Issue 48

M. Tirenifi et alii, Frattura ed Integrità Strutturale, 48 (2019) 357-369; DOI: 10.3221/IGF-ESIS.48.34 366 Figure 13 : Numerical K and G values for cruciform and butt weld in which the crack is located in weld toe. Weld root The results were plotted in Fig. 14, as values of K and G versus a length of crack. It can be seen that the effect of a in the cruciform welded joint is less than that in the butt-welded joint. However, in this case, the welding profile has a significant effect on the parameters of the fracture mechanics. For all the different crack lengths and pressures, the butt-welded joint has the greater values of K and G than the cruciform welded joint. Figure 14 : Numerical K and G values for cruciform and butt weld in which the crack is located in weld root. As observed from Fig. 14, 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 130,97 %, 132,71 %, and 132,83 % 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 99,25 %, 158,27 %, and 158,04 % at P= 120, 160, and 200 MPa, respectively. 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. Model 3D dimensions In this section, a 3D model is analyzed by ABAQUS (see Fig. 15), One end of the main plate parallel to crack face is restrained and a uniform axial stress 120, 160 and 200 MPa is applied at the other end of the plate to provide the loading condition. The material employed in the analyses is SA 516 Gr 70 [23] with Young’s modulus E and Poisson’s ratio ν being 220 GPa and 0.3, respectively. 0,5 1,0 1,5 2,0 2,5 0 2 4 6 8 10 12 G (N/mm) Crack length (mm) Cruciform weld 120 MPa Butt weld 120 MPa Cruciform weld 160 MPa Butt weld 160 MPa Cruciform weld 200 MPa Butt weld 200 MPa Weld toe 0,5 1,0 1,5 2,0 2,5 0,0 0,2 0,4 0,6 0,8 1,0 G (N/mm) Crack length (mm) Cruciform weld 120 MPa Butt weld 120 MPa Cruciform weld 160 MPa Butt weld 160 MPa Cruciform weld 200 MPa Butt weld 200 MPa 120 MPa 160 MPa 200 MPa Weld root