A life prediction model of fatigue-creep interaction with stress controlled fatigue

Based on the ductility dissipation theory and effective stress concept of continuum damage mechanics (CDM), the mean strain rate at half life is used as control parameter to propose a new model for stress controlled fatigue or fatigue-creep life prediction. The model not only considers the interaction between cyclic and static creep, but also considers the effect of mean stress. Test data have been assessed on continuous stress fatigue test data or fatigue-creep test data with hold time of three low alloy steels (16MnR steel, ASTM A-516 Gr.70 steel. 1.25Cr0.5Mo steel) at RT or high temperature. Most of the life prediction results are within a factor of +/- x 1.5. This model is suitable for stress controlled fatigue or fatigue-creep life prediction of ductile material.