Abstract
Welding induces local residual stress and strain in workpiece joining. These local phenomena lead to distortions in the workpieces and aspect defaults. The consequence is aspect defaults (distortions), which can be corrected by heating and hammering. When the assembled elements have large dimensions and need many joints executed by welding sequences, the aspect defaults can be created by non-optimized sequences. The focus of this study is the optimization of joint sequences (through the numerical simulation of sequences) to minimize distortions induced in wall train shell car manufacturing. The parts are assembled with hybrid laser-MAG welding technology. The metallurgical transformations of the material microstructure are taken into account. A new analytical function called “diaboloid” has been developed to reproduce the morphology of the molten zone and the heat affected zone created by the laser welding. This analytical function is associated with the double ellipsoid analytical function in order to model the laser-arc hybrid welding process. The material thermo-physical properties according to temperature and phase transformation are taken into account in the numerical model. Experimental measurements (cooling rate, residual stresses) have been done in order to correlate numerical and experimental results. The effects of clamping conditions and tack welds are also considered in the numerical model. All these developments made it possible to reduce the displacement of large structures by a factor of 5.
Published Version
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