A virtual experimental approach to microscale composites testing

This paper presents a method for virtual testing composite microstructures with real fibre distributions, and compares the debonding and crack response with experimental results of identical microstructures under similar loading conditions. Prior to physical testing of HTA/6376 composite laminates, the fibre distribution of the undamaged physical specimen is automatically detected through image analysis and reconstructed as a 2D model in Abaqus software and tested following a sub-modelling approach. Once in-situ SEM micro-mechanical testing of the physical specimen is completed, the virtual and experimental crack paths can be directly compared to determine the viability of the virtual testing method. The influence of thermal residual stress on premature fibre-matrix debond initiation and crack propagation is also investigated. The results of the virtual testing presented in this paper give a strong correlation to the experimentally observed crack growth, where significant improvement on similar previously published virtual experimental results for composite materials in terms of both microstructure scale and accuracy of the crack representation, is observed. For the thermo-mechanically loaded models, thermal residual stresses were found to influence the crack path around certain fibres where localised thermal residual stresses were present, leading to a more accurate representation of damage than that given by the purely mechanically loaded models.