Probing the influence of weld nugget pitch distance on resistance spot-welds of aluminum alloys: A combined experimental and FEM analysis

The effect of varying inter- weld nugget pitch distance in a resistance spot welded joint of AL-6082-T651 was investigated both experimentally and computationally. The joint was fabricated at a pitch distances of 10, 20, 40, and 55 mm at different weld parameters. It was found that at lower pitch distances (∼10, 20 mm), the shunting of electric current was dominant. However, at pitch distances of 40 mm and 55 mm, the resulting uniform weld nuggets suggest a minimal influence of weld current shunting. It was also explored that for similarly sized weld nuggets, joints formed at lower pitch distances exhibited poorer quality than those formed at higher inter-weld nugget pitch distances. A three-dimensional finite element analysis was carried out to mechanistically investigate the effect of inter-weld nugget pitch distance on the governing failure mechanisms and criteria. The computationally derived failure loads exhibited strong validation against the experimental data, registering a maximum relative error of less than 11.5%. The simulations revealed that the superposition of localized stress fields at reduced inter-weld nugget pitch distances precipitates premature joint failure, whereas achieving the optimal spacing facilitates a more uniform stress distribution, thereby achieves a maximum safety factor of 0.67. These outcomes provide new insights and practical design guidelines for optimizing weld parameters and spacing, thereby enhancing the mechanical integrity of lightweight aluminum joints used in automotive and aerospace structures.