Beam-type versus Solid-type Spot Weld in LS-DYNA

Spot welds are part of automobile body structure. The tearing of spot welds has a direct impact on the structural stiffness. To simulate spot welds in a vehicle finite element model, two different element types are mostly used in LS-DYNA: beam and solid spot weld. Though much research has been done on the beam-type spot weld, it is not clear how sensitive the solid-type spot weld element is to the element location and the shell element formulation. Also, it remains to be seen how added spot welds may mitigate the sensitivity. This paper presents some findings through the lap-shear component study and vehicle level simulations. It is found that the performance of both types is subject to the location and the shell element formulation. If the tearing of spot welds is considered, the better choice is to use the fully integrated formulation for structural shells and the solid element to represent the spot weld.