Issue 30

P. Corigliano et alii, Frattura ed Integrità Strutturale, 30 (2014) 304-310; DOI: 10.3221/IGF-ESIS.30.37 308 circumferential direction, and 1.2 mm along the thickness direction. Different material zones (BM, HAZ, WM) were considered in the FE model with their different σ-ε curves according to Fig. 6, no misalignment was considered in the FE model. Figure 12 : Different material zones defined in the FE model. A preliminary FE analysis at high nominal stress (0<  n <530 MPa) was performed in order to capture and highlight the influence of the different hardnesses. The geometry and the boundary conditions were the same as in the experimental test, the load is applied to the superior vertical plate, while the inferior vertical plate is clamped. The nominal stress (  n ) was determined from the introduced force. Fig. 13 to 15 show the results in terms of strains and stresses in the x direction. In the elastic phase, the values of ε x are higher getting closer to the notch, while, as  n exceeds the  y value, the strain in the notch depicted in Fig. 15 is higher than that the one in Fig. 13, but it is smaller near the notch than in the base material (excluding the sharp notch). This effect is due to the differences induced by the hardness values to the material characteristics. Figure 13 :  x for  n =180 MPa (  n <  y ). Figure 14 :  x for  n =180 MPa (  n <  y ). Figure 15 :  x for  n =530 MPa (  n >  y ). Figure 16 :  x for  n =530 MPa (  n >  y ). Moreover, a FE analysis was performed using the same boundary and loading conditions of the experimental tests (the load was introduced by prescribing a displacement of ±1.2 mm to the superior vertical plate). Fig. 17 and 18 show a comparison between the deformed shapes of the real specimen and the FE model at F min . Fig. 19 and 20 confirm the result of the experimental analysis: there are both the components of axial and bending stresses, especially at F min . Furthermore, the strains are larger along the base material than in the weld metal.