Coupled Weld-Rupture Analysis of Automotive Assemblies

Lightweight driven design in the automotive industry and the push for Electric Vehicles mandate the use of innovative materials such as Steel (HSS, UHSS, AHSS) and Aluminum alloys. For steel suppliers to meet the strength requirements of high strength steels, they often alloy the steel chemistry (depending on mill capability, rolling capacity, quenching capacity, etc.). When used in welded assembly constructions, these steels, as compared to traditional steels, behave differently. Depending on the welding heat input, the material chemistry and thickness, they either harden or soften in the heat affected zone. Similar behavior is observed with the most commonly used aluminum alloys (5000 and 6000 series) in the automotive sector. For both alloy types, different strengthening mechanism are used to meet their initial strength requirements (by work hardening and by heat treating respectively) but they both undergo softening in the heat affected zone during welding. Regardless of the alloys, the material in the heat affected zone is affected and so is the performance of the weldment during service. FE analyzes of Welding and Performance have traditionally been performed independent of each other. Welding effects (i.e.: change of microstructure and mechanical properties in the heat affected zone and fusion zone) are not typically considered during performance analysis. Given the fact that welding processes affect the mechanical properties in the heat affected zone, using base material properties to represent the HAZ will result in erroneous performance prediction. The present investigation demonstrates the impact of welding processes on the performance of weldments. The goals of this study are to demonstrate the impact of welding processes on the performance of weldments and the use of computational software for coupled weld-rupture analyses pertinent to a specific battery application.