Development of a non-local approach for life prediction of notched specimen considering stress/strain gradient and elastic-plastic fatigue damage

In this study, a non-local approach is developed for the fatigue life prediction of notched specimens, considering stress/strain gradient and elastic-plastic fatigue damage. The damage coupled constitutive models are presented to model the mechanical behavior of material. The critical plane method and triaxiality factor are employed to determine the location of the couple point. The gradient values of mechanical quantities are then computed, and the modified coefficients in damage models are acquired. The numerical simulations are implemented to compute the damage evolution process and predict fatigue life. Meanwhile, the coupling effects between stress field and damage field are considered. The predicted results are verified by experimental data, and also compared with the local method. Finally, the influence of stress concentration factor, shape of notch, and cyclic variation of stress/strain gradient are further investigated.