Coupled Weld-Rupture Analysis of Automotive Assemblies: A Study to Demonstrate the Impact of Welding Processes on the Performance of Weldments 2020-01-1076

Welding processes are complex in nature. They affect the mechanical properties of a weldment in and around the welding joint (in the heat affected zone: HAZ), causing deformation and inducing high level of residual stress and plastic strain which are detrimental to the weldment performance. After welding some materials soften while others harden in the heat affected zone, depending on the process heat input, the thickness of the material and its chemical composition.

Traditionally, finite element (FE) performance analyses (crash, rupture, fatigue, static and dynamic tests) of weldments are performed without accounting for the effects of welding processes and as such the real performance of a weldment is not accurately predicted. On one hand, if base material properties are used to represent a weldment which hardens in the heat affected zone, the performance analysis results would be too conservative which would hinder/limit potential weight reduction strategies. On the other hand, if base material properties are used to represent a weldment which softens after welding, the performance analysis would predict a higher strength as compared to the real performance. This would lead to under-design.

Computational weld mechanics analyses (weld modeling based on finite element method) can accurately predict the changes in microstructures and mechanical properties in the heat affected zone as well as predict the deformation, residual stresses and plastic strains after welding. These quantities can be extremely valuable if efficiently used during performance analyses.

The study presented in this paper portrays an approach to perform coupled weld-rupture analysis using ESI’s SYSWELD and VPS software. The goal of the study is two-fold. First, it shows the impact of welding processes on performance of weldment made from high strength steels and Aluminum alloys and second, it demonstrates the capability to perform such complex coupled analysis in a more effective and streamline manner for dedicated applications.