Predicting transverse crack formation in cross-ply laminates

As a contribution to the exercise to compare methods of predicting damage in composites and subsequent failure, this paper describes a method of predicting the values of the applied stresses for which transverse cracks form in a cross-ply laminate subject to biaxial loading, taking full account of both anisotropy and thermal residual stresses. The analysis is based upon an accurate technique for determining the stress and displacement distributions in multiple-ply cross-ply laminates having ply cracks in one orientation. The resulting relationships governing crack formation are exceedingly simple in form involving parameters that may be defined and measured at the macroscopic laminate level, thus offering engineering methods that have great potential for use in design. The methods are then applied to the prediction of transverse cracking in a specific glass-reinforced plastic system for the case of the uniaxial loading of a [0/90](s) GRP laminate, and for the equi-biaxial loading of a [+/- 45](s) laminate. Crown Copyright (C) 1998 Published by Elsevier Science Ltd. All rights reserved.