Issue 48

M. Tirenifi et alii, Frattura ed Integrità Strutturale, 48 (2019) 357-369; DOI: 10.3221/IGF-ESIS.48.34 364 transversal residual stresses increase sharply away from the center of weld. There are small compressive stresses ~10 MPa, range_2 and tensile stresses ~50 MPa, range_1 for the butt-welded plate. Fig. 8b shows the vertical displacements of a node during the welding for the tow plates of weld. The thicknesses of all plates are 5 mm. The non-symmetric welding sequence results in asymmetry of the vertical displacement in the cruciform welded plate. The left side of the plate where the second welding operation completed has bigger deflections. The maximum displacement (2.9 mm) occurs in the right side of the cruciform welded plate (first pass) and is much bigger than the one in the left side (4.3 mm, second pass) and is much bigger than the one in the left side (4.9 mm, third pass). The maximum displacement is 5.29 mm occurs the four passes. Figure 9 : vertical displacement in the welded plates. The vertical displacement of the welded plates is plotted in Fig. 9. The distribution behaves almost linearly from the weld to the transverse edges. Maximum displacement (5.29 mm for the cruciform weld, 5.51 mm for the butt weld) occurs in the corner of the end section in terms of the welding direction. It is also observed that the displacements on the two edges of the plate are not exactly equal. Consequently, minor differences appear between the angular distortions in two types of weld. E XTRACTION OF SIF AND G VALUES n fracture mechanics, the Stress intensity Factor is frequently used to predict the stress state close to the crack tip. The stress may be caused by a remote load. It can be theoretically used to provide a criterion for failure of homogeneous elastic materials. The linear elastic material constitutive properties are defined by the Young’s modulus E and Poisson’s ratio ν. The temperature-independent elastic modulus and Poisson’s ratio are assumed to be 220 GPa and 0.3, respectively. The factor K gathers with him only the influence of the dimension of the crack, the forces applied and the geometry of the cracked part. The success of the fracture mechanics comes from what the conditions at the end of the crack depend on only and single parameter. In this study, we make a comparison between a cruciform welded joint and a butt-welded joint for 2D dimensions and 3D dimensions to see the differences parameters of linear fracture mechanics between the two configurations. Model 2D dimensions FE simulations are conducted by ABAQUS. The specimens having a thickness B of 5 mm with the length of 180 mm, with various dimensions of the cracks 0.5,1.0,1.5,2.0 and 2.5 mm (see Fig. 10 and Fig. 11). Three different pressures 120,160 and 200 MPa are applied on the right side of the tow specimens. Figure 10 : The location of the crack examined for 2D dimensions, a) the cruciform weld toe, b) the butt weld toe. I