PSI - Issue 58

Mirjana Opačić et al. / Procedia Structural Integrity 58 (2024) 87 – 94 M. Opa č i ć et al. / Structural Integrity Procedia 00 (2019) 000–000

91 5

Fig. 4. Finite element mesh used for the pressure vessel 970 model.

Fig. 5 shows the boundary conditions and the loads in the model, whereas Fig. 6 shows the location of the crack within the weld metal of the second model. Boundary conditions were initially defined as fixed on both ends. Load in the model was defined as internal pressure corresponding to the maximum working pressure magnitude, which as mentioned earlier, was 7.7 MPa.

Fig. 5. Boundary conditions (orange triangles) and load (purple arrows) defined in the model.

Fig. 6. Location of the internal crack (75x20 mm) in the central part of the vertical welded joint.

Results of the first two simulations are shown in Fig. 7, including a relevant vertical cross-section where the crack was located. The reason why only one model (with the crack) is shown in the figure is simple - there was no observable differences in the stress values and distribution in both models. This was due to relatively low stresses, which were around 270 MPa in the welded joint (maximum values of ~355 MPa were located in the boundary conditions themselves, and can be neglected as such), but this still did not explain why there was no stress concentration in the