Theoretical And Experimental Research On Gas Squeeze Film Levitation

Gas squeeze film lubrication is a new lubrication method. The gas between the two parallelsurfaces is constantly squeezed due to high frequency vibration produced by piezoelectric actuator orother ways, then the pressure of the gas in the gap increases, and levitating force is generated.Comparing to other lubrication methods, gas squeeze film lubrication has some advantages of simplestructure, good self-adaptive ability and so on. But its levitation force is relatively smaller than otherlubrication methods, so it is usually used in light load occasions, precision instruments andmicro-machines. Gas squeeze film lubrication has broad application prospect, so the study issignificant. With the development of Micromachining and MEMS techniques, the gas film thicknessbecomes smaller and smaller. Sometimes it can reduce to nanometer scale. In this situation, surfaceroughness and gas rarefaction effect must be taken into consideration.The thesis begins with establishing theoretical model of squeeze film lubrication. Then theReynolds equation is solved by numerical method and the levitation capacity of the gas film isobtained. Furthermore, influences of vibration amplitude, frequency and film thickness on the gasfilm capacity are analyzed. In order to research the influence of surface roughness, theoretical modelof average height model and average flow model are also established. For ultra thin gas film, theinfluence of gas rarefaction effect is obtained by the use of the speed-slip model. At last, combiningeffect of surface roughness and gas rarefaction effect are analyzed.An experiment system is designed to verify theoretical results，which include an frame, forcemeasurement sensor. Then a high precision laser displacement sensor is used to measure the filmthickness. A high speed data acquisition card PCI9114is used to gather the experimental data.Theoretical results and experimental data show that gas squeeze film can induce large levitationforce. Vibration amplitude and film thickness have great influence on it. What’s more, choosingsuitable machining method to get certain surface roughness will increase its levitation capacity. Thispaper also proves that gas rarefaction effect can influence squeeze film when the film is very thin.