Influence of distribution parameters of rough surface asperities on the contact fatigue life of gears

Abstract

The influence of the distribution parameters of asperities, i.e. mean radius of curvature of asperities β, density of asperities η, and standard deviation of asperity heights σ, on the contact fatigue life of gears is first studied in this paper. Based on the elastic–plastic contact model of asperities, the surface contact pressure and subsurface stress field during the gear meshing process are calculated by the iterative calculation method. According to the multi-axis fatigue life model, the calculation method of fatigue life under different distribution parameters of asperities in the gear meshing process is obtained. The quantitative calculation results of fatigue life and measured distribution parameters of asperities are analyzed. The relationship between the fatigue life and the distribution parameters of asperities on the measured gear surface is calculated and analyzed quantitatively. The following conclusions are drawn: (1) when the roughness value Ra is less than 0.3 µm, the contact fatigue life of gears with rough surfaces is close to that of smooth surfaces; (2) when the roughness value Ra ranges from 0.5 µm to 0.9 µm, the contact fatigue failure occurs near the surface (micro-pitting); (3) under the same roughness value Ra, the contact fatigue life of the gear decreases with the decrease of the density of the asperity and the mean curvature radius of the asperity. The mean radius of curvature of the asperity has a greater influence on the contact fatigue life than the density of the asperity.

Correlation between surface roughness parameters and contact stress of gear

“…With the help of a single-peak contact model of a single asperity and 3D rough surface contact model based on asperities parameters in Wen et al, 43,44 surface stress and shear stress of the workpiece surface can be obtained under a given load. Similar to the work of others, [21][22][23][24][25][26][27][28] for the convenience and efficiency of the calculation of contact model, the interaction between asperities is not taken into account.…”

“…To solve this problem, Wen and Tang, 17 Wei et al, 18 Wen et al, 19 and Wang et al 20 used the elastic-plastic mechanics theory to propose that in the meshing and contact analysis of rough tooth surface, the plastic hardening of asperities resulted in complicated influences of surface roughness on tooth surface contact. At the same time, some researchers put forward a series of contact models [21][22][23][24][25][26][27][28] to analyze the influence of asperities on rough surfaces. The above analysis shows that the influence of tooth surface roughness on gear contact or fatigue performance cannot be ignored.…”