Investigating Spot Weld Fatigue Failure with Experimental and Finite Element Analysis Methods

Abstract

Resistance spot welding (RSW) is the most commonly used method for joining sheet metals structures in the automotive industry. The cyclic loading conditions on RSW joints can lead to fatigue failure, hence, affecting their reliability and durability. The comprehension of the fatigue strength for the RSW is very critical, especially for the dissimilar RSW joints. This study presents analyses to characterize the fatigue behavior of these joints. Therefore, the crack propagation, and fatigue life under specific loading conditions have been studied. The fatigue strength of similar aluminum Al-1050, and dissimilar copper with aluminum Cu-Al RSW joints was examined experimentally and numerically. The lap-sheet materials were spot welded using optimum welding parameters to ensure a consistent range for the produced weld nugget. In this work, the experimental test rig has been designed and established to have an axial fatigue load. The high cycle fatigue tests were performed, and the P-N curves were obtained. The work was analyzed numerically using finite element (FE) analysis, in conjunction with experimental results. Aluminum sheet joint has the highest fatigue limit as compared to dissimilar Cu-Al joints. The crack growth rate of the similar RSW joint is slower than those of dissimilar joints because it has higher stress intensity factor (SIF). The coefficients of the Paris' constants, C and m, have been determined.