Numerical Study on Mechanism of Twisting Deformation Observed in Bilge Block during Welding Assembly and Its Control

摘要

It is generally experienced by engineers in shipyards that it is difficultto predict and control distortions of curved 3D blocks during assembly.Even in case of bilge blocks in the parallel part, twisting of the block isoften observed. So far, there is no theoretical explanation why ithappens. According to the Authors’ understanding, the distortion of thewelded structure is produced by two causes. One is the local shrinkageintroduced by welding, such as transverse shrinkage and angulardistortion. The other is the gap and misalignment introduced duringsequential welding process. In this study, the mechanism of the twistingdeformation is investigated from these points of views. For this, elasticshell FEM developed by authors based on the concept of inherentdeformation and interface element is employed. Further, the method tostraighten the twisting distortion by line heating is proposed based onthe numerical study.