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Abstract: This paper presents a new method to generate the random distribution of fibres in the transversal cross-section of fibre reinforced composites with high fibre volume fraction. The algorithm, named random sequential expansion (RSE) algorithm by the authors, is based on the hard-core model, but overcomes the jamming limit of hard-core model and is able to generate random distributions for high values of fibre volume fractions. By adjusting the inter-fibre distance parameters, it can generate microstructures with different fibre volume fractions expediently. Statistical analysis is performed on the generated distributions and a good agreement with the completely spatial random (CSR) pattern is found in all statistics analysed. Finite element analysis (FEA) is conducted to predict the effective properties of the generated microstructures. The predicted properties show reasonable agreement with the experimental results. The present algorithm is simple, highly efficient and provides a useful alternative to generate random numerical models that can be used in micromechanical analysis of composites. [Copyright &y& Elsevier]

Abstract: The mechanical behavior of unidirectional fiber-reinforced polymer composites subjected to tension and compression perpendicular to the fibers is studied using computational micromechanics. The representative volume element of the composite microstructure with random fiber distribution is generated, and the two dominant damage mechanisms experimentally observed – matrix plastic deformation and interfacial debonding – are included in the simulation by the extended Drucker–Prager model and cohesive zone model respectively. Progressive failure procedure for both the matrix and interface is incorporated in the simulation, and ductile criterion is used to predict the damage initiation of the matrix taking into account its sensitivity to triaxial stress state. The simulation results clearly reveal the damage process of the composites and the interactions of different damage mechanisms. It can be concluded that the tension fracture initiates as interfacial debonding and evolves as a result of interactions between interfacial debonding and matrix plastic deformation, while the compression failure is dominated by matrix plastic damage. And then the effects of interfacial properties on the damage behavior of the composites are assessed. It is found that the interfacial stiffness and fracture energy have relatively smaller influence on the mechanical behavior of composites, while the influence of interfacial strength is significant. [Copyright &y& Elsevier]