Size effect of failure modes in composite laminates under compression

The size effect of interfacial failure and buckling in composite laminates under uniaxial compression are investigated in this work. It is found that interfacial failure by excessive separation (normal mode) dominates for short composite laminates; as the length/thickness of a composite laminate increases, shear failure in the interface dominates, accompanied by buckling of the laminate. When the interface of a composite laminate fails, corresponding critical load to trigger buckling decreases. The size effect of failure modes in composite laminates is divided into six regions governed by the length to thickness ratio of composite laminates. The critical length to thickness ratios of each region are estimated using both theoretical analysis and finite element simulation. At the end, a failure mode map based on stress and length/thickness ratio relation is constructed.