A finite element model for the prediction of Advanced High Strength Steel spot welds fracture

A finite element model has been developed for the simulation of resistance spot welds behavior in Cross Tension. The model is able to capture the competition between semi-brittle fracture at the faying surface and ductile failure at the weld boundary. For this purpose, ductile damage and fracture are considered in the different weld zones in addition to a cohesive zone at the faying surface and an evaluation of the Rice integral (J) at the notch tip. The model is run for different weld configurations made of TRIP780 steel. It reproduces the proper level of load at the onset of cracking and predicts the governing damage mechanism leading to final fracture as a function of the geometrical features of the welds.

► Ductile failure model for button pullout fracture. ► Rice integral (J) for the onset of crack propagation at the faying surface. ► Cohesive zone for crack onset and propagation at the faying surface. ► Competition between these failure mechanisms to predict spot weld strength and failure type.