Speaker
Description
During welding of large, massive and complex assemblies, such as the ITER Vacuum Vessel PS3, the accumulated shrinkage of parallel welds may cause a cumulative distortion effect which significantly varies the dimensions and geometry of the welded portion while still unfinished. In case of the PS3, as consequence of such distortion, the space left to fit the outer shell plates into to the welded portion is expected to differ from nominal dimension by several millimeters. The outer shell plates to be added and welded to complete the assembly are foreseen to be customized to the proper size after dimensional survey of the space to allocate them. Such customization will allow the bevel dimensions for the remaining welds to be nearly of nominal size and the weld parameters and procedures still to be valid.
In the field of welding distortion simulation with the use of the finite element birth and death technique, all parts of the assembly and bevels between them are included in the model from the beginning of the simulation with their nominal sizes. The process described of part customization needs to be taken into account in the simulation. Otherwise the distortion of the welded portion will deform the still dead elements of un-welded bevels in the model. This would be a relevant source of inexactitude for the analysis since such bevels would not have anymore the proper size, and dimensions of parts added to the assembly would also differ between simulation and the actually manufactured ones.
A methodology is presented to simulate, through morphing techniques, the size customization of the parts being added to fit into a distorted assembly, maintaining also the bevel sizes within proper dimensions. The results show the outcome of the investigation carried out for welding distortion analysis of PS3 using such methodology.
“The work leading to this publication has been funded partially by Fusion for Energy under Supply of ITER Vacuum Vessel Sectors F4E-2010-OPE-068-01 (MS-VV). This publication reflects the views only of the author, and Fusion for Energy cannot be held responsible for any use which may be made of the information contained therein.”
