PSI - Issue 75

J. Havia et al. / Procedia Structural Integrity 75 (2025) 43–52 Havia et al. / Structural Integrity Procedia (2025)

49

7

N

N N

Fig. 6. Fatigue strength analysis with multiparametric 4R method considering local cyclic behavior.

3. Results and discussion Fatigue test results considering nominal stress method are illustrated in Fig. 7. The fatigue strength of the joints at high stress range is similar with all three different test series. However, some differences can be identified at lower stress levels. DED on base plate specimens had the highest fatigue performance in the nominal stress system. Considering all data points (excluding the run-out), the results are well-aligned with the detail category of longitudinal gussets. Characteristic Δ σ c,97.7% = 24 MPa m = 3 was obtained in contrast to IIW recommended value FAT 25 MPa m = 3. Furthermore, FAT 31 MPa m = 3 represents the mean fatigue performance.

200

Continued run-out

DED on Base plate DED welded on base plate DED on top DED surface

Nominal stress range [MPa]

20

20000

200000

2000000

Fatigue life [cycles]

Fig. 7. Fatigue test results considering nominal stresses. The stress concentration values acquired by Eq. 1 are given in Table 5, and η values that are specimen specific are tabulated in Appendix A, where the detailed information of experiments is provided. The acquired structural and notch stress concentration factors were reasonable for the longitudinal gusset specimen, and the used stress component classification provided adequate results.