Interaction Diagram for Time Dependent Fatigue

Abstract

Interaction of fatigue with corrosion and creep has been analyzed through a parameter [Fi ] introduced at the crack propagation stage. Assuming the effect of corrosion and creep to become dominant below a certain frequency, a model is proposed which is able to explain the stress-hold and the strain-hold effects on the fatigue life in time dependent fatigue. Beyond a certain period stress-hold leads to time-dependent and strain-hold leads to cycle-dependent interaction life. By suitably evaluating the parameter [Fi ], life under any type of loading condition can be estimated. Based on the parameter, an interaction diagram is proposed for predicting the fatigue life in time dependent high temperature low cycle fatigue.