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This paper presents a detailed finite element simulation of the longitudinal rib welds of Vessel Advanced Technology Segment (VATS) by e-beam welding. Nine different simulation sequences were carried out to explain the different mechanisms that drive the distortions process during welding and to lead to an optimum sequence which minimizes the final distortions. The simulations were used to guide the manufacture of the final sequence of the VATS. Distortion measurements taken after welding compared very well with the simulated results.

In this paper, an Electron Beam (EB) welded mock-up is used for the calibration of the finite element method welding simulation developed. Once the method is validated, a new simulation welding sequence is proposed with the objective to reduce the mock-up final distortions. The final distortions should be reduced from 7 mm to 1 mm. Distortion measures and final deformed shapes are compared between two simulation scenarios to establish the effects of the new provisions assumed. The new simulation scenario includes a balanced longitudinal weld sequence in order to minimize the effects of the accumulative angular distortion process. The power of the FE method developed is demonstrated and will allow the optimization of the welding sequences to carry out previous simulation in FEM in future applications of ITER.