Effects of dislocation shielding on interface crack initiation and growth in metal/ceramic layered materials

摘要

Interface crack initiation and growth in layered materials are investigated in this paper for mixed mode I and mode II loading. The dislocation plasticity in the metal layer is considered, and the energy for initial emission of a dislocation is assumed to be attained before the cleavage of the interface crack. Superdislocation modeling is employed to obtain the critical strain energy release rate, for crack initiation and growth. When a stress separation law is satisfied at the interface crack tip, interface debonding occurs and the crack propagates with an atomically sharp tip until interactions with other slip sources cause arresting by a new blunting event. This process repeats itself periodically, and based on this process, interface crack growth is simulated until a steady-state condition is reached. This model predicts the strong dependence of interfacial fracture toughness on mixed mode loading. The role of the metal layer thickness and interfacial strength is also investigated.