A study of interface fracture criteria by using a cohesive force model

The aim of this paper is to investigate the mixed mode fracture criteria of an interface crack based on a cohesive interface model proposed by Ma and Kishimoto (1996). The stress intensity factors of an interface crack are influenced by the definition of the characteristic length. By the numerical analysis under the small scale yielding condition, the characteristic length has been related to the crack tip radius. In this study, the mixed mode fracture tests for the various types of adherent specimens were carried out. The mixed mode dependence of the fracture toughness and the fracture boundary curves based on the stress intensity factors were discussed. The material parameters of the Ma-Kishimoto model were decided from the experimental results. This constitutive relation was embedded at the crack tip of the interface and the propagation of the interface crack was simulated by the Finite Element Method. The interface fracture toughness and the interface stress intensity factors obtained by the numerical calculation were in good agreement with the experimental results.