Finite element modeling and simulation of large perforated plates welding

Large perforated plates (with diameters even bigger then 8 m) are critical components of huge heat exchangers and they have to be fabricated by welding together two or more pieces. These ones should be drilled before in order to get a reasonable productivity, but they will be affected by welding induced residual stress and distortion. The tube holes are an important issue as several thousands of tubes will be fastened to them, so it is crucial to evaluate their welding distortion, to properly design the manufacturing process. The present thesis deals with the development of a finite element based procedure for simulation of large tubesheets multipass welding, in order to compute induced residual stress and deformation, with a focus on tube holes distortion. The effects of material data on computed temperature distribution and residual stress were extensively investigated and some results, together with the conclusions, are included. A welding experiment, designed to acquire data for FEM model set-up and verification is presented. Also, the mechanical testing of employed steel grade, together with the methodology for both solid and perforated material modeling are discussed.