Prediction and measurement of welding distortion of a spherical structure assembled from multi thin plates

A spherical structure assembled from 14 thin bent plates and two circular polar plates was taken as the research object and its welding distortion was investigated in this study. Firstly, the welding distortion due to each welding line is measured by experiment. Then, the spherical structure was modeled by shell element and its welding distortion produced by each welding line was evaluated using the inherent deformation method proposed by authors. The computational process requires a short time when the inherent deformation method is employed. To determine the inherent deformation existing in the welding lines, a computed model with 3D solid element for a typical butt welded joint was applied and one case of the detail transient analysis by Thermal Elastic Plastic Finite Element Method was performed. The computed and measured welding distortion show that the radial displacements on the welding lines and at the center of the top and the bottom polar plates are toward the inside of the spherical structure. The radial displacements at the positions between the welding lines are toward the outside of the spherical structure. The welding distortion at the measuring points changing with each welding line is well predicted using the inherent deformation method compared with the measured results.