Accurate FE Computation for Out-of-plane Welding Distortion Prediction of Fillet Welding with Considering Self-Constraint

Inherent deformation as key parameter plays an essential role in elastic finite element (FE) analysis for welding distortion prediction. In this study, the self-constraints supported by surrounding base material and lateral stiffener were presented, where their influences on magnitudes of inherent deformation components were qualitatively examined. In detail, self-constraint supported by the surrounding base material will distinguish the inherent deformation as an individual physical representation; and self-constraint supported by the lateral stiffener will significantly influence the bending component and final deformed mode. Taking into account fillet welding and orthogonal stiffened welded structure as the application, experiments were conducted for out-of-plane welding distortion measurement. Transient nonlinear thermal elastic-plastic FE analysis of fillet welding was carried out to evaluate inherent deformation after validation with the measured data; then, elastic FE analysis with inherent deformation was carried out to accurately predict the out-of-plane welding distortion and welding buckling behavior in fabrication of an orthogonal stiffened welded structure which is a part of typical ship panel, and there is a good agreement between the predicted and measured welding distortion. Up to now, fusion welding which is considered as a main joining method because of its practical and high productive features is almost employed for component assembly in fabrication of marine structures, automobiles, trains, aircraft, bridges, pressure vessels, and others. However, during the fast heating and cooling processes, a narrow region near the welding line will expand and subsequently shrink because of the constraint of the surrounding base material, and then plastic strains are generated which are the primary cause of welding distortion and residual stress. Therefore, welding-induced distortion is inevitably generated during the welding process, and it will result in loss of dimensional control and structural integrity, trouble of subsequent alignment with the adjacent component, and increment of fabrication cost with straightening such as flame heating (Wang et al. 2015).