The welding distortions are still one of the main problems in welding technology. It decreases the quality of the welded structure, complicate the smoothly accomplishment of the manufacturing process and increase the cost of post treatments. To find the ideal welding parameters, clamping conditions or pre-deformations, the procedure of time- and cost-intensive experiments is still popular. For this purpose the employment of the thermomechanical finite-element-simulation is increasing. However, in range of large structures with multiple weld seams, the complete thermomechanical FE-simulation is not rational.

The aim of this research project is the development of an analytic-numerical hybrid model for determination of distortions of large welded structures. To satisfy a large application range, the basis of the model – the analytical shrinkage force model – has to be upgraded. Basics are methodical thermomechanical finite-element-simulations and the analysis of the zone of plastic deformations. The objects of research will cover short welds, non-linear trajectories, a large number of common joints, high strength steels and new welding processes with reduced heat and processes with high power density. Furthermore the buckling of thin walled structures due to welding is reviewed. The effect of the welding position on the zone of plastic deformations will be analyzed experimental. The evaluated influence will be summarized and implemented with appropriate effect functions in the existing shrinkage force model. 

In regard of industrial application of the model, the developed program for calculating the shrinkage forces WELDIS will be upgraded with the new functions and exemplary coupled with commercial finite-element-software. The outcome is a coupled hybrid model with an analytic calculation of the shrinkage forces and an elastic numerical simulation of distortions under those mechanical loads. This model will enable calculation of welding distortions of complex structures in a large application range without the needs of special knowledge about the thermomechanical weld simulation. 

The result will be an extended shrinkage force model, involved in a capacious hybrid model. The analytic calculation of plastic strains and the numerical calculation of distortions is a basically new approach in the determination of weld distortions. The hybrid model will be validated on realistic structures with different complexity. Additionally, the results will be concluded in a guideline that contains the obtained experiences and usage of the model.

The functionality of the described approach is already demonstrated in lots of foregone works of the proposer. The grand interest of the industry in this field of research is shown by the numerous members of the project’s accompanying committee, consisting of members from railway vehicle manufacturing, shipbuilding and crane construction.