Affiliation:
1. College of Engineering, Applied Technology College of Soochow University, Suzhou 215000, China
2. School of Mechanical and Automotive Engineering, Shanghai University of Engineering Science, Shanghai 201600, China
Abstract
Automotive parts are usually subjected to random loads with large mean tensile/compressive stresses under working conditions. It is important for automotive parts to have a long fatigue life under mean stress in practical engineering applications. An equivalent strain model is established here to predict fatigue life considering the influence of mean strain and stress under asymmetric cycles. To predict the fatigue life more accurately, the coefficient of surface roughness and temperature correction is introduced in this model. The effectiveness of the improved equivalent strain (IES) model is verified by comparing it with multiple sets of experimental data. The IES is also compared with Smith–Watson–Topper (SWT), Manson–Coffin, and equivalent strain models. The results show that the developed model has a higher prediction accuracy than the other models. An improved fatigue strength exponent is introduced to modify the equivalent strain model, and the effectiveness of the model is verified by experimental data. The IES model demonstrates significantly reduced standard deviations under various strain ratios (−0.06, 0.06, 0.5), with measurements of 0.0936, 0.0721, and 0.0636, respectively. The method provides a certain reference for the life prediction of automotive parts.