Study on gear bending fatigue considering gradient characteristics: Numerical analysis and experiments

Abstract

The bending fatigue of the case hardened gear, one of the essential components used in high-end equipment such as helicopters, wind turbines and automobiles, significantly limited the safety, reliability and service life of such equipment. In this work, we proposed a novel gear bending fatigue model incorporating gradient characteristics of hardness and residual stress based on the continuum damage theory to evaluate the bending fatigue behavior of case hardened wind turbine gear. The damage equations involving the residual stress and hardness gradients and damage coupled constitutive equations are derived. This model is then experimentally validated on the bending stress, bending fatigue failure position, mechanical properties deterioration and bending fatigue life. The evolutions of damage, stress response and mechanical properties are investigated. Results show that the predicted gear bending fatigue lives of different case hardened gears are within the 1.5 scatter factor bond.