The integral approach of Cook and Erdogan was used to obtain the asymptotic behaviour of a crack close to a bimaterial interface. It was found that, in addition to the square-root singularity which dominates the stresses in the vicinity of a conventional crack, there are two additional contributions to stress which should not be neglected. One contribution is due to an "image singularity" and the second is due to an O(1) term which can become very large for smaU tip to interface distances. It is shown how these features of the stress distribution can be used to advantage in the numerical calculation of stress intensity factors.
NOMENCLATURE
half crack length stress intensity factor ratio of shear moduh of the two materials dimensionless distance dimensionless distance of the near interface crack tip from the interface small dimensionless distance measured from the crack tip elastic constant, K = 3 -4v for plane strain, K = e for plane stress shear modulus Poisson ratio cleavage stress along the crack axis ~~k~o~~~~ge~~~~-The authors gratefully aGkoawl~ge the financial support for this work provided by Esso Resources of Canada Ltd. and the Natural Sciences and ~~~~~ Research Couocil of Canada.