Empirical Formula for Stress Intensity Factor of Crack Initiated from an Interface Edge

Bi-material has been widely used in engineering. Due to the edge singularity, failure usually occurs from interface edge. For the evaluation of such failures, fracture mechanics approach is considered useful to avoid the edge singularity, by introducing an edge crack with various directions. However, this evaluation method is inconvenient for engineering application due to its complicity. In this paper, based on a huge amount of numerical analysis, an empirical formula of stress intensity factors (SIFs) for cracks initiated from the interface edge with various directions and crack length has been proposed. Since the cracks initiated from the interface edge is induced and dominated by the edge singular stress field, which can be characterized by the singular order and the corresponding stress intensity coefficient (SIC), this empirical formula relates their SIFs with the SIC and singular order of the edge singular stress field. With this empirical formula, it is possible to evaluate the fracture occurring from the interface edge by fracture mechanics approach, only with the numerical analysis of non-cracked bonded dissimilar materials.