ON FRACTURE CRITERIA FOR BI-MATERIAL CORNERS

Abstract

The prediction of crack nucleation near interface end in bi-material corners with definite wedge angles is fairly established. It takes Irwin-like form involving the stress intensity factor. Such a criterion requires the stress intensity factor of bi-material corners with same dimension, but the dimension of stress intensity factor of bi-material corner depends on wedge angles. The paper aims at the dimension problem. Particular attentions are paid to both the rigorous and asymptotic solutions of bi-material corners, because the asymptotic solution describes the stress singularity with stress intensity factor, and the rigorous solution describes the stress singularity with stress components. Studies on solutions of edge-bonded quarter and quarter planes and edge-bonded half and quarter planes lead to the following results. A unique point is found which divides the interfacial shear stress curve into an asymptotic part and a basic part. This point is called the transition point. Then, a relation between the stress intensity factor in the asymptotic part and the interfacial shear stress at the transition point is derived. This relation enables a fracture criterion of Irwin-like form for edge-bonded quarter and quarter planes and edge-bonded half and quarter planes to be formulated. To formulate a unified fracture criterion for arbitrary bi-material corners, further works are needed.