Finite element modeling of electron beam welding of a large complex Al alloy structure by parallel computations

This paper describes features of a three-dimensional finite element model to simulate the temperature field of a large complicated Al alloy structure during electron beam welding (EBW), aiming to control the final distortion of the welded structure. The actual workpiece is about 1m in length, with over 8m aggregate weld length. Because a much finer mesh was required to describe the electron beam heat source, computational work would be substantially increased due to the three-dimensional model. In order to improve calculation speed and quality of simulation, parallel calculation was performed by establishing a computer cluster system composed of four PCs. At the same time, a dynamic three-dimensional keyhole was applied in this model to simulate the heat generation in the cavity. Following the heat source, the keyhole moved along the weld line, allowing a more complex expression to describe the heat source of EBW. Several welding process parameters including input energy and welding speed were studied systematically, as well as the influence of pre-deformation before welding on the ultimate distortion. The results show that the input energy and welding speed have a direct effect on the temperature field, especially on the shape and dimensions of the weld pool, and they seriously influence the final distortion. Pre-deformation also has an effect on distortion, but not apparently as strong as the parameters mentioned above.