Numerical analysis of distortions by using an incorporated model for welding-heating-cutting processes of a welded lifting lug

A lifting lug is a widely used welded structure in the shipbuilding industry. Welded lugs with holes that are attached to heavy blocks are hooked onto and transported by a crane. The lugs are cut away after the heavy blocks are set up at the right position. In this study, a new thermal compensation method was proposed to improve the productivity of removing a lifting lug by band saw cutting. A lifting lug employs a welding process, a heat treatment process, and a cutting process, and thus a coupled 3D finite element model was developed to investigate the distortion and residual stress redistribution during the three processes. The results of the numerical and the experimental studies indicated that the thermal compensation method was effective in improving the productivity of removing the lifting lug. The numerical simulation ensured that the mechanism and influence of various local heating conditions were well illustrated and discussed. It is expected that the coupled finite element model developed in this study can solve practical problems of industrial production.