Theoretical Modeling And In-situ Optical Observation Of Mixed Lubrication Considering Restricted Solid Particles

In reality,because the surface of mechanical parts is rough and uneven,so the problem of friction energy consumption has been troubling us all the time.In engineering practice,grease lubricated parts such as gears,bearings and worm gears work in mixed lubrication under low speed,heavy load and low viscosity lubricants.In recent years,people have gradually deepened their understanding of mixed lubrication,and put forward the concept of mixed lubrication state,that is,there are film lubrication,boundary lubrication and fluid lubrication in the contact zone at the same time.In the actual contact process,because of the existence of abrasive wear,solid particle flow lubrication medium,abrasive particles and bonding particles formed in the friction and wear process,it often constitutes a mixed lubrication system with a third body.In this paper,based on the autoregressive model,the rough surface and rough contact state of Gauss were simulated by two-dimensional digital filtering and fast Fourier transform.The modified average flow Reynolds equation,G-T contact model and liquidsolid two-phase flow model was used to establish the mixed lubrication model with thirdbody particles,then study the effects of particles on the friction characteristics of point contact mixed lubrication.The G-T contact model was used to calculate the actual contact area between the micro-convex body and the micro-convex body.The binomial flow model was used to calculate the load and shear forces of particles.The average flow Reynolds equation was used to calculate the fluid carrying capacity and friction force of lubricant film.The surface elastic deformation and film thickness were calculated according to the above load.Then,we calculated the friction force and coefficient of friction on the mixed contact surface with particles.This paper considers the actual situation of the lubrication interface and particles from the macroscopic point of view,and improves the situation of neglecting the influence of particles in the previous mixed lubrication model.In order to verify the accuracy of the model,reciprocating friction tests was carried out based on optical in situ method.The test content mainly introduces the construction of reciprocating friction test bed,the principle of measurement and control system,test scheme and basic steps.The distribution of particles in the mixed friction interface was analyzed by experiments.The friction characteristics of the mixed lubrication is analyzed by four factors: root mean square roughness,particle concentration,sliding speed and load.In this study,the theoretical model and calculation method were proposed to determine the friction characteristics of the mixed lubrication with particles,which filled the blank of the study on the influence of particles on the mixed lubrication interface,and explored the effect of particles on the friction surface of mechanical parts.