Optimization of the Spot Weld Locations for Increasing the Joint Strength of the welded plates

Resistance spot welding is one of the most common methods of joining especially in sheet metal assemblies. The number of spot welds and their pattern, strongly affects the joint strength, time and costs. So, a hybrid method of finite element and particle swarm optimization was introduced for determining the pattern of spot welds in this paper. At first, one spot weld joint was created on a sheet specimen, and mechanical properties of this joint were determined. The spot welding process of three cases was simulated and verified by three different experimental data. Particle swarm optimization and finite element method were linked to determine an optimum pattern of spot weld joint. This method was utilized for two, three and four spot welds. According to this research, fracture force of two, three, and four spot welds were 1.9, 2.13 and 2.76 times of one spot with the optimal pattern. The results indicate that the best pattern has four spots distributed on a circle with a radius of 18mm and the angle between loading axis and symmetric axis was 66 degrees.