A Model of Mixed Lubrication for the Repeated Sliding Problem Considering the Reloading Characteristic: Application to Ring/Liner Conjunction

Loading, unloading, and reloading of rough surface contacts are common for most friction pairs. However, usually, only loading characteristic is concerned in the modeling of the cyclic loading problem. In this paper, a comprehensive mathematical model of mixed lubrication was developed for the lubricated friction pairs under cyclic loading. The metal contact was calculated by an improved asperity contact model of elastic-plastic with the loading, unloading, and reloading characteristics in consideration. The developed model was applied to the ring/liner conjunction, as its contact problem was the typical cyclic loading problem. Different from the previous studies, assuming the "virgin" topography of the rough surface, the current one accounts for the plastic deformation of surface asperities, occurring during the first few cycles and leading to the significant roughness modification. It appears that considering the reloading characteristics is necessary, whether it is a Gaussian surface contact or a non-Gaussian surface contact.