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Structural battery composites fall under the category multifunctional materials with the ability to simultaneously store electrical energy and carry mechanical load. While functioning as the negative electrode, the carbon fibres also act as mechanical reinforcement. Lithium ion insertion in the carbon fibres is accompanied by a large radial expansion of 6.6 % and an axial expansion of 0.85 % of the fibres. Furthermore, the elastic moduli of the carbon fibres are significantly affected by the insertion of lithium. Current structural battery modelling approaches do not consider these features. In this paper, we investigate the effect of lithium insertion in carbon fibres on the structural electrode mechanical properties by developing a computational model considering finite strains and lithium concentration dependent fibre moduli. The computational model enables representation of morphological change, whereby, features such as internal stress state, homogenized tangent stiffness and effective expansion of the electrode caused by carbon fibre lithiation can be predicted. The adopted finite strain formulation allows for consistent consideration of measurement data at varying state of lithiation. The significance of adopting the finite strain formulation is also shown numerically. Finally, by implementing a novel approach to homogenized stress-free expansion, it is shown that the computed expansion of the structural electrode follows a similar trend to what is observed from experiments. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract In current composite design, stacking sequence symmetry around the laminate mid-plane is an unarguable constraint to avoid warpage during manufacturing. However, several load cases induce unevenly distributed stresses through the laminate thickness, such that symmetric laminates may not be the optimal solution. In this paper, we explore the damage resistance to out-of-plane low velocity impact loading of an unsymmetrical laminate with zero extension-bending coupling matrix ([B]), thereby assuring no undesired coupling deformations during mechanical or thermal loads. Using impact and quasi-static indentation tests, C-scan inspection and numerical modelling, we compare the damage pattern between an unsymmetrical laminate with ply clustering at the impacted face and a laminate with ply clustering at the non-impacted face (produced by flipping the former laminate upside down). The laminate with clusters at the impacted side exhibits better damage resistance for lower impact energies. More importantly, the location of the damage events obeys the predictions assumed when the laminate was designed, demonstrating the room for improvement by tailoring unsymmetrical laminates to particular load cases. [ABSTRACT FROM AUTHOR]

Abstract Experimental results on the influence of bolt hole to edge eccentricity for Double Shear Bolted Joints (DSBJ) used to attach fiber reinforced composite laminates are presented. Four different eccentricities of DSBJs were examined and microCT imaging conducted at different stages of the loading history are presented. The macroscopic load-hole elongation results along with the microCT images exhibit a distinct progression of failure which dictate not only the bearing load but also the ultimate load of the joint. The experimental procedure, microCT images and failure progression mechanisms are reported in this paper. The results can serve to develop a mechanism based model of DSBJ failure progression. [ABSTRACT FROM AUTHOR]

Abstract: In order to understand the nature of nonlinearity in the in-plane shear behaviour of fibre reinforce composites (FRC), experimental data of such materials under loading cycles, involving loading, unloading, reversed loading and unloading from reversed loading, are essential. Using the standard ASTM D 4255/D 4255M method, it will require the fixture to be subjected to tension as well as compression. It has been proven in this paper that the standard ASTM D 4255/D 4255M fixture is incapable of delivering such data as premature buckling is expected when the fixture is under tension, even though it claimed that the fixture could be loaded in tension as well as in compression. A cyclic rail shear fixture (CRSF) as a modified version of ASTM D 4255/D 4255M fixture has been proposed in this paper and it has been designed and manufactured. The new fixture, which maintains all the capabilities of its standard counterpart, is truly capable of sustaining loading in tension as well as in compression so that specimens can be tested for loading and reversed loading. A series of experiments have been carried out using the new fixture to characterise the nonlinear in-plane shear stress–strain relationship of unidirectional fibre reinforced composite specimens under various cyclic loading conditions. Some new experimental data of this nature are presented in this paper, which are novel in contents and crucial in guiding the formulation of theoretical models for the nonlinear behaviour of in-plane shear for general applications. [Copyright &y& Elsevier]

This paper addresses the fracture behaviour of bonded composite plates featuring a kissing bond along the crack growth path. Double cantilever beam (DCB) experiments are carried out under a displacement controlled loading condition to acquire the load response. The experimental data are collected and analysed analytically for specimens with and without kissing bond. The following aspects are observed and discussed: effect of the adhesive carrier film, non-smooth crack growth and rising R curve. An analytical model taking into account the aforementioned effects is proposed. The kissing bond leads to unstable crack growth resulting in a loss of the load carrying capacity. The presence of the knit carrier in the adhesive film results in the crack growth process characteristic for the stick-slip phenomena and a significant increase of the resistance to fracture of the bondline by triggering a bridging phenomenon. The model shows a very good agreement with the experimental data. A sound understanding of the fracture process is gained enabling analysis and prediction of the effects of kissing bonds and supporting carrier. [ABSTRACT FROM AUTHOR]

In this paper, experimental results for rate dependence of interlaminar mode I fracture of a polymer matrix composite laminate are presented. A modified wedge-insert fracture (MWIF) method for conducting mode I fracture testing at elevated loading rates is used. A correction factor has been introduced to the modified beam theory method for measuring the mode I interlaminar fracture toughness using the MWIF method. The experimental method was successfully verified against the most widely used standardized method at quasi-static loading rates. Mode I interlaminar fracture testing was conducted at loading rates ranging from 0.01 mm/s to 3600 mm/s. A reduction in fracture toughness with rate was seen. The fracture behavior at elevated rates differed from the lower rates. The effect of bridging (and process zone) lengths on the fracture toughness were seen decreasing drastically with increased loading rate. [ABSTRACT FROM AUTHOR]

In the present paper, a new macro-mechanical model for tracing damage-evolution in composite materials is proposed. The present model represents a new extension and a new approach to a previous model (Ghazi-Farid model), which can be applied for a general state of stress. The model is verified by comparing its results with those corresponding to Ghazi-Farid model for different composite materials and it seems to give very close correlations. The proposed model can be applied to both elastic and inelastic materials as well as generally orthotropic fibrous composite nonlinear-materials. It was concluded that shear damage is always higher than any other damage types due to the high nonlinear-material shear behavior, which causes high plastic strain-energy density. Damage in a composite lamina causes a reduction in its stiffness. Therefore, a new quantum-damage variable is proposed: '' tangential quantum-damage variable '' to quantify the overall-damage in a composite lamina. Percentage reduction of composite stiffness depends mainly on the amount of resulting damage irrespective of fiber-orientation angle. So, a new trend for the behavior of composite materials is introduced which states that the relation between damage-evolution and corresponding stiffness-reduction follows a certain behavior and it is independent of fiber-orientation. Each composite material has a unique trend which is verified using three different composite materials; Boron-Epoxy-Narmco 5505, Graphite-Epoxy 4617/Modmore-II, and Carbon-Epoxy AS4/3501–6. A new damage-term is introduced as: "directional damage-variable", to simplify tracing damage in the case of a uniaxial off-axis loading. The new damage-variable was used to predict damage-evolution in the three laminas made of the indicated composite materials. It is concluded that, Graphite-Epoxy 4617/Modmore-II has the minimum damage at all stress levels and Boron-Epoxy-Narmco 5505 has the maximum damage. The importance of the new damage-term makes it easier to predict damage and make preferences between several composite materials subjected to uniaxial off-axis loading. [ABSTRACT FROM AUTHOR]

This paper focuses on the design of the appropriate geometry for cruciform coupons conceived to be tested under tensile biaxial transverse loads. To this end, Finite Element models were developed and their results were used to propose a geometry which minimizes undesirable effects such as stress concentrations, develops a uniform state of biaxial stresses in the central zone of the coupon and assures that the failure takes place at this zone. The experimental results confirm the validity of the numerical models. [ABSTRACT FROM AUTHOR]

A theoretical investigation on the reversible plasticity shape memory (RPSM) properties of Multi-Walled Carbon Nanotubes (MWCNT) reinforced epoxy nanocomposites is presented. A typical RPSM cycle involves loading and stress relaxation below the glass transition temperature and unconstrained strain recovery above glass transition temperature. This paper attempts to study the underlying mechanisms by employing a thermo-visco-elastic model incorporating structural and stress relaxation mechanisms. The effective properties of the nanocomposites were determined from basic micro-mechanics models and standard thermo-mechanical experiments. The variations in model parameters between neat and filled epoxy were studied and the influence of MWCNT on the material behavior are discussed. The simulations agreed quite well with the experimental results for both neat and filled epoxy. The model was further able to capture the thermo-mechanical behavior under different programming conditions like strain rate, strain level and relaxation time. [ABSTRACT FROM AUTHOR]

The damage of glass fiber-reinforced epoxy composites (GFRP) caused by mechanical loads is an important reason for the related electrical breakdown. In this paper, the L-shaped needle-wire electrode is used to simulate the coupling direction of mechanical stress and electric field, and the influences of equivalent tension and compression load on the electrical tree degradation of GFRP are obtained. It is found that both tensile and compressive loads will aggravate the electrical tree degradation in GFRP and reduce the average breakdown time. Under tensile load, the damage area of electrical tree increases, and even the sample breaks at the moment of electrical breakdown. However, the color of electrical tree channels is light and the number of branches is small under compression load. The narrow carbonization channels after breakdown will be accompanied by spherical damage areas. The simulation results of GFRP interface damage confirm that the increase of tension and compression load will lead to different degrees of damage at the fiber-matrix interface, and then cause local electric field distortion. At the same time, the combined action of high temperature and high pressure and external mechanical load will aggravate the electrical tree degradation process of GFRP. [Display omitted] [ABSTRACT FROM AUTHOR]

Long-term illumination can damage the mechanical properties of high strength fiber composites, resulting in the material aging and loss of mechanical properties. To reveal the mechanism of ultraviolet- (UV-) induced damage, in this paper, a nonlinear constitutive model is developed to describe the elastic and inelastic deformation behavior of high strength fibers under UV-radiation and mechanical loadings. Two internal variables are employed to measure the effects of damage caused by UV-radiation and by mechanical loadings, respectively. The Helmholtz free energy function and the evolution equations of these two internal variables are investigated elaborately and given explicitly for high strength fibers. The proposed theoretical model is then applied to analyze the mechanical degradation of high-performance high strength fibers under uniaxial tension. The modulus and strength of the material predicted by the theoretical model match the aging experimental results rather well, which verifies the rationality and accuracy of the present model. This model is expected to predict the evolution of mechanical properties of high-strength fibers under UV-radiation, which can also provide a theoretical basis for the development of anti-UV technology of fiber reinforced composites. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: Fibre-reinforced composites are being used more and more widely in many fields. However, the theoretical prediction of the failure of these composites is still a challenging task. In this paper, the physically-based failure theory developed by Puck and co-workers is combined with the fracture mechanics based in situ strength theory developed by Wang and Karihaloo. The latter considers the influence of both the thickness of the lamina itself and the ply angles of its neighbouring laminae. This combined failure theory also incorporates a new final failure mode. It is able to predict accurately the initial failure stress, thus overcoming one of the weaknesses of Puck’s theory which significantly underestimates this stress. Also, it explains why the number of non-fatal failure modes predicted by Puck’s theory is different from those observed in experiments under certain loads. Finally, it is able to overcome the problem of discontinuities in the failure envelope under some load combinations predicted by Puck’s original theory. [Copyright &y& Elsevier]

Abstract: Thin-ply based laminates are a promising development in composite materials and are expected in the near future to outperform conventional laminates in mechanical performance. A rational design with thin plies requires understanding the effect of ply thickness on each damage mechanism. This paper presents an experimental investigation into damage occurrence in a quasi-isotropic laminate made from thin-ply, bi-axial, Non-Crimp-Fabric (NCF), under different off-axis uniaxial loadings. The NCF layers are positioned through the laminate thickness creating two regions, namely THICK and THIN (with and without ply clustering). Then, the onset and progress of three damage mechanisms (transverse matrix cracking, matrix crack induced delamination and free-edge delamination) for both regions are analyzed by monitoring the specimen’s free-edge. The results show that the critical region where damage occurs is that with ply clustering (THICK), whereas delamination originating from matrix cracks or free edge effects are delayed or even suppressed in the THIN region. [Copyright &y& Elsevier]

Abstract: In this paper, an experimental study is performed to characterise the behaviour of fabric-reinforced composites used in sports products under large-deflection bending in Izod-type impact tests. X-ray micro computed tomography (micro-CT) is used to investigate various damage modes in the impacted CFRP specimens. It revealed that matrix cracking, delaminations, tow debonding, and fibre fracture were the prominent damage modes. Three-dimensional finite-element models are developed to study the onset, progression and interaction of some damage modes such as delamination and fabric fracture observed with micro-CT. A damage modelling technique based on a cohesive-zone method, which is more efficient than continuum damage mechanics approach, is proposed for analysis of interaction of damage modes. The developed numerical models are capable to simulate the damage mechanisms and their interaction observed in the tests. In this study, the pattern of damage formation observed in specimens was front-to-back, unlike bottom-to-top one in drop weight impact tests. The effect of boundary conditions on the dynamic response and damage evolution of composite laminates is also investigated. [Copyright &y& Elsevier]

Abstract: This paper presents a bistable twisting CFRP-metal hybrid laminate which has an external isotropic metallic layer. Different from the pure unsymmetric CFRP laminate and the hybrid unsymmetric laminate with an inner metallic layer, the laminate presented can be transformed from one negative curvature to another negative curvature instead of from one negative curvature to another positive curvature. Their room temperature shapes can be a unique paraboloid shape, a twisted cylindrical shape, or a twisted cylindrical shape that can be snapped through to another twisted cylindrical shape. The cured shape of the hybrid laminate is studied using analytical, finite element and experimental techniques. The investigation is focused on the hybrid laminate with lay-up of [0/90/metal]T, and shows that the principal direction of cured curvature is 45°. The predicted cured shape and the snap-through loads agree well with experimental results. [Copyright &y& Elsevier]

Abstract: The paper presents the measurement strategy and results of electrical resistivity of carbon-fiber reinforced hybrid carbon and SiC matrix composite commonly used for high heat load applications. Electrical resistance is measured for varying tensile stress up to 120MPa and temperature in a range from room temperature to 1970K. At room temperature, the resistivity is 37.4±0.4μΩm and increases with tensile load. With each 10MPa load step, resistivity increases by up to 0.7μΩm with residual resistivity increase of up to 0.4 μΩm. For the elastic regime, the gauge factor is determined to 6.41. Dependence of temperature is even stronger with linear trend. It has negative trend until 1700K with a resistivity decrease with e α/T with coefficient α =207K. An empirical formulation is given to relate resistivity to stress and temperature. [Copyright &y& Elsevier]

Abstract: This paper presents analytical and numerical models of liquid moulding of hybrid composites. An 1-D analytical solution of Darcy’s problem, accompanied by nanoparticle filtration kinetics and conservation, has been developed. A non-linear finite difference model incorporating variations in permeability, porosity and viscosity as a function of local nanoparticle loading was formulated. Comparison of the two models allowed verification of their validity, whilst a mesh sensitivity study demonstrated the convergence of the numerical scheme. The limits of validity of the analytical solution were established over a range of infiltration lengths and filtration rates for different nanoparticle loadings. The analytical model provides an accurate and efficient approximation of through thickness infusion of hybrid composites, whereas use of the numerical scheme is necessary for accurate simulation of in-plane filling processes. The models developed here can serve as the basis of process design/optimisation for the production of hybrid composites with controlled distribution of nano-reinforcement. [Copyright &y& Elsevier]

Abstract: This paper presents an experimental study of low energy impacts on composite plates covered with a protective layer. In service, composite materials are subjected to low energy impacts. Such impacts can generate damage in the material that results in significant reduction in material strength. In order to reduce the damage severity, one solution is to add a mechanical protection on composite structures. The protection layer is made up of a low density energy absorbent material (hollow spheres) of a certain thickness and a thin layer of composite laminate (Kevlar). Energy absorption ability of these protective layers can be deduced from the load/displacement impact curves. First, two configurations of protection are tested on an aluminium plate in order to identify their performance against impact, then the same are tested on composite plates. Test results from force–displacement curves and C-scan control are compared and discussed and finally a comparison of impact on composite plates with and without protection is made for different configurations. [Copyright &y& Elsevier]

Abstract: In this paper we present the biaxial failure curve of a chopped glass-reinforced polyester composite. The curve has been obtained combining the results of experimental tests with the results of numerical simulations developed by means of the Finite Element Method. The experimental tests have been performed applying perpendicular loads to cruciform specimens. Then, taking into account the numerical results, we have constructed the failure envelope in the tensile–tensile quadrant. Moreover we propose to modify the cruciform geometry to obtain, varying the widths of the loaded arms and the tapered central zone, points of the failure curve in which the two components of the plane stress tensor are different. [Copyright &y& Elsevier]

Abstract: This paper presents the development of a highly efficient user-defined finite element for modelling the bolt–load distribution in large-scale composite structures. The method is a combined analytical/numerical approach and is capable of representing the full non-linear load–displacement behaviour of bolted composite joints both up to, and including, joint failure. In the elastic range, the method is generic and is a numerical extension of a closed-form method capable of modelling the load distribution in single-column joints. A semi-empirical approach is used to model failure initiation and energy absorption in the joint and this has been successfully applied in models of single-bolt, single-lap joints. In terms of large-scale applications, the method is validated against an experimental study of complex load distributions in multi-row, multi-column joints. The method is robust, accurate and highly efficient, thus demonstrating its potential as a time/cost saving design tool for the aerospace industry and indeed other industries utilising bolted composite structures. [Copyright &y& Elsevier]

Abstract: In this paper an experimental investigation is performed to describe the fracture behavior and failure mechanisms of woven fabrics composites, under static loading, using a compact tension test (CT). We studied the development of the different damage phases using the digital image correlation and the compliance method. The crack length was estimated at in the front of the notch tip. The approach of the effective crack length via the compliance procedure was compared to the measures of the damage in the epoxy/glass fiber composite obtained by the digital image correlation (DIC). [Copyright &y& Elsevier]

Abstract: The experimental study of composite delaminations and adhesive joints is usually carried out using beam-type specimens with bonded metallic fixtures to transfer the applied load. However, bonded joints between the composite specimen and the metallic parts might fail, especially under extreme temperature or fatigue test conditions. Moreover, the quality and alignment of the bonding procedure highly depends on the operator skills and is time consuming. In this paper the design of an improved mechanical hinge is introduced. The new hinge eliminates bonded joints by mechanically clamping the sides of the specimen and avoids the misalignment effects between specimen and fixture. The new system has proven to be easy to use, fast and reliable. [Copyright &y& Elsevier]

Abstract: This paper presents the development of a constitutive model able to accurately represent the full non-linear mechanical response of polymer–matrix fibre-reinforced composites with unidirectional (UD) plies under quasi-static loading. This is achieved by utilising an elasto-plastic modelling framework. The model captures key features that are often neglected in constitutive modelling of UD composites, such as the effect of hydrostatic pressure on both the elastic and non-elastic material response, the effect of multiaxial loading and dependence of the yield stress on the applied pressure. The constitutive model includes a novel yield function which accurately represents the yielding of the matrix within a unidirectional fibre-reinforced composite by removing the dependence on the stress in the fibre direction. A non-associative flow rule is used to capture the pressure sensitivity of the material. The experimentally observed translation of subsequent yield surfaces is modelled using a non-linear kinematic hardening rule. Furthermore, evolution laws are proposed for the non-linear hardening that relate to the applied hydrostatic pressure. Multiaxial test data is used to show that the model is able to predict the non-linear response under complex loading combinations, given only the experimental response from two uniaxial tests. [Copyright &y& Elsevier]

Abstract: In response to the growing interest in replenishable, lightweight, stiff and strong materials, a novel sandwich panel with a hollow core has been manufactured using commercially produced 3-ply veneer. In this paper, the out-of-plane shear behaviour of the novel hollow core is analysed and the expressions for the failure loads are developed. A strength-based optimisation problem is formulated for predicting the optimum values of the panel dimensions that would produce minimum panel weight when subjected to bending. It has been found that the minimum weight, as predicted by the full four-parameter optimisation, is slightly lower than that obtained by using the closed form expressions derived on the basis of simplified three-parameter optimisation. Relationships between the active failure modes are explored. Design maps are shown for a wide range of loading that can be used to calculate the minimum panel weight and the corresponding values of the geometric parameters. The approach developed is general and is equally applicable for sandwich panels with similar hollow cores made of other materials. [Copyright &y& Elsevier]

Abstract: Numerical procedures based on the combined use of the Virtual Crack Closure Technique and of a fail release approach have been widely used to simulate delamination growth phenomena of composite material structures. This paper starts explaining why this kind of methodologies might not be robust due to mesh and load step size dependency and introduces a novel approach able to cope with the problems identified. Finally the effectiveness and robustness of the proposed procedure, implemented into a commercial finite element software by means of user subroutines, are assessed by comparing the obtained numerical results for a delamination growth phenomenon against literature experimental data on a stiffened panel with a circular embedded delamination under compressive load. [Copyright &y& Elsevier]

Abstract: Enhancing the thermal conductivity and reducing the thermal expansion for electronic packaging applications can be achieved by compositing carbon nanofibers in copper-matrices. Though achieving these optimal thermal properties is theoretically possible, such composites are currently not available due to many unresolved practical problems. Conventional compositing processes are incapable of obtaining the desired fiber distribution while controlling the fiber–matrix interfaces for effective heat and load transfers. In this paper, three different powder metallurgy based processes are presented; two based on conventional techniques and the third a relatively new method. The first method is basically the conventional powder metallurgy process. The second and the third methods are also powder metallurgy processes with different ways of modifying the surface of the fibers using either electroless coating or the novel salt decomposition method. It is shown that the salt decomposition method is capable of achieving the desired high thermal conductivity values while the thermal expansion values remain the same in all the three processes. [Copyright &y& Elsevier]

Abstract: In this paper, a modified adaptive cohesive element is presented. The new elements are developed and implemented in LS-DYNA, as a user defined material subroutine (UMAT), to stabilize the finite element simulations of delamination propagation in composite laminates under transverse loads. In this model, a pre-softening zone is proposed ahead of the existing softening zone. In this pre-softening zone, the initial stiffness and the interface strength are gradually decreased. The onset displacement corresponding to the onset damage is not changed in the proposed model. In addition, the critical energy release rate of the materials is kept constant. Moreover, the constitutive equation of the new cohesive model is developed to be dependent on the opening velocity of the displacement jump. The traction based model includes a cohesive zone viscosity parameter (η) to vary the degree of rate dependence and to adjust the maximum traction. The numerical simulation results of DCB in Mode-I is presented to illustrate the validity of the new model. It is shown that the proposed model brings stable simulations, overcoming the numerical instability and can be widely used in quasi-static, dynamic and impact problems. [Copyright &y& Elsevier]

Abstract: To better understand the imperfection influence on the ultrananocrystalline diamond (UNCD) properties under various loading conditions, a numerical study is performed to investigate the effect of vacancies on the mechanical responses of pure and nitrogen (N)-doped UNCD films under tensile and shear loading paths at elevated temperatures. A simple procedure is developed by combining kinetic Monte Carlo with molecular dynamics (MD) methods to form a polycrystalline UNCD block. Different numbers of vacancies are introduced by randomly removing carbon atoms from the resulting UNCD blocks. The responses of the simulated pure and N-doped UNCD blocks with different numbers of vacancies are then investigated by applying displacement–controlled loading under different temperatures in the MD simulations. The simulation results presented in this paper provide a better understanding of the imperfection effect on the mechanical responses of pure and N-doped UNCD films as compared with the grain boundary effect. [Copyright &y& Elsevier]

Abstract: The reinforcement of cement with glass fibre textiles imbues the composite with a tensile as well as compressive load-bearing capacity. The tensile capacity allows the elimination of steel reinforcement as well as the concrete corrosion cover in structural applications. With textile reinforced concrete (TRC) thin and/or free form shells could be realized. In this paper, a parametric study is used to evaluate the structural applicability of TRC for small span (2–15m) doubly curved roof shells. The application of two different, existing TRC material combinations demonstrates the influence of the applied composite material on the design of the shell. [Copyright &y& Elsevier]

Abstract: This paper quantitatively investigates the effect of chemical functionalization on the axial Young’s moduli of single-walled carbon nanotubes (SWCNTs) based on molecular mechanics (MM) simulation, in which the COMPASS force field is used to model the interatomic interactions in a nonfunctionalized nanotube or a functionalized nanotube grafted with vinyl groups. We obtain the axial Young’s moduli of both functionalized and nonfunctionalized SWCNTs. The influences of the number and distribution density of the sp3-hybridized carbon atoms and the radius and chirality of the SWCNTs on Young’s moduli are studied. The results indicate that Young’s moduli depend strongly on the chirality of the SWCNTs and the distribution density of the sp3-hybridized carbon atoms. A 37.50% content of sp3-hybridized carbon atoms may degrade Young’s modulus by up to 33.36%. In addition, MM simulations show that the functionalization of SWCNTs results in a decrease of Young’s moduli of the corresponding SWCNT/polyethylene composites. [Copyright &y& Elsevier]

Abstract: This paper presents the results of current research on the fatigue life prediction of carbon/epoxy laminate composites involving twelve balanced woven bidirectional layers of carbon fibres and epoxy resin manufactured by a vacuum moulding method. The plates were produced with 3mm thickness and 0.66 fibre weight fraction. The dog bone shape specimens were cut from these plates with the load line aligned with one of the fibre directions. The fatigue tests were performed using load control with a frequency of 10Hz and at room temperature. The fatigue behaviour was studied for different stress ratios and for variable amplitude block loadings. The damage process was monitored in terms of the stiffness loss. The fatigue life of specimens submitted to block loading tests was modelled using Palmgren–Miner’s law and taking in to account the stress ratio effect. The estimated and experimental fatigue lives were compared and good agreement was observed. [Copyright &y& Elsevier]

Abstract: In this paper, a multi-particle finite element [Nguyen VT, Caron JF. A new finite element for free edge effect analysis in laminated composites. Comput Struct, accepted for publication] is applied for general laminated and is shown to be capable of simultaneously predicting global and local responses. The analysis of free-edge stresses of composite laminates subjected to mechanical and thermal loads is performed using this eight-node layer-wise finite element after a classical bending validation. Laminates with finite dimensions are considered and three-dimensional out-of-plane stresses in the interior and near the free edges are evaluated. The results obtained with this finite element modelling are compared with those available in the literature. The present calculation provides accurate stresses and can be utilised as and operational tool to predict interlaminar stresses under the loads of mechanical and thermal combined. [Copyright &y& Elsevier]