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  • Effects of surface modification on dispersion, mechanical, thermal and dynamic mechanical properties of injection molded PLA-hydroxyapatite composites
    Compos. Part A Appl. Sci. Manuf. (IF 4.075) Pub Date : 2017-09-21
    John O. Akindoyo, Mohammad D.H. Beg, S. Ghazali, Hans P. Heim, Maik Feldmann

    In this study, poly(lactic acid) (PLA)/hydroxyapatite (HA) composites were produced through extrusion and injection moulding. In order to foster good interaction between PLA and HA, a phosphate based modifier (Fabulase(R) 361) was used to modify the HA surface. Spectroscopic analysis reveals that surface of the HA was effectively modified without changing the HA into another material. Morphological study shows effective dispersion of HA in the PLA matrix after modification, with significant influence on the composite properties. Thermal properties of the modified HA composite was improved, alongside an enhancement of about 25%, 20% and 42% in tensile, modulus and impact properties of the modified PLA-HA composite respectively. Furthermore, dynamic properties of the modified HA composite was notably improved with obvious reduction of the damping factor. Thus, surface modification was effective to enhance dispersion and compatibility of HA and PLA to produce polymeric biomaterials suitable for good load bearing applications.

    更新日期:2017-09-21
  • Improving thermal and flame retardant properties of epoxy resin by functionalized graphene containing phosphorous, nitrogen and silicon elements
    Compos. Part A Appl. Sci. Manuf. (IF 4.075) Pub Date : 2017-09-20
    Yuezhan Feng, Chengen He, Yingfeng Wen, Yunsheng Ye, Xingping Zhou, Xiaolin Xie, Yiu-Wing Mai

    As alternative flame-retardant additive for polymers, reduced graphene oxide (RGO) is often limited by its poor interfacial compatibility with matrix. In this work, a new flame retardant, containing phosphorous, nitrogen and silicon elements was used to functionalize RGO. The wrapped flame retardant chains induced the improvement in the dispersion and compatibility of RGO in epoxy (EP) matrix. As a result, the mechanical, thermal and flame retardant properties of EP-based composites were significantly improved by adding flame retardant-functionalized RGO. The peak heat release rate, total heat release and total smoke production reduced by 34%, 14% and 30%, respectively, compared to neat resin. Based the char analyses, the enhancement in flame retardancy is attributed to the outstanding char layers with high strength and thermal stability resulting from the template effect of graphene, the charring effect of phosphorus and nitrogen elements and the enhancing effect of silicon element in grafted flame retardant chains.

    更新日期:2017-09-20
  • The effect of fiber undulation on the strain field for pinned composite/titanium joints under tension
    Compos. Part A Appl. Sci. Manuf. (IF 4.075) Pub Date : 2017-09-20
    L Eberl, Avila Gray L, S Zaremba, K Drechsler

    The way fiber undulation around pins affects pinned composite/titanium joints’ stiffness and strength properties is illustrated for double-lap-shear joints under quasi-static tensile loading. 3D digital-image-correlation techniques were employed to measure in-plane strain distribution on the surface of the composite joint member. Pinned joints with formed holes and three different composite stacking sequences were manufactured and compared to joints with drilled holes. Whereas in the case of joints with formed holes, the process of inserting the pin into uncured prepreg material created undulations, joints with drilled holes are characterized by a uniform fiber direction but partly broken fibers. Due to homogenization of the strain field within the load-carrying 0° layers, pinned composite/metal joints with formed holes proved to significantly outperform joints with drilled holes in terms of tensile stiffness and strength.

    更新日期:2017-09-20
  • An effective route for the fabrication of multi-walled carbon nanotubes-reinforced ROMP-based nanocomposites by solution casting technique
    Compos. Part A Appl. Sci. Manuf. (IF 4.075) Pub Date : 2017-09-17
    Guang Yang, Jing Yan, Young Gyu Jeong, Jong Keun Lee

    This work reported the solvent-soluble multi-walled carbon nanotubes (MWCNTs), which could be used for the fabrication of ring-opening metathesis polymerization (ROMP)-based nanocomposites by solution casting technique. As the first and most important step of the solution casting technique, the excellent dispersibility of the MWCNTs in different solvents was achieved by the functionalization of the nanotube surface with norbornene oligomers. The norbornene-functionalized MWCNTs (nMWCNTs) had outstanding dispersion stability in water, tetrahydrofuran (THF), acetone, and ethanol, especially the maximum nanotube concentration of 3.9 mg/mL in THF. The incorporation of nMWCNTs into poly(5-ethylidene-2-norbornene) (poly(ENB)) by solution casting technique resulted in significant improvements in the mechanical properties over the neat poly(ENB) and the pristine MWCNT-reinforced poly(ENB) nanocomposites. The route developed here not only avoids the dramatic increase of the viscosity occurring in the bulk polymerization but also provides the feasibility of high loadings of MWCNT reinforcements, consequently broadening the potential applications of ROMP-based nanocomposites.

    更新日期:2017-09-19
  • Hybrid Bicomponent Fibres for Thermoplastic Composite Preforms
    Compos. Part A Appl. Sci. Manuf. (IF 4.075) Pub Date : 2017-09-15
    Christoph Schneeberger, Joanna C.H. Wong, Paolo Ermanni

    Hybrid bicomponent fibres – materials in which reinforcement fibres are individually sheathed in thermoplastic polymer – are proposed as a novel class of preform materials for thermoplastic composites. We assert that by reducing the scale of hybridization between the reinforcement fibres and the matrix polymer to the level of the fibre, a thermoplastic intermediate material with both high drapeability and short consolidation times can be developed. The manufacture of hybrid bicomponent fibres is demonstrated in a scalable, coating process in which glass fibres are combined with several thermoplastic polymer matrix systems in dimensions and proportions suitable for use in thermoplastic composite structures. This novel class of thermoplastic composite preforms is expected to expedite the high volume production of geometrically complex thermoplastic composite parts.

    更新日期:2017-09-15
  • In-situ space-confined synthesis of well-dispersed three-dimensional graphene/carbon nanotube hybrid reinforced copper nanocomposites with balanced strength and ductility
    Compos. Part A Appl. Sci. Manuf. (IF 4.075) Pub Date : 2017-09-13
    Xiang Zhang, Chunsheng Shi, Enzuo Liu, Fang He, Liying Ma, Qunying Li, Jiajun Li, Naiqin Zhao, Chunnian He

    It is a tough issue to design and fabricate discontinuously reinforced metal matrix composites (DRMMCs) with desired mechanical and physical properties. Utilizing nanocarbon materials such as one-dimensional (1D) carbon nanotubes (CNTs), two-dimensional (2D) graphene or their hybrids as reinforcements for DRMMCs is now considered to be a good solution because of their outstanding intrinsic characterizations. In this work, we proposed a novel in-situ space-confined strategy to circumvent the problem of the controllable interconnection and bonding between CNTs and graphene and thus constructed a well-dispersed CNTs embedded in three-dimensional graphene network (3D GN) hybrid structure for fabricating reinforced Cu matrix nanocomposites. The as-obtained 3D GN/CNT hybrids reinforced copper bulk nanocomposites exhibited a significant strengthening efficiency and a more balanced strength vs. ductility relation compared with Cu matrix composites reinforced by single component (CNT or 3D GN) with the same volume fraction.

    更新日期:2017-09-13
  • The importance of translaminar fracture toughness for the penetration impact behaviour of woven carbon/glass hybrid composites
    Compos. Part A Appl. Sci. Manuf. (IF 4.075) Pub Date : 2017-09-11
    Yentl Swolfs, Yoran Geboes, Larissa Gorbatikh, Silvestre T. Pinho

    The impact resistance of fibre-reinforced composites is vital in many applications, and can be improved by exploiting synergies in fibre-hybridisation. These effects are however not sufficiently well understood in the literature. Penetration impact tests were hence performed on carbon/glass hybrids, and the results were linked to the flexural behaviour and translaminar fracture toughness. The results revealed large synergetic effects of up to 40% compared to the linear rule-of-mixtures. The results are also the first to reveal that creating a translaminar fracture surface can strongly contribute to the energy absorbed during penetration impact: 56% for an all-carbon fibre composite and 13% for an all-glass fibre composite. These results prove that strategies for maximising the translaminar fracture toughness can also be exploited to maximise the penetration impact resistance of fibre-hybrids. In carbon fibre composites in particular, ply blocking, using larger yarns and introducing micro-cuts should therefore increase the penetration impact resistance.

    更新日期:2017-09-11
  • New BN-epoxy composites obtained by thermal latent cationic curing with enhanced thermal conductivity
    Compos. Part A Appl. Sci. Manuf. (IF 4.075) Pub Date : 2017-09-09
    Isaac Isarn, Lluís Massagués, Xavier Ramis, Àngels Serra, Francesc Ferrando

    A series of boron nitride (BN) composites, with different BN content, were prepared and characterized by cationic curing of DGEBA/BN formulations. As cationic initiator a commercial benzylanilinium salt was used. This cationic system shows good latent characteristics that were not lost on adding the filler. The performance of the catalytic system was optimized by varying the amount of initiator and adding little proportions of glycerol. The kinetics of the curing process was evaluated by calorimetric measurements. The addition of BN allowed increasing thermal conductivity without loss of mechanical properties like Young modulus, impact resistance, adhesion and other thermal characteristics like Tg or thermal stability. In addition, dielectric properties were improved with the increment of filler.

    更新日期:2017-09-10
  • The influence of N-doping types for carbon nanotube reinforced epoxy composites: A combined experimental study and molecular dynamics simulation
    Compos. Part A Appl. Sci. Manuf. (IF 4.075) Pub Date : 2017-09-08
    Hana Jung, Hoi Kil Choi, Soyoung Kim, Hun-Su Lee, Yonjig Kim, Jaesang Yu

    In this study, nitrogen doped carbon nanotube reinforced epoxy nanocomposites were characterized through experiments and molecular dynamics (MD) simulation. Carbon nanotubes were functionalized by nitrogen inductively coupled plasma. They were made into a nanocomposite by a solvent-free mixing method. The various characteristics of nanocomposites, including nitrogen doped carbon nanotubes were analyzed by the following experiments: a Raman spectra, an X-ray photoelectron spectroscopy (XPS), quasi-static tensile tests, a scanning electron microscopy (SEM), and a transmission electron microscopy (TEM). In addition, an MD simulation was performed to predict the mechanical properties of nanocomposites and the results were compared to the test measurements. It showed that the effective dispersion of nitrogen doped carbon nanotubes was important to improve the mechanical characteristics of the nanocomposites.

    更新日期:2017-09-08
  • Graphene based Strain and Damage Prediction System for Polymer Composites
    Compos. Part A Appl. Sci. Manuf. (IF 4.075) Pub Date : 2017-09-08
    R. Balaji, M. Sasikumar

    Glass fibre reinforced polymer composites are extensively used as an advanced engineering material, particularly in aviation industries because of its superior properties. Unlike metals, damage and failure of the composites are complicated to predict under real-time loading due to its anisotropic nature. With that focus, reduced Graphene Oxide (rGO) based Structural Health Monitoring for polymer composite is proposed in this work. The prioritised aim of this study is to measure the strain induced and the degree of damage accumulated in the composites. To achieve this, the rGO coated glass fibres are embedded into polymer composite to evaluate the strain and damage induced in the composites by measuring the fractional change in the piezoresistance of the coated fibre. The piezoresistive response of the coated fibres showed linear variation under low (elastic) deformation. However, under high (plastic) deformation, the piezoresistance varied nonlinearly with an irregular stepped increment. This nonlinear stepped increment is marked due to the initiation and propagation microcracks in the polymer composites. The damage accumulation in the composite is predicted by measuring the deviation of piezoresistance from the elastic response line using statistical analysis. A statistical correlation is established between the damage accumulation and the experimentally calculated residual strength. The electromechanical study on the rGO coated glass fibres suggested as potential applications for the strain and damage monitoring of composite materials.

    更新日期:2017-09-08
  • Magnetoactive elastomer/PVDF composite film based magnetically controllable actuator with real-time deformation feedback property
    Compos. Part A Appl. Sci. Manuf. (IF 4.075) Pub Date : 2017-09-08
    Jiabin Feng, Shouhu Xuan, Li Ding, Xinglong Gong

    This work reported a high performance flexible magnetically controllable actuator based on magnetoactive elastomer (MAE) and poly (vinylidene fluoride) (PVDF) composite film. The magnetic-mechanic-electric coupling properties of the actuator were systematically investigated by cyclical wrinkle, magnetic bending, and stretching test. The induced charge under a magnetic bending can reach as large as 158 pC even at small magnetic field of 100 mT with the bending angle up to almost 90 degrees within 0.6 s. Moreover, a new model was proposed to theoretically reveal the intrinsic correspondence. The model matches well with the experimental results. Based on this kind of actuator, a magnetically controllable tentacle is developed, which could grasp, transport, and release object by switching the supplied current. Due to the real-time deformation feedback characteristics, this kind of actuators can find wide applications in actively controllable engineering, artificial robotics, and biomedicine.

    更新日期:2017-09-08
  • A fast water-induced shape memory polymer based on hydroxyethyl cellulose/graphene oxide composites
    Compos. Part A Appl. Sci. Manuf. (IF 4.075) Pub Date : 2017-09-07
    Yongkang Bai, Xin Chen
    更新日期:2017-09-08
  • Environmentally Assisted Crack Growth in Adhesively Bonded Composite Joints
    Compos. Part A Appl. Sci. Manuf. (IF 4.075) Pub Date : 2017-08-26
    Jared Tracy, Yikai Yin, Jeffrey Yang, John C. Osborne, Kay Y. Blohowiak, Reinhold Dauskardt

    Adhesively bonding composite components is a reliable alternative to conventional joining processes that minimizes part weight and reduces fabrication costs. Regarding performance and reliability, of particular interest is developing adherend surface treatments that enhance adhesion of the joint interfaces in aggressive chemical environments. Using fracture mechanics-based adhesion metrologies, critical and subcritical crack growth were evaluated for several peel- ply-treated, adhesively bonded composite joints. Fracture toughness, Gc, and corresponding failure modes were evaluated for specimens constructed using two different bonding processes (co-bonding and secondary bonding) and four different peel ply treatments. Environmentally assisted crack growth was evaluated as a function of time in several environments: humid, high temperature humid, and hydraulic fluid immersion. It is shown that humid environments accelerate crack growth rates, da/dt, relative to the strain energy release rate, G. This effect was amplified at elevated temperatures and further amplified in the presence of hydraulic fluid.

    更新日期:2017-08-28
  • Fabrication of high quality composite laminates by pressurized and heated-VARTM
    Compos. Part A Appl. Sci. Manuf. (IF 4.075) Pub Date : 2017-08-22
    M. Akif Yalcinkaya, E. Murat Sozer, M. Cengiz Altan

    Although vacuum-assisted transfer molding (VARTM) is preferred for manufacturing medium to large composite parts due to its simple tooling and low cost, part quality dictated by dimensional tolerances, void content and mechanical properties is usually low due to inherent limitations of the process. In this study, the conventional VARTM process was modified by external pressurization of a heated mold to increase fiber volume fraction and improve mechanical properties of laminates. During post-filling, various levels of external pressure were applied in a pressure chamber mounted on top of the mold. It was observed that pressurized VARTM led to laminates with less than 1% void content. In addition, fiber volume fraction and flexural strength were increased 25% and 13% with respect to non-pressurized VARTM, respectively which demonstrates the potential for manufacturing considerably higher quality composites by pressurized VARTM.

    更新日期:2017-08-22
  • Highly aligned graphene oxide/poly(vinyl alcohol) nanocomposite fibers with high-strength, antiultraviolet and antibacterial properties
    Compos. Part A Appl. Sci. Manuf. (IF 4.075) Pub Date : 2017-08-15
    Xinjun Hu, Nan Ren, Yuanzhi Chao, Huilin Lan, Xiaojie Yan, Yan Sha, Xiaolin Sha, Yongxiao Bai

    Demands for the strong and multifunctional fiber has substantially increased in textile industry, biomedical, and biotechnological applications. This study explores to fabricate nanocomposite functional fibers by embedding highly oriented graphene oxide (GO) into the poly (vinyl alcohol) (PVA) matrix. The GO/ PVA nanocomposite fibers were prepared via gel spinning and subsequent hot drawing process. The tensile strength of the produced GO/PVA nanocomposite fibers was significantly enhanced owing to the uniformly dispersed and oriented GO nanosheets. Additionally, the ultraviolet protection factor of the highly aligned GO/PVA nanocomposite fibers is about 16 times than that of the neat PVA fiber. The as-prepared GO/PVA nanocomposite fibers also exhibit significant activity against both Gram-negative and Gram-positive bacteria. This highly aligned and integrated approach suggests an effective method to prepare graphene-based nanocomposites fibers with high performances and novel functional characteristics.

    更新日期:2017-08-17
  • The effect of multi-wall carbon nanotube morphology on electrical and mechanical properties of polyurethane nanocomposites
    Compos. Part A Appl. Sci. Manuf. (IF 4.075) Pub Date : 2017-08-14
    Jatin Sethi, Essi Sarlin, Seyyed Shayan Meysami, Reija Suihkonen, Arunjunai Raja Shankar Santha Kumar, Mari Honkanen, Pasi Keinänen, Nicole Grobert, Jyrki Vuorinen
    更新日期:2017-08-17
  • Preparation and performance of bio-based carboxylic elastomer/halloysite nanotubes nanocomposites with strong interfacial interaction
    Compos. Part A Appl. Sci. Manuf. (IF 4.075) Pub Date : 2017-08-12
    Xinxin Zhou, Qinan Zhang, Runguo Wang, Baochun Guo, Yuri Lvov, Guo-Hua Hu, Liqun Zhang

    Poly(dibutyl itaconate-co-isoprene-co-methacrylic acid) (PDIM)/halloysite nanotubes (HNTs) nanocomposites with strong interfacial interaction were prepared by co-coagulation of PDIM latex and HNTs aqueous suspension, followed by mechanical kneading with rubber additives. The interfacial interaction, thermal properties, morphology, and mechanical properties of the nanocomposites were investigated. The hydrogen bonds were confirmed in the nanocomposites. Morphology investigation showed uniform and individual dispersion of HNTs in the PDIM matrix. With the incorporation of HNTs into the PDIM matrix, the tensile strength and the fracture energy were significantly improved without sacrificing the extensibility. The improved mechanical properties were correlated to the co-coagulation and the strong hydrogen bonds. Especially, the morphology investigation of tensile fracture surfaces revealed a mechanism for the improved mechanical performance, in which the stress was efficiently transferred from PDIM to HNTs via hydrogen bonds and then the dissociation of the hydrogen bonds dissipated energy to increase the fracture energy of the nanocomposites.

    更新日期:2017-08-17
  • Enhance interfacial properties of glass fiber/epoxy composites with environment-friendly water-based hybrid sizing agent
    Compos. Part A Appl. Sci. Manuf. (IF 4.075) Pub Date : 2017-08-16
    Yubing Dong, Yaofeng Zhu, Yongzhen Zhao, Fuyao Liu, Enliang Wang, Yaqin Fu

    The interface improvement of fiber-reinforced composites has remained a vexing problem that limits the use of the excellent properties of fiber in composite applications. In this study, a novel water-based hybrid sizing agent was synthesized by in-situ generated silica within waterborne epoxy/waterborne epoxy curing agent system, which was used as a glass fiber (GF) surface modifier to enhance the interfacial properties of GF/epoxy (EP) composites. The morphology and wetting ability of GF after treated with the hybrid sizing agent, the single-GF tensile strength and the interfacial shear strength (IFSS) of the single-GF/EP composites were investigated. Experimental results showed that the wetting ability of GF and the IFSS of the single-GF/EP composites were significantly improved after being treated by the hybrid sizing agent. This work is aimed at developing an environment-friendly, safe, and effective water-based sizing for substituting the traditional solvent-based sizing.

    更新日期:2017-08-16
  • A macroscopic approach to simulate the forming behaviour of stitched unidirectional non-crimp fabrics (UD-NCF)
    Compos. Part A Appl. Sci. Manuf. (IF 4.075) Pub Date : 2017-08-12
    F.J. Schirmaier, D. Dörr, F. Henning, L. Kärger

    Thin composite shell structures manufactured from stitched unidirectional non-crimp fabrics (UD-NCF) in a liquid composite moulding process provide high lightweight design capabilities. For complex geometries, the forming process of the textile pre-products is challenging and requires intensive investigations to avoid defects like macroscopic wrinkling or fibre gapping. In contrast to biaxial engineering fabrics, UD-NCF has been investigated only sparsely in terms of its forming behaviour, both experimentally and numerically. To close this gap, a macroscopic forming simulation model for UD-NCF is proposed in this work, including a new non-orthogonal and linear strain measure for large strains and the corresponding nominal stress measure. To parametrize the constitutive laws and to investigate the multiaxial deformation behaviour of UD-NCF, supplementary off-axis-tension tests with optical strain measurement are performed in this work. The new forming simulation model is validated via forming simulation of a hemisphere test and of a preforming process of an automotive component.

    更新日期:2017-08-13
  • Carbon nanotubes coated hybrid-fabric composites with enhanced mechanical and thermal properties for tribological applications
    Compos. Part A Appl. Sci. Manuf. (IF 4.075) Pub Date : 2017-08-12
    Junya Yuan, Zhaozhu Zhang, Mingming Yang, Fang Guo, Xuehu Men, Weimin Liu

    Poor interfacial adhesion and inferior thermal property of resin matrix severely obstruct the continued development of fabric-reinforced polymer composites for potential advanced tribological applications. Herein, carbon nanotubes (CNTs) encapsulated by copolymer of polydopamine (PDA) and polyethylenimine (PEI) directly deposited onto hybrid Nomex/PTFE fabric leading to a hierarchical reinforcing structure was successfully carried out via a facile one-pot synthesis. The achieved organic-inorganic hybrid functional coating significantly increased the wettability, reactive functional groups and surface roughness of hybrid-fabric. Tensile and peeling tests show that the hierarchical composites exhibited 38.4% and 63% enhancement in tensile strength and interfacial bonding strength compared to that of the pristine fabric composites. Furthermore, CNTs modification forming percolating networks on hybrid-fabric within the resin matrix effectively promotes the thermal stability of the fabric composites. Results of wear tests prove that the hierarchical composites exhibited outstanding tribological properties under varied applied loads.

    更新日期:2017-08-13
  • Enhanced thermal conductivity of commercial polystyrene filled with core-shell structured BN@PS
    Compos. Part A Appl. Sci. Manuf. (IF 4.075) Pub Date : 2017-08-10
    Weifang Han, Yufeng Bai, Shicai Liu, Chunhua Ge, Lixia Wang, Zhiyan Ma, Yuxuan Yang, Xiangdong Zhang

    Polystyrene-wrapped boron nitride/commercial polystyrene (BN@PS/CPS) composites with high thermal conductivity were fabricated by a novel approach. The route included two steps, BN@PS core-shell structured fillers were prepared by using modified BN and styrene (St) as the raw materials via suspension polymerization, and then the BN@PS were kneaded with the CPS by mechanically mixed method. The composite achieves a high thermal conductivity of 0.692 W/mK containing 30 wt% BN@PS (∼15.9 wt% BN), which is 3.72 times higher than that of pure CPS of ∼0.186 W/mK and 1.78 times higher than that BN/CPS blend composite with at the same BN loading of 0.332 W/mK. Compared with traditional routes, the novel preparation process requires less BN fillers when improving the same thermal conductivity. Importantly, other polymers can also encapsulate BN through this strategy, which paves a new way for preparing thermally conductive polymer-matrix composites.

    更新日期:2017-08-10
  • Amending the thermo-mechanical response and mechanical properties of epoxy composites with silanized chopped carbon fibers
    Compos. Part A Appl. Sci. Manuf. (IF 4.075) Pub Date : 2017-08-09
    Subhankar Das, Sudipta Halder, Jialai Wang, M.S. Goyat, A Anil Kumar, Yi Fang

    This study demonstrates the ability of functionalized chopped carbon fibers (CCFs) chosen from industrial waste to improve the thermo-mechanical properties of CCFs/epoxy composites. The defect sites onto the CCFs were created by their oxidation and the oxidized CCFs were covalently linked with siloxane functional groups to conceal their defects. The surface functionalization of CCFs was characterized by a simple chemical route, FTIR and TGA analysis, respectively. The surface morphology of functionalized CCFs showed the generation of highly dense networked globules. Epoxy composites filled with 0.5 wt% of siloxane attached CCFs (S-CCFs) showed a tremendous enhancement in storage modulus (∼ 376%) without sacrificing their thermal stability. Furthermore, the S-CCFs reinforced epoxy composites demonstrate a significant improvement in the tensile and fracture properties. Such enhancement in the mechanical properties can open up the scope for the utilization of CCFs as a potential cost-effective candidate for high-performance next generation structural composites.

    更新日期:2017-08-10
  • Complete Simulation Process Chain for the Manufacturing of Braided Composite Parts
    Compos. Part A Appl. Sci. Manuf. (IF 4.075) Pub Date : 2017-08-08
    E.E. Swery, T. Hans, M. Bultez, W. Wijaya, P. Kelly, R. Hinterhölzl, S. Bickerton

    A complete simulation process chain has been used to predict the production and subsequent injection of over-braided textile preforms. A range of mandrel geometries and braiding configurations were used to illustrate how these factors affect the resin injection of the part. Braiding simulations were first completed, predicting the geometry of the braided textile throughout the mandrel. Following this, a range of multi-layered unit-cells were modelled, capturing the variations in geometry. These virtual stacks were produced with both no and maximum in-plane ply shift so as to capture the range of stacking configurations possible. Following a compaction simulation of these stacks, their in-plane permeability tensor was predicted and used to identify the permeability of the braided preform at different regions. This was used to predict the propagation of the resin flow front, highlighting the effects that the mandrel geometry, braiding process parameters and stacking method have on the resulting resin injection.

    更新日期:2017-08-09
  • Enhancing thermal conductivity and mechanical properties of poly(methyl methacrylate) via adding expanded graphite and injecting water
    Compos. Part A Appl. Sci. Manuf. (IF 4.075) Pub Date : 2017-08-08
    Min Wu, Han-Xiong Huang, Jun Tong, Dong-Ying Ke

    Poly(methyl methacrylate)/expanded graphite (PMMA/EG) composites are prepared using water-assisted mixing extrusion (WAME) technique. Scanning and transmission electron microscopy micrographs show that the EG exhibits better exfoliation and dispersion in the composite samples prepared with water injection than that in those without water injection. More EG layer networks and stronger PMMA-EG interfacial interaction are formed in the composite samples prepared with water injection, which are confirmed by the FTIR and rheological measurements and the linear fits of experimentally obtained tensile yield stresses. The composite samples with well exfoliated and dispersed EG layers exhibit higher thermal conductivity and mechanical properties, which are ascribed to lower interfacial thermal resistance and stronger interfacial interaction, respectively. Finally, a mechanism for promoted EG exfoliation and dispersion in the PMMA matrix during the WAME is interpreted by analyzing the combined effect of injected high-pressure water with the shear force provided by the extruder screw.

    更新日期:2017-08-09
  • A clustering method for analysis of morphology of short natural fibers in composites based on X-ray microtomography
    Compos. Part A Appl. Sci. Manuf. (IF 4.075) Pub Date : 2017-08-08
    Anna Madra, Jérôme Adrien, Piotr Breitkopf, Eric Maire, François Trochu

    The work presented here concerns the methodology for the analysis of X-ray micro-CT scans of composite materials with a discontinuous phase. An automatized method has been devised for the measurement of geometric features and identification of distinct morphological types. This approach offers new insights into the composition of a microstructure based on the analysis of phase morphology and its relative volume percentage. It stays in contrast to the frequency-based approach that attributes the same importance to all elements of the structure, and is thus biased towards numerous, but not necessarily essential components of the material. The method is general and can be applied to any type of discontinuous, dispersed phase in composites identified with X-ray micro-tomography. We have verified our approach for short natural fibers but it may be of interest for characterizing void distribution in RTM manufactured composites or cracks after failure.

    更新日期:2017-08-08
  • Understanding and predicting defect formation in automated fibre placement pre-preg laminates
    Compos. Part A Appl. Sci. Manuf. (IF 4.075) Pub Date : 2017-08-05
    Jonathan P.-H. Belnoue, Tassos Mesogitis, Oliver J. Nixon-Pearson, James Kratz, Dmitry S. Ivanov, Ivana K. Partridge, Kevin D. Potter, Stephen R. Hallett

    Fibre path defects are detrimental to the structural integrity of composite components and need to be minimised through process optimization. This requires understanding of the uncured pre-preg material, which is influenced by multiple process parameters, and sophisticated multi-scale modelling tools. Even though the capabilities of process modelling techniques have been improved over the past decades, the occurrence of localised wrinkles remains challenging to predict. One of the processes known to influence the formation of fibre path defects is the consolidation of laminates manufactured by automated fibre placement. The particular focus of this paper is to understand how out-of-plane wrinkles form during debulking and autoclave curing of laminates with embedded gaps and overlaps between the deposited tapes. Predictions are made using a novel modelling framework and validated against micro-scale geometry characterisation of artificially manufactured samples. The paper demonstrates the model’s ability to predict consolidation defects for the latest generation of toughened pre-pregs.

    更新日期:2017-08-07
  • Measurement method of multi scale thermal deformation inhomogeneity in CFRP using in situ FE-SEM observations
    Compos. Part A Appl. Sci. Manuf. (IF 4.075) Pub Date : 2017-08-04
    Y. Tanaka, K. Naito, H. Kakisawa

    The measurement of nano scale thermal deformation and strain inhomogeneity in the transverse direction in carbon fiber-reinformed polmer (CFRP) in the temperature range 170K to 370K has been carried out by in-situ Field Emission Scanning Electron Microscopy (FE-SEM) observation using a heating and cooling stage in the FE-SEM chamber. A grid pattern and also random patterns were drawn on the polished sample surface at different length scales. The electron moiré method was applied to measure the macroscopic deformation and the digital imaging correlation method was applied to measure the nano-scale deformation around the fiber/matrix interface. The strain inhomogeneity of the pitch-based carbon fiber in the transverse direction and the debonding at the interface between fiber and matrix has been evaluated quantitatively.

    更新日期:2017-08-07
  • The Tsai-Wu Failure Criterion Rationalised in the Context of UD Composites
    Compos. Part A Appl. Sci. Manuf. (IF 4.075) Pub Date : 2017-08-04
    Shuguang Li, Elena Sitnikova, Yuning Liang, Abdul-Salam Kaddour

    This paper is to rationalise the empirical aspect of the Tsai-Wu failure criterion in the context of UD composites associated with the determination of the interactive strength property F12 based on the analytic geometry. It reveals that the condition of closed failure envelope cannot be satisfied by all UD composites and hence the restriction should be abandoned. Depending on the way the failure envelope opens, UD composites can be classified into two categories. (a) F12 can be determined uniquely using the conventional strength properties with an additional assumption that the material exhibits very high or infinite strength under triaxial compression at a specific stress ratio; or (b) The Tsai-Wu criterion leads to one of the two scenarios: either allowing infinite strength for an in-plane stress state or allowing infinite strength under triaxial stresses involving tension along fibres.

    更新日期:2017-08-07
  • Enhanced mechanical and thermal properties of SBR composites by introducing graphene oxide nanosheets decorated with silica particles
    Compos. Part A Appl. Sci. Manuf. (IF 4.075) Pub Date : 2017-08-03
    Zijin Liu, Yong Zhang

    Synergistic enhancement of fillers in the polymer matrix has emerged as a subject of scientific and industrial interest. A hybrid with the silica decorating on GO surface (SiO2@GO) was fabricated by an electrostatic self-assembly method, and its morphology, structure and composition were characterized. GO, silica, silica/GO mixture (SiO2-GO), and SiO2@GO were separately filled in styrene-butadiene rubber (SBR) to obtain composites. SBR/SiO2@GO (100/20) composite exhibited the best performance, and its tensile strength increased by 308% compared with that of SBR. This is due to SiO2@GO was uniformly embedded in the SBR matrix brought by the synergistic dispersion of silica and GO. SiO2@GO acted as the barrier in SBR composites, and increased the temperature at 50% weight loss for SBR/SiO2@GO (100/20) by 13.1°C compared to SBR. Anchoring silica on GO surface is an effective way to develop various high-performance rubber composite materials with good potential in industrial applications.

    更新日期:2017-08-07
  • Multistep modeling of Young’s modulus in polymer/clay nanocomposites assuming the intercalation/exfoliation of clay layers and the interphase between polymer matrix and nanoparticles
    Compos. Part A Appl. Sci. Manuf. (IF 4.075) Pub Date : 2017-08-03
    Yasser Zare, Kyong Yop Rhee

    In the present paper, a multistep technique for prediction of Young’s modulus in polymer/clay nanocomposites (PCN) is developed considering the intercalation/exfoliation of clay layers and the interphase between polymer matrix and nanoparticles. This methodology is evaluated by the experimental data of various samples. In addition, the effects of several parameters attributed to intercalation/exfoliation of clay layers and interphases on the modulus are examined. The predictions demonstrate good agreement with the experimental data by proper levels of intercalation/exfoliation of clay layers and interphase properties, while the modulus is under-predicted by disregarding of these factors. The findings also indicate that more exfoliation of thinner clay layers and stronger interphase cause a higher modulus in PCN.

    更新日期:2017-08-07
  • Elastomer reinforcement by graphene nanoplatelets and synergistic improvements of electrical and mechanical properties of composites by hybrid nano fillers of graphene-carbon black & graphene-MWCNT
    Compos. Part A Appl. Sci. Manuf. (IF 4.075) Pub Date : 2017-08-02
    Soumya Mondal, Dipak Khastgir

    Present work deals with the reinforcement behaviour of graphene nanoplatelets (GNP) in elastomer matrix of acrylonitrile butadiene (NBR) co-polymer. The addition of 20 phr GNP in NBR matrix a significant improvement in tensile strength (∼528%), and elongation at break (∼60%) compared to neat NBR is observed. Hybrid composites of NBR filled with GNP-CB and GNP-MWCNT at judicious proportion exhibit further improvement in the mentioned properties compared to those exhibited by composites containing individual fillers at same loading. This reflects strong synergistic effect on properties by hybrid fillers. Morphological studies reveal the state of dispersion of filler in matrix polymer, and this can be correlated with property improvements. The better synergistic effect of GNP-CB hybrid filler in comparison to GNP-MWCNT for improvement in mechanical and electrical properties as well as thermal stability may be attributed to the better filler dispersion and higher polymer-filler interaction for NBR-GNP-CB hybrid system compared to NBR-GNP-MWCNT system.

    更新日期:2017-08-07
  • Creep behaviour of graphite oxide nanoplates embedded glass fiber/epoxy composites: Emphasizing the role of temperature and stress
    Compos. Part A Appl. Sci. Manuf. (IF 4.075) Pub Date : 2017-08-02
    Sohan Kumar Ghosh, Rajesh Kumar Prusty, Dinesh Kumar Rathore, Bankim Chandra Ray

    Graphene based nano-reinforcements have emerged as promising fillers in polymeric materials. The objective of the present article is to elucidate the reinforcement effect of graphite oxide nanoplates (GONP) on the thermal, flexural and creep performance of glass fiber/epoxy (GE) composites. Thermal analyses by DSC, DMA and TGA showed reduced glass transition temperature of GE composite due to GONP incorporation, whereas no significant impact has been observed on the decomposition temperature. GONP addition has been found to be beneficial on the flexural properties of GE composite. To understand the effect of temperature on long-term mechanical durability, creep tests have been performed at various temperatures (50, 80 and 110 °C). Further, elevated temperature creep behaviour has been assessed at various stresses (10, 20 and 40 MPa) to comprehend the combined effect of temperature and stress. Improved creep resistance has been observed in GONP modified GE composites at relatively lower temperature and stress.

    更新日期:2017-08-07
  • Spatial Confining Forced Network Assembly for preparation of high-performance conductive polymeric composites
    Compos. Part A Appl. Sci. Manuf. (IF 4.075) Pub Date : 2017-07-29
    Daming. Wu, Xiaolong. Gao, Jingyao. Sun, Dan. Wu, Ying. Liu, S. Kormakov, Xiuting. Zheng, Lili. Wu, Yao. Huang, Zhanhu. Guo

    Constructing a network of conductive fillers in polymeric matrix is essential for the preparation of conductive polymer composites. Although the conductivity of the composites could increase remarkably after the percolation threshold, it is still much lower than expected due to a limited self-assembly interaction between filler particles. In this paper, high-performance conductive polymer composites were prepared by the method of Spatial Confining Forced Network Assembly (SCFNA). The compound of homogenous polymer and conductive fillers, prepared by conical twin-screw mixer, was placed in a compression mold with confining space to carry out two-stage compression, free compression and spatial confining compression. The electrical conductivity of the SCFNA prepared polypropylene/short carbon fibers was increased up to 4 orders of magnitude higher than that of by ordinary compounding technology.

    更新日期:2017-07-29
  • CFRP Manufacturing Method using Electrodeposition Resin Molding for Curvilinear Fiber Arrangements
    Compos. Part A Appl. Sci. Manuf. (IF 4.075) Pub Date : 2017-07-27
    Kazuaki Katagiri, Katsuhiko Sasaki, Shiniya Honda, Hikaru Nakashima, Shimpei Yamaguchi, Tomoatsu Ozaki, Hirosuke Sonomura, Atsushi Kakitsuji

    Recently, theoretical and experimental methods were proposed for organizing carbon fibers in straight and curvilinear arrangements to obtain a uniform stress distribution in the design of three-dimensional (3D) carbon fiber reinforced thermosetting plastic (CFRP). In this study, to establish an efficient CFRP manufacturing method and realize the curvilinear arrangement of carbon fibers, we develop an electrodeposition resin molding technique. That is, immersing a noncrimp fabric in the electrodeposition solution and energizing electricity, the fabric is impregnated by the resin; thus, a CFRP with curvilinear carbon fibers can be efficiently produced without autoclaving and vacuum packing. We then confirm the optimal electrodeposition conditions for maximizing the tensile strength of the CFRP, and obtain the 3D shape of the CFRP by keeping the noncrimp fabric in solution along the mold.

    更新日期:2017-07-29
  • Enhanced tensile properties of Al matrix composites reinforced with β-Si3N4 whiskers
    Compos. Part A Appl. Sci. Manuf. (IF 4.075) Pub Date : 2017-07-25
    Chenxu Zhang, Jinwei Yin, Dongxu Yao, Kaihui Zuo, Yongfeng Xia, Hanqin Liang, Yuping Zeng

    Al matrix composites reinforced with β-Si3N4 whiskers (β-Si3N4w) were fabricated by hot pressing method. The microstructures showed that the whiskers were uniformly dispersed in the matrix and the Al/β-Si3N4 interface was well bonded without interface reaction. Effects of β-Si3N4w content and sintering parameters on the densification and tensile behavior of composites were investigated. The results indicated that β-Si3N4w could both enhance the ultimate tensile strength (UTS) and maintain the ductility of Al matrix when the whisker content was 5 vol.%, corresponding to an elongation at break and an UTS of 21.2% and 239 MPa, respectively. However, higher whisker content could improve UTS of composites to the maximum value of 312 MPa, which was 158 MPa higher than pure Al, while reducing elongation of composites. The fracture mechanism changed from ductile fracture to a combination of both ductile and brittle fracture mechanism with the increase of whisker content.

    更新日期:2017-07-29
  • Thermo-gravimetric analysis method to determine the fiber volume fraction for PAN-based CFRP considering oxidation of carbon fiber and matrix
    Compos. Part A Appl. Sci. Manuf. (IF 4.075) Pub Date : 2017-07-25
    YunHo Kim, Chunghyeon Choi, Sarath Kumar Sathish Kumar, Chun-Gon Kim, Sun-Won Kim, Jae Hyuk Lim

    The properties of fiber reinforced composites are mainly determined by the fraction of reinforcement and matrix. Thus, to design a system based on composite materials, it is vital to carefully measure the volume fractions of the composites with a proper method. Digestion by strong acid or ignition at high temperature in an oxidizing environment are conventional for measuring content fractions. In essence, these methods assume that the reinforcement does not lose weight by digestion or ignition. However, by neglecting the vulnerable oxidization characteristic of carbon fiber, these conventional methods result in inaccurate fiber volume fractions of carbon fiber / epoxy composites. In this study, an effective and accurate method for determining the fiber volume fractions of two different PAN (Polyacylonitrile)-based carbon fiber reinforced composites via thermo-gravimetric analysis is developed and subsequently verified using the results from 80 microscopic images.

    更新日期:2017-07-29
  • A simple chemical approach to regenerating the strength of thermally damaged glass fibre
    Compos. Part A Appl. Sci. Manuf. (IF 4.075) Pub Date : 2017-07-25
    S.T. Bashir, L. Yang, R. Anderson, P.L. Tang, J.J. Liggat, J.L. Thomason

    Process-induced strength loss is a major technical barrier to the effective reuse of thermally recycled glass fibres in composite applications. We have developed a novel approach to effectively restore strength in glass fibres through treatment in alkaline solutions. Glass fibres were treated at elevated temperature and experienced significant strength loss found typically after thermal recycling processes. Different alkaline treatments were then applied to the thermally damaged fibres in an attempt to restore strength which had been lost as a result of the heat conditioning procedure. Results indicated that these treatments were able to generate considerable fibre strength recovery. The degree of strength regeneration was found to be highly dependent on reaction conditions, which were investigated and optimised. The positive effect of these simple chemical treatments demonstrated great potential for facilitating the reuse of thermally recycled glass fibres in composite applications.

    更新日期:2017-07-29
  • Experimental study of the effects of graphene oxide on microstructure and properties of cement paste composite
    Compos. Part A Appl. Sci. Manuf. (IF 4.075) Pub Date : 2017-07-22
    Haibin Yang, Manuel Monasterio, Hongzhi Cui, Ningxu Han

    Graphene oxide (GO) has been utilized to strengthen composite materials. In this study, the effects of GO on hydration degrees, macro-mechanical strength and calcium-silicate-hydrate (C-S-H) structure of cement based composites were investigated through comprehensive experimental tests. In addition, the aggregation mechanism of GO was verified by alkaline solution simulations, using Ca(OH)2 and NH3·H2O. Based on the experimental results, it was found that the 3-day and 7-day compressive strengths of cement based composites with 0.2 wt% of GO were increased by 35.7% and 42.3%, respectively as compared to the control. Moreover, the C-S-H structure of cement paste with GO was not observed to have undergone any change via qualitative and quantitative analyses combined with FT-IR, XRD and 29Si-NMR. Besides, the test results of TGA, DTG and 29Si-NMR showed that the hydrated degree of cement paste increased to 10.4% at 28 days when incorporating with 0.1% of GO.

    更新日期:2017-07-29
  • A Critical Review on Research Progress of Graphene/Cement Based Composites
    Compos. Part A Appl. Sci. Manuf. (IF 4.075) Pub Date : 2017-07-21
    Haibin Yang, Hongzhi Cui, Waiching Tang, Zongjin Li, Ningxu Han, Feng Xing

    Cement based composite materials (CBCM) with superior mechanical strength and excellent durability are always desirable in practical applications. Although considerable research has been reported in the past decades about the use of Nano materials (NMs) for strength and durability enhancement of cement matrix, there is little information available on the use of graphene nano-sheets and their derivatives (GND) in cement-based materials. Particularly the role of GND in hydration processes and their mechanisms of strengthening in cement matrix are unclear. In this paper, a critical review on recent research findings about GND modified cement-based materials was conducted. The review mainly discussed the influence of GND on properties of cement matrix including microstructure, hydration, mechanical properties, etc. The information revealed in this paper would not only provide a comprehensive understanding of the effect of GND on cement composites, but also provide valuable ideas and guidance for similar studies in the future.

    更新日期:2017-07-29
  • Experimental investigation of randomly-oriented tow-based discontinuous composites and their equivalent laminates
    Compos. Part A Appl. Sci. Manuf. (IF 4.075) Pub Date : 2017-07-14
    Yizhuo Li, Soraia Pimenta, Jordan Singgih, Stefan Nothdurfter, Karsten Schuffenhauer

    The equivalent laminate assumption is a commonly-used method to model the random architecture of discontinuous composites, but which has never been validated experimentally. This study aims to verify the equivalent laminate assumption, focusing on tow-based discontinuous composites (TBDCs), which have higher fibre-content and thus improved modulus and strength, compared to conventional discontinuous-fibre composites. This verification was achieved by manufacturing and testing (i) actual TBDCs with randomly oriented tows and (ii) their equivalent laminates (ELs), at two different tow thicknesses. The results show that ELs exhibit the same failure mechanisms as TBDCs, and are similarly weakened by an increase in tow thickness. However, ELs lack the spatial variability in local fibre-content and local tow orientations, which makes ELs stronger than TBDCs. Therefore, the equivalent laminate assumption is suitable for predicting the modulus of discontinuous composites, but cannot predict their strength without considering the local variability in their microstructure.

    更新日期:2017-07-29
  • Layer-by-layer assembly of layered double hydroxide/rubber multilayer films with excellent gas barrier property
    Compos. Part A Appl. Sci. Manuf. (IF 4.075) Pub Date : 2017-07-14
    Lumei Wang, Yibo Dou, Jiajie Wang, Jingbin Han, Li Liu, Min Wei

    Rubber nanocomposites with high gas barrier property have extensive application prospects in sealing and packing industry, while developing a novel and cost-effective rubber-based material with low gas permeability and good mechanical property still remains a challenge. Herein, we designed and fabricated an excellent gas barrier film by using polyvinyl pyrrolidone modified ultrathin layered double hydroxide nanoplatelets (U-mLDH) and nitrile butadiene rubber (NBR) as building blocks. The resultant (U-mLDH/NBR)30 film displays significantly decreased (reduced by 92.2% compared with NBR film) oxygen transmission rate with 0.626 cm3 m–2 day–1 atm–1, and much lower relative permeability in comparison with reported rubber composites. The improved gas barrier performance is ascribed to the prolonged passage of oxygen molecules and the decreased free space arising from large aspect ratio of U-mLDH and good interfacial compatibility. In addition, the (U-mLDH/NBR)30 film also possesses high thermal stability and satisfactory mechanical property, which would guarantee its practical applications.

    更新日期:2017-07-29
  • Automated braiding of a complex aircraft fuselage frame using a non-circular braiding model
    Compos. Part A Appl. Sci. Manuf. (IF 4.075) Pub Date : 2017-07-14
    Philippe Monnot, Jonathan Lévesque, Louis Laberge Lebel

    Braided structural composites have the potential to replace aerospace primary structure traditionally manufactured with preimpregnated fabrics and cured in autoclave. An improved braiding model was developed and applied to a complex fuselage frame technological demonstrator. Numerical case studies were performed in order to assess their effectiveness and to determine the best braiding parameters. A radial braiding machine was coupled to an industrial robot. The fuselage frame demonstrator mandrel was overbraided with carbon fiber yarns. Measured braid angles showed a greater difference than what was expected between the web and the flange faces. Yarn friction and interlacing forces caused the yarns to curve near the edges of the face, therefore causing the measured braid angles to vary along the face width. Moreover, discrepancies in the model’s outputs prevented the braid fell front to conform around the severe cross-section variations as well as causing yarn slip over the corners.

    更新日期:2017-07-29
  • Influence of damage accumulation under fatigue loading on the AE-based health assessment of composite materials: Wave distortion and AE-features evolution as a function of damage level
    Compos. Part A Appl. Sci. Manuf. (IF 4.075) Pub Date : 2016-03-25
    M. Kharrat, V. Placet, E. Ramasso, M.L. Boubakar

    Pattern recognition of Acoustic Emission (AE) data is generally performed based on prior knowledge about the acoustic signatures of material damage mechanisms. Traditionally, these signatures are implicitly assumed to be unaffected by damage accumulation during the fatigue life of the material. This study investigates the influence of cumulated damage under cyclic loading on the acoustic signatures of local fracture mechanisms in composites. Artificial AE sources are created using an ultrasonic transmitter and a Pencil Lead Break in order to reproduce various real-like AEs, such that the waveforms, measured at the sensor level, are characterized as similar to real acoustic signatures of local fractures in carbon/epoxy composites. It is shown that these waveforms are distorted with damage accumulation in both time and frequency domains, leading to important changes in the AE-features used in data classification. Consequently, this can engender unreliable statistical representation of the AE sources in such non-stationary media.

    更新日期:2017-07-29
Some contents have been Reproduced with permission of the American Chemical Society.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.
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