A comparative study of the residual deformation of an automotive gear-case assembly due to deep-penetration high-energy welding

A three-dimensional elastic-plastic finite element model was used to investigate the relative effects of different joint forms on the welding distortion and residual stresses in an automotive differential assembly due to deep-penetration high-energy welding. Numerical studies were carried out to determine optimal selections of heat generation rate and the number of weld segments to ensure both computational efficiency and accuracy of the calculation. To model the constraints and boundary conditions realistically, contact elements were used at the mating surfaces of different structural components and the shrink fit between the gear and differential case was modeled using couple sets. Two situations representing welded gear-case assemblies where the weld joints were oriented at 0° and 30° with respect to the radial direction were analyzed. Predicted welding distortions and residual stresses are compared and discussed in detail. The results indicate that the residual tensile stresses in the 0° radial joint are larger than those in the 30° angled joint and that residual distortion is sensitive to joint form.