Analysis of residual stress distribution along interface asperity of thermal barrier coating system on macro curved surface

Based on the study of the radial residual stress distribution on the macro curved interfaces of thermal barrier coating system (TBCs) for the hollow curved substrate structures, the hollow four-concentric-circle model was developed. And the concentric-circle model with a fine scaled sinusoidal interface was proposed to describe the stresses distribution on the rough interface of TBCs with macro curved geometry. The influences of the geometric and thermophysical parameters were discussed by the developed model. The results showed that the radial stress on the rough interface can be separated into two sections: the overall level stress from macro surface curvature and the local stress from local asperity of the interface. The overall level stress was determined by the thicknesses and the thermophysical parameters of each layer. It has been found that the ratio of local stress and overall level stress was influenced by the interface asperity, the ratio of elastic modulus and the ratio of thermal expansion coefficients of the layers beside the rough interface. Furthermore, the convex macro curvature of the substrate can induce tensile stress onto the interface. Especially at the sharp corners of the substrate, the small curvature radius can cause high stress which should be taken more care about the occurrence of spalling cracking at interface