ABSTRACT
Unlike other welding processes, resistance spot welding (RSW) is dif cult to directly monitor on the weld nugget development, because melting and solidi cation processes primarily take place between the workpieces. A common practice is to control the input, such as welding parameters, and monitor the output, such as the attributes of a weld and process signals. However, little can be learned about the nugget formation process from the input and output. Complexity rises because of the interacting electrical, mechanical, thermal, and metallurgical processes. Numerical simulation (e.g., nite element analysis) is a powerful tool in this situation. Detailed thermal pro le, stress and strain distributions, as well as distortion at various stages can be revealed by numerical simulations. Welding process parameters, such as electrode force, welding current, and welding machine stiffness, can be easily altered using the nite element method to study their in˜uence. Performing a similar study experimentally would be extremely dif cult if not impossible.
