A micromechanical study on the effect of intra-ply properties on transverse shear fracture in fibre reinforced composites

A micromechanics damage model is presented which examines the influence of intra-ply properties on the transverse shear deformation of a carbon fibre/epoxy composite. It was found that while thermal residual stress influenced the initial location of damage in the microstructure, its influence on the overall shear response was less pronounced. The fibre–matrix interface strength was found to control transverse shear strength, while the interface fracture energy had marked effect on the strain to failure and the interaction of damage mechanisms during fracture. It was also found that regions of low fibre volume fraction, such as areas near the ply boundary, were more susceptible to yielding due to the lack of reinforcement in these regions. The micromechanical model developed shows similar behaviour to in situ experimental observations and could thus prove useful in determining optimum constituent properties allowing for increased interlaminar shear strength of fibre reinforced composite laminates.