Research On The Performance Of Reaction Wheel Vibration Isolator Based On Manganese-copper Alloy Spring

With the rapid development of space technology,the imaging environment required by optical sensitive equipment for satellite is also increasing.When the spacecraft is in orbit,the reaction wheel,the control moment gyro and the antenna driving mechanism will produce a series of micro-vibrations with small amplitude and wide frequency band.This kind of vibration will affect the quality of the image and lead to blurred image.At present,micro-vibration isolation and test technology has gradually become the key technology to ensure the orbit operation of high resolution remote sensing satellite.Reaction wheel is a common attitude control device for modern high resolution optical satellites.Under the influence of unbalance of rotor and rotor,the reaction wheel will produce complex harmonic disturbance and noise during operation,which will reduce the stability of optical load imaging.It is found that reaction wheel is the main interference source of satellite micro-vibration through a lot of research and inorbit test.In this paper,taking reaction wheel as the object of vibration isolation,a vibration isolation platform with high damping Mn-Cu alloy spring is designed and its vibration isolation performance is studied.Firstly,the structural components and corresponding functions of the reaction wheel are briefly described,the causes of disturbance and torque are analyzed,the mathematical model of rotor unbalance is established,and the mathematical expressions of disturbance and torque are calculated.The mode,mode shape and damping ratio of reaction wheel were measured by operating mode analysis,and the relevant disturbance data of reaction wheel were collected based on Kistler platform,which laid a foundation for the next step of vibration isolation system dynamics modeling and related microvibration suppression work.Then,a damping test platform was built to test the damping of springs made of different metal materials by using the half-power bandwidth method to verify the high damping characteristics of Mn-Cu alloy.The stiffness characteristics of vibration isolation elements are analyzed.The vertical stiffness of the metal spring can be regarded as a constant,while the force of the horizontal stiffness characteristics is more complex.The metal spring is regarded as a cantilever beam structure with equal section,and the horizontal displacement of the moving end of the metal spring under the influence of both vertical and transverse forces is deduced.The horizontal stiffness of the rectangular coil spring is obtained.Taking the ratio of height to diameter,axial load and the ratio of section to side length as reference variables,the variation rule of horizontal stiffness of rectangular helical spring is discussed,which provides guidance for the design of low stiffness vibration isolation system in the future.Then,the Lagrange equation is used to establish the dynamic model of vibration isolation system,and according to the modal analysis theory,the first six modes of vibration isolation system and the transfer formula are obtained.Based on the bandwidth evaluation index of vibration isolation performance,the spring installation Angle,vertical stiffness,installation distance,height of the center of mass and stiffness ratio between diameters and axes were designed.At the same time,the rectangular coil spring is used as the vibration isolation element,and the finite element method is used to analyze its stiffness characteristics,and then the best configuration of vibration isolation element is selected.Finally,the finite element method is used to analyze the modal and vibration transmission characteristics of the vibration isolation system,and the vibration suppression performance under each degree of freedom is discussed.The modal method is used to test the transfer rate of vibration isolation system and verify the transmission characteristics of vibration in six directions.The Kistler micro-vibration test platform was used to measure the micro-vibration of reaction wheel after vibration isolation,and the damping effect of vibration isolator was analyzed and verified.The results show that the high-damping Mn-Cu spring vibration isolation platform has significant vibration isolation effect in the six disturbance directions and the range of middle and high frequency,and the vibration isolation effect is more than 40 d B at the 1000 Hz main frequency vibration.The vibration isolation system reduces the micro-vibration by one order of magnitude after suppressing the vibration of the reaction wheel,and the vibration reduction percentage of the maximum vibration amplitude in the Fz direction reaches 92.42 % at the speed of 0～2500 rpm.