硅基超短微空气径向轴承的非线性动态特性研究

Study on Nonlinear Dynamic Characteristics of Ultra Short Micro Silicon-Based Air Journal Bearings

考虑稀薄效应及黏性摩擦力的影响,对润滑方程和运动学方程耦合求解,研究了考虑与不考虑黏性摩擦力2种情况下超短微空气径向轴承-转子系统的稳态及非线性动力学特性。结果表明:宽径比小于0.2时,黏性摩擦力对系统的稳态性能及非线性性能影响较大;随着轴承数的增加,系统由周期运动逐渐过渡到混沌运动;考虑黏性摩擦力时的转子中心振动幅度、运动状态及转折点比不考虑黏性摩擦力时均有较大变化,且转子在轴承数较大时出现2倍周期运动;不考虑黏性摩擦力下系统在高轴承数下呈现低频涡动,且幅度较大;黏性摩擦力对超短微空气径向轴承-转子系统的影响不可忽略。

The steady - state and nonlinear dynamic characteristics of ultra short micro air journal bearing - rotor system in the cases of with and without viscous friction force considered are studied with the consideration of rarefaction effects and viscous friction force. The lubrication equations are systematically coupled with the kinetic equations and solved simultaneously. The results show that the inlluences of viscous friction force on steady - state and nonlinear dynamic charac-teristics of system become more important when the width diameter ratio is less than 0.2. The motion state of system varies from synchronous motion to chaotic motion as the increase of bearing number. If the viscous friction force is taken into account, the vibration amplitude of rotor center, motion state and turning point will be quite different, especially in large bearing numbers, for which the system exhibits 2 - period motion. If the viscous friction force is not taken into account, the system has low frequency whirling motion with larger amplitude under large bearing numbers. As a result, the influence of viscous friction force on ultra short micro air journal bearing - rotor system should not be ignored.