOI: 10.1177/0021998319886043
       
  • Evaluation of the effects of nanomaterials on durability of engineered
           cementitious composites exposed to the aggressive environment
    • Authors: Alireza Mansoori, Kiachehr Behfarnia
      Abstract: Journal of Composite Materials, Ahead of Print.
      The present study was aimed to evaluate the effect of micro silica, nano silica and carbon nanotube in the engineered cementitious composites made with polyvinyl alcohol fibers. Accordingly, the compressive strength and the modulus of the samples rupture were studied to evaluate the impact of micro silica, nano silica and carbon nanotube in engineered cementitious composite. In addition, different curing conditions were considered to investigate the durability of the mixes. In this regard, the mechanical properties of the samples cured in sulphuric acid and freeze and thaw cycling were compared to those cured in water. The results indicated that the mechanical properties were reduced upon exposure to acid and freeze and thaw cycling. It was also found that the application of micro silica and nano silica made the mixtures compacted and reduced the permeability. The module of rupture was increased significantly by the addition of carbon nanotube. Moreover, the evaluation of the samples cured in the aggressive environment showed that the role of carbon nanotube was significant in increasing the durability of the mixes. Further, the scanning electron microscopy images showed that the crack width was reduced by the addition of carbon nanotube. It was also revealed from the scanning electron microscopy images that the polyvinyl alcohol fibers were completely interacted and connected to the paste.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-08T06:04:25Z
      DOI: 10.1177/0021998319887208
       
  • Investigation of thermal and mechanical properties of styrene–butadiene
           rubber nanocomposites filled with SiO2–polystyrene core–shell
           nanoparticles
    • Authors: Mujahid Khan, Satyendra Mishra, Debdatta Ratna, Shriram Sonawane, Navinchandra Gopal Shimpi
      Abstract: Journal of Composite Materials, Ahead of Print.
      The present study investigates the effect of SiO2–polystyrene core–shell nanoparticles on properties of styrene–butadiene rubber nanocomposites. Meanwhile, SiO2–polystyrene core–shell nanoparticles were synthesized under controlled ultrasound assisted microemulsion technique. Further, as-synthesized SiO2–polystyrene nanoparticles were subjected to various characterization techniques, such as X-ray diffraction, field emission scanning electron microscope, transmission electron microscope, and Fourier transform infrared spectroscopy to know its size, shape, and presence of functional groups. The average diameter of SiO2–polystyrene nanoparticles was found to be ∼45 nm. SiO2–polystyrene nanoparticles were reinforced in styrene–butadiene rubber using two-roll mill and molded on compression molding machine, which then subjected to various testings (X-ray diffraction, field emission scanning electron microscope, thermogravimetric analysis, and universal testing machine). Moreover, the crosslinking density was investigated using solvent sorption technique. The properties of styrene–butadiene rubber nanocomposites were found to be improved with increasing amount of SiO2–polystyrene nanoparticles (2.0 wt%) and decreases subsequently (2.5 wt%). This enhancement in properties was due to uniform dispersion of core–shell nanoparticles with embedded chains of rubber. Also this enhancement in properties was due to smooth surface of core–shell nanoparticles (2.0 wt%) and decreases subsequently at higher amount of loading (2.5 wt%). However, the minimal crosslinkage leads to more solvent sorption, which leads to increase in average molecular weight. This decrement in the crosslinkage density with increase in average molecular weight was due to voids or free volume inside the matrix, which allows the solvent to get penetrated inside the matrix. This effect was not due to styrene–butadiene rubber matrix but due to shell of polystyrene over SiO2.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-08T06:04:24Z
      DOI: 10.1177/0021998319886618
       
  • Temperature dependence of statistical fatigue strengths for unidirectional
           carbon fiber reinforced plastics under tension loading
    • Authors: Masayuki Nakada, Yasushi Miyano
      Abstract: Journal of Composite Materials, Ahead of Print.
      The formulation for time- and temperature-dependent statistical static and fatigue strengths for carbon fiber reinforced plastics laminates is newly proposed based on the physically serious role of resin viscoelasticity as the matrix of carbon fiber reinforced plastics. In this study, this formulation is applied to the tensile strength along the longitudinal direction of unidirectional carbon fiber reinforced plastics constituting the most important data for the reliable design of carbon fiber reinforced plastics structures which are exposed to elevated temperatures for a significant period of their operative life. The statistical distribution of the static and fatigue strengths under tension loading along the longitudinal direction of unidirectional carbon fiber reinforced plastics were measured at various temperatures by using resin-impregnated carbon fiber reinforced plastics strands as specimens. The master curves for the fatigue strength as well as the static strength of carbon fiber reinforced plastics strand were constructed based on the time–temperature superposition principle for the matrix resin viscoelasticity. The long-term fatigue strength of carbon fiber reinforced plastics strand can be predicted by using the master curve of fatigue strength.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-08T06:04:24Z
      DOI: 10.1177/0021998319886629
       
  • Abrasive waterjet machining of Ti/CFRP/Ti laminate and multi-objective
           
    • Authors: Dhiraj Kumar, Suhasini Gururaja
      Abstract: Journal of Composite Materials, Ahead of Print.
      In present work, abrasive waterjet machining has been used to machine adhesively bonded titanium-carbon fiber-reinforced plastics-titanium hybrid laminate with varying traverse speed, jet pressure, and stand-off distance. The effect of varying abrasive waterjet machining parameters on cut quality has been quantified by material removal rate, metal composite interface damage factor, taper ratio (Tr), and surface roughness (Ra). Response surface methodology along with central composite design has been used to analyze the influence of process parameters on output responses. Additionally, analysis of variance was performed to identify the significant parameters on the output responses. For better abrasive waterjet cut quality, the optimal values of process parameters obtained were 200 MPa jet pressure, 237.693 mm/min traverse speed, and 1 mm stand-off distance. The corresponding material removal rate, metal composite interface damage factor, taper ratio, and surface roughness are 5.388 mm3/s, 1.41, 1.16, and 3.827 µm, respectively. Furthermore, validation tests have been performed with obtained optimal parameters that deliver satisfactory outcomes with an error of 5.35%, 3.07%, 2.29%, and 0.39% for material removal rate, metal composite interface damage factor, taper ratio, and surface roughness, respectively.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-06T06:10:17Z
      DOI: 10.1177/0021998319884611
       
  • Fatigue responses of cracked Ti/APC-2 nanocomposite laminates at elevated
           temperature
    • Authors: MHR Jen, GT Kuo, YH Wu, YJ Chen
      Abstract: Journal of Composite Materials, Ahead of Print.
      The mechanical properties and fatigue responses of Ti/APC-2 neat and nanocomposites with inclined single-edged cracks due to tensile and cyclic tests at elevated temperature were investigated. Two types of composite laminates [Ti/(0/90)s/Ti] were fabricated with and without (W/WO) nanoparticles SiO2 of optimal 1 wt.%. The geometry and dimensions of specimens were L × W × t = 240 × 25 × 1.55 mm3. The cracks were of constant length 3 mm and width 0.3 mm. The inclined angles were 0°, 45°, and 60°. Both the tensile and cyclic tests were conducted at elevated temperatures 25℃ (RT), 100℃, 125℃, and 150℃. From the tensile tests we obtained the load vs. displacement curves for both types of laminates with varied inclinations at elevated temperatures. Next, we received the applied load vs. cycles curves for the same laminates with inclined cracks at the corresponding temperature due to cyclic tests. According to the experimental data of both tensile and cyclic tests the mechanical properties, such as strength, stiffness, and life, decreased as the temperature rises. The greater the inclined angles were, the greater the strength and stiffness were. Similarly, the fatigue life was in the same trend. However, the effect of inclined angle on mechanical properties was more strong than those of temperature. The mechanical properties of nanocomposite laminates were higher than those of neat composite laminates, but not significant. The main reason was that the enhancement of spreading nano-powder silica on the laminate interfaces did not effectively eliminate the stress intensity at the crack tip locally.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-06T06:10:16Z
      DOI: 10.1177/0021998319883928
       
  • Temperature variation during continuous laser-assisted adjacent hoop
           winding of type-IV pressure vessels: An experimental analysis

         This is an Open Access Article Open Access Article

    • Authors: Amin Zaami, Martin Schäkel, Ismet Baran, Ton C Bor, Henning Janssen, Remko Akkerman
      Abstract: Journal of Composite Materials, Ahead of Print.
      Laser-assisted tape winding is an automated process to produce tubular or tube-like continuous fiber-reinforced polymer composites by winding a tape around a mandrel or liner. Placing additional layers on a previously heated substrate and variation in material and process parameters causes a variation in the bonding temperature of fiber-reinforced thermoplastic tapes which need to be understood and described well in order to have a reliable manufacturing process. In order to quantify the variation in this critical bonding temperature, a comprehensive temperature analysis of an adjacent hoop winding process of type-IV pressure vessels is performed. A total of five tanks are manufactured in which three glass/HDPE tapes are placed on an HDPE liner. The tape and substrate temperatures, roller force and tape feeding velocity are measured. The coefficient of variation for each round is characterized for the first time. According to the statistical analysis, the coefficient of variation in substrate temperature is found to be approximately 4.8–8.8% which is larger than the coefficient of variation of the tape temperature which is 2.1–7.8%. The coefficient of variations of the substrate temperatures in the third round decrease as compared with the coefficient of variations in the second round mainly due to the change in gap/overlap behavior of the deposited tapes. Fourier and thermographic analysis evince that the geometrical disturbances such as unroundness and eccentricity have a direct effect on the temperature variation. In addition to the temperature feedback control, a real-time object detection technique with deep learning algorithms can be used to mitigate the unwanted temperature variation and to have a more reliable thermal history.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-06T06:10:15Z
      DOI: 10.1177/0021998319884101
       
  • Modeling transverse micro flow in dry fiber placement preforms
    • Authors: Oliver Rimmel, David May
      Abstract: Journal of Composite Materials, Ahead of Print.
      Dry fiber placement has a large potential for manufacturing preforms for primary-load components at minimum scrap rate and fiber crimp. Yet, challenging impregnation behavior due to low permeability of these preforms during liquid composite molding imposes a need for further research to optimize preform structure for higher permeability. For full understanding of flow behavior within these preforms, flow has to be considered on micro scale (in between single fibers), on meso scale (in between single rovings or strands), and on macro scale (on scale of parts to be manufactured). While macro and meso scale can be measured in experiments or derived from filling times in real processes, micro scale is usually not easily assessable and accessible for standard textile materials. Analytical approaches are limited to regular fiber arrangements (square and hexagonal) that are strongly differing from real arrangements. The present work deals with application of a numerical solver to random fiber arrangements to determine micro permeability transverse to the fiber orientation, for later use in meso- and macro-scaled models. As a premise for reliable calculation, guidelines for boundary conditions as well as size and resolution of the representative volume element are elaborated in the course of this work. Calculated out-of-plane micro permeabilities are subsequently compared to real experiments and show good accordance. The influence of binder particles on micro permeability has not yet been conclusively clarified.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-05T07:34:40Z
      DOI: 10.1177/0021998319884612
       
  • The effect of high TiC particle content on the tensile cracking and
           corrosion behavior of Al–5Cu matrix composites
    • Authors: Burak Dikici, Fevzi Bedir, Mehmet Gavgali
      Abstract: Journal of Composite Materials, Ahead of Print.
      The high-TiC particle volume fraction on the mechanical properties and corrosion behavior of the A–5Cu matrix composites were investigated with porosity, hardness, tensile tests, and polarization measurements. The composites reinforced with 18, 27, and 50 vol% TiC particulates were produced successfully by using hot-pressing technique under Ar atmosphere and characterized by scanning electron microscope, electron dispersive spectroscope, and X-ray diffraction. The corrosion susceptibilities of the composites were compared with potentiodynamic scanning technique. It was found that the hardness of the composites increases while the fracture strength decreases with increasing TiC reinforcement content in the matrix. The corrosion susceptibilities of 18 and 27 vol% TiC-reinforced composites are almost the same; the corrosion rate of 50 vol% TiC-reinforced composite was approximately 10 times higher than the composites reinforced with 18 and 27 vol% TiC particles in the 3.5% NaCl. In addition, some preferential corrosion attacks were detected at TiC/matrix interfaces and in TiC clusters during the corrosion process of the composites. Therefore, the porosity content in the composites was almost the same level.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-04T05:02:26Z
      DOI: 10.1177/0021998319884098
       
  • The determination of thermal residual stresses in unidirectional and
           cross-ply titanium matrix composites using an etch removal method
    • Authors: Gerald CR Watt, Andrew D Crocombe, Stephen L Ogin, Stephen Kyle-Henney
      Abstract: Journal of Composite Materials, Ahead of Print.
      Recent work has shown that a simple rule-of-mixtures approach may be used to predict the stress–strain behaviour of a cross-ply metal matrix composite laminate. However, the low-strain behaviour was not predicted accurately, probably because thermal residual stresses are obviously not included in such an approach. To increase the understanding of the limitations of the rule-of-mixtures approach for predicting the stress–strain response, the residual strain-state of the fibre reinforcement has been determined using an etching technique (henceforth referred to as the ‘total etch removal method’), and results have been compared both with finite element modelling and with thermal residual strain measurements derived from stress–strain curves. The results show that the residual strain distribution in a cross-ply composite may be more complex than previously thought, with the fibres in internal 0° plies having considerably higher thermal residual strains than fibres in external plies. The results confirm that the rule-of-mixtures approximation can be used, with some reservations with regard to the low-strain behaviour.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-01T12:02:20Z
      DOI: 10.1177/0021998319883167
       
  • Influence of humidity on the dielectric behaviour of BaTiO3–epoxy
           composites
    • Authors: C Gonzalez Aguilar, M Reboredo, M Castro
      Abstract: Journal of Composite Materials, Ahead of Print.
      Epoxy resin and their particulate composites are widely used in different industries, as aeronautical, automotive, microelectronics and coatings. The water absorption can deteriorate the properties on these materials when they are used in service. Many factors influence in water absorption process, as the quantity of hydroxyls groups, the glass transition temperature of the resin or the presence of a dispersed second phase. Thus, the objective of this work is to determine the dielectric behavior of BaTiO3–epoxy composites in different humid environments (controlled moisture of 80, 50 and 30%) and at room temperature. Results of pure resin samples show that dielectric permittivity increases with the percentage of absorbed water and that this increase is greater for the samples exposed to more humid environments. Interestingly, the addition of ceramic particles not only increases the composite dielectric properties but also reduces the water absorption in all the cases.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-01T12:02:20Z
      DOI: 10.1177/0021998319885008
       
  • Direct numerical simulation of infusion and flow-front tracking in
           
    • Authors: Arthur Levy, James Kratz
      Abstract: Journal of Composite Materials, Ahead of Print.
      This paper explores the use of thin film piezoresistive pressure mapping sensors as a means to improve resin transfer moulding processes. The pressure mapping sensor was located between the preform and mould, giving information regarding the permeability map prior to infusion. The permeability map is used as an input to a direct numerical simulation of the infusion step of a highly variable reclaimed carbon fibre preform. The pressure sensor was also used to track the flow front position in-situ, due to a change in load sharing between the preform and liquid during the infusion experiment. Flow front tracking with the pressure mapping sensor was validated against conventional camera images taken through a transparent mould. The direct numerical simulation was able to account for local permeability variation in the preform, providing improved flow-front prediction than homogeneous permeability only, and could be part of a wider strategy to improve resin transfer moulding process robustness.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-01T12:02:19Z
      DOI: 10.1177/0021998319883931
       
  • Multiscale analysis of interlaminar stresses near a free-edge in a
           [±45/0/90]s laminate
    • Authors: M Keith Ballard, John D Whitcomb
      Abstract: Journal of Composite Materials, Ahead of Print.
      A multiscale model for a [±45/0/90]s tape laminate under uniaxial extension was used to investigate the effect of modeling the heterogeneous microstructure near a free-edge. A random fiber arrangement was used for the 0° and 90° plies and homogenized properties for the 45° and −45° plies. The predicted interlaminar normal stress was compared to the prediction using a classical homogeneous model. When fibers and matrix were modeled discretely, the local stress state was shown to be sensitive to the proximity of fibers, which caused a complex stress distribution along the 0–90 ply interface. Next, the effect of reducing the size of region modeled at the microscale was investigated, since this would significantly reduce the computational effort. Reducing the region modeled at the microscale in the direction normal to the 0–90 ply interface to a size that was 25% and 10% of the ply thickness only changed the peak stresses by 3% and 8%, respectively. Reducing the microscale region in the direction normal to the free-edge to be one and two ply thicknesses in size did not have a significant effect on the predicted interlaminar normal stress at points within 75% of a ply thickness of the free-edge.
      Citation: Journal of Composite Materials
      PubDate: 2019-11-01T12:02:18Z
      DOI: 10.1177/0021998319883918
       
  • Ultrasonically assisted electrophoretic deposition of oxidized graphite
           nanoparticle onto carbon fiber, amending interfacial property of CFRP
    • Authors: Ankush Nandi, Subhankar Das, Sudipta Halder, Anirban Chakraborty, Muhammad A Imam
      Abstract: Journal of Composite Materials, Ahead of Print.
      The performance of fiber-reinforced composites significantly relies on the microstructure and properties of the fiber–matrix interface. Escalating the aspect ratio of the fiber surface by coating with nanoparticles is a proven technique for improving the fiber/matrix adhesion. Subsequently, improved adhesion between epoxy and fiber, which is ascribed due to improved interfacial friction, chemical bonding, and resin toughening would enhance the interfacial strength of such laminated composites. Here, graphite nanoparticles were oxidized, and these charged particles were coated onto the carbon fibers (CFs) surface using ultrasonically assisted direct current electrophoretic deposition. Functionalization of the graphite nanoparticle upon oxidation was confirmed through dispersion analysis, Fourier transformed infrared spectroscope, thermogravimetric analysis, and field emission scanning electron microscope. The CFs fabrics were grafted with different sets of samples prepared by varying voltage and deposition time. The deposition of oxidized graphite nanoparticle over the CFs was authenticated through field emission scanning electron microscope. A transverse fiber bundle test was carried out to assess interfacial strength between CF and epoxy matrix. The transverse fiber bundle test strength is found 113% higher for CF coated with oxidized graphite nanoparticles at 50 V for 5 min compared to that of as-received sized CF composites. Field emission scanning electron microscopy analysis of transverse fiber bundle test fractures samples identified multiple crack propagation zone owing to the presence of graphite nanoparticle on CF.
      Citation: Journal of Composite Materials
      PubDate: 2019-10-26T04:57:54Z
      DOI: 10.1177/0021998319884109
       
  • Experimental study of void evolution in partially impregnated prepregs
    • Authors: Leyla Farhang, Mohammad Mohseni, Navid Zobeiry, Göran Fernlund
      Abstract: Journal of Composite Materials, Ahead of Print.
      Controlling voids to minimize the final porosity level is an important concern when processing advanced composite structures. In this study, the porosity evolution during processing of partially impregnated prepregs is investigated using interrupted cure cycles and optical microscopy. Laminates made of MTM 45-1/5HS carbon/epoxy prepreg subjected to different cure cycles, bagging conditions, and humidity levels were studied. Fiber tow geometry and gas permeability were measured to determine the amount of compaction and the interconnectivity of unsaturated zones in the laminates. Three types of voids were identified: inter-laminar, fiber tow and resin voids, all with different origins and evolution patterns. It is shown that gas transport (both in-plane and through-thickness), fiber bed compaction, and resin infiltration govern void evolution during processing. The results provide insights for development of representative transport models and to optimize processing cycles.
      Citation: Journal of Composite Materials
      PubDate: 2019-10-25T06:07:46Z
      DOI: 10.1177/0021998319883934
       
  • High-velocity perforation behaviour of sandwich panels with Al/SiCp
           composite foam core
    • Authors: M Golestanipour, A Babakhani, S Mojtaba Zebarjad
      Abstract: Journal of Composite Materials, Ahead of Print.
      Aluminium foam core sandwich panels are good energy absorbers for impact protection applications, such as light-weight structural panels, packing materials and energy absorbing devices. In this study, the high-velocity perforation response of a range of sandwich panels with Al A356/SiCp composite foam core and 1100 aluminium face-sheets has been investigated using a conventional gas gun. Impact perforation tests were carried out using a 10-mm diameter conical nosed indenter at velocities up to that required to achieve complete perforation of the target (i.e. 230 m/s). The effects of face-sheet thickness, density and thickness of aluminium composite foam core on the total, specific and extra absorbed energy and also ballistic limit of the panels during impact penetration were experimentally investigated. During test, top face-sheets globally bended and tore into several pieces and so absorbed part of impact energy. Rupture and densification are two deformation modes and energy absorption mechanisms of foam core. Localized indentation and tearing, global bending and delamination were also observed on back face-sheets. Higher foam core density and thickness and also thicker face-sheets resulted in higher absorbed energy and ballistic limit.
      Citation: Journal of Composite Materials
      PubDate: 2019-10-25T05:48:09Z
      DOI: 10.1177/0021998319883331
       
  • Electrical, optical and mechanical properties of chitosan biocomposites
    • Authors: Ömer Bahadır Mergen, Ertan Arda, Gülşen Akın Evingür
      Abstract: Journal of Composite Materials, Ahead of Print.
      In this work, chitosan/graphene nanoplatelets (CS/GNP) and chitosan/multi-walled carbon nanotube (CS/MWCNT) biocomposite films were prepared using a simple, eco-friendly and low-cost method. The electrical, optical and mechanical properties of these composite films were investigated. The optical, mechanical and electrical properties of the biocomposites were significantly improved, which make them promising materials for food packaging, ultraviolet protection and biomedical applications. With the increase of carbon filler content (GNP or MWCNT) in CS biocomposites, the surface conductivity (σ), the scattered light intensity (Isc) and the tensile modulus (E) increased significantly. This behaviour in the electrical, optical and mechanical properties of the CS/carbon filler biocomposites was explained by percolation theory. The electrical percolation thresholds were determined as Rσ = 25.0 wt.% for CS/GNP and Rσ = 10.0 wt.% for CS/MWCNT biocomposites, while the optical percolation thresholds were found as Rop =12.0 wt.% for CS/GNP and Rop = 2.0 wt.% for CS/MWCNT biocomposites. Conversely, the mechanical percolation thresholds for both CS/GNP and CS/MWCNT biocomposites were found to be negligibly small (Rm = 0.0 wt.%). The electrical (βσ), optical (βop) and mechanical (βm) critical exponents were calculated for both CS/carbon filler biocomposites and found compatible with the applied percolation theory.
      Citation: Journal of Composite Materials
      PubDate: 2019-10-25T05:48:09Z
      DOI: 10.1177/0021998319883916
       
  • Structural study and thermal behavior of composites: Polyamide 66/glass
           
    • Authors: Azzedine Makhlouf, Abdelheq Layachi, Imane Kouadri, Ahmed Belaadi, Hamid Satha
      Abstract: Journal of Composite Materials, Ahead of Print.
      The present research aims at studying the kinetics of non-isothermal crystallization of the polyamide 66 matrix and its composites with the presence of a glass fiber load. To achieve that goal, the non-isothermal crystallization of polyamide 66 has been studied by means of DSC. The ratio of tested reinforcement varies from 7% to 50% of glass fiber in mass. The modeling, by the theories of Jeziorny and those of Mo, has allowed us to study the influence of adding this reinforcement, as well as the variation of the rate of cooling, on the kinetics of crystallization of the composites in question, which has been manifested by a remarkable change in the nucleation mechanism of the polyamide 66 matrix. Regarding the reinforcement effect, the incorporation of the glass fibers load into the polyamide 66 matrix has caused the appearance of exothermic peaks in a higher temperature range and that for all the working materials. Finally, the results showed that the Mo model is the most suitable for the study of polyamide 66/glass fiber crystallization kinetics.
      Citation: Journal of Composite Materials
      PubDate: 2019-10-24T05:58:34Z
      DOI: 10.1177/0021998319883913
       
  • Tensile properties of ultra-high-molecular-weight polyethylene single
           yarns at different strain rates
    • Authors: Hongxu Wang, Paul J Hazell, Krishna Shankar, Evgeny V Morozov, Zlatko Jovanoski, Andrew D Brown, Zongjun Li, Juan P Escobedo-Diaz
      Abstract: Journal of Composite Materials, Ahead of Print.
      This paper presents the details of experimental work on characterising the tensile properties of UHMWPE (Spectra® 1000) single yarns at different strain rates from 3.3 × 10−5 to 400/s. According to the measured stress–strain curves, there was a transition from ductile to brittle behaviour as the strain rate increased from 3.3 × 10−5 to 0.33/s; the tensile properties were highly sensitive to strain rate in this range. Specifically, the tensile strength and Young’s modulus increased distinctly with increasing strain rate while the failure strain and toughness decreased. However, these tensile properties were not dependent on strain rate over the range from 0.33 to 400/s. The results showed that the measured tensile strength, failure strain and Young’s modulus were independent of the tested gauge lengths (25 and 50 mm). Moreover, yarn type (warp and weft) had a noticeable effect on tensile strength, but the effect of yarn type on failure strain and Young’s modulus was negligible. The microscopic examination of fractured fibres’ ends revealed that fibrillation and axial splitting were the dominant fracture modes at low strain rates, while the fibres failed in a more brittle manner with little fibrillation at high strain rates.
      Citation: Journal of Composite Materials
      PubDate: 2019-10-23T06:36:19Z
      DOI: 10.1177/0021998319883416
       
  • The influence of fiber surface profile and roughness to fiber–matrix
           interfacial properties
    • Authors: Ichsan Setya Putra, Bentang Arief Budiman, Poetro Lebdo Sambegoro, Sigit Puji Santosa, Andi Isra Mahyuddin, Kikuo Kishimoto, Kazuaki Inaba
      Abstract: Journal of Composite Materials, Ahead of Print.
      This work investigates the influence of fiber surface profile and roughness to fiber–matrix interfacial properties. A series of the push-out test is performed using specimens with different fiber surface profile and roughness. Numerical simulation is then carried out by employing a finite element method to fit the experimental data. The model contains an indenter which pushes in a single fiber from the matrix, while the cohesive zone model is applied to represent the interface resulting in force–displacement curves. Our results suggest that continuous cavities formed in graphite-based fiber may not be beneficial to interfacial properties since it can accelerate a debonding process along with the interface. In contrast, scattered cavities on the fiber surface create strong mechanical locking, which increases the interfacial strength. These results broaden the understanding of the surface profile, which would shed light on a new perspective in designing composite structures.
      Citation: Journal of Composite Materials
      PubDate: 2019-10-22T05:44:38Z
      DOI: 10.1177/0021998319883418
       
  • Assessment of the load carrying performance of composite cross joints
    • Authors: Liyang Liu, Mengfei Cai, Xiaoliang Geng, Peiyan Wang, Zhufeng Yue
      Abstract: Journal of Composite Materials, Ahead of Print.
      Composite cross joints are common structures in an airframe. When this type of joint is used on an air inlet stiffened structure, it will undertake large bending moment, especially under overpressure of the engine. In this paper, two types of cross joints are tested experimentally and simulated to investigate the load bearing characteristics and make comparative remarks. Four-point bending tests are conducted and the load deflection curves are obtained; besides, the damage pattern of the joints is reported. Based on composite progressive damage model, the numerical simulations have a good agreement with experimental results, revealing the joint failure mechanism and fastener force feature of various joints. The comparative assessment of two types of joints is summarized.
      Citation: Journal of Composite Materials
      PubDate: 2019-10-21T05:05:40Z
      DOI: 10.1177/0021998319881486
       
  • Influence of machining damage generated during trimming of CFRP composite
           on the compressive strength
    • Authors: N Nguyen-Dinh, C Bouvet, R Zitoune
      Abstract: Journal of Composite Materials, Ahead of Print.
      Machining of composite materials is a challenging task due to the heterogeneity and anisotropy of composite structures. The induced defects reduce integrity of the machined surface as well as the loading capacity of the composite structure in service. Therefore, it is necessary to quantify the damage induced during trimming and correlate the quality of the machined surface to mechanical properties. The correlation of the surface roughness criteria, widely used in literature, to the mechanical behavior raise several contradictions. For this reason, new parameters for the characterization of the machined surface are proposed and correlated to the mechanical behavior under compressive loading. In this context, carbon fiber-reinforced plastic laminates are conventionally trimmed, and the machining damage is characterized using scanning electron microscope observations, X-ray tomography, and 3D optical topography. The results reveal that crater volume and maximum depth of damage quantify the machining damage more realistic compared to the classical surface roughness criteria.
      Citation: Journal of Composite Materials
      PubDate: 2019-10-18T06:53:19Z
      DOI: 10.1177/0021998319883335
       
  • Morphological, physical, and mechanical properties of silanized
           wood-polymer composite
    • Authors: Maryam Ghorbani, Najmeh Poorzahed, S Mojtaba Amininasab
      Abstract: Journal of Composite Materials, Ahead of Print.
      For investigation on the effect of silane compound on practical properties of poplar wood polymer composite, samples were impregnated using vacuum/pressure method with 3-trimethoxysilyl propyl methacrylate, and subsequently with styrene, methyl methacrylate, and mixtures of styrene/methyl methacrylate. Field emission scanning electron microscopy observations and Fourier transform infrared analysis indicated that styrene/methyl methacrylate copolymerized with 3-trimethoxysilyl propyl methacrylate and the resultant polymer tightly contacted to the wood cell walls without noticeable gaps. Impregnation with styrene resulted in a higher density of wood polymer composite compared to methyl methacrylate, which was more obvious in the presence of 3-trimethoxysilyl propyl methacrylate. Mechanical strength of the wood polymer composites improved and the highest strength was obtained for the 3-trimethoxysilyl propyl methacrylate/styrene/methyl methacrylate-modified samples. Maximum hardness was found in 3-trimethoxysilyl propyl methacrylate/styrene/methyl methacrylate-modified samples due to the cross-link formation between modified cell wall and polymer.
      Citation: Journal of Composite Materials
      PubDate: 2019-10-16T06:06:52Z
      DOI: 10.1177/0021998319881493
       
  • Evaluation of the environmental aging of the glass fiber-reinforced
           polymer composite when in contact with the effluent of a treatment plant
    • Authors: Yldeney Silva Domingos, Renata Carla Tavares dos Santos Felipe, Raimundo Nonato Barbosa Felipe, Glauber José Turolla Fernandes
      Abstract: Journal of Composite Materials, Ahead of Print.
      This paper presents an evaluation of the mechanical and physical behavior of the type E glass fiber-reinforced polymeric composite when exposed to environmental aging agents in an effluent treatment plant. The composite was made by the hand layup process, and the test bodies were made according to the American Society for Testing and Materials standards D3039-14 and D790-10 for the uniaxial tensile and three-point bending tests, respectively, where they were exposed for a period of eight months, conditioned above and immersed in the effluent of the treatment plant. The physicochemical characterization of the effluent was evaluated considering the following parameters: pH, conductivity, sulfate, alkalinity, acidity, sulfide, and temperature, aiming to characterize the effluent conditions in direct and indirect contact with the composite. After the exposure period, tests were carried out for morphological evaluation, structural integrity evaluation, mechanical performance evaluation, and fracture characterization of the polymer composite, thereby leading to a comparison of the mechanical characteristics in the original state to that of the aged state (after exposure in the effluent treatment plant). The polymeric composite studied was stable after the aging period, with little mass variation, less than 0.5%, and slight changes in color. The mechanical properties evaluated also did not change significantly during the study period. Variations in uniaxial tensile strength were less than 1.4% and for three-point bending less than 10%, thus showing that the type E glass fiber-reinforced polymer composite has potential for use in harsh environments such as in effluent treatment plants.
      Citation: Journal of Composite Materials
      PubDate: 2019-10-11T01:21:34Z
      DOI: 10.1177/0021998319878766
       
  • Failure behavior of woven fiberglass composites under combined compressive
           and environmental loading
    • Authors: Ariana Paradiso, Isabella Mendoza, Amanda Bellafato, Leslie Lamberson
      Abstract: Journal of Composite Materials, Ahead of Print.
      The purpose of this study is to quantitatively characterize the compressive and damage behavior of a woven fiberglass composite under combined environmental loading. Cuboidal samples of a commercially available woven fiberglass epoxy resin composite, garolite G10, are examined under uniaxial compressive loading perpendicular to the plies at quasi-static (10−3 s−1) and dynamic (103 s−1) strain rates using a standard load frame and Kolsky (split-Hopkinson) bar. In order to simulate environmental conditions, a subset of samples were soaked in either distilled or ASTM standard seawater prior to loading. Two time periods of environmental conditioning were investigated: short term at two weeks and long term at four months. Results demonstrate that, on average, the dynamic compressive strength of the fiberglass increased 35% from the quasi-static. Moreover, environmentally treated samples generally experienced a decrease strain to failure, and composites exposed to water for only short periods exhibited signs of the absorbed water sustaining additional load under quasi-static rates. Ultra-high-speed photography combined with digital image correlation, a full-field surface kinematic measurement technique, is used to map 2D strains on the sample during loading. In all cases, a clear shear failure mechanism from local instabilities appears, and a Mohr–Coulomb failure criterion is used to extract a mesoscale cohesive shear stress and coefficient of internal friction.
      Citation: Journal of Composite Materials
      PubDate: 2019-10-09T08:14:40Z
      DOI: 10.1177/0021998319878771
       
  • Use of a chain extender as a dispersing agent of the CaCO3 into PBAT
           matrix
    • Authors: Edilene de CD Nunes, Alana G de Souza, Derval dos S Rosa
      Abstract: Journal of Composite Materials, Ahead of Print.
      This paper investigates the effect of the incorporation of chain extender on the poly(butylene adipate-co-terephthalate) (PBAT) and their mixture with calcium carbonate (CaCO3) composites. Chain extender (ADR) was used to enhance the compatibility between PBAT and CaCO3, which have poor interfacial adhesion. Mechanical, thermal, and morphological properties of PBAT, PBAT/chain extender, and their composites were studied. The incorporation of the chain extender enhanced Young’s modulus and elongation at break of the neat PBAT, which is an indicator of the interaction between both materials. These results were confirmed by 1H NMR and 13C NMR (proton – hydrogen and carbon nuclear magnetic resonance, respectively). The chain extender acted by dispersing the CaCO3 particles; however, with an increase in the filler content, there is a decrease in the mechanical properties. Thermogravimetric analysis showed that chain extender has no influence on neat PBAT thermal behavior and their composites containing CaCO3. Differential scanning calorimetric analysis showed a decrease in crystallinity values of the PBAT and its composites, which is due to the physical impediment in the organization of polymer chains. Photomicrographs, obtained by scanning electron microscopy, showed that chain extender does not influence PBAT morphology. However, in the composites, chain extender enhanced the dispersion on CaCO3 particles.
      Citation: Journal of Composite Materials
      PubDate: 2019-10-09T05:31:31Z
      DOI: 10.1177/0021998319880282
       
  • Characterization of applied tensile stress to carbon epoxy composites by
           measuring the variation of transverse thermal conductivity using
           transmission thermography
    • Authors: M Bayat, MS Safizadeh
      Abstract: Journal of Composite Materials, Ahead of Print.
      Using the method of step heating thermography, this study seeks to detect and characterize the existence of stress in a beam sample of carbon epoxy composite with the stacking sequence of [08] aided by empirical and simulation approaches. The applied stress in the longitudinal direction of sample, while considering the Poisson’s ratio, changes the lateral dimensions of sample. Furthermore, it is shown that the thermal conductivity along the sample thickness varies as a result of stress existence. Accordingly, to obtain a relation between transverse thermal conductivity and longitudinal tensile stress, one should calculate and eliminate the effect of lateral deformation caused by stress. To this end, by combining the experimental and simulation results of composite sample under the action of different tensile loads, an equation describing the variation of thermal conductivity along the sample thickness with respect to applied stress is developed. Using the relation of transverse thermal conductivity variation in terms of applied stress, the finite element modeling is again carried out by rectifying the values of thermal conductivity. Simulation results are compared with experimental ones, indicating very good agreement between the two approaches.
      Citation: Journal of Composite Materials
      PubDate: 2019-10-09T05:31:30Z
      DOI: 10.1177/0021998319880596
       
  • Rate effects on fiber–matrix interfacial transverse debonding
           behavior
    • Authors: Jou-Mei Chu, Benjamin Claus, Boon Him Lim, Daniel O’Brien, Tao Sun, Kamel Fezzaa, Wayne Chen
      Abstract: Journal of Composite Materials, Ahead of Print.
      The rate effect of fiber–matrix interfacial debonding behavior of SC-15 epoxy with S-2 glass and aramid fiber reinforcements was studied via in-situ visualization of the transverse debonding event. In this study, the debonding force history, debonding initiation, debonding crack velocity, and crack geometry were characterized using a quasi-static load frame and a modified tension Kolsky bar at loading velocities of 0.25 mm/s and 2.5 m/s. Cruciform-shaped specimens were used for interfacial transverse debonding between SC-15 epoxy matrix and two types of fiber reinforcements. The load history and high-speed images of the debonding event were simultaneously recorded. A major increase was observed for the average peak debonding force and a minor increase was observed for the average crack velocity with increasing loading velocity. The crack geometry of the cruciform specimens under both loading velocities was also tracked. Scanning electron microscopy of the recovered specimens revealed the debonding direction along the fiber–matrix interface through angled patterns on the failure surface.
      Citation: Journal of Composite Materials
      PubDate: 2019-10-04T12:39:43Z
      DOI: 10.1177/0021998319866904
       
  • Hot-stamping technology for carbon fiber reinforced thermoplastic plates
           based on electrical resistance heating
    • Authors: Mitsuhiro Okayasu, Masaya Sato
      Abstract: Journal of Composite Materials, Ahead of Print.
      In the present work, a hot-stamping system for carbon fiber reinforced thermoplastic (CFRTP) plates based on electrical resistance heating was developed, where CFRTP consisted of polyphenylene and polyacrylonitrile. With the hot-stamping process, a simple hat-shaped sample was made. The heating rate and maximum sample temperature varied depending on the electrical resistance of the CFRTP plate. Moreover, the contact conditions between the electrodes and the CFRTP plate also affected the sample temperature owing to their influence on the electrical resistance, which was determined by the amount of exposed carbon fiber (CF) on the sample surface. Temperature measurements performed using samples with various amounts of exposed CF (20%–95% CF) revealed that approximately 65% CF afforded the highest sample temperature and fastest heating rate. The CFRTP plate underwent non-uniform heating, especially during the early stages, e.g. less than 10 s. Sample heating to 150℃ resulted in permanent deformation of the hat-shaped CFRTP samples with less springback, whereas heating to higher temperatures above the melting point led to meandering of the samples. In contrast, CFRTP samples subjected to hot-stamping at lower temperatures, such as 110℃, exhibited rough surfaces. In addition to the sample temperature, the formability of CFRTP during hot-stamping was affected by the holding time. When hot-stamping was performed without a holding time, even at high temperatures of 150℃ and above, low-quality samples with dented surfaces and irregular sample thickness were obtained. The results of this study indicate that a temperature of 150℃ and a holding time of 10 s are optimal for fabricating high-quality hot-stamped CFRTP with smooth surfaces and uniform thickness.
      Citation: Journal of Composite Materials
      PubDate: 2019-10-02T04:16:18Z
      DOI: 10.1177/0021998319877559
       
  • Mechanical properties of nano-silica and nano-clay composites of phenol
           formaldehyde short carbon fibers
    • Authors: Ali Asghar Jahangiri, Yasser Rostamiyan
      Abstract: Journal of Composite Materials, Ahead of Print.
      The mechanical properties of phenol formaldehyde (phenolic novolac) and short carbon fiber T300 polymer-based nano-composites-reinforced with nano-silica and nano-clay particles have been studied experimentally. By increasing the weight percentage of the short carbon fiber in the phenol formaldehyde, the strength of the composite increases, but its plastic deformation is severely limited. Also, in the case of composite reinforced with nano-silica particles, the tensile and flexural strength of the composite with the increase in the weight percentage of the nano-silica increase by 1% to 3%, whereas with the nano-clay particles, the tensile and flexural strength of the composite decrease by 1% to 3%. It is composite with 1% weight percentage of the nano-clay particle which has the highest strength in comparison to the other samples. Regardless of the type of corrosive solution, the composite strength decreases significantly over 25 days. However, with an increase in the duration from 25 days to 45 days, a slight change has been observed. The outcomes indicate that the corrosion of PF/CF40% composites and the composite reinforced with silica nanoparticles are higher corrosion rate in acid than in salt solution. In contrast, the nano-clay composite has more corrosion in salt solution. Furthermore, the analysis of the fracture surface of samples done by SEM microscopy shows reduction of the porosity in the case of using nanoparticles.
      Citation: Journal of Composite Materials
      PubDate: 2019-09-26T05:33:47Z
      DOI: 10.1177/0021998319877225
       
  • Evaluation of the protective performance of hydrophobic coatings applied
           on carbon-fibre epoxy composites
    • Authors: Heather O'Connor, Denis P Dowling
      Abstract: Journal of Composite Materials, Ahead of Print.
      Carbon–fibre epoxy composites are widely used for high-performance structural applications, where they are often exposed to harsh environments. The result of moisture ingress has been extensively studied, causing significant deterioration in the mechanical properties of these composites. This study evaluates the performance of five commercial hydrophobic coatings as protective layers, to inhibit moisture ingress into the composite. The coatings evaluated were NeverWet, HydroBead, SHC, Aculon and LiquidGlass. These coatings were characterised and compared in terms of hydrophobicity, surface energy, roughness and chemical composition. This study also evaluated two atmospheric plasma pre-treatments as a means of enhancing the adhesion performance of these coatings. The pre-treatments involved the use of an air plasma for the activation of the epoxy, as well as the plasma deposition of a nanometre thick SiOx interlayer coating. The durability and protective performance of the coatings, with and without the pre-treatments were then compared using an abrasion test as well as a water immersion study.The use of both plasma pre-treatments was found to enhance the adhesion and the abrasion performance of four out of the five coatings. Of the coatings and pre-treatments investigated, the LiquidGlass in conjunction with a SiOx-coating interlayer was found to exhibit the highest abrasion resistance. This was followed by the composite, which was plasma activated prior to the application of the Aculon coating. Only minor differences were observed when comparing the total moisture ingress (M%) of the epoxy, coated with the different hydrophobic layers. The composite coated with the Aculon and SiOx interlayer exhibited the least amount of moisture ingress, at 0.90%, compared to 1.08% of the uncoated specimen. The shear strength of epoxy composite, coated with the LiquidGlass, NeverWet and the activated Aculon combination, were within the range of the uncoated specimens, therefore the moisture ingress was reversible upon heating and no permanent damage to the epoxy–fibre interface was observed. It is concluded that, of the five coatings investigated, both the Aculon coating and LiquidGlass in combination with a SiOx interlayer coating, exhibit the greatest potential as protective layers for carbon fibre epoxy composites.
      Citation: Journal of Composite Materials
      PubDate: 2019-09-26T05:33:47Z
      DOI: 10.1177/0021998319877454
       
  • Temperature rise caused by adiabatic shear failure in 3D braided composite
           tube subjected to axial impact compression
    • Authors: Zhongxiang Pan, Xianyan Wu, Liwei Wu
      Abstract: Journal of Composite Materials, Ahead of Print.
      Previous investigation on the crashworthiness of braided composite tubes did not take the relationship between adiabatic shear failure and temperature rise into account during dynamic loading. In this study, transient temperature rise caused by adiabatic effect was detected and captured for the three-dimensional braided carbon/epoxy composite specimens during axial impact compression under 600–800/s. A mesostructure model was established based on three-dimensional braided tube architecture to numerically characterize the mechanical and thermal response in material. Based on the results, non-uniform temperature distribution shows good correlation with adiabatic shear failure in the material. Key scientific issues are discovered including the position, morphology, time sequence, and response process of the temperature rise. The catastrophic shear behavior with accelerated temperature rise occurs after the peak force and accompanies the progressive failure process. Nodes having room temperature in the adiabatic shear zone indicates that some positions in plastic zone may still behave as elastic state. There exists different plastic slip distances due to shear instability in the path along or crossing the adiabatic shear band. Through this investigation, the model considering the adiabatic effect was able to show the dynamic shear mechanism involving the fracture position, morphology, and progressive thermo-mechanical response of the temperature rise, which cannot be revealed by experimental testing.
      Citation: Journal of Composite Materials
      PubDate: 2019-09-26T05:33:46Z
      DOI: 10.1177/0021998319877558
       
  • Improvement of fracture toughness and thermo-mechanical properties of
           carbon fiber/epoxy composites using polyhedral oligomeric silsesquioxane
    • Authors: Kunal Mishra, Libin K Babu, Ranji Vaidyanathan
      Abstract: Journal of Composite Materials, Ahead of Print.
      The influence of polyhedral oligomeric silsesquioxanes–polyvinylpyrrolidone on the interlaminar fracture toughness of carbon fiber-reinforced composites (CFRPs) is investigated in this study. Baseline composite material is fabricated using novolac epoxy-infused carbon fiber prepreg. Glycidyl isobutyl polyhedral oligomeric silsesquioxanes (GI) is introduced in the CFRP at loading of 1, 3, 5, and 10 wt.% with respect to polyvinylpyrrolidone used as a compatibilizer. Results of the double cantilever beam test indicate an increase of 70% in interlaminar fracture toughness for 5 wt.% GI-POSS loading compared to the baseline composite. Scanning electron microscopy shows polyhedral oligomeric silsesquioxanes enhanced the adhesion between fiber and the resin that leads to the fiber pull-out. Dynamic mechanical analysis result captures the reduction in the storage modulus with addition of polyvinylpyrrolidone due to the plasticization effect. Nonetheless, the introduction of polyhedral oligomeric silsesquioxanes increases the storage modulus for the GI/PVP composite. Additionally, an increase in the glass transition temperature with the reinforcement of polyhedral oligomeric silsesquioxanes is observed.
      Citation: Journal of Composite Materials
      PubDate: 2019-09-25T01:24:24Z
      DOI: 10.1177/0021998319876339
       
  • Energy absorption capacity of composite thin-wall circular tubes under
           axial crushing with different trigger initiations
    • Authors: JE Chambe, C Bouvet, O Dorival, JF Ferrero
      Abstract: Journal of Composite Materials, Ahead of Print.
      The purpose of this study is to evaluate and compare the ability of various composite structures to dissipate the energy generated during a crash. To this end, circular composite tubes were tested in compression in order to identify their behavior and determine their absorbing capabilities using the specific energy absorption (energy absorbed per unit weight). Several composite tubular structures with different materials and architectures were tested, including hybrid composition of carbon–aramid and hybrid configuration of 0/90 UD with woven or braided fabric. Several inventive and experimental trigger systems have been tested to try and enhance the absorption capabilities of the tested structures. Specific energy absorption values up to 140 kJ.kg−1 were obtained, achieving better than most instances from the literature, reaching around 80 kJ.kg−1. Specimens with 0°-oriented fibers coincidental with the direction of compression reached the highest specific energy absorption values while those with no fiber oriented in this direction performed poorly. Moreover, it has consequently been established that in quasi-static loading, a unidirectional laminate oriented at 0° and stabilized by woven plies strongly meets the expectations in terms of energy dissipation. Incidentally, an inner constrained containment is more effective in most cases, reducing the initial peak load without drastically reducing the specific energy absorption value.
      Citation: Journal of Composite Materials
      PubDate: 2019-09-25T01:24:22Z
      DOI: 10.1177/0021998319877221
       
  • Fabrication and investigation on the properties of ilmenite (FeTiO3)-based
           Al composite by accumulative roll bonding
    • Authors: Medhat Elwan, A Fathy, A Wagih, A R S Essa, A Abu-Oqail, Ahmed E EL-Nikhaily
      Abstract: Journal of Composite Materials, Ahead of Print.
      In the present study, the aluminum (Al) 1050–FeTiO3 composite was fabricated through accumulative roll bonding process, and the resultant mechanical properties were evaluated at different deformation cycles at ambient temperature. The effect of the addition of FeTiO3 particle on the microstructural evolution and mechanical properties of the composite during accumulative roll bonding was investigated. The Al–2, 4, and 8 vol.% FeTiO3 composites were produced by accumulative roll bonding at room temperature. The results showed improvement in the dispersions of the particles with the increase in the number of the rolling cycles. In order to study the mechanical properties, tensile and hardness tests were applied. It was observed that hardness and tensile strength improve with increasing accumulative roll bonding cycles. The microhardness and tensile strength of the final composites are significantly improved as compared to those of original raw material Al 1050 and increase with increasing volume fraction of FeTiO3, reaching a maximum of ∼75 HV and ∼169 MPa for Al–8 vol.% FeTiO3 at seventh cycle, respectively.
      Citation: Journal of Composite Materials
      PubDate: 2019-09-24T05:22:56Z
      DOI: 10.1177/0021998319876684
       
  • Effective shear modulus of a damaged ply in laminate stiffness analysis:
           Determination and validation
    • Authors: Mohamed Sahbi Loukil, Janis Varna
      Abstract: Journal of Composite Materials, Ahead of Print.
      The concept of the “effective stiffness” for plies in laminates containing intralaminar cracks is revisited presenting rather accurate fitting expressions for the effective stiffness dependence on crack density in the ply. In this article, the effective stiffness at certain crack density is back-calculated from the stiffness difference between the undamaged and damaged laminate. Earlier finite element method analysis of laminates with cracked 90-plies showed that the effective longitudinal modulus and Poisson’s ratio of the ply do not change during cracking, whereas the transverse modulus reduction can be described by a simple crack density dependent function. In this article, focus is on the remaining effective constant: in-plane shear modulus. Finite element method parametric analysis shows that the dependence on crack density is exponential and the fitting function is almost independent of geometrical and elastic parameters of the surrounding plies. The above independence justifies using the effective ply stiffness in expressions of the classical laminate theory to predict the intralaminar cracking caused stiffness reduction in laminates with off-axis plies. Results are in a very good agreement with (a) finite element method calculations; (b) experimental data, and (c) with the GLOB-LOC model, which gives a very accurate solution in cases where the crack face opening and sliding displacements are accurately described.
      Citation: Journal of Composite Materials
      PubDate: 2019-09-24T05:22:54Z
      DOI: 10.1177/0021998319874369
       
  • Dielectric characterization of white birch–activated biochar composites:
           A sustainable alternative to radar-absorbing materials
    • Authors: Alan FN Boss, Flavia L Braghiroli, Gisele Amaral-Labat, Ariane AT Souza, Mauricio R Baldan, Hassine Bouafif, Ahmed Koubaa, Guilherme FB Lenz e Silva
      Abstract: Journal of Composite Materials, Ahead of Print.
      Sustainability can be defined as the ability of meet presents needs without compromise the ability of future generations to find their own needs. In this matter, scientists have been warning about natural resource scarcity, and now several researchers are aiming their efforts to develop sustainable technologies. Here, we focus on finding novel uses to biochar, a carbon rich material made from biomass that is usually applied on soil amendment. To expand its applications, biochars were activated using two different methods: a physical activation using CO2; and a chemical one using KOH. We investigate here the dielectric properties of composites made with both activated biochars from white birch, where composites were made using silicone rubber matrix. It was also investigated the influence of composites made with biochar in powder and in flakes. All samples were characterized over the X-band frequency range. Composites made with powder presented a linear permittivity over the frequency range, while composites made with flakes presented oscillations on different frequencies. These oscillations are related to the composite surface, which induces reflection effects because of flakes arrangement in the top surface. Such effects widen opportunities to engineer new materials to be explored as radar-absorbing materials.
      Citation: Journal of Composite Materials
      PubDate: 2019-09-24T05:22:54Z
      DOI: 10.1177/0021998319877493
       
  • Experimental investigation of seismic strengthening of reinforced concrete
           short columns using externally bonded reinforcement, near surface mounted,
           and hybrid techniques
    • Authors: A Kargaran, A Kheyroddin
      Abstract: Journal of Composite Materials, Ahead of Print.
      Nowadays, the existence of short columns is a major factor in the failure and collapse of structures during the earthquake. In this article, 10 reinforced concrete short columns are prepared and experimentally investigated under cyclic lateral displacements. Since failure in short columns under earthquake was in the form of diagonal cracks and shear rupture, two new techniques are proposed to strengthen short columns against seismic loads. These techniques include externally bonded reinforcement with carbon fiber-reinforced polymer sheets and near surface mounted with glass fiber-reinforced polymer bars in the form of transverse, diagonal, and hybrid strengthening techniques. The experimental results demonstrated that the above-mentioned strengthening techniques in short columns lead to a change in the type of failure from shear to flexural, and the change of crack patterns and columns failure. The mentioned strengthening methods lead to an increase of ductility, increase of load carrying capacity and increase of dissipated energy.
      Citation: Journal of Composite Materials
      PubDate: 2019-09-24T05:22:53Z
      DOI: 10.1177/0021998319874499
       
  • Experimental analysis of adhesively bonded joints in synthetic- and
           natural fibre-reinforced polymer composites
    • Authors: HFM de Queiroz, MD Banea, DKK Cavalcanti
      Abstract: Journal of Composite Materials, Ahead of Print.
      The application of adhesively bonded joints in automotive industry has increased significantly in recent years mainly because of the potential for lighter weight vehicles, fuel savings and reduced emissions. The use of composites in making automotive body components to achieve a reduced vehicle mass has also continuously increased. Natural fibre composites have recently attracted a great deal of attention by the automotive industry due to their many attractive benefits (e.g. high strength-to-weight ratio, sustainable characteristics and low cost). However, the literature on natural fibre-reinforced polymer composite adhesive joints is scarce and needs further investigation. The main objective of this study was to evaluate and compare the mechanical performance of adhesively bonded joints made of synthetic- and natural fibre-reinforced polymer composites. Similar and dissimilar single lap joints bonded with a modern tough structural adhesive used in the automotive industry, as well as the epoxy resin AR260 (the same resin used in composite fabrication) were tested. It was found that the average failure loads varied significantly with adhesive material strength and adherend stiffness. Furthermore, it was also observed that failure mode has a significant effect in failure load. The jute-based natural fibre composites joints, both hybrid and purely natural, were superior in strength compared to the sisal-based natural composites joints.
      Citation: Journal of Composite Materials
      PubDate: 2019-09-24T05:22:53Z
      DOI: 10.1177/0021998319876979
       
  • The influence of variability and defects on the mechanical performance of
           tailorable composites
    • Authors: James M Finley, Joël Henry, Milo SP Shaffer, Soraia Pimenta
      Abstract: Journal of Composite Materials, Ahead of Print.
      Aligned hybrid-fibre discontinuous composites offer the ability to tailor their mechanical response through careful microstructural design. However, with tailorability comes microstructural complexity, which in turn leads to many sources of variability and defects. A virtual testing framework was further extended to investigate the influence of variability and defects on the mechanical performance of various aligned discontinuous composite material systems. This approach identified the most critical sources of variability as (i) fibre strength, (ii) the distance between fibre ends, or (iii) the level of fibre-type intermingling, depending on the material system. Fibre vacancy defects were shown to have the most significant influence on the strength and ductility of aligned discontinuous composites, although this sensitivity can be reduced through hybridisation of the fibre types.
      Citation: Journal of Composite Materials
      PubDate: 2019-09-24T05:22:51Z
      DOI: 10.1177/0021998319862855
       
  • Experimental and numerical analyses of stiffened composite panels with
           delamination under a compressive load
    • Authors: Yujiao Bai, Zhonghai Xu, Jieren Song, Linlin Miao, Chaocan Cai, Fan Yang, Rongguo Wang, Xiaodong He, Yi Hong, Xulun Dong
      Abstract: Journal of Composite Materials, Ahead of Print.
      L-shaped stiffened composite panels provide an efficient structure for engineering applications. However, they often produce delamination in the preparation and service process due to a series of factors. To study the effect of different types of delamination on the compressive strength of stiffened composite panels, ABAQUS finite element software was used in combine with the progressive damage subroutine user-defined field variable (USDFLD), and the finite element model was established based on cohesive theory to realize the prediction of the progressive failure process and strength of the stiffened composite panels. The results showed that the delamination of a stringer had a greater impact on the strength of the stiffened composite panels than did the debonding between the skin panel and a stringer and the delamination of the skin panel. The debonding delamination and delamination of a stringer exhibited delamination growth near the damage position during static compression, but delamination of the skin panel exhibited no delamination growth. The experimental results were in good agreement with the finite element simulation results, which verified the validity of the finite element model.
      Citation: Journal of Composite Materials
      PubDate: 2019-09-24T05:22:51Z
      DOI: 10.1177/0021998319875209
       
  • Bending strength and notched-sample fatigue life of hBN/TiC-reinforced
           steel 316 L: A numerical and experimental analysis
    • Authors: Ali Sadooghi, Gholamhassan Payganeh, Mahdi Tajdari, Amir Dehghan Ghadikolaei, Amir H Roohi
      Abstract: Journal of Composite Materials, Ahead of Print.
      Mechanical failure under cyclic and dynamic loading has always been a concern in engineering applications. Many different properties can be achieved by adding different materials to the metal matrix nanocomposites. In this study, steel 316 L is selected as the matrix, and the additive materials of titanium carbide and hexagonal boron nitride in 3.5 wt% for each one are added as the reinforcement particles. The samples are fabricated by powder metallurgy, compacted in pressure of 410 MPa, and sintered in temperature of 1375℃ for 4 h. In addition, some pure steel 316 L samples were provided for comparison purposes. Numerical simulation of bending strength and fatigue life of the notched samples were conducted and verified with experimental tests on the mechanical parts. It appeared that the nanocomposite specimens present a higher mechanical reliability relative to the pure 316 L as a result of adding nanoparticles. Steel 316 L S–N curves of the notched samples are also obtained from numerical analysis.
      Citation: Journal of Composite Materials
      PubDate: 2019-09-24T05:22:50Z
      DOI: 10.1177/0021998319875211
       
  • Porosity analysis of carbon fibre-reinforced polymer laminates
           manufactured using automated fibre placement
    • Authors: Ebrahim Oromiehie, Ulf Garbe, B Gangadhara Prusty
      Abstract: Journal of Composite Materials, Ahead of Print.
      Automated fibre placement-based manufacturing technology is increasingly being used in several engineering applications. Manufacture of carbon fibre-reinforced plastic’s small/large structures have been made possible due to its remarkable capabilities like productivity and accuracy. Nevertheless, making high-quality composite laminate using automated fibre placement relies on the proper selection of critical processing variables to avoid internal flaws during the fibre placement process. Consequently, a reliable non-destructive inspection technique is required for quality assurance and structural integrity of fabricated laminates. Neutron radiography/tomography offers unique imaging capabilities over a wide range of applications including fibre-reinforced polymer composites. The application of this technique towards tomographic reconstruction of automated fibre placement-made thermoplastic composites is presented in this paper. It is shown that the porosity analysis using neutron imaging technique provides reliable information. Additionally, using such technique valuable data regarding the size and the location of the voids in the laminate can be acquired and informed. This will assist the composite structural analysts and designers to select the appropriate processing parameters towards a defect free automated fibre placement part manufacture.
      Citation: Journal of Composite Materials
      PubDate: 2019-09-24T05:22:50Z
      DOI: 10.1177/0021998319875491
       
  • Experimental and numerical investigation of stiffener effects on buckling
           strength of composite laminates with circular cutout
    • Authors: T Shojaee, B Mohammadi, R Madoliat
      Abstract: Journal of Composite Materials, Ahead of Print.
      In the notched structures, to achieve maximum buckling resistance in comparison with structural weight, the optimal design of a stiffener is very important. In this research, after a review of the existing literature, nonlinear buckling behavior of composite plates containing the cutout with three different designs of stringer was investigated. The considered stiffeners are planer, longitudinal, and ring types. The buckling experiments were carried out on the stiffened plates containing a circular notch. Moreover, to achieve an efficient prediction of the buckling in the stiffened laminate with the hole, a finite strip method is developed based on the Airy stress function and von Karman’s large deformation equations. Studies show that there is a good agreement between the postbuckling behaviors derived from developed finite strip method with experimental results. Fast convergence of the considered finite strip method compared with the finite element results shows its efficiency for prediction of buckling behavior in laminated composites. The results show that the buckling load-bearing capacities of perforated plates with a longitudinal and planer stiffener are higher compared with the other stiffener, respectively. The detailed parametric study on the effects of thickness of the plate and stiffener and opening diameter on buckling behavior was performed using experiments and modeling.
      Citation: Journal of Composite Materials
      PubDate: 2019-09-24T05:22:46Z
      DOI: 10.1177/0021998319874101
       
  • Structure and mechanical properties of Ni/Ti multilayered composites
           produced by accumulative roll-bonding process
    • Authors: Mohammad Mokhles, Morteza Hosseini, Seyed Mojtaba Zebarjad, Habib Danesh-Manesh
      Abstract: Journal of Composite Materials, Ahead of Print.
      This research studies the structure and mechanical properties of Ni/Ti multilayered composites produced from commercial pure Ni and Ti foils by accumulative roll-bonding technique. To investigate these properties, scanning electron microscopy, Vickers microhardness, and uniaxial tensile tests were conducted at different processing cycles. Studies showed that in terms of structure, Ni and Ti layers maintain their continuity even up to 10 cycles of accumulative roll-bonding. Moreover, the energy-dispersive spectroscopy in scanning electron microscopy detected no deformation induced diffusion or reactive interfacial zones. It was found that by increasing the accumulative roll-bonding cycles, tensile and yield strengths as well as the hardness of the composite enhance and the total elongation reduces continuously.
      Citation: Journal of Composite Materials
      PubDate: 2019-09-23T06:06:18Z
      DOI: 10.1177/0021998319874391
       
  • Analytic solution of angle-ply laminated plates under extension, bending,
           and torsion
    • Authors: Shen-Haw Ju, Wen-Yu Liang, Hsin-Hsiang Hsu, Jiann-Quo Tarn
      Abstract: Journal of Composite Materials, Ahead of Print.
      This paper develops a Hamiltonian state space approach for analytic determination of deformation and stress fields in multilayered monoclinic angle-ply laminates under the combined action of extension, bending, and torsion. The present solution satisfies the equations of anisotropic elasticity, the end conditions, the traction-free boundary conditions on the four edge surfaces of the rectangular section, and the interfacial continuity conditions in multilayered laminates. The proposed method only requires the solutions of matrix and eigen equations, regardless of the number or lamination of the layers. The finite element analyses are used to validate the accuracy of the analysis. The analytical solution and the numerical solutions are in excellent agreement.
      Citation: Journal of Composite Materials
      PubDate: 2019-09-10T01:49:38Z
      DOI: 10.1177/0021998319873025
       
  • Fabrication of Al5083 surface hybrid nanocomposite reinforced by CNTs and
           Al2O3 nanoparticles using friction stir processing
    • Authors: Farhad Ostovan, Sattar Amanollah, Meysam Toozandehjani, Ehsan Shafiei
      Abstract: Journal of Composite Materials, Ahead of Print.
      In the present study, friction stir processing was adopted for surface treatment of Al5083 by incorporation of CNT and Al2O3 nanoparticles. Microstructural, mechanical and tribological properties of the surface of Al5083/CNT, Al5083/Al2O3 and hybrid Al5083/CNT/Al2O3 nanocomposite were investigated and compared. The friction stir processing yielded a nearly uniform dispersion of CNTs and Al2O3 nanoparticles, irrespective of nanoparticle reinforcements and their weight fraction. Microstructural observations revealed that Al2O3 nanoparticles have dispersed in different zones including intra-grain and grain boundary zones while, CNTs are pinned into grain boundaries during friction stir processing. From mechanical point of view, hybridization of CNT/Al2O3 enhances the hardness (126 HV at stirred zone), strength (UTS of ∼487 MPa) and also wear resistance of Al5083/CNT/Al2O3 nanocomposites. The enhancement is attributed to the presence and combination of features of both CNT and Al2O3 nanoparticles which are different in nature; one spherical oxide and one nanotube.
      Citation: Journal of Composite Materials
      PubDate: 2019-09-10T01:49:38Z
      DOI: 10.1177/0021998319874849
       
  • Single-walled carbon nanotubes–polyaniline composites: Synthesis and
           field-emission analysis
    • Authors: Nagma Ansari, Shumaila, Mohd Yaseen Lone, Javid Ali, M Husain, Samina Husain
      Abstract: Journal of Composite Materials, Ahead of Print.
      In this article, we report a facile synthesis and comparative analysis of field emission behavior of polyaniline (PANI)-coated as-received and annealed single-walled carbon nanotube (SWCNT) films by in-situ polymerization and ex-situ synthesis routes, respectively. Amongst all the samples, the sample prepared by in-situ polymerization method with more fraction of annealed SWCNTs in the composite gave an enhanced field emission characteristics with Eto = 3 V/μm and β = 1.2 × 104 probably because of good formation of pi-pi non-covalent bonds between the SWCNTs and PANI represented by pi-pi interaction between the quinoid rings of PANI and π bond of the SWCNTs lattice. A significant increase in the threshold field is observed after annealing and doping of nanocomposite films. Field emission behavior of as-prepared nanocomposite samples are also analyzed and discussed with two PANI forms: micro-PANI particles and PANI nanofibers. It is also speculated that PANI may have helped in lowering the overall work function of the composite structure which gave an enhanced field emission. The stability of all the samples are also presented and it is analyzed that nanocomposite sample films synthesized by in-situ polymerization method showed a stability for at least 8 h. The surface morphology analysis by field emission scanning electron microscopy of nanocomposite sample films reveal an increase in SWCNTs diameter upon PANI wrapping. The high-resolution transmission electron microscopy and Raman spectra and X-ray diffraction analysis are also presented.
      Citation: Journal of Composite Materials
      PubDate: 2019-09-10T01:49:37Z
      DOI: 10.1177/0021998319870571
       
  • A numerical investigation on ultrasonic bulk wave propagation features in
           functionally graded plates
    • Authors: Saeed Farahmand, Mohammad Hossein Soorgee
      Abstract: Journal of Composite Materials, Ahead of Print.
      The goal of this research is to numerically look for a proper feature for functionally graded materials mechanical property distribution function evaluation based on through transmitted ultrasonic bulk wave amplitude variation. A numerical approximation called homogenous layers approximation is introduced and employed for wave propagation formulation in functionally graded plate, followed by finite element utilization for verification. As the amplitude of the propagated ultrasonic wave is affected by acoustic impedance and wave divergence angle variation in the functionally graded material plate thickness, while neglecting the attenuation phenomenon, numerical investigation has been performed in order to quantify the contribution of each mechanism on the wave amplitude behavior. One-dimensional investigations, using homogenous layers approximation and finite element method, show that the final value of the wave amplitude is the same for all functionally graded material property distribution function power index, while two-dimensional results, obtained from finite element method, provide a suitable amplitude variation manner based on the wave divergence angle variation in functionally graded material thickness direction. The final results shows that it is possible to calibrate the received wave amplitude distribution on the receiving side of the plate, in a through transmission test, for the material property distribution function power index evaluation. Moreover, the concept of functionally graded material ultrasonic shoe is introduced, suitable for beam focusing applications instead of expensive phased array systems.
      Citation: Journal of Composite Materials
      PubDate: 2019-09-06T01:38:44Z
      DOI: 10.1177/0021998319874104
       
  • Micromechanics-based analyses of short fiber-reinforced composites with
           functionally graded interphases
    • Authors: Yang Yang, Qi He, Hong-Liang Dai, Jian Pang, Liang Yang, Xing-Quan Li, Yan-Ni Rao, Ting Dai
      Abstract: Journal of Composite Materials, Ahead of Print.
      A micromechanical model for short fiber-reinforced composites (SFRCs) with functionally graded interphases and a systematic prediction scheme to determine the effective properties are presented. The matrix and the fibers are regarded to be linear elastic, isotropic, and homogeneous. Fibers are assumed to be ellipsoids coated perfectly by functionally graded interphases, which is supposed to be formed chemically or physically by the constituents near the interface. First, to analyze the grading interphase effect, layer-wise concept is followed to divide the functionally graded interphases into multi-homogeneous sub-layers. Next, to take the effect of functionally graded interphases into account, a combination of multi-inclusion method and Mori–Tanaka method is applied to predict effective elastic properties of this unidirectional SFRCs with respect to the content and aspect ratio of the inclusions. By employing coordinate transformation, spatially elastic moduli are obtained. Finally, Voigt homogenization scheme is used to obtain the overall, averaged, symmetrical elastic properties of the SFRCs. Numerical examples and analyses demonstrate the applicability of the proposed method and indicate the influences of graded interphase, orientation, and aspect ratio of inclusions as well as properties and contents of the constituents on the overall properties of SFRCs.
      Citation: Journal of Composite Materials
      PubDate: 2019-09-02T02:55:50Z
      DOI: 10.1177/0021998319873033
       
  • Investigation of composite fabric impregnated with non-Newtonian fluid for
           protective textiles
    • Authors: Danmei Sun, Fuyou Zhu, George K Stylios
      Abstract: Journal of Composite Materials, Ahead of Print.
      Commercial high-performance fibre materials for body armour have very low surface friction and this has become an issue in the effectiveness of ballistic impact energy absorption. Also, the incidence of sports injuries in high contact sports is high. The severity of injuries of police and sportsman can be reduced by wearing enhanced protective clothing that have the ability to absorb the shocks. In this study, a type of non-Newtonian fluid has been developed. It became hardened upon a shock impact which was observed through a drop-on-weight test. The non-Newtonian fluid was successfully applied on to a traditional plain weave body armour fabric made of Twaron®. The treated fabric was studied by scanning electron microscopy and a yarn pulling-out test. It shows that the force to pull out a yarn from the non-Newtonian fluid treated fabric is four times higher than that of the untreated one. The flexibility of the non-Newtonian polymer treated fabric remains unchanged. The polymer can be used for applications where impact protection can be a highly desirable property.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-30T01:48:28Z
      DOI: 10.1177/0021998319873067
       
  • Electrical and thermal conductivities of the Cu–CF composite
    • Authors: J Koráb, S Krcho, P Štefánik, J Kováčik
      Abstract: Journal of Composite Materials, Ahead of Print.
      The paper presents a new approach in the field of metal–matrix composite characterisation where an electrical conductivity measurement was used to calculate the electron part of composite thermal conductivity by using the Wiedemann–Franz law. The electrical and thermal conductivities of the composite were characterised and their relationship was analysed. Results showed that in comparison with simple analytical models, this method can also be used for predicting the thermal conductivity of the copper matrix–continuous carbon fibre composite in a transverse direction. The unidirectional composite was produced by diffusion bonding and contained 40–60 vol.% of unidirectional fibres. Experiments were performed in directions parallel and normal to the fibre orientation and showed that with an increasing ratio of fibre volume, both thermal and electrical conductivities decreased from 221.6 W/m·K to 38.7 W/m·K and from 35.8 MS/m to 5.3 MS/m, respectively.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-30T01:48:27Z
      DOI: 10.1177/0021998319872261
       
  • Microstructure characterization and evaluation of mechanical properties of
           stir rheocast AA2024/TiB2 composite
    • Authors: Semegn Cheneke, D Benny Karunakar
      Abstract: Journal of Composite Materials, Ahead of Print.
      In this research, microstructure and mechanical properties of stir rheocast AA2024/TiB2 metal matrix composite have been investigated. The working temperature was 640℃, which was the selected semisolid temperature that corresponds to 40% of the solid fraction. Two weight percentage, 4 wt%, and 6 wt% of the TiB2 reinforcements were added to the matrix. The field emission scanning electron microscope micrographs of the developed composites showed a uniform distribution of the particles in the case of the 2 wt% and 4 wt% of the reinforcements. However, the particles agglomerated as the weight percentages of the reinforcement increases to 6%. The optical microscope of the liquid cast sample showed the dendritic structure, whereas the rheocast samples showed a globular structure. The X-ray diffraction analysis confirmed the distribution of the reinforcements in the matrix and the formation of some intermetallic compounds. Mechanical properties significantly improved by the addition of the reinforcements in the matrix. An increase in tensile strength of 13.3%, 40%, 28%, and 5% was achieved for the unreinforced rheocast sample, 2 wt%, 4 wt%, and 6 wt% reinforced rheocast samples respectively, compared to the liquid cast sample. An increase in 20% of hardness was attained for the composite with 2 wt% TiB2 compared to the liquid cast sample. According to the fractography analysis, small dimples were observed on the fractured surface of the unreinforced rheocast sample, whereas small and large voids were dominant on the fractured surface of the 2 wt% composite, which shows the ductile fracture mode.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-28T04:30:06Z
      DOI: 10.1177/0021998319871693
       
  • Investigation of interlayer hybridization effect on burst pressure
           performance of composite overwrapped pressure vessels with load-sharing
           metallic liner
    • Authors: Serkan Kangal, Osman Kartav, Metin Tanoğlu, Engin Aktaş, H Seçil Artem
      Abstract: Journal of Composite Materials, Ahead of Print.
      In this study, multi-layered composite overwrapped pressure vessels for high-pressure gaseous storage were designed, modeled by finite element method and manufactured by filament winding technique. 34CrMo4 steel was selected as a load-sharing metallic liner. Glass and carbon filaments were overwrapped on the liner with a winding angle of [±11°/90°2]3 to obtain fully overwrapped composite reinforced vessel with non-identical front and back dome endings. The vessels were loaded with increasing internal pressure up to the burst pressure level. The mechanical performances of pressure vessels, (i) fully overwrapped with glass fibers and (ii) with additional two carbon hoop layers on the cylindrical section, were investigated by both experimental and numerical approaches. In numerical approaches, finite element analysis was performed featuring a simple progressive damage model available in ANSYS software package for the composite section. The metal liner was modeled as elastic–plastic material. The results reveal that the finite element model provides a good correlation between experimental and numerical strain results for the vessels, together with the indication of the positive effect on radial deformation of the COPVs due to the composite interlayer hybridization. The constructed model was also able to predict experimental burst pressures within a range of 8%. However, the experimental and finite element analysis results showed that hybridization of hoop layers did not have any significant impact on the burst pressure performance of the vessels. This finding was attributed to the change of load-sharing capacity of composite layers due to the stiffness difference of carbon and glass fibers.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-28T04:30:05Z
      DOI: 10.1177/0021998319870588
       
  • Impact of silane treatment on the dielectric properties of pineapple
           leaf/kenaf fiber reinforced phenolic composites
    • Authors: F Agrebi, H Hammami, M Asim, M Jawaid, A Kallel
      Abstract: Journal of Composite Materials, Ahead of Print.
      This work deals with the dielectric properties of silane treated pineapple leaf fiber and kenaf fiber reinforced phenolic hybrid composites. The aim of the present paper is to investigate the effect of silane treatment on the pineapple leaf fiber–kenaf fiber/matrix interfacial adhesion using the dielectric relaxation spectroscopy in the frequency range from 0.1 Hz to 1 MHz and temperature range from 50 to 180℃. Our hybrid composites were fabricated by hand lay-up method at 50% total fiber loading. All the results obtained were discussed in terms of dynamic molecular and interfacial process. Two interfacial polarizations identified as the Maxwell–Wagner–Sillars effect are observed. We note that silane treatment improved the interfacial adhesion between pineapple leaf fiber/kenaf fiber and phenolic resin and it will help to develop high performance kenaf fiber/pineapple leaf fiber reinforced polymer composites for industrial applications. In fact, as known, the silane treatment developed hydrophobic nature in pineapple leaf fiber and kenaf fiber which is very positive for fiber/matrix compatibility.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-27T06:23:53Z
      DOI: 10.1177/0021998319871351
       
  • Transverse Young's modulus of carbon/glass hybrid fiber composites
    • Authors: Ganesh Venkatesan, Maximilian J Ripepi, Charles E Bakis
      Abstract: Journal of Composite Materials, Ahead of Print.
      Hybrid fiber composites offer designers a means of tailoring the stress–strain behavior of lightweight materials used in high-performance structures. While the longitudinal stress–strain behavior of unidirectional hybrid fiber composites has been thoroughly evaluated experimentally and analytically, relatively little information is available on the transverse behavior. The objective of the current investigation is to present data on the transverse modulus of elasticity of unidirectional composites with five different ratios of carbon and glass fiber and to compare the data with predictive and fitted models. The transverse modulus increases monotonically with the proportion of glass fiber in the composite. Finite element analysis was used to evaluate different ways to model voids in the matrix and allowed the unknown transverse properties of the carbon fibers to be backed out using experimental data from the all-carbon composite. The finite element results show that the transverse modulus can be accurately modeled if voids are modeled explicitly in the matrix region and if modulus is calculated based on stress applied along the minimum interfiber distance path between adjacent fibers arranged in a rectangular array. The transverse modulus was under-predicted by the iso-stress model and was well predicted by a modified iso-stress model and a modified Halpin–Tsai model.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-27T06:23:53Z
      DOI: 10.1177/0021998319871689
       
  • Cellulose nanofibrils and nano-scaled titanium dioxide-reinforced
           biopolymer nanocomposites: Selecting the best nanocomposites with
           multicriteria decision-making methods
    • Authors: Havva Gumus, Deniz Aydemir, Ertugrul Altuntas, Rıfat Kurt, Erol Imren
      Abstract: Journal of Composite Materials, Ahead of Print.
      The aim of the paper is to determine the effects of nano fillers such as cellulose nanofibrils and nano-scaled titanium dioxide on some properties of polyhydroxybutyrate and polylactic acid biopolymers; it also determined the selection of biopolymer nanocomposites with the optimum properties by using multicriteria decision-making methods such as multi-attribute utility theory, simple additive weighting, and weighted aggregated sum product assessment. Test results showed that the mechanical properties of the biopolymer nanocomposites generally increased with the addition of the cellulose nanofibrils and nano-scaled titanium dioxide. However, the addition of nano-scaled titanium dioxide decreased the tensile modulus. The addition of the cellulose nanofibrils had a higher effect on the tensile and flexure modulus of elasticity than the addition of the nano-scaled titanium dioxide. Thermal properties were generally found to improve with the addition of the cellulose nanofibrils and nano-scaled titanium dioxide. Melting temperature (Tm) generally decreased with the addition of the nano fillers. The scanning electron microscopic images showed that the nano fillers were dispersed as white dots in the biopolymer matrix. After accelerated weathering and decay test, outdoor performance of the biopolymer nanocomposites was found to be improved with the addition of the nano fillers. Multicriteria decision-making methods were conducted to determine the biopolymer nanocomposites having the optimum properties, and all the methods showed that the best biopolymer nanocomposites was polylactic acid with 1% cellulose nanofibrils.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-23T05:06:52Z
      DOI: 10.1177/0021998319870842
       
  • The role of electrical anisotropy and effective conducting thickness in
           understanding and interpreting static resistance measurements in CFRP
           composite laminates
    • Authors: Robert J Hart, OI Zhupanska
      Abstract: Journal of Composite Materials, Ahead of Print.
      This study is focused on (i) the experimental characterization of the anisotropic electrical resistivity of carbon fiber reinforced polymer (CFRP) composites and (ii) the development and experimental validation of predictive finite element (FE) models of the electrical response in CFRP laminates based on the concept of the effective conducting thickness. Two experimental methods have been developed to characterize the anisotropic electrical resistivities in three principle directions for the CFRP composite laminates using a direct current source. One method utilizes a traditional 6-probe resistance scheme and the alternative point-type 4-probe method is based on a handheld probe device similar to the JIS K7194 standard for homogenous plastics. An extensive experimental study has been conducted to characterize the anisotropic electrical resistivities of 16-ply unidirectional and 16-ply symmetric cross-ply IM7/977-2 and 32-ply unidirectional IM7/977-3 composites using the developed methods. Exploiting the concept of the effective conducting thickness, which describes the effective depth of current penetration through the thickness of an electrically anisotropic material, a unique methodology is developed for constructing FE models of these highly anisotropic CFRP materials. The concept of effective conducting thickness was identified as a critical component in achieving accuracy of the FE results as well as recovery of experimental resistivity from the alternative point-type 4-probe method. The FE models have been validated using the experimental results on the CFRP specimens of varying layup and thickness, and the techniques developed in this work may lead to advancements in non-destructive techniques in the areas of electrical characterization and damage sensing.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-21T05:27:33Z
      DOI: 10.1177/0021998319870860
       
  • Preparation of fluorescent calcium carbonate and visualization of its
           dispersion states in polypropylene
    • Authors: Xiangmeng Lv, Ming Kang, Kexu Chen, Lu Yuan, Simin Shen, Rong Sun, Lixian Song
      Abstract: Journal of Composite Materials, Ahead of Print.
      The dispersion states of fillers in the polymer matrix is an important factor to determine the properties of the polymer composites. Mastering the dispersion structure of inorganic minerals such as calcium carbonate in the polymer matrix is of great significance for the design of high performant polymer composites. Currently, due to the limitations of conventional electron microscope imaging capabilities, it is difficult to understand the internal dispersion structure of fillers in polymer composites comprehensively, regionally and stereoscopically. Here, we successfully embed the rare earth complex into the silica of the calcium carbonate surface to realize the fluorescent labeling of the calcium carbonate fillers. The fluorescent calcium carbonate exhibited broad excitation band ranging from 220 nm to 440 nm and showed bright red under ultraviolet light (365 nm). The two-dimensional dispersion states of the fillers at different depths in the polymer composite were obtained by the fluorescent imaging ability of laser scanning confocal microscope; these two-dimensional confocal images were further three-dimensionally reconstructed through Avizo Fire VSG software, and the spatial distribution of fillers in polymer composite was obtained without damage. This characterization method provides a new noninvasive method for studying the dispersion structure of fillers in polymers.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-21T05:27:32Z
      DOI: 10.1177/0021998319869822
       
  • Development of N-doped bamboo-shaped carbon nanotube/magnesium oxide
           nanocomposites
    • Authors: László Vanyorek, Ádám Prekob, Emőke Sikora, Gábor Muránszky, Bilal El Mrabate, Mahitha Udayakumar, Péter Pekker, Béla Viskolcz, Zoltán Németh
      Abstract: Journal of Composite Materials, Ahead of Print.
      Nitrogen-doped bamboo-shaped carbon nanotubes/magnesium oxide composites were prepared using a simple impregnation method. Magnesium oxide nanoparticles with different crystal morphologies were obtained using magnesium oxide powder and stearic acid precursors. The calcination of bamboo-shaped carbon nanotubes/magnesium stearate mixture in a 1:1 ratio with different temperatures (300 and 400℃) in an inert atmosphere was carried out. The prepared composites were further analyzed by X-ray powder diffraction, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, specific surface area measurement, Fourier transform infrared spectroscopy, transmission and scanning electron microscopy and thermogravimetric analysis techniques. Results revealed that the characteristic morphology and the crystal structure of the composites rely primarily on the heat treatment temperature chosen. To obtain a proper crystalline magnesium oxide, at least 400℃ is required. As-prepared bamboo-shaped carbon nanotube-based composites would be an ideal candidate as a catalyst or a membrane additive material for water purification technology.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-21T05:27:32Z
      DOI: 10.1177/0021998319870843
       
  • Overall buckling prediction model for fibre reinforced plastic laminated
           tubes with balanced off-axis ply orientations based on Puck failure
           criteria
    • Authors: Ruoyu Li, Ruijie Zhu, Feng Li
      Abstract: Journal of Composite Materials, Ahead of Print.
      Fibre reinforced plastic tubes with balanced off-axis ply orientation exhibit excellent mechanical properties and are widely used in various types of structures. In this study, a theoretical prediction model was proposed to determine the overall buckling load and the failure mode of fibre reinforced plastic laminated tubes with off-axis ply orientation under axial compression. This model considers the transverse shear effect and adopts Puck failure criteria to perform an analysis based on deduced three-dimensional stress and strain fields. A series of carbon fibre reinforced plastics tubes with varying off-axis ply orientations and lengths were designed and prepared. Axial compression tests with effective end-reinforcement and hinge support were performed to validate the proposed prediction model. The results indicated that the predicted model results were in good agreement with the test results, with respect to ultimate loads, failure modes, and locations of failure. Parametric analysis on the influence of transverse shear effect was also conducted, which further explained the influencing degree of transverse shear effect considering different tube lengths, ply sequences, and initial deflection.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-21T05:27:32Z
      DOI: 10.1177/0021998319871086
       
  • Neurofuzzy modelling of moisture absorption kinetics and its effect on the
           mechanical properties of pineapple fibre-reinforced polypropylene
           composite
    • Authors: J Lilly Mercy, R Velmurugan, T Sasipraba, Chrystella Jacob
      Abstract: Journal of Composite Materials, Ahead of Print.
      Natural fibres possess low density, less abrasiveness, good strength and sound absorption capacity and its significance lies in being renewable and biodegradable. The mechanical characteristics and moisture absorption of pineapple fibres reinforced with polypropylene resin are focused in this study. Chopped fibres and unidirectional fibre mats of pineapple were reinforced with polypropylene resin to make pineapple fibre/polypropylene composites. The length of the pineapple fibres and the orientation of the layup of the fibre mats are varied to make composite specimens and the mechanical properties are tested. Moisture absorption studies were carried out and it was confirmed to follow Fickian diffusion. A total of 384 samples were tested and it was observed that all the samples reached its saturation in moisture absorption before 720 h and the strength was inversely proportional to the moisture absorbed. Specimens reinforced with unidirectional fibre mats of alternate orientation possessed high strength irrespective of the moisture absorbed when compared to the specimens reinforced with chopped fibres of random orientation. Neuro fuzzy modelling using ANFIS tool box in MATLAB was used to correlate the static mechanical properties of pineapple fibre-reinforced polymer under different moisture conditions, fibre orientations, fibre volume percentage, fibre size, etc.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-21T05:27:31Z
      DOI: 10.1177/0021998319870581
       
  • Experimental investigation on impact, sound, and vibration response of
           natural-based composite sandwich made of flax and agglomerated cork
    • Authors: S Prabhakaran, V Krishnaraj, Krishna Shankar, M Senthilkumar, R Zitoune
      Abstract: Journal of Composite Materials, Ahead of Print.
      In recent years, material scientists have been focusing on the utilization of materials from natural resources due to environmental concerns. In the same context, the aim of this work is to evaluate impact response, sound absorption behavior, and vibration damping characteristics of natural-based composite sandwich made of flax as skin reinforcement and agglomerated cork as core. Vacuum bagging method was used for manufacturing composite sandwiches with different cork densities of 240, 280, and 340 kg/m3. Composite sandwiches have also been manufactured by using glass as skin reinforcement for comparison. Low velocity impact test was conducted and found that glass fiber reinforced composite sandwich required 73–77% more energy to perforate when compared to the flax fiber reinforced composite sandwich irrespective of core density. Flax fiber reinforced composite sandwich has 45–96% higher sound absorption capacity and 27–32% higher vibration damping ratio than glass fiber reinforced composite sandwich irrespective of core density. This is due to multiscale structure and cellular nature of the flax fiber and the cork materials, respectively. These enhancements in sound and vibration are accomplished with just little forfeits in perforation energy. This study recommends that, if optimized, the natural-based composite sandwich could be an ecologically appealing answer for automobile and construction applications, where impact behavior is important, along with sound and vibration properties.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-21T04:35:33Z
      DOI: 10.1177/0021998319871354
       
  • Electrical impedance analysis of carbon nanotube/epoxy nanocomposite-based
           piezoresistive strain sensors under uniaxial cyclic static tensile loading
           
    • Authors: Abdulkadir Sanli, Olfa Kanoun
      Abstract: Journal of Composite Materials, Ahead of Print.
      Carbon nanotubes-based nanocomposites have gained a great amount of attraction and play a key role in the realization of strain sensors owing to their remarkable physical properties. In this study, the piezoresistivity of multi-walled carbon nanotubes (MWCNTs)/epoxy-based nanocomposite-based strain sensor under static tensile load is examined using electrochemical impedance spectroscopy. Morphological examinations show that MWCNTs are randomly and homogeneously distributed in the epoxy polymer matrix. A simplified resistance constant phase element model is proposed and validated by impedance spectrum to fit the impedance spectra and the equivalent circuit parameters are extracted under uniaxial static load. Impedance results suggest that depending on the frequency regions, the sensor exhibits different responses under loading. Moreover, the proposed sensor gives high sensitivity, linearity and low hysteresis under cyclic quasi-static loading and unloading that makes the sensor a promising candidate for practical strain sensor applications.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-19T05:55:36Z
      DOI: 10.1177/0021998319870592
       
  • Fastening composite structures using braided thermoplastic composite
           rivets
    • Authors: Vincent Fortier, Jean-E Brunel, Louis L Lebel
      Abstract: Journal of Composite Materials, Ahead of Print.
      Aerospace composite material components are currently joined using heavy titanium bolts. This joining method is not ideal when considering its weight, thermal expansion, electrical conductivity, and risk of unbalanced load distribution. We propose here an innovative fastening technology using thermoplastic composite rivets. A rivet blank is heated above its melting temperature using Joule heating and is formed directly in the composite laminates by an automated process. Carbon fiber and polyamide blanks were used with two fiber architecture: 2D braid and unidirectional. The braided architecture showed superior manufacturing performance and repeatability. Joints were riveted in less than 40 s per rivet. The temperature measured in the riveted composite laminate in the vicinity of formed rivet reached only 136℃ during riveting. Double fastener lap shear testing showed breaking load of 6146 N per fastener. This joint strength is higher than comparable aluminum-riveted joints, and the specific joint strength is higher than titanium-bolted joints. With these advantages, the technology could be developed and used in the next generations of lighter, cleaner, and safer aircraft.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-15T06:42:23Z
      DOI: 10.1177/0021998319867375
       
  • Design and finite element assessment of fully uncoupled multi-directional
           layups for delamination tests
    • Authors: Torquato Garulli, Anita Catapano, Daniele Fanteria, Julien Jumel, Eric Martin
      Abstract: Journal of Composite Materials, Ahead of Print.
      In this paper, a procedure to obtain fully uncoupled multi-directional stacking sequences for delamination specimens is outlined. For such sequences, in-plane, membrane-bending and torsion–bending coupling terms are null (in closed-form solution in the framework of classical laminated plate theory) for the entire stack and for both its halves, which form two arms in the pre-cracked region of a typical delamination specimen. This is achieved exploiting the superposition of quasi-trivial quasi-homogeneous stacking sequences, according to appropriate rules. Any pair of orientations of the plies embedding the delamination plane can be obtained. To assess the effectiveness of the proposed approach, a fully uncoupled multi-directional sequence is designed and compared to other relevant sequences proposed in the literature. Finite element simulations of double cantilever beam test are performed using classic virtual crack closure technique and a revised state-of-the-art virtual crack closure technique formulation too. Some interesting conclusions regarding proper design of multidirectional stacks for delamination tests are drawn. Moreover, the results confirm the suitability of fully uncoupled multi-directional sequences for delamination tests. Thanks to their properties, these sequences might lay the foundations for the development of standard test procedures for delamination in angle-ply interfaces.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-15T06:42:23Z
      DOI: 10.1177/0021998319868293
       
  • Development of a methodology for characterizing reaction kinetics,
           rheology, and in situ compaction of polyimide prepregs during cure
    • Authors: James Magato, Donald Klosterman
      Abstract: Journal of Composite Materials, Ahead of Print.
      PMR-type polyimide prepregs are challenging to fabricate into high quality composites due to volatiles that are generated and must be removed in situ during processing. The current work was conducted to develop accurate, reliable, and practical characterization techniques of the prepreg rheology, volatile generation, and subsequent volatile removal from the prepreg during composite fabrication. Thermal analysis was used to characterize volatile generation, reaction rates, and rheology. A novel approach was used to measure the thickness of the prepreg in situ during vacuum bag/oven processing using a high-temperature LVDT. Experimental results are presented for the commercially available RM-1100 polyimide/carbon prepreg system, including the reaction rate, rheology, and panel thickness results for a series of heating rates and ply counts. The results show the key interrelationships in these coupled phenomena and how that information can be used to select the optimum temperature of pressure application to minimize the final void content.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-15T06:42:22Z
      DOI: 10.1177/0021998319869433
       
  • Micromechanical evaluation of failure models for unidirectional
           fiber-reinforced composites
    • Authors: Azam Arefi, Frans P van der Meer, Mohammad Reza Forouzan, Mohammad Silani, Mahmoud Salimi
      Abstract: Journal of Composite Materials, Ahead of Print.
      In this paper, micromechanical simulations are employed to evaluate the performance of the Tsai–Wu and Hashin failure criteria for fiber-reinforced composites, especially in stress states whose experimental reproduction is complicated. Micromechanical responses are generated using a finite element model of a representative volume element, in which only the matrix material experiences damage and the fibers are assumed to be elastic. Micromechanical simulations of basic load cases are used to calibrate macrolevel criteria. Finally, the response of the micromodel and macromodels is compared for various load combinations. Despite a good agreement between Tsai–Wu criterion predictions and micromodel results in a wide range of stress states, some stress combinations are highlighted for which the strength is not predicted accurately. Additionally, accuracy of the Hashin criterion suffers from ignoring the influence of stress in fiber direction on matrix failure.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-15T06:42:21Z
      DOI: 10.1177/0021998319867470
       
  • HAp/TiO2 nanocomposites: Influence of TiO2 on microstructure and
           mechanical properties
    • Authors: Ajay Kumar Vemulapalli, Rama Murty Raju Penmetsa, Ramanaiah Nallu, Rajesh Siriyala
      Abstract: Journal of Composite Materials, Ahead of Print.
      Hydroxyapatite is a very attractive material for artificial implants and human tissue restorations because they accelerate bone growth around the implant. The hydroxyapatite nanocomposites (HAp/TiO2) were produced by using high energy ball milling. X-ray diffraction studies revealed the formation of HAp and TiO2 composites. Cubic-like crystals with boundary morphologies were observed; it was also found that the grain size gradually increased with the increase in TiO2 content. It was found that the mechanical properties (hardness, Young's modulus, fracture toughness, flexural strength, and compression strength)of the composites significantly improved with the addition of TiO2, which was sintered at 1200℃. These properties were then also correlated with the microstructure of the composites. This paper investigates the effect of titania (TiO2 = 0, 5, 10, 15, 20, and 25 wt%) addition on the microstructure and mechanical properties of hydroxyapatite (Ca10(PO4)6(OH)2) nanocomposites.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-12T04:47:11Z
      DOI: 10.1177/0021998319868517
       
  • Nonlinear interphase effects on plastic hardening of nylon 6/clay
           nanocomposites: A computational stochastic analysis
    • Authors: Vahid Yaghoubi, Mohammad Silani, Hossein Zolfaghari, Mostafa Jamshidian, Timon Rabczuk
      Abstract: Journal of Composite Materials, Ahead of Print.
      In this paper, the nonlinear effect of interphase properties on the macroscopic plastic response of nylon 6/clay nanocomposites is investigated by applying a stochastic analysis on a multiscale computational model of nanocomposites. The mechanical behavior of interphase is described with respect to that of the matrix by a weakening coefficient. The interphase thickness and properties are considered as the stochastic inputs and the hardening modulus and hardening exponent describing the plastic hardening characteristics of the nanocomposite are the random outputs. The stochastic analysis consists of three procedures including (i) model selection using Akaike information criterion, (ii) uncertainty propagation using Latin Hypercube sampling in conjunction with chi-square test, and (iii) sensitivity analysis using Sobol indices. The results indicate that the exponential hardening model best describes the flow stress–plastic strain response of the nanocomposite. It is also shown that increasing the clay content generally increases the plastic hardening rate of the nanocomposite up to 4% clay content. Besides, the hardening characteristics of the nanocomposite are more sensitive to the weakening coefficient than the interphase thickness.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-12T04:47:11Z
      DOI: 10.1177/0021998319868523
       
  • Electromagnetic analysis of composite structures subjected to transient
           magnetic fields
    • Authors: Jerome T Tzeng, Kou-Ta Hsieh
      Abstract: Journal of Composite Materials, Ahead of Print.
      When carbon composites are exposed to a transient electromagnetic field, a rapid temperature increase can be observed due to joule heating from magnetic induction. The electromagnetic induction heating and heat transfer in the composite are anisotropic and concentrated upon the carbon fiber orientation and distribution. In addition, the strength and frequency of transient electromagnetic fields have great influence on the final quality of the composite. A computational model has been developed by solving coupled Maxwell’s and heat transfer equations. The analysis accounts for the three-dimensional transient electromagnetic field and electrical conductivity of the composite material. This paper will illustrate the derived formulation and numerical solution based on finite element methods. The developed code is validated with a 2D closed-form solution. Numerical simulations of a cylinder and a flat laminated plate are conducted to illustrate the computational capability. The induction heating for composite manufacture is also discussed for current Army’s applications.
      Citation: Journal of Composite Materials
      PubDate: 2019-08-10T05:55:54Z
      DOI: 10.1177/0021998319868005
       
  • 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
       
  • 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
       
 
 
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