A coupled mixed-mode delamination model for laminated composites

Cohesive elements have now become commonplace in many commercial finite element codes. Their use in impact and crash and other complex composite design problems requires the development of more advanced cohesive element formulations capable of predicting mixed-mode behavior during a complex loading. A cohesive zone model is developed for the simulation of delaminations in laminated composites under mixed-mode loadings, based on a coupling between the normal and tangential components of the relative displacement across an interlaminar interface. Featuring a unique characterization of degraded states, this coupling enables a simultaneous loss of loading capacity of the interface in normal and tangential directions, once the criteria on delamination growth are satisfied. Moreover, the variation of mode participation during the delamination process is effectively considered. A comparison between numerical simulations and experimental data on typical delamination tests shows the robustness and the potential of the model.