Methodologies for Linking Nucleation and Propagation Approaches for Predicting Life Under Fretting Fatigue

Abstract

During the past 25 years, models for predicting either the nucleation or propagation of fretting fatigue cracks have been developed and verified to a limited extent. Current nucleation models can predict the location of the crack nucleus by correlating the level of fatigue damage with the local state of stress. Fracture mechanics methods are used to predict fretting fatigue crack growth by assuming an initial crack length and orientation. This paper describes multiaxial fatigue criteria based on critical plane approaches that can potentially bridge current nucleation and fracture mechanics methods. Conventional and critical plane models are compared in light of some recent experiments on PH 13-8 Mo stainless steel. A critical plane damage model can predict the orientation and growth direction of crack nuclei. The link between critical plane and fracture mechanics approaches for predicting the early stages of crack propagation is discussed.