Elastic–plastic analysis of a sub-interface crack in a coating-substrate composite

In the present work, elastic–plastic analysis of a crack paralleling a bonded plane interface between a coating and a semi-infinite substrate is carried out. The sub-interface crack is simulated by continuously distributed dislocations. The mixed mode Dugdale model is used to investigate the plastic zone sizes and the crack tip opening displacement. In the numerical examples, a uniform tensile load on the crack surfaces is considered, and the dependence of the plastic zone size and the crack tip opening displacement on the crack depth, the coating thickness and material properties is analyzed in detail. The numerical results show that a thinner coating will enlarge the plastic zone size and the crack tip opening displacement. And if the crack is far away from the interface, the values of the plastic zone size and the crack tip opening displacement tend to the corresponding values when the crack is embedded in a homogenous material.