Characterisation and analysis of transverse crack-induced delamination in cross-ply composite laminates under fatigue loadings

The delamination growth represents one of the main phenomena involved in the fatigue damage evolution in composite laminates. With the aim of characterising qualitatively and quantitatively this mechanism and its interaction with the other damage modes occurring during the fatigue life, an experimental campaign was carried out on glass/epoxy infused laminates. Two lay-ups were adopted, namely [02/904]s and [0/902]s. The damage evolution was characterised at the macro and micro-scales. The adopted macro-scale damage indicators were the laminate stiffness drop, the crack density and the delamination ratio, of which the evolution along with the fatigue cycles is shown. Damage evolution and final failure were seen to be sensitive to scale effect. Micro-scale edge observations were useful to understand the interaction between transverse cracks, delamination and fibre failure, all these mechanisms concurring in the laminate final failure.