Abstract: Abstract： The microamplitude and multifrequency vibrations can make the system unable to meet the requirements for the attitude precision and stability, which are produced by the highspeed rotor operation in flywheels installed on the spacecraft. Based on the structure of flywheel isolation system, a natural property of the isolator is validated. For the flywheel isolation system with a flexible bracket, a mathematical model is established. The effects on the characteristics of flywheel microvibration are studied, The research results show that the isolator presents a superior property on vibration isolation. The decrease of stiffness of the flexible bracket can help flywheel isolation system suppress the vibrations. The stiffness of flexible bracket can reduce the second order of the system natural vibration frequency, but almost has no effects on the whirl characteristics.

Key words: Keywords：flexible bracket, flywheel, passive isolation, microvibration