Continuum Damage Model of Creep-Fatigue Interaction in Ni-Base Superalloy

A methodology for evaluating and predicting component lives in creep-fatigue interaction region was investigated for Waspaloy. A unified viscoplasticity constitutive equation including multi-back stresses was used to describe cyclic material behaviors. Also, a continuum damage model coupling with the creep-fatigue damage rules was established based on the analysis of creep and low cycle fatigue behavior. Multi-axial fatigue and creep equivalent stress concepts were employed to predict three dimensional component lives. Notched cyclic tests under various stress conditions in the creep-fatigue interaction region were carried out to validate the life prediction methodology with FEM simulation based on the continuum damage model. The comparison of experimental data and prediction results indicates that the continuum damage model is a powerful approach for the prediction of component lives.