Finite element investigations on the microstructure of fibre-reinforced composites

The effect of residual stress due to the curing process on damage evolution in unidirectional (UD) fibre-reinforced polymer-matrix composites under longitudinal and transverse loading has been investigated using a three-dimensional micromechanical representative volume element (RVE) model with a hexagonal packing geometry and the finite element method. Residual stress has been determined by considering two contributions: volume shrinkage of matrix resin from the crosslink polymerization during isothermal curing and thermal contraction of both resin and fibre as a result of cooling from the curing temperature to room temperature. To examine the effect of residual stress on failure, a study based on different failure criteria and a stiffness degradation technique has been used for damage analysis of the RVE subjected to mechanical loading after curing for a range of fibre volume fractions. Predicted damage initiation and evolution are clearly influenced by the presence of residual stress