A novel microscale fatigue failure indicator considering plastic irreversibility for microstructure-based lifetime simulation

Abstract

Lifetime predictions of metals using a crystal plasticity simulation approach and fatigue indicator parameters (FIPs) are increasingly used in recent years. In this work, the critical FIPs (FIPcrit) for three widely applied definitions are shown to be dependent on strain amplitude and material for eleven ferritic and martensitic steels under fully reversed strain, which leads to inaccurate lifetime predictions. Therefore, a modification of the critical FIP approach considering the reversibility of cyclic plastic slip is proposed. The modified approach achieves a significant increase in prediction accuracy and reduces FIPcrit variation, yielding good results even when assuming a material-independent FIPcrit average.