When a 3D vertical crack propagates on the interface between bi-materials, there are three route choices. To study this problem, a crack propagation model of the 3D vertical crack on material interface is established. A linear spring layer model is used to simulate the imperfect interface and calculate the shear displacement and the shear stress along the interface. Then, the distribution of the energy release rate is calculated along the edge of the crack. The influencing factors of route choices, such as the crack length, the interface parameters and the elasticity modulus, are analyzed. It is shown that the interface shear displacement increases with the increase of the crack length, which means that the interface slips easily. The larger the interface parameters, the smaller the energy release rate and the interface shear displacement will be. In other words, the crack propagation through and along the interface might be greatly hampered if the interface parameters increase. When the crack is in the harder material, it might penetrate the interface and goes into the softer material easily.

3D vertical crack  /  virtual crack closure technique  /  linear spring model  /  interface shear displacement  /  energy release rate