Study On Liquid-Solid Lubrication Considering Particle Behaviors

It has been known for many years that various types of particles that come from wear and environment dispersed in oil during the operation of hydrodynamic tribological pairs and formed so called liquid-solid lubrication. Interactions between particles and oil, particles and bounding surfaces of tribological pairs will greatly affect the performance of tribological pairs. Therefore research on liquid-solid lubrication is significant both in theory and practice. This dissertation researches the liquid-solid lubrication both theoretically and experimentally.A mixed liquid-solid lubrication model is studied which considering rheological Reynolds equation, viscosity of liquid-solid lubricant equation, density of liquid-solid lubricant equation. The load carrying of spherical particle and the contacting equation of asperities of surface are also introduced in the model. The results show that it is closer to the reality to do research on liquid-solid lubrication considering surface roughness , the load carrying capacity of particles, asperities and oil has a great relation to average oil film thickness, particle concentration, particle diameter, particle yield stress, surface modulus of elasticity and so on.The effect of solid particles distribution on the liquid-solid lubrication is discussed. The governing lubrication equation for the liquid-solid lubrication is established with the consideration of particles location, diameter and the distance of particles. Based on finite element method, the modelling equation is solved numerically. It shows that a noticeable pressure build-up occurs near the particles, particles distribution have a big effect on pressure distribution and oil load capacity.Based on Eular-Lagrange model, liquid-solid lubrication considering moving particle behaviors is deeply studied. It is shown that: there are three kinds of particles movement forms in lubrication system, which are escaping form inlet, escaping from outlet and encircling near the inlet of lubrication area. The initial location of the particle has a big influence on particle movement, and the velocity of tribological pairs and the viscous of oil also have some influence on it.Using end-face friction and wear tester made by our institute, an experiment of liquid-solid lubrication is designed, the effects of particle properties, sizes and concentration on liquid-solid lubrication are studied by online measurement of the friction pair's temperature and friction coefficient. In summary, both static behaviors and dynamic behaviors of particles on liquid-solid lubrication are studied in this dissertation, a proper experiment designed and carried out. The research results will play an important role on promoting the development of liquid-solid lubrication theory.