A stress gradient-based fatigue life prediction method for multiaxial notched specimen considering additional hardening effect

In this paper, the damage parameter considering stress field distribution near the notch root is employed to overcome the deficiency of the equivalent stress method (ESM) ignoring the influence of stress gradient, and a new multiaxial fatigue life prediction method is then developed taking into account stress gradient effects and additional hardening effects. Firstly, the equivalent stress distribution on the critical plane is analyzed using the finite element method (FEM), and the equivalent stress field intensity of fatigue damage affected area is defined as the multiaxial fatigue damage parameter to estimate the fatigue life of notched specimens. Secondly, a new non-proportional additional hardening coefficient is defined to consider the influence of phase difference and material characteristics on multiaxial fatigue life. Finally, in order to verify the reliability of the proposed model, the estimated lives using the proposed method and the equivalent stress method are compared with the test life, and the comparison results show that the accuracy of the proposed method considering stress gradient effect and additional hardening effect is higher than that of the equivalent stress method under proportional and non-proportional loading.