Abstract: The gears bending fatigue problem has become increasingly prominent due to the increasing requirement of gear power density and service life for sophisticated equipment such as wind turbines, high-speed rails, shield tunneling et al. In order to improve the bending fatigue performance of gears, carburizing heat treatment, shot peening and other processes have become commonly used methods to introduce high compressive residual stress (RS) on gear. The RS influence coefficient is introduced into the maximum principal strain life prediction criterion to quantitatively reveal the influence of RS on gear bending fatigue performance. The optimal RS influence coefficient is determined through bending fatigue test, and then verified by the new test data. Based on engineering applications, the concept of modified stress is introduced to unify gear bending stress-life (S-N) curves under different residual stress states. The research results show that the optimal RS influence coefficient in the maximum principal stress criterion is 0.15. The best RS influence coefficient in the revised and unify S-N curve is found as 0.25. The research results can be used for rapid assessment of gear bending fatigue in engineering practice.

Key words: gear bending fatigue, residual stress, experimental test, life prediction