A generalized mean stress correction model based on distortional strain energy

A new fatigue damage model based on the distortional strain energy is presented and discussed to account for the mean stress effects on fatigue life. The proposed model is compared to the Morrow and the SWT mean stress correction models using experimental mean stress fatigue data for Incoloy 901 superalloy, 120-90-02 ductile cast iron and 7075-T651 aluminum alloy under tensile and compressive mean stress loadings. The proposed model and the SWT model are found to show similar fatigue predictions and show good agreement for positive mean stress data and moderate negative mean stress data. The proposed model shows reasonably good agreement while the SWT model is unable to correlate mean stress data under large compressive mean stress conditions. The Morrow model provides poor correlations for all fatigue data analyzed by yielding conservative results for compressive mean stresses and non-conservative results for tensile mean stresses.