Mixed-mode ply cracking in multidirectional continuous fiber composite laminates

In this contribution the transverse cracking in general multidirectional composite laminates other than the cross-ply lay-ups is studied under a combined in-plane extension and shear loading. The formation of a new full-width ply crack is modeled by analyzing such a problem that the through-thickness-crack in the considered lamina initiating from the laminate edge propagates into the interior of the laminate, quickly reaching a steady state. In particular, included in the study is the evaluation of the energy release rate (ERR) that is considered as a driving force for the ply cracking. The total ERR and the mode-I and mode-II components are computed by utilizing the solutions for the ply stresses and displacements. The effect of the lay-up parameters on the ERR is examined, suggesting that the closest neighbor layer imposes a primary constraint on the lamina to prevent it from cracking, whereas the constraining influence of remote plies could be ignored.