Investigation On Micro-Vibration Isolation Technology For Typical Units Of Spacecraft

In order to fulfill the requirement of developing science andtechnology, the payloads onboard spacecraft with high pointing precisionand stability and fine observation resolution are becoming much moredemanding. The micro-vibration disturbance from spacecraft on-orbitoperation has become a bottle neck which restricts the effective use ofhigh sensitive payloads. Among all the disturbances, the main one iscaused by normal operation of spacecraft attitude and orbit control units,such as momentum wheels (MW), reaction wheels, flywheels and controlmoment gyroscopes (CMG). So it is necessary to suppress suchdisturbances. This thesis analyzes the micro-vibration isolation system ofspacecraft attitude control units for two satellite models with differentarrangements. For oneof them, the octo-strut parallel vibration isolationplatform with each strut composed of a three-parameter viscous fluiddamping is used for CMG units micro-vibration isolation, the isolation performance is analyzed, and the optimization of characteristic parametersof the isolation platform is performed. For the other one, a new type ofisolator as named as elastic planar cable net vibration isolation device isproposed for MW units. The dynamic properties of the device areinvestigated theoretically, and experiments are conducted to verify thevibration isolation efficiencyof thedevice and study the influence ofstructural parameters on the isolation performance. The study can providetheoretical basis and reference for further design.In Chapter1, the background and significance of the investigation, aswell as the main content in this thesis is introduced. Reviews onmicro-vibration isolation technology for spacecraft are presented,especially the isolation of attitude and orbit control units are summarized.In Chapter2, the dynamic properties of the octo-strut parallelvibration isolation platform with each strut composed of a three-parameterviscous fluid damping for CMG units are analyzed based on ANSYSsoftware. The finite element modeling process of the octo-strut parallelvibration isolation platform is introduced first, which is followed by thedynamic analysis of model, as well as the investigation of isolationperformance of such a platform. Work in this chapter is the base of isolatorparameters optimization. In Chapter3, the Frequency Response Function-based (FRF-based)substructuring method is used to optimize the characteristic parameters ofthe octo-strut parallel vibration isolation platform. Firstly, the isolationsystem is divided into several independent substructures, and the FRFmatrice or the transmission matrice of each substructure is deduced. Then,the relationship between input and output of the isolation system isderived via the displacement continuation and force equilibrium betweendifferent substructures. Next, the optimization model is developed forchoosing appropriate optimization objectives, and sensitivity analysis isadopted to optimize characteristic parameters of the isolation platform.In Chapter4, according to the micro-vibration isolation requirements,a new type isolator named as elastic planar cable net vibration device isproposed. The dynamical characteristics of a tensioned string, which formsas the basic element of the cable net, is investigated. Then an equivalentnonlinear SDOF model was used to investigate the nonlinear dynamicresponse of the cable net based on the results derived previously.In Chapter5, Experiments on elastic planar cable net vibration deviceunder different working conditions are conducted to verify the vibrationisolationefficiency. Some valuable conclusions are acquired through theexperiments, which can provide some useful guidelines for further design.