Research on multiaxial fatigue life of notched specimens based on Weibull distribution and Bayes estimation

Abstract

In this study, based on the nominal stress method and the influence of stress gradient on fatigue life, a fatigue life prediction method combined with the Weibull distribution is proposed. Firstly, the strain energy density is defined as the damage parameter to determine the location of the critical plane. Then, the equivalent stress function is established by extracting the equivalent stress of the specific path on the critical plane, which is used to establish the modified nominal stress method by combining with the stress gradient factor. Secondly, the Weibull distribution is combined to establish a new fatigue life prediction model of the notched specimens under different failure probabilities. The accuracy of the model is verified with three materials, then the prediction life of the proposed model is compared with that of the SWT model, the FS model and the Manson-Coffin equation. The results show that the accuracy of the proposed model is higher than the other three models. Finally, the reliability of the proposed model is evaluated by the lower confidence limit (LCL) estimation and interval estimation to explore the feasibility of this method. In addition, the P-S-N curves under different failure probabilities are established to guide actual projects.