Multiaxial fatigue life prediction using an improved Smith‐Watson‐Topper model

• Published in: Fatigue & fracture of engineering materials & structures Vol. 47; no. 6; pp. 1944 - 1961
• Main Authors: Li, Jing, Shao, Feng‐shan, He, Zheng‐wei, Ma, Juan, Qiu, Yuan‐ying, Beer, Michael
• Format: Journal Article
• Language: English
• Published: Oxford Wiley Subscription Services, Inc 01.06.2024
• Subjects: Damage; Data points; Fatigue failure; Fatigue life; fatigue life prediction; Life prediction; multiaxial cyclic loading; Strain; strain energy density; SWT model; Walker exponent
• ISSN: 8756-758X; 1460-2695
• DOI: 10.1111/ffe.14285

In this paper, the SWT model was improved by incorporating the Walker equation into the strain–life curve. The established model takes into account the material's sensitivity to mean stress by introducing the Walker exponent, w. Under uniaxial loading condition, the proposed model can reduce to the SWT model, Manson‐Coffin equation, and Walker model for w values of 0.5, 1, and 0, respectively. Under multiaxial symmetric loading, when w = 0.5, the proposed model can be simplified as another SWT correction model (CXH) proposed by Chen et al. The prediction accuracy of the established model was validated using about 200 data points collected from literature. These data points were obtained from tests conducted on eight different kinds of metals under various multiaxial loading paths. The verification results indicate that 96.8% and 97.9% of the data points fall within the factor‐of‐three boundary for the loading paths without and with mean stresses, respectively. Highlights Shear terms have significant influence on fatigue damage under non‐proportional loading. An improved SWT model is proposed by incorporating Walker equation into strain–life curve. Procedures for determining the critical plane and damage parameters were presented. Good predictions are obtained for loadings with/without mean stress.