The influence of plastic deformation on interface fracture behavior

The purpose of this paper is to investigate the influence of plastic deformation on the mixed mode fracture toughness of an interface crack. Based on the internal variable theory of thermodynamics, a continuum interface constitutive relation between interface traction and interface separation has been developed. To simulate the crack propagation of the interface crack, this cohesive force model is applied to FEM analyses of the interface crack between two elastic-plastic materials. The results show that plastic deformation affects the interface separation ahead of the interface crack tip. This effect yields the enhancement of the mixed mode fracture toughness. Therefore, in bimaterial systems, the fracture toughness varies with the mixed mode condition at the crack tip. The tendency of the fracture toughness curve is roughly consistent with the experimentally measured mixed mode fracture toughness.