Matrix Crack Initiation and Propagation in Laminates with Off-Axis PLIES

Abstract

Matrix cracking damage in composite laminates is a generic type of damage, common to carbon, glass and aramid fibre composites fabricated using unidirectional plies, as well as more complex fibre architectures (e.g. textile reinforced composites). For such a common type of damage, it is perhaps surprising that currently proposed failure criteria are unable to predict matrix crack development, especially for off-axis plies. Previous work on GFRP laminates by Crocker et al. [1] suggested that matrix crack propagation in off-axis plies is governed by the transverse normal stress. The overall aim of the present work is to provide validated constitutive relations for crack accumulation in off-axis plies of CFRP under mixed mode loading. In this paper, results on crack initiation and crack propagation are presented for a range of multi-layer angle-ply laminates.