PSI - Issue 38

Hendrik Bissing et al. / Procedia Structural Integrity 38 (2022) 372–381 Hendrik Bissing, Markus Knobloch, Marion Rauch / Structural Integrity Procedia 00 (2021) 000 – 000

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2.1. Effect of single parameters on the fatigue service life This section deals with an investigation of 2.5 % and 97.5 % quantile values, implemented in the two submodels SLA and CPM to show the impact of single parameters on the fatigue service life according to the individual concept. The study uses quantile values of the probability distributions that are taken from the HAZ, Table 1. The HAZ is chosen, because it represents the domain, where the crack initiation of butt welds most likely occurs. For this analysis, in which the effect of one parameter is assessed while keeping the other parameters constant, the constant values are set to the mean values of the same domain (HAZ) for the SLA. The notch stress calculation is performed with the modified Neuber equation, Seeger et al. (1980), applying the plastic form factor K p as 1.0, which is suitable for butt welded specimens. The damage law within the SLA is specified by the approach according to Smith et al. (1970), P SWT . The analysis uses constant stress amplitudes with a stress ratio R equal to 0.0.

a) Parameter K’

b) Parameter n’

c) Parameter b

d) Parameter c

e) Parameter E

f) Parameter K t

Fig. 3. SN i curves of various input parameters with 2.5 % and 97.5 % quantile values of the probability density functions