Numerical welding simulation of an aluminium automotive component

For an automotive component made from aluminium alloy numerical simulations of the welding process have been performed in order to determine the resulting distortions and residual stresses. For the simulation the Finite Element code SYSWELD® was used. The heat input from the welding process was modelled via a moving equivalent heat source, which intensity and heat distribution have been adapted to measurements from the real welding process. Besides temperature measurements also macro-sections from the welds as well as measurements of distortion and residual stresses were used for verification of the simulation. The component under investigations is a laser-welded joint of a B-pillar and a roof profile of an automotive space-frame. The investigations revealed that the modelling of the heat source and its adjustment to the measured temperature profiles and macro-sections of the welds have an essential influence on the results of distortion and residual stresses. Even smal l deviations of calculated and measured values could lead to significant differences in distortion results. An extended heat source was developed which enables a good adjustment of the real behaviour by modelling an anisotropic heat conductivity in the melt pool. Using this method, an excellent agreement between calculated and measured distortion of the laser beam welded aluminium structure was reached.