Effect of elastic mismatch in intersonic crack propagation along a bimaterial interface

Recent experiments showed that the speed of a crack tip propagating along a bimaterial interface can exceed the shear wave speed of the more compliant constituent in the bimaterial. This experimental observation has motivated analytical and numerical investigation on fast crack growth. Among these investigations, Huang et al. obtained a simple, analytic full-field solution for an elastic/rigid bimaterial with crack-face contact. Although this solution compares quite favorably with all available experimental data, it is not clear which bimaterial can be approximated by the elastic/rigid model. In this paper, we use the method of analytical continuation to obtain the asymptotic stress fields near the crack tip and near the trailing end of the contact zone. It is established that the elastic/rigid model is an excellent approximation to all bimaterials that have been used in fast crack growth experiments. Therefore, the simple, analytic solution of elastic/rigid model provides a useful means for analyzing experimental fringe patterns and data. It is shown that, as the elastic mismatch decreases, the elastic/rigid model may become invalid.