A method for prediction of S-N curve of spot-welded joints based on numerical simulation

• Published in: Advances in production engineering & management 2022-06, Vol.17 (2), p.141-151
• Main Authors: Yang, L., Yang, B., Yang, G.W., Xiao, S.N., Zhu, T., Wang, F.
• Format: Article
• Language: English
• Subjects: Bending stresses; Crack propagation; Equivalence; Fatigue life; Fatigue limit; Fatigue tests; Finite element method; Least squares method; Load; Manufacturing; Mathematical models; Metal fatigue; Methods; S N diagrams; Shear stress; Simulation; Steel; Tensile strength; Welded joints
• ISSN: 1854-6250; 1855-6531
• DOI: 10.14743/apem2022.2.426

Currently, ΔF-N curves are often used to predict the fatigue lives of spot-welded joints, but the method for obtaining these ΔF-N curves is time-consuming, laborious, and non-universal. Tensile-shear fatigue tests were performed to obtain the fatigue lives and the corresponding normalized S-N curves of spot-welded joints. Subsequently, the force acting at the spot-welded joints was obtained by extracting the force and moment of the beam element in the shell-element-based finite element model, and the equivalent structural stress at the spot-welded joint was obtained based on the equiva-lent structural stress method. Finally, the S-N curves of the spot-welded joints were fitted using the least-squares method. A comparison of the S-N curves of the spot-welded joints with those of different materials revealed that the material type had a significant influence on the S-N curve. To avoid this influence, a method for predicting the S-N curve of the spot-welded joints was proposed based on the relationship between the ratio of the ten-sile strength and that of the fatigue limit of each material. This research provides guidance for predicting the fatigue life of spot-welded joints in engineering applications.