A spot weld element formulation and implementation for mesh-insensitive fatigue evaluation of lightweight structures

Abstract

With the rising importance of virtual engineering in an increasingly competitive marketplace, there is a growing need for simplified representations of finite element (FE) modeling for spot joints in lightweight structures without losing accuracy in structural life evaluation. For this purpose, this paper presents a spot weld element with an implicit weld representation and its numerical implementation as a user element for deployment in commercial FE code for reliably computing traction structural stress in a mesh-insensitive manner. The spot weld element is formulated by degenerating conventional first-order four-nodes shell elements by imposing kinematic constraints with respect to a series of virtual nodes placed in the region around a spot weld. The simplicity and effectiveness of the spot weld element have been validated by comparing with the explicit weld representation for computing mesh-insensitive structural stresses and fatigue life correlation of welded components.