THE INFLUENCE OF ELASTIC MISMATCH ON THE SIZE OF THE PLASTIC ZONE OF A CRACK TERMINATING AT A BRITTLE-DUCTILE INTERFACE

This paper presents the results of an investigation of the effects of elastic mismatch on the size of the plastic zone at the tip of cracks terminating at a bimaterial interface. Using the Williams technique, a n asymptotic solution is obtained for the magnitude of the crack tip s tress singularity lambda and for the stress field associated with a se mi-infinite crack impinging on an interface. This solution, together w ith the Von Mises yield criterion, is used to estimate the location of the plastic zone boundary ro for various levels of the elastic mismat ch, which are expressed in terms of the Dundurs constants. Results are expressed in terms of the non-dimensional quantity r0[1/square-root 2 pi k(I)/sigma0]-1/lambda, where k(I) is the stress intensity factor an d sigma0 is the yield stress. These results, together with an integral equation solution for k(I), are used to calculate the size of the pla stic zone of a crack of length 2a loaded by uniform pressure. It is sh own that the location of the boundary of the plastic zone depends stro ngly on the elastic mismatch.