An approach to life prediction for a nickel-base superalloy under isothermal and thermo-mechanical loading conditions

Scope of the present work is the development of a unified approach for the life prediction under isothermal and thermo-mechanical loading conditions. The basis for the life prediction is the stress–strain response of the material for one selected cycle obtained in the context of a Finite Element Analysis. Here the application of an appropriate inelastic constitutive model is essential. A phenomenological fatigue model is proposed which is able to describe mean-stress effects, as well as dependencies on hold time and cycle duration with reasonable accuracy. The model performance is compared with that of a mechanism based literature model. The model accuracy is evaluated on a statistical basis through an evaluation of the variance in the ratio between predicted life and actual life.