Generalization of Gough and Pollard Criterion for the Finite Fatigue Life Regime in Proportional Loading Conditions

In this article, it was shown that for high cycle multiaxial fatigue life prediction, models based only on material parameters in the form of fatigue limits of component loadings should not be used. This is because stress to number of cycles to failure curves of component loadings may be highly nonparallel. The article presents a method of fatigue life prediction including out-of-parallelism of fatigue. In this method, material parameters in the form of fatigue limits were substituted with the α function based on the Basquin equations for tension-compression (or bending) and torsion. The proposal of a new model can be considered as a generalization of the Gough and Pollard criterion. Validation performed using experimental data for ten different materials allowed for fatigue life prediction for multiaxial proportional loading conditions with satisfactory accuracy.