FEM simulation of welding distortion in thin curved structures during assembly considering gap and misalignment

Ships and automobiles are fabricated from thin curved plates. To assemble parts, welding is commonly used. However, it is impossible to avoid the deformation produced by welding. The deformation causes problems not only in the assembling process but also in the final products. The shrinkage of the weld zone is just one of the reasons for the distortion during assembly. Other factors, such as positioning, fixture and welding sequence must be controlled to achieve the required precision. Since it is influenced by various factors, the quantitative prediction and the control of the welding deformation is difficult. Regardless of the types of structures, the correction or straightening of the deformation, which requires skill and cost, is one of the essential parts of the assembly process. If the welding deformation can be predicted before welding, appropriate measure can be taken to maintain sufficient geometrical accuracy without special skill or large cost. In this research, a finite element method (FEM) for predicting the welding deformation of three-dimensional curved structures with considering welding sequences is proposed. In this method, the interface element is introduced to model the joining process. The usefulness of the proposed method is demonstrated through the prediction of the welding distortion of the curved plate structures and the influence of the gap correction is investigated.