Probabilistic Fatigue Life Framework of Notched Specimens Based on the Weibull Distribution Under Multiaxial Loading

In engineering applications, the notch effect and size effect significantly influence the evaluation of fatigue performance in components, necessitating special attention in life prediction. This study proposes a new probabilistic model, based on the theory of critical distance (TCD), to predict fatigue life, with the aim of quantitatively assessing the impact of notch effect and size effect. The stress distribution on the critical plane is first characterized using a sixth-order multinomial function, and the relative stress gradient function is utilized to calculate the value of the critical distance. Furthermore, the effect of the ratio of shear strain to normal strain on fatigue life under multiaxial loading is considered. Additionally, the integration of the Weibull distribution into the TCD is employed for conducting probabilistic modeling of fatigue life. Finally, fatigue experiments are conducted on notched specimens of Q355D steel, demonstrating that the life prediction results under 50% survival probability are superior to the traditional TCD method.