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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Fig. 8. SN-curve without the influence of geometrical variability using the NS method with r ref = r actual + 1 mm and FAT 200.

3.3.2 Influence of geometrical variability The PDF of the SCF, K t , in Fig. 9a is less skewed and centered than the one in Fig. 7a because the stochastic variability of toe radius are included which has a major influence on the S , together with leg length and toe angle. The difference of fatigue life using K t = 1.85 and K t with variability included is large at the lower tail which is the interest of the work ( P s =97.7%).

a b Fig. 9. In the NS method with r ref = r actual + 1 mm and FAT 200: (a) PDF of K t computed using MC simulations and FEA; (b) CDF of N when the K t in Fig. 9a is used as well as when a deterministic value of K t =1.85 computed using mean values of geometrical parameters is applied.

3.4. Comparison

The SN-curves at P s = 97.7% of four different cases using different NS methods are shown in Fig. 10. The four cases are: Case 1) The NS method with r ref = 1 mm and FAT 225 and a deterministic SCF, Case 2) The same NS method as Case 1 but where a probability distribution of K t is used instead of a deterministic value, Case 3) The NS method with r ref = r actual + 1 mm and FAT 200 and Case 4) The same NS method as in Case 3 but where a probability distribution of K t is used instead of a deterministic value, see Table 2.

Table 2. Studied cases

Case 1 1 mm

Case 2 1 mm

Case 3

Case 4

r actual + 1 mm

r actual + 1 mm

r ref

FAT

225 2.61

225

200 1.85

200

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K t