A cohesive zone model for thermomechanical fatigue

In this study, a temperature dependent elastic-viscoplastic cohesive zone model is developed to predict the thermomechanical fatigue (TMF) behaviour of superalloys. The theory is based on rheological models enhanced with fatigue and creep damage variables which are micro-mechanically motivated. This cohesive law can capture monotonous, cyclic, thermomechanical, and rate dependent loads. The material model is used to simulate the deformation behaviour and to determine the lifetime for isothermal, in-phase- (IP) and out-of-phase- (OP) TMF loading. The capability of the model to capture phase difference between mechanical and thermal loading is demonstrated, and the effects are analysed.