Manufacturing Effects on the Fatigue Life Assessment by Finite Element Methods

Many of the vehicle components are manufactured by sheet metal forming process together with joining methods like the spot or seam weld, which will cause work hardening and thermal deformations in the products. As result, undesirable residual stresses, uneven thickness distribution and weld notches can be generated in the final product. Since the fatigue life of an automotive component depends on the manufacturing effects, much care should be given on the estimation of the process effects. In this study, fatigue life of a vehicle suspension component is estimated with finite element methods with considering the stamping and welding process effects. Residual stress distribution due to work hardening and thermal deformation is obtained, and used in determining the fatigue life as the mean stress effect. The simulation result is compared with test result and it shows the fatigue life is affected much more by welding rather than stamping.