Micromechanical modelling of the transverse damage behaviour in fibre reinforced composites

A micromechanics damage model is presented which examines the effect of fibre-matrix debonding and thermal residual stress on the transverse damage behaviour of a unidirectional carbon fibre reinforced epoxy composite. It is found that for a weak fibre-matrix interface, the presence of thermal residual stress can induce damage prior to mechanical loading. However, for a strong fibre-matrix interface the presence of thermal residual stress is effective in suppressing fibre-matrix debonding and improving overall transverse strength by approximately 7%. The micromechanical model is subjected to a multiple loading cycle (i.e. tension-compression-tension), where it is shown to provide novel insight into the microscopic damage accumulation that forms prior to ultimate failure, clearly highlighting the different roles that fibre-matrix debonding and matrix plasticity play in forming the macroscopic response of the composite. Such information is vital to the development of accurate continuum damage models, which often smear these effects using non-physical material parameters.