Optimization of the Thermal Tensioning Process for Minimum Residual Stress and Distortion

Welding distortion in thin section large structures is usually caused by buckling due to the residual stress. In cases here the design is fixed and minimum weld size requirements are in place, the thermal tensioning process can be used to reduce the welding residual stress bellow the critical level and eliminate buckling distortion. In this work, a systematic design approach using conventional finite element analysis, analytic sensitivity analysis, and numerical optimization is implemented to investigate and optimize the thermal tensioning process. We clearly demonstrate that: 1) thermal tensioning with localized heating produces welds with negligible residual stress at the critical locations. Such panels will have no buckling distortion. 2) The systematic approach is very robust and cost effective.