A Theoretical Study on the Influence of Frequency on the Dynamic Characteristics of Air Film

Abstract

A general method is developed to deal with the compressibility of air film and to predict the linear dynamic stiffness and damping coefficients of air-lubricated bearings over the whole range of frequency. Numerical results reveal that both stiffness and damping coefficients are functions of not only the static parameters such as eccentricity and attitude angle, but also the frequency of disturbance. The coefficients are continuous and tend to certain values even when the frequency approaches zero or positive infinity. In general, the direct terms of the dynamic stiffness increase with the increase of the frequency, while the cross-coupling terms tend to an equal value when the frequency becomes infinite, and all the damping coefficients decrease in the higher frequency region and vanish when the frequency approaches positive infinity.