A computational and experimental study in resistance spot welding of thin-gauge and highly conductive dissimilar sheets for battery tab interconnects

We present a combined computational and experimental study of the role of electrical and thermal contact resistances in resistance spot welding of thin-gauge, dissimilar metal sheets with high electrical conductivity, relevant for battery manufacturing for electric vehicles. In this application, the electrical and thermal contact resistances play a dominant role in heat generation and temperature evolution within the work pieces. Previously reported approaching for simulating resistance spot welding have limited capability for representing dissimilar and thin-gauge metal sheets, particularly at higher temperatures when multiple physical phenomena become increasingly interdependent. The approach presented here uses resistivity measurements, combined with thermal modeling and known bulk resistance relationships, to infer the relationship between electrical contact resistance and temperature for different material interfaces. Corresponding thermal contact resistance models are then developed using the Wiedemann-Franz law combined with a scaling factor to account for nonmetallic behavior. The model is validated by comparing experimental and predicted voltage histories and final weld diameters of three- and five-layer stack-ups consisting of alternating aluminum and copper layers. We also analyze heat generation and redistribution during welding to elucidate the dominance of contact resistance over bulk resistivity in these stack-ups as it evolves during the welding process.