Abstract
Micropitting is a typical surface contact fatigue in rolling–sliding contact. The kinematic sliding is of great significance in the initiation and progression of micropitting. A numerical surface fatigue model considering rolling–sliding contact and surface evolution is developed based on mixed-EHL (elastohydrodynamic lubrication) theory, rainflow cycle counting method and Archard’s law. Surface evolution is evaluated using Archard’s wear law based on measured teeth surface topography. Surface damage is determined via the Palmgren–Miner line rule and Goodman diagrams. The effect of rolling speed and surface roughness are discussed in detail. Results show that stress micro-cycles are introduced by rough sliding in the rolling–sliding contact. The mild wear reduces the height of asperities, the maximum pressure and alleviates subsurface stress concentration. For rolling–sliding contact, the faster moving surface dominates the composite height of asperities, then decides the fluctuations of pressure, as well as stress ranges. The combination of surface topography should be considered in the surface design.
Highlights
Micropitting is a typical surface contact damage widely reported in operating bearings and gears
It is understood that micropitting is highly associated with rolling–sliding motion, surface topography as well as lubricant condition
As a type of contact fatigue at roughness asperity level, micropitting is heavily affected by severe stress concentration near the surface, in both the magnitude, as well as cycles, of stresses [1]
Summary
Micropitting is a typical surface contact damage widely reported in operating bearings and gears.If left unchecked, micropitting can further lead to pitting, spalling or tooth flank breakage. Micropitting is a typical surface contact damage widely reported in operating bearings and gears. It is understood that micropitting is highly associated with rolling–sliding motion, surface topography as well as lubricant condition. As a type of contact fatigue at roughness asperity level, micropitting is heavily affected by severe stress concentration near the surface, in both the magnitude, as well as cycles, of stresses [1]. The interaction of lubricants and asperities, the presence of sliding, and the variation in geometry generate micro-contacts at the interface that can greatly influence the stress cycles [2]. A micropitting model should incorporate the effects of kinematical sliding and mixed lubrication. The coupled effect of the surface roughness evolution and damage accumulation is of great importance for micropitting analysis
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