Boundary element analysis of cracked film–substrate media

This study evaluates the stress behavior of a cracked ®lm±substrate medium by applying the multi-region boundary element method. Four problems addressed herein are the crack tip within a ®lm, the crack tip terminating at the interface, interface debonding, and the crack penetrating into the substrate. The multi-region boundary element method is initially developed and, then, the stress intensity factors or the energy release rates are evaluated according to the di€erent stress singularities of the four considered problems. These results indicate that the stress intensity factors or the energy release rates of the four problems rely not only on the di€erent elastic mismatches and crack lengths, but also on the thickness ratio of the ®lm and the substrate