The Interface Crack in a Tension Field

Abstract

The correct formulation of the interface crack must incorporate contact between the crack faces, because the tips of an interface crack are closed for all applied loads. A numerical solution of the resulting integral equation for an interface crack in a tension field was considered by Comninou several years ago. The present paper shows how to solve the integral equation exactly. The solution is found in the form of a slowly convergent series involving elliptic functions and it is demonstrated how to convert the results into a rapidly convergent series. Specifically, we give simple formulae valid over the entire range of the physical parameters for (1) the length of the contact zones, (2) the Mode II stress intensity factor, and (3) the finite but very large normal stress at the tip of the interface crack.