Research on welding simulation methods and software development

To develop highly efficient and useful software, we need to understand the essential feature of the welding phenomenon. From the mechanical point view, welding is a transient nonlinear problem in which small but strongly nonlinear region is moving with the welding torch. Noting this characteristic, ISM (Iterative Substructure Method) was developed for the thermal-elastic-plastic analysis of large scale structures. It is also known that the welding distortion and the residual stress are produced by inherent strain. The inherent strain is the sum of irreversible strains such as plastic strain due to welding thermal cycles or phase transformation and creep strain. In addition to the inherent strain, the mismatch produced by cutting error and fitting is also an important cause of the welding distortions and residual stresses. Based on this understanding, an elastic FEM introducing the inherent strain and mismatch is developed. The potential capabilities of these methods are demonstrated through some examples. © right.