Fatigue life prediction of notched components based on energy gradient using reconstructed critical distance theory

In this paper, a reasonable explanation is given to unify notch effect and geometric size effect into notch geometric feature effect (NGFE), and energy gradient is utilized to depict the influence of the NGFE on the critical distance. The correlation of energy gradient with critical distance and fatigue life is discussed respectively. The weight index of the high energy region is used to quantify the contribution of the high energy region to the fatigue damage. Finally, a model of the reconstructed critical distance theory considering the geometric notch characteristic effect is established. The fatigue test of Q355 (D) alloy steel notched components was carried out, and the evaluation precision of the presented method is compared with Yang’ model and Shen’ model combining with the existing fatigue test data of En8. The results indicate that prediction results of the proposed method are consistent with the test results. Highlights Based on the energy gradient to characterize notch geometric feature effect, the critical distance theory is reconstructed. The association degree of the energy gradient with fatigue life and critical distance is discussed. The high energy region weight index is defined to quantify the contribution of high energy region to fatigue damage.