Numerical simulation of laser beam welding using an adapted intensity distribution

The automotive industry has a high demand for lightweight solutions for car body components to reduce the carbon dioxide emissions and to increase the range of electric cars. In this context, the joining methods play a significant role in enabling the lightweight construction. Specifically, the use of aluminum alloys for structural components or body panels poses a major challenge for joining technologies. These parts are often made from aluminum alloys AA6xxx, which are very susceptible to hot cracks during fusion welding. As laser beam welding is increasingly used for welding car body components, special techniques are required to avoid hot cracks in weld seams. Besides the use of filler wire, laser welding using an adapted intensity distribution is an innovative approach to get a defect-free weld seam coupled with a high surface quality. Due to the lack of flexible beam shaping optics for investigations on high power material processing using an adapted intensity distribution, a simulation method for this technique is presented. The impact of the adapted intensity on the process characteristics, e.g., the temperature field, the temperature gradients, or the molten pool geometry, can be determined by using this numerical model. The heat input by the adapted intensity distribution is composed of a stationary capillary geometry for the deep penetration welding process and an additional surface heat source. An experimental analysis was carried out to calibrate the simulation model. Using design of experiments, the weld seam geometry depending on the laser parameters can be predicted. Finally, the impact of an adapted intensity distribution on the geometry of the molten pool and the temperature field is shown.