PSI - Issue 47

V. Giannella et al. / Procedia Structural Integrity 47 (2023) 892–900 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 2. Mechanical and thermal properties for low carbon steel: (a) yield stress, (b) Young’s modulus, (c) thermal expansion coeffi cient, (d) thermal conductivity, (e) specific heat and (f) stress-strain curves.

A FEM thermal analysis was performed to numerically replicate the temperature field during the welding process. The simulation of the process was based on the “birth -and- death” method. This latter allows to simulate the explicit formation of the weld bead during the simulation, see Figure 3. The first step of the analysis is the deactivation of the weld bead elements in order to activate them along with the simulation to simulate the production of the bead. The deactivation process was implemented by multiplying the elements stiffness by a reduction factor of 1e-6, thus excluding them from the analysis. These elements were combined in 38 groups of elements for each pass and they were progressively reactivated during the simulation, at given time steps. This reactivation was achieved by removing the reduction factor according to the welding speed v . Concerning the mesh, a full 3D model was preferred to 2D models. In particular, 8-noded brick elements, DC3D8, considering the temperature as a unique degree of freedom for each node, were sel ected from the elements’ library . The finest mesh was built up for the