Rapid Finite Element Evaluation of Welding Distortions for Large Assemblies

The prediction of welding distortions of large welded assemblies is a complex issue which is even more difficult when an accurate and fast analysis is demanded. Distortion simulation is always associated with huge computational costs in terms of computer memory and CPU time. The vertical tool RED-WeldS "Rapid Evaluation of Distortions in Welding Structures" developed in commercial software NSYS®, allows obtaining a fast and enough accurate solution for the prediction of structure distortions due to the welding process. Thus, the manufacturing of large welded assemblies can be simulated considering different welding sequences in order to choose the one which distortion is minimal. In-plane and out-ofplane distortions are taken into account through thermal shrinkage model, which combined with a static linear-elastic analysis leads to fast solutions. A very important reduction of computational time is achieved when using this simplified mechanical model instead of more traditional transient thermo-mechanical-metallurgical or thermo-mechanical non-linear analyses. As application / validation, the distortions due to the welding operations for the connection of two carbon steel nozzles to the shell of a pressure vessel were simulated and the results were compared to the true measurements performed in the workshop after welding. Pre-processing and computational times are summarised to show the power of this numerical approach which will help manufacturers to determine optimum welding sequences to fulfill dimensional criteria.