Assessment of the Existing Models to Estimate the Fatigue Life under Both Multiaxial in Phase and 90° Out of Phase Loading Conditions

The objective of this paper is to evaluate the validity of commonly used multiaxial fatigue criteria for different multiaxial loading conditions. The best criterion is identified through comparative analysis. The assessment is based on the experimental research findings of the SAE notched shaft, which is used as a benchmark. The relative performance of the three existing multiaxial fatigue theories based on the strain criteria and the critical plane approaches are investigated. There is no fixed strain life criterion that can predict the fatigue life best for different loading cases. Among all the critical plane models considered, Fatemi and Socie model gives best fatigue life prediction for both multiaxial in phase and 90° out of phase loading cases.