Finite element modeling of deformation and fracture of advanced high strength steels dissimilar spot welds

Abstract A finite element model is built for the prediction of deformation and fracture behavior of Usibor1500/DP600 dissimilar resistance spot welds. The model relies on image-based discretization of the weld zones, metallurgical modeling of their respective yield and hardening behavior coupled to a modified ductile damage model and a cohesive zone model at the faying surface. The model allows quantitative prediction of load bearing capacity, damage location and failure type when compared to experimental tests. It was evaluated in 24 configurations of varying weld size, sheet thickness distribution and loading type (cross tension and tensile shear). These outputs give a deeper understanding of the key parameters influencing the overall behavior of the welds and the directions for improvement. The model shows strong potential for the design of optimized heterogeneous assemblies favoring button pullout failure types and allowing to reduce the weight of the body in white in the automotive industry.