PSI - Issue 38

Jinchao Zhu et al. / Procedia Structural Integrity 38 (2022) 621–630 Author name / Structural Integrity Procedia 00 (2021) 000 – 000

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the following, the influence of neglecting the concavity and convexity of the weld shape for the studied non-load carrying cruciform joint is assessed. Contour plots of the first principal stress are shown in Fig. 5(a) and (b), for a toe angle of 40° and 50°, respectively, when a straight line is used to model the weld geometry. In Fig. 5(c) and (d), the corresponding contour plots are shown for the case where the concave and convex shape of the weld is modelled, respectively. As seen in Table 1, the influence of neglecting the convexity/concavity of the weld shape on the SCF is negligible for toe angles in the interval of 30° to 60°. This is expected for non-load carrying fillet cruciform joints, since the leg length at the vertical direction has a minor influence on the SCF at the weld toe at the horizontal side. In the remaining of this paper, the influence of weld shape modelling is therefore negligible.

a

b

c

d

Fig. 5. First principal stress distribution of models with leg length of 10 mm at the horizontal direction and r ref = 3 mm for (a) Toe angle 40° and straight line weld shape; (b) Toe angle 50° and straight line weld shape; (c) Toe angle 40° and concave weld shape; (d) Toe angle 50° and convex weld shape.

Table 1. Stress concentration factor K t for different toe angles and weld shape assumptions.

Toe angle

30°

40°

50°

60°

Weld Shape

Concave

Straight

Concave

Straight

Convex

Straight

Convex

Straight

1.762

1.759

1.836

1.834

1.867

1.867

1.879

1.880

K t

3.2. Notch stress approach with r ref = 1 mm and FAT 225 3.2.1 SN-curve without the influence of geometrical variability

The SN-curve is computed using the NS method with r ref = 1 mm and FAT 225 from Eq. (4) using Eq. (3) and Eq. (5), see Fig. 6. An SCF value of K t = 2.61 is determined using the mean values of leg length and toe angle (Section