PSI - Issue 4

M. Filippini et al. / Procedia Structural Integrity 4 (2017) 11–18

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M. Filippini et al. / Structural Integrity Procedia 00 (2017) 000–000 log S

k

1

S D

N D

log N

Fig. 2. Schematic of the SN diagram with a uniform scatter band .

Steel

S D

N D

k

σ log S

grade MPa cycles EA4T 373.19 1133300 15.05 0.020966 EA1N 251.6 2230000 18.80 0.01588

Table 2. Parameters for the SN curve and the fatigue endurance strength of EA4T and EA1N steels estimated by the ML method (small scale specimens, constant amplitude loading).

Fig. 3. SN curve of small specimens of EA4T steel.

3. Variable amplitude fatigue tests

3.1. From measured spectrum to test spectrum

For the fatigue tests with variable amplitude loading, a measured service loading spectrum that was made available by Trenitalia within the Euraxles project was chosen as a basis for deriving a test spectrum that could be employed in laboratory tests. This in-service loading spectrum was measured, in terms of bending moment occurrences, on the 2 front axles (front bogie wheelsets) of a locomotive of a intercity train hauling 8 wagons (1 laboratory coach + 7 lug-