Issue 48

M. Tirenifi et alii, Frattura ed Integrità Strutturale, 48 (2019) 357-369; DOI: 10.3221/IGF-ESIS.48.34 368 As observed from Fig. 17, for the cruciform welded joint, K at the surface point also increases with an increase of a . When the crack length varies from 0.5 to 2.5 mm, K at the surface point increases by 35,49 %, 37,45 %, and 37,53 % at P=120, 160, and 200 MPa, respectively. Moreover, for the butt-welded joint, K at the surface point also increases with an increase of a . When the crack length varies from 0.5 to 2.5 mm, K at the surface point increases by 59,16 %, 59,30 %, and 59,30 % at P=120, 160, and 200 MPa, respectively. Figure 17 : Numerical K and G values for cruciform weld and butt welds. C ONCLUSION detailed thermal and thermo-mechanical analysis procedure was applied to a butt joint and cruciform weld with four passes. The objective of this work is to access the importance of an accurate prediction of the weld induced residual stresses and distortion based on numerical simulations. The welding simulation has shown that at the time of the deposition of the filler metal and during the heating and cooling of the assembled edges, compressive and tension stresses have been produced, this is due to the change in phases and the birth of the two welding zones, the fusion zone and the heat affected zone, the following conclusions can be illustrated:  The obtained maximum temperature in the weld is 1500 °C for butt weld (first pass) and 900 °C for cruciform weld (first pass), and the temperature profile has a typical parabolic shape in the weld bead.  There are stresses of tension and compression for all the passes in the both welded plates.  Maximum displacement is 5.29 mm for the cruciform weld, 5.51 mm for the butt weld.  We have used a numerical method of analysis, which can calculate K and G of a crack in a tow-dimensional and three- dimensional model. For this part, the values of K and the energy release rate for the case when the mechanical efforts are applied with different lengths of the crack  The values of the stress intensity factor and G for cruciform and butt-welded joint are almost similar in which the crack is located in the weld toe.  Comparison of the results between cruciform and butt welded joint, such as the weld toe, has stress intensity factor and G values higher than the stress intensity factor and G values for the weld root crack.  It notices that K and G increase when the length of the crack and the load applied increase. As future work, the SIF and G will be calculated with the consideration of the residual stresses, furthermore, a special research will be established for the extraction of SIF and G during welding. Finally, further application of the numerical simulation of welding will be extended to 3D models. A