Analysis Of Elasto-hydrodynamic Lubrication On Ceramic Materials With Surface Texture

Taking the friction reducing effect of surface textures as background,this dissertation analyzes the micro-elastohydrodynamic lubrication（MEHL）problems numerically based on the ceramic materials widely used in modern industry,which aims to provide references for ceramics usage and surface design in engineering practice.It includes five parts from simple to complex:study on the thermal lubrication mechanism under steady-state conditions;discussion on the MEHL problems of ceramics surface with Gaussian random profile;analysis of transient MEHL based on transverse surface textures;the rheological model of different lubricating oils and the transient MEHL of various combinations of surface textures.Firstly,lubrication mechanism of thermal effect was discussed by using three ceramic materials with different properties.The influences of thermal conductivity,moving parameter,and contact size on lubrication performance were discussed.The differences in viscosity,film thickness and friction coefficient based on the thermal viscosity wedge mechanism were clarified,which provides a valuable reference for the selection of various ceramics from the perspective of lubrication.Moreover,the ZrO₂-Steel contact pair was selected to study the problem of quasi-steady state MEHL problems of solid surfaces with Gaussian random surfaces.The effect of root mean square and texture direction of Gaussian random surfaces on pressure,film thickness,temperature,and friction coefficient were investigated in detail.Furthermore,the work was extended to the time-dependent problems caused by the movement of the contact solids with transverse textures.The influence of relative positions of micro morphology,the wavelength of the transverse surface topography,and the contact size on the lubrication performance were revealed.Finally,based on Eyring and Carreau rheological models,the lubricating properties of three different lubricants are discussed.Then the Carreau model considering the transient effect were used to analyze the MEHL problems of solid surfaces with different combinations of textures.The coefficients of friction under various combinations were compared,which provides a theoretical reference for the study of ceramic surface textures on antifriction properties.