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 1 m in length, with over 8 m 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.