Growing crack along elastic/creeping bi-material interface

The stress field near the tip of a plane strain crack, growing quasi-statically along an elastic/elastic power law creeping bi-material interface, is studied. Both the elastic and creeping materials are incompressible. It is found that when n≥3, where n is the power law creeping exponent, the leading order term of the stress field has a separable form, and the amplitude of the field is determined by current crack tip velocity and material parameters. Furthermore, the solution exhibits only two modes, one of which is close to pure mode I and the other one is close to pure mode II. They approach pure modes I and II as the value of n approaches 3. Thus, arbitrary mode mixity cannot be prescribed, and the near tip field is independent of the far field loading conditions. When n<3, the near tip field is similar to that of a crack along the interface of two linear elastic materials.