Iterative substructure method employing concept of inherent strain for large-scale welding problems

When structures such as ships, automobiles, and bridges are assembled by welding, distortion and residual stress are produced as unavoidable consequence of local shrinkage due to welding. The dimensional error deteriorates the performance of the structures and becomes an obstacle to achieve smooth manufacturing if the error exceeds the tolerable limit. On the other hand, residual stress plays an important role in crack initiation and fatigue life. Thus, it is necessary to predict the welding distortion and stress beforehand, so that effective measure and control can be taken. Since the welding is a highly nonlinear problem, it is difficult to predict the distortion quantitatively. For accurate prediction, finite element analysis (FEA) can be a powerful tool. In this research, an enhanced FEA scheme namely i-ISM is developed based on the inherent strain concept and iterative substructure method (ISM). Its capability of solving large-scale practical problems is demonstrated through typical models.