Investigation of the stress intensity factors for interface corners

From the viewpoint of linear elastic fracture mechanics, the stress intensity factor is an important parameter denoting the magnitude of stress singularity. If the singular order is a single real value, no ambiguity or inconsistency occurs about the definitions of the stress intensity factors such as the singular order 0.5 for a crack in homogeneous materials. Since the singular order of general interface corners may be real or complex, distinct or repeated, the definitions proposed in the literature may not be consistent with each other. Due to the inconsistency of the definitions and units, a direct comparison of the magnitude of the stress intensity factors for different interface corners is meaningless. Thus, the fracture toughness or fracture criterion established for a certain interface corners (e.g. a crack specimen) cannot be applied directly to the other interface corners. In order to build a direct connection among all general interface corners (including cracks and interface cracks), some unified definitions of stress intensity factors were proposed in the literature. Based upon the analytical near tip solutions of singular stresses, a new unified definition valid for almost all possible interface corners is proposed in this paper. To calculate this newly defined stress intensity factor accurately and efficiently, the path-independent H-integral is used and a relation between the H-integral and the stress intensity factors is also derived. The comparison and discussion between the present definition and those proposed in the literature are then presented through some analytical relations and numerical examples.