Crystal elasticity analysis of contact fatigue behavior of a wind turbine gear

Rolling contact fatigue is the main factor limiting the service performance of wind turbine gears. The inherent microstructure of the gear material has a significant impact on its contact fatigue behavior and service life. In this research, a two-dimensional contact fatigue model considering the gear material microstructure and the elasticity anisotropy characteristics of the crystals is established. The predicted results reveal a pronounced scatter phenomena of the stress distribution in the subsurface and the localized stress concentration at the grain boundaries caused by crystal elasticity anisotropy. Changes of initial grain orientations can cause a certain fluctuation in the critical stress and its depth in the subsurface. Under the same load level, the gear contact fatigue life calculated by the crystal elasticity anisotropy model is lower compared to isotropic material. Considering the anisotropic properties of the crystal elasticity, an S-N curve based on the maximum contact pressure for the wind turbine gear is drawn.