A Study on the Prediction of Deformations of Welded Ship Structures

Abstract

Welding deformations injure the beauty of appearance of a structure and decrease its buckling strength. In addition, welding deformations cause errors during the assembly of the structure and prevent increase of productivity. Welding deformations of real structures are complicated and the accurate prediction of welding deformations has been a difficult problem. This study presents a method to predict welding deformations of large structures accurately and practically based on the accumulated research results. The presented method uses the finite element method combining the inherent strain theory and the experimental results for accurate and efficient analysis. The weld joint is assumed to be divided into 3 regions: inherent strain region, material softening region and base metal region. The simplified elasto-plastic analysis method is introduced and representative material values during the thermal elasto-plastic process are used in this method. It is revealed from the analysis results for the simple welded model that the inherent strains are changed by joint restraint as well as heat input and elastic modulus of the inherent strain region, and the material softening region must be different from that of the base metal region. These results have been supported by the experimental data. The method proposed in this study can be combined with the commercial finite element analysis software to predict reasonably an efficiently the welding deformations of large structures.