Approximate model for laser welding

The industrial application of laser welding implies a reliable and efficient production process. In order to facilitate this, modeling and simulation is used to reveal the crucial points of the welding process. The welding process is described by transport phenomena for mass, momentum and energy. The three involved phases (solid, liquid, gaseous) interact over the free moving phase boundaries. The present boundary layer characters allow to reduce the dimension of these Free Boundary Problems. However, the boundary layer character of the melt flow is lost close to the stagnation point. This can be understood as perturbation of the asymptotic solution in the boundary layer. This perturbation is identified to be singular. The description of the flow near the stagnation point leads to a modified Hiemenz problem which can be solved analytically. The resulting welding model reproduces the time-dependent spatially 3d-distributed welding process. Technical relevant prediction of seam width and depth are compared to experimental results. The reproduction of thermal monitoring signals from the interaction zone between laser and material will be approached.