Mixed Mode Fracture Criteria of Interface Crack between Dissimilar Materials

This paper presents an application of fracture mechanics to the evaluation of strength of an interface crack between dissimilar materials. Special emphasis is given to mixed mode fracture criteria. The stress intensity factor is one of the basic fracture mechanics parameters, but there exist few applications of the stress intensity factor to fracture criteria of an interface crack. In this study, a concept of the stress intensity factor for an interface crack is discussed in detail, and various types of specimens are tested experimentally for investigating the mixed mode fracture toughness of an interface crack. The specimens are acrylic resin-epoxy resin and aluminum-epoxy resin joints. The mixed mode stress intensity factors for various specimens are analyzed by using BEM and MI-integral method, an extended version of the J-integral. Two types of the mixed mode fracture criteria of an interface crack are derived. One is characterized by the total energy release rate G for acrylic resih-epoxy resin joints, and the other is characterized by the stress intensity factors KI and KII for aluminum-epoxy resin joints.