PSI - Issue 57

Tobias Pertoll et al. / Procedia Structural Integrity 57 (2024) 250–261 Author name / Structural Integrity Procedia 00 (2019) 000 – 000 Figure 3 (b). The range of the stress intensity factor threshold ∆ ℎ at an R -ratio of 0.1 is defined with 6.65 MPa√m and with 13.00 MPa√m for an R -ratio of -1. a b 255 6

Figure 3. (a) Nominal bending stress profile in cross section of the initial fatigue crack in INARA and (b) multi-linear approximation of the crack propagation curve for the high strength steel 34CrNiMo6+QT (Lütkepohl et al. 2009)

2.5. Loading

The load is defined according to a typical loading scenario of rail vehicles. Therefore, the block load sequence presented in (Gänser et al. 2021) and used for example in (Rieger et al. 2020) is selected. The load spectrum is based on measurement data sets during a measurement run of 3600 km with different loading conditions in Germany, details can be taken from (Gänser et al. 2021). To achieve the same utilization rate of the material, the load spectrum is linearly scaled in relation to the higher fatigue strength and the corresponding higher safety factor due to the higher notch sensitivity of the material 34CrNiMo6 according to the European standard (EN 13103-1: 2017+A1). Figure 4 (a) shows the applied block load sequence and Figure 4 (b) the resulting load spectrum. The maximum nominal bending stresses are approximately 169 MPa.

a

b

Figure 4. (a) Used block load sequence and (b) derived load spectrum

2.6. Investigated scenarios

This investigation examines the influence of deep rolling in general and further the effect of different deep rolling residual stress profiles on the crack propagation behavior in railway axles. Therefore, calculations without