PSI - Issue 80

Simone Messina et al. / Procedia Structural Integrity 80 (2026) 232–243 Simone Messina/ Structural Integrity Procedia 00 (2019) 000–000

241

Min Dan Vang

Max

Fig. 9 Safety factor distribution for gear 2 no microgeometry model

Min Dan Vang

Max

Fig. 10 Safety factor distribution for gear 2 microgeometry model

Table 2. Results Modelling No micro-geometry Micro-geometry

Safety factor gear 1

Safety factor gear 2

Simulation time

Reference

Reference

90 hours 120 hours

+ 2%

+ 2%

6. Discussion At first glance, the static and full gear mesh models might appear unrelated, potentially leading to the assumption that the static model alone was sufficient for analyzing tooth stress. However, this was not the case. While the static model served as a valuable preliminary tool, useful for validating the simulation setup and verifying that the contact behavior between gear teeth aligned with theoretical expectations, it was insufficient for a comprehensive assessment of fatigue behavior, particularly in the case of helical gears. This limitation arose from the fact that a complete gear meshing operation cannot be known in advance. Static models provided only a single snapshot of the contact condition, representing an instantaneous loading scenario that did not capture the dynamic evolution of stresses over time. Furthermore, due to the high contact ratio characteristic of helical gears, the load distribution along the tooth surface varied continuously throughout the meshing cycle. As a result, it was not possible to predict in advance which specific time instant would have generated the highest stress levels. Therefore, full mesh simulations were essential to accurately capture the load history and identify critical stress conditions for reliable fatigue life predictions. The microgeometry had a non-negligible impact on the fatigue safety factors, leading to their increase.