Notch-based probabilistic fatigue analysis of automobile transmission gear considering size effect

Abstract

Notch fatigue is regarded as a major issue of damaging the structural integrity for notched components in engineering. Based on the theory of critical distance (TCD), this study proposes a novel probabilistic fatigue analysis model to quantify the influence of notch size effect on fatigue life. Specifically, Weibull distribution is integrated into TCD for probabilistic modelling, and the impact of size effect on critical distance is characterized with highly stressed volume (HSV) method and stress concentration factor (SCF). The effectiveness and superiority of the proposed model with point method (PM) and line method (LM) are verified and compared by the experimental data of En3B, TC4 and Al-7075-T6 materials respectively. Moreover, the fatigue test of notched automobile transmission gear (ATG) is conducted, and the corresponding PSN curves are estimated with the proposed model. The test data are basically scattered in the predicted PSN curves, and the results under 50% survive probability are better than the traditional TCD, which indicates the availability of predicted PSN curves and the accuracy of the proposed model.