PSI - Issue 57

Dr.-Ing. D. Jbily et al. / Procedia Structural Integrity 57 (2024) 199–216 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

209 11

Fig. 10. Wheel tooth profile deviations at the end of test

We also compared the profile deviations of the REF teeth after testing (65.5 hours) with those of the shot peened teeth (SP) (after 18.5 hours and after 139 hours). As the running times were different, the aim was to obtain an estimate of the loss of material from the profile that had been subjected to micropitting.

10 15 20 25 30

REF SP

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Profile loss (µm)

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Time (h)

Fig. 11. Profile loss comparison

A profile loss of 11 µm was observed on the REF tooth after 65.5 hours of running, whereas the loss was approximately 11 µm after 18.5 hours on the shot peened tooth. After 18.5 hours until 139 hours, the loss of profile is approximately 11 µm during 120 hours of operation, which is less than the loss obtained during the first 18 hours of operation. On the shot peened tooth, the profile loss seems to have two different speeds: faster loss of profile up to 18.5 hours and slower thereafter up to 139 hours. This phenomenon could be due to the compliance of the contact surfaces during the first hours of operation. This conformation can occur on two scales: evolution at the roughness scale and evolution at the contact scale. However, further tests and investigations are required to confirm these hypotheses. 3.5. Evaluation of residual stresses after test Residual stresses on tooth flanks of the pinion after testing (239 hours) were measured Fig. 12 shows the position of measurements and the direction of the radial (profile direction) and longitudinal (helix direction) stresses.