Fundamental Study of Buckling Caused by Welding Using the Inherent Deformation Method

When thin plates are used to assemble welded structures, the welding process can easily produce large distortion. The buckling type distortion is the most critical mode of welding distortion compared with other distortion modes because straightening process becomes more difficult. In this paper, the mechanism of buckling behavior during welding is clarified. Green-Lagrange strain which is a non-linear function of displacement is employed to model the buckling behavior, and the Tendon Force produced along the welding direction during welding is introduced to explain the buckling mechanism. On the other hand, FEM Analysis is introduced to compute the magnitude and mode of buckling distortion using the inherent deformation method. This method based on the assumption that a welded joint in a plate structure has an inherent amount of deformation generated during the thermal cycle. The inherent deformation can be measured by experiments or estimated by 3D Thermal Elastic Plastic FE analyses. If the inherent deformation is known, buckling distortion can be predicted by elastic FE analysis using the inherent deformation as internal force. This method needs much less computer resources and computing time than the Thermal Elastic Plastic analysis. Finally, a thin plate butt joint is taken as an example. Different welding conditions are examined to study the buckling behavior. The influence of boundary conditions during welding on the buckling mode is also studied and the effect of initial conditions, such as initial deflection and residual stress produced during the process in the previous stage, is considered.