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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chamfer region with a linear grading through the heat affected zone as shown in Figure 3. The FEM model comprised a total of nearly 5.5k elements and nearly 6.8k nodes.

Fig. 3. FEM mesh highlighting the mesh grading and the two groups of elements of first pass (in green) and second pass (in red); only one plate modelled thanks to symmetry. The energy supplied to the welding bead during the simulation was calculated through the following equation: = ∙ ∙ ∙ ⁄ , (1) where and are the voltage and the electrical current respectively, is the welding efficiency, is the welding speed and is the length of the weld bead (i.e. 150 mm). The energy was applied as volumetric heat flux to each group of elements of the bead for a total time lapse needed to cover the length each pass and according to timing measured during the actual welding (Murugan et al. (1998)). A cooling phase was considered between the two passes to simulate the interpass time by considering 120 s of heat dissipation. Film conditions were applied to all the free surfaces to simulate such heat transfer with the environment (convective and radiative heat losses). A temperature dependent convective film coefficient was calculated as the sum of temperature dependent convective and radiative film coefficients see Figure 4. At last, a fourth and final step for simulating 11 minutes of heat dissipation was added after the second pass, to reproduce the final cooling of plates to reach room temperature (~ 25 °C).

Fig. 4. Heat loss coefficient (sum of convective and radiative coefficients) to simulate heat dissipation.