The effect of spot weld failure on dynamic vehicle performance

Spot welds are the dominant joining method in the automotive assembly process. As the automated assembly process is not perfect, some spot welds may be absent when the vehicle leaves the assembly line. Furthermore, spot welds are highly susceptible to fatigue, so that a substantial number may fail during the vehicle lifetime. The scope of this article is twofold. First, the impact of spot weld quality and design on a vehicle's functional performance is reviewed, addressing strength and stiffness, NVH and durability. The overview briefly covers both experimental tests and predictive finite element (FE) modeling approaches, explains the complexity of a spot weld design problem and discusses optimization strategies. Second, an industrial robustness study is presented, that assesses the effect of spot weld failure on dynamic vehicle characteristics. Damaged models are generated automatically, by breaking a subset of the vehicle's spot welds, using a weighted-uniform selection probability. Monte Carlo simulations are then used to assess the scatter on dynamic vehicle characteristics.