Failure behavior and crash modelling of resistance rivet spot welding (RRSW) for joining Al and steel in vehicle structure

Abstract

Resistance Rivet Spot Welding (RRSW) is a joining technique with high flexibility and cost efficiency for connecting steel and aluminum sheet metal parts in an automotive body in white (BIW). Using this method, both pure steel and steel–aluminum mixed BIW can be produced in the same assembly line. The prediction of the load-bearing capacity and failure behavior in crashworthiness calculation by the OEMs requires a stable finite element (FE) simulation model for both static and dynamic load cases. In this paper, an experimental and numerical study on the behavior of RRSW connections is presented. After the analysis of different material models with varying FE codes, the material model MAT 100DA of LS-DYNA was chosen as the starting point for crash simulation. For the determination of the model parameters as well as the entire FE model, material tests with different strain rates and KS-II-tests with three different velocities were performed. The FEM parameters were determined via iterative parameter calibration. Lap shear, peeling, and component tests were conducted for parameter validation along with the FE calculations. In the experiment, the loading rate-dependent behavior of the RRSW joining was observed in terms of force-displacement curves and the failure phenomenon. The simulation’s results show that the performance of vehicle components joined by RRSW are predicable by using the material model MAT_100DA. The prediction of failure behavior can be further improved by using a detailed meso-scale model.

Keywords:

• Resistance spot welding
• KS-II sample
• crash simulation
• failure behavior

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work has been funded by the German Federal Ministry of Economics and Technology (BMWi) under Grant [ZF4162307PO7] and supervised by the German Federation of Industrial Research Associations (AiF). The authors thank them for their financial support.