Control of Longitudinal Bending Distortion of Built-Up Beams by High-Frequency Induction Heating

Abstract

Longitudinal bending distortion is induced by fillet welding during the build-up process of T-section beams. This distortion decreases productivity and the quality of welded structures because it requires additional correction work in the assembly stages of ship construction. Longitudinal bending distortion is caused by the, welding moment, which is calculated by multiplying the shrinkage force due to welding by the distance between the welding heat source and a neutral axis on the cross section of built-up beams. However, this distortion can be mitigated by induction heating on the web plate of built-up beams, generating a reverse moment of the same magnitude as the bending moment due to fillet welding. In this study, location and intensity of induction heat input were determined based on experiments and simple equations. The mechanism of longitudinal bending distortion in the build-up process was investigated using three-dimensional thermal elastic-plastic analysis. A new control method of longitudinal bending distortion was proposed using high-frequency induction heating with verification of its validity.