PSI - Issue 75

D. Jbily et al. / Procedia Structural Integrity 75 (2025) 158–175 Author name / Structural Integrity Procedia (2025)

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tooth dedendum for both REF and SP gears, with notable progression observed after just three hours of operation (0.405 × 10⁶ cycles). On REF gear teeth, micropitting is primarily localized along the grinding marks. In contrast, SP gears exhibit more extensive degradation (Fig. 5, Fig. 6). Surface profile measurements reveal that the micropits appear as craters ranging from 10 to 100 µm in width and length, and from 1 to 5 µm in depth (Fig. 7, Fig. 8). No significant dimensional differences are noted between the craters of the REF and SP gears.

REF Pinion

SP Pinion

As-manufactured state

After 30 min

After 18min

After 3hours

After 2hours and 48 min

Fig. 5. Microscopic view of the replica of the pinion flank surface at the dedendum.