Modeling of mixed-mode delamination by cohesive zone method

Cohesive zone modeling of interface delamination requires proper values of the critical energy release rate of the interfaces being under investigation. In general, these values have been obtained thru dedicated delamination experiments. In cohesive zone modeling a complication to deal with is the fact that the critical energy release rate is not just a single value. Instead, it is a function of the socalled mode-mixity, a parameter depending from the ration between shear stress and tensile stress near the crack front. Most of the standard FEM packages include one or more types of cohesive zone elements, but generally, a mode-mix dependency cannot be specified. This might hinder a proper usage of cohesive zones in FEM modeling of microelectronic components. Therefore, the suitability of various FEM packages to deal with mixed mode delamination through cohesive zone modeling should be explored. The present paper describes such an exploration using the ANSYS package. Various mixed mode delamination experiments have been modeled using an available mixed mode cohesive zone model. The results are compared to the experimental results.