Static And Dynamic Characteristics Of Disc Aerostatic Thrust Bearing And Methods Of Vibration Suppression

Gas bearing,with its advantages of low friction loss,small temperature rise and error homogenization,greatly reduces the errors caused by friction,heating and deformation between moving parts.It has become one of the key components of ground microgravity environment simulation experiment and precision/ ultra-precision machining.However,the vibration caused by gas flow in gas bearings can still not be ignored,especially the unsteady pneumatic hammer vibration,which directly leads to the instability of gas bearings to be unable to work.It is one of the major factors restricting the gas bearing structure to achieve high capacity,stiffness and accuracy.It has important engineering application value to discuss the effective method of restraining the self-excited vibration of gas bearing.In order to make a preliminary discussion on the principle,the disc-shaped aerostatic thrust bearing with single orifice compensation is selected as the research object.In this thesis,the static and dynamic characteristic of this kind of bearings are mainly analyzed,and the methods to reduce the self-excited vibration of aerostatic bearings are discussed.The research contents and results of this thesis are as follows:1.Based on the theory of gas hydrostatic lubrication,the static characteristic analysis model of gas bearing is established.The influence of four parameters on the static characteristic of gas bearing is studied and analyzed,which are supply pressure,film thickness,orifice radius and bearing radius.It provides reference and guidance for the parameter design of gas bearing.2.By disturbing the gas bearing,the dynamic characteristic analysis model of the gas bearing is established.By methods of numerical simulation,the influence of the variation of supply pressure and film thickness on the dynamic stiffness and damping of gas bearing are studied and summarized,and the mechanism of self-excited vibration of gas bearing is revealed.3.For the divergent gas bearing self-excited vibration system,the Tuned Vibration Absorber(TVA)and the Nonlinear Energy Sink(NES)are introduced to suppress the self-excited vibration of the system.Both kinds of vibration absorbers can suppress the self-excited vibration of gas bearings,but when the natural frequency of the vibration absorber is far away from the natural frequency of the system,the vibration suppression effect of NES is more stable.4.Due to the common "over-slit" working conditions in ground microgravity environment simulation experiments,the variation of bearing capacity of gas bearings at different slit positions is analyzed,and the effect of NES on vibration of gas bearings in “over-slits” is studied.The results of theoretical analysis and numerical simulation in this paper show that: from the point of view of dynamics,it is feasible to suppress the self-excited vibration of aerostatic thrust bearings by using NES;however,from the point of view of Engineering application,the realization of NES still faces challenges,which need to be discussed from the aspects of new materials and new structures.