Crack initiation and evolution in glass/epoxy laminates under two-stage block loadings

In this work, the transverse crack initiation, propagation, and the crack density evolution in cross-ply laminates are analysed under two-stage block loadings. A theoretical formulation for the cracking probability under variable amplitude blocks is obtained based on the linear damage accumulation rule, often adopted in crack density prediction models from the literature. The comparison between the experimental results and the predictions for the cracking probability and the crack density evolution validate, from the phenomenological point of view, the adequacy of the linear damage accumulation rule for crack initiation under block loadings. Investigations of the damage evolution at the micro-scale are also presented, providing a mechanistic support to this approach.