A CRACK VERY CLOSE TO A BIMATERIAL INTERFACE

This paper presents the plane elastostatics analysis of a semi-infinit e crack perpendicular to a perfectly bonded bimaterial interface. Both cases of the crack approaching the interface and penetrating the inte rface are addressed. The distance from the tip of the crack to the int erface is delta. A singular integral equation approach is used to calc ulate the stress intensity factor, K-1, and the crack-opening displace ment at the interface, eta, as functions of delta, the Dundurs paramet ers alpha and beta, and the stress intensity factor K-1 associated wit h the same crack terminating at the interface (the case delta = 0). Th e results are presented as K-1 = K-1 delta(1/2-lambda)f(alpha, beta) a nd eta = Ck(1) delta(1-lambda)<(eta)over tilde> (alpha, beta) where la mbda is the strength of the stress singularity associated with delta = 0, f and <(eta)over tilde> are functions calculated numerically and C is a material constant. These results can be used to determine the st ress intensity factor and crack opening displacement of cracks of fini te length 2a with one tip at a distance delta from the interface for d elta/a much less than 1. The selected results presented for a crack lo aded by a uniform far-field tension in each half-plane show that the s tress intensity factors approach their limits at a relatively slow rat e.