Mesh Sensitivity Analysis of Weld Spot Fatigue Damage Calculation Based on ACM Modeling

Fatigue crack in a vehicle generally initiates on the weld spot position. It is important to ensure that the fatigue damage of weld spot can be accurately estimated by CAE in the early stage of vehicle design. In this paper, the mesh effect on weld spot fatigue damage calculation was analyzed systematically. Area Contact Model (ACM) was used to build the weld spot model. For mesh sensitivity analysis, three factors were considered, including loading type, mesh size and spacing distance. The results show that under pure shearing loads, the fatigue damage of weld spot is not sensitive to the mesh size, but increases with the spacing distance. While under tensile peel loading, fatigue damage increases with mesh size, but decreases with the spacing distance increasing. In the last part, we analyzed the effect of mesh minimization on the calculation of spot weld fatigue damage in some components of a vehicle. The mesh sensitivity were then evaluated by comparing the fatigue damage of 229 welds spot under three element sizes. It can be concluded that a coarse element size can be used in a vehicle fatigue analysis. For most concerned elements, a mesh refining is needed, when one should consider the spacing size and loading type.