Computational investigation on transient thermal tensioning for mitigation of welding induced buckling by elastic FE method

Abstract

Transient thermal tensioning (TTT) as an in-process technique is extensively used to mitigate welding induced buckling during the fabrication of thin plate welded structures, which drastically influences dimensional accuracy and manufacturing costs due to post-straightening work. In this study, the processes with conventional welding (CW) and TTT technique during the butt welding with thin plates were investigated by elastic FE method based on welding inherent deformation theory. In detail, thermal elastic plastic (TEP) FE analysis for the butt welded joint was validated, while the computed welding induced buckling and residual stress during CW process were in good agreement with experimental results. Then, TTT technique was implemented with above TEP FE analysis; it consists of two additional heat sources, which were symmetrically distributed and offset 150 mm with respect to the welding line. Moreover, the influence of energy intensity Q for additional heat sources on welding induced buckling mitigation was numerically examined. Elastic FE analyses during CW and TTT processes were carried out with welding inherent deformation evaluated by results of TEP FE analysis. The comparison between elastic FE analysis and TEP FE analysis suggests that the developed elastic FE analysis can accurately and efficiently represent welding distortion during CW and TTT processes with less than 5 % error. There is an appropriate interval of energy intensity Q during TTT process, which can significantly decrease relative displacement Urelative in the butt welded joint by up to 89.1 %. Furthermore, the reduction of tendon force and transverse inherent bending is the primary reason for welding buckling distortion mitigation during TTT process, and the decrease of tendon force is more critical.