Numerical analysis of gear contact fatigue based on machine vision

The traditional macro gear contact fatigue life prediction method was based on the assumption of uniform continuous material, without considering of material microstructure and it was difficulty to describe the influence of real microstructure characteristics on the gear rolling contact fatigue life. In order to break through the limitations of traditional method, a numerical analysis method of gear contact fatigue based on machine vision digital image processing technology considering material microstructure was proposed. Firstly, the real grain morphology of material in the meshing area at the gear node was obtained through characterization experiment. Secondly, the grain morphology image was identified by MATLAB image processing toolbox to generate real micro geometric topology. Thirdly, the constitutive relationship of elastoplastic continuous damage coupling was constructed and the two-dimensional finite element numerical model for gear contact fatigue analysis was established. Finally, the distribution of maximum contact pressure, grain boundary shear stress and grain boundary damage during cyclic loading of gear was studied. The effects of different microstructure characteristics of gear node meshing area on damage were analyzed. The results show that the image processing technology based on machine vision can be applied to simulate the real microstructure of gear material. In the process of gear contact fatigue failure, the maximum contact pressure decreases gradually and the damage of the grain boundaries displays localization phenomenon by degrees with the increasing number of loading cycles. In the later stage of damage, when the image processing method is used to reconstruct microstructure, the damage rate is obviously accelerated. © 2021, Central South University Press. All right reserved.