A fatigue life prediction method for resistance spot welds based on average stress intensity factor

The traditional fatigue simulation analysis methods of spot weld joints are mainly LBF method based on force and LMS method based on stress. As the prediction accuracy is not high, modeling and computational efficiency is low and other issues for these two methods, a new fatigue life prediction method for spot welds is proposed, which considers the fatigue failure of spot welds from the point of fracture mechanics. A modular spot weld model is adopted, the node force and moment around the spot weld is extracted through the finite element analysis, then the average stress intensity factor through the crack propagation path is calculated as the evaluation parameters of fatigue life. Shear fatigue test is conducted for two high-strength steel-HSLA340GI and DP600GI, four different thickness resistance spot welding joints, then double logarithmic regression analysis is conducted for the average stress intensity factor and the fatigue life data of spot weld joints, then a curve between the average stress intensity factor and the fatigue life is obtained as the fatigue life prediction curve for spot welds, then comparative analysis of prediction accuracy is conducted among these three method, the results show that the prediction accuracy of fatigue life forecasting method of spot welds in this paper is higher than traditional LBF and LMS methods. ©, 2015, Journal of Mechanical Engineering. All right reserved.