A simplified non-linear numerical method for the assessment of welding induced deformations

Welding numerical simulation has always been a formidable challenge because of the involved complex phenomena to be modelled. The task is increasingly challenging when multi-runs welding or welding of ships is needed to be modelled. In these cases, the computational effort is so high that solving the problem via computational welding mechanics is impossible so far. Alternatively, different simplified numerical strategies were developed to overcome this issue such as those based on the inherent strain. Unfortunately, such numerical models are rarely able to capture the effects induced by a variation of the welding sequence or clamping conditions since they are solved in the elastic filed; most of them are therefore not useful to the design optimization of a welded assembly. In this scenario, a new approach is proposed to quantify the welding induced deformations that uses virtual elements to model the weld bead in the elastic-plastic filed and auxiliary elements to apply equivalent loads determined by experiments on a single welded joint. A specific inverse analysis algorithm has been developed to use the method. The model was applied to a real welded assembly in which both the welding sequence and clamping condition were varied. In addition, for the numerical validation, a novel registration algorithm has been developed to move from solid geometries to middle plane representations. Numerical results were found in good agreement with those obtained by experiments even when the welding sequence and clamping conditions are changed.