Multiple crack initiation in cross-ply laminates under spectrum loadings

Abstract

The present work investigates the damage evolution in glass/epoxy cross-ply laminates under variable amplitude spectrum loadings. The attention is focussed on the effect of variable amplitude loadings on the life to the initiation of transverse cracks and the crack density evolution. Cross-ply specimens were manufactured through the infusion process using unidirectional glass fibres and an epoxy matrix to obtain a semi-transparent material, where transverse cracks could be detected using a back-illumination system. During the fatigue tests the damage was monitored by taking periodical front images using a full-frame camera. These were then processed to obtain the number of cracks and their length throughout the test