A generalized fatigue damage parameter for multiaxial fatigue life prediction under proportional and non-proportional loadings

In this paper, two different forms of an original multiaxial fatigue damage parameter related to the maximum fatigue damage plane are proposed for performing fatigue life prediction under various loading conditions loadings. The proposed fatigue damage parameters have been applied to uniaxial and multiaxial loading conditions for geometrically different bodies. Both the damage parameters are correlated to sets of experimental data published in the literature to verify the prediction accuracy of the damage parameters. The damage parameter in the form of the GSA, when applied to the uniaxial loading, provides very good correlations with four sets of experimental mean stress fatigue data for Incoloy 901 super alloy, ASTM A723 steel, 7075-T561 aluminum alloy and 1045 HRC 55 steel. In the case of multiaxial loadings, both the GSE and GSA parameters are found to correlate well with fatigue data of 1045 steel and Inconel 718 tubular specimens under proportional and non-proportional loadings. In addition, the damage parameters show reasonably acceptable correlations with experimental fatigue data of SAE 1045 steel notched shafts subjected to proportional and non-proportional loadings.