Numerical Simulation And Experimental Investigation Of The Static Characteristics Of A Vacuum Preloaded Aerostatic Bearing

Aerostatic bearings have a great number of advantages, such as substantially lowfriction, absence of contact, high accuracy of motion and cleanness. Therefore they havebeen widely used in many applications such as precision/ultra-precision metrology systemsand lithography associated fabrication equipments. Compared with traditional aerostaticbearings, vacuum preloaded aerostatic bearings have attracted researchers’widespreadattentions, because of the extra strengths such as much higher and double diretion staticstiffness, excellent environmental adaptability. However the presence of vacuum chambersand associated rarefaction effects make it difficult to numerically predict bearingcharacteristics due to the lack of pertaining theories in lubrication and vacuum science.The static characteristics of vacuum preloaded aerostatic bearing is investgated by theconbination methods of theoretical analysis, simulation and experiment in this thesis.First, the three dimension mechanics model of vacuum preloaded aerostatic bearing iseatsblished by theoretical analysis. Then, the fluid simulation modals of vacuum preloadedaerostatic bearing are built up based on compressible ideal gas. The calculation analysis ofpressure distrbution and static characteristics is accomplished using fluent software. Thecurves of load carrying capcity&thickness and static stiffness&thickness are acquired.Some disciplinary conclusions on the influence of the supply pressure and the vacuumpressure are drawn. What is more, a test bench was constructed which made it possible tomeasure the static load carrying capacity, the thickness of the air film and air consumptionunder different supply pressure and vacuum pressure values. An orthogonal experimentdesign was constructed to optimize the experimental measurement. At last,the experimentalresearch on the static characteristics of vacuum preloaded aerostatic bearings areaccomplished to make sure that the simulated result is credible and authentic. Regressionanalysis was performed on the experimental results to obtain an analytical model of the bearing stiffness as a function of the load carrying capacity, air supply pressure and vacuumpressure. Accuracy of this analytical model in predicting static characteristics of theaerostatic bearing was validated by comparison with experimental data.