Structural adhesives are used for the purpose of weight saving and rigidity improvement in recent automotive development. In this study, fracture behaviors of a cohesive zone under mixed-mode conditions were focused on, and an evaluation method for the parameters of J-integral using the crack tip opening displacement was proposed. The method is an application of the Dugdale model which is known as an idea to deal with localized plasticity region of a crack tip for adhesive joints. Validity of the method was verified using finite element analysis. Furthermore, the method was applied for adhesive joint on galvannealed steel and its fracture mechanism was investigated.
