RESEARCH ON WHOLE-SPACECRAFT VIBRATION ISOLATION BASED ON PARALLEL LOAD-BEARING AND DAMPING SYSTEM

Whole-satellite vibration isolation is an effective measure to improve the satellite vibration environment. Traditional Whole-Satellite vibration isolation schemes mainly insert flexible and high-damping structures between satellite and rocket. Due to the series of flexible components, the scheme achieves vibration reduction, and also causes a significant decrease in the modal frequencies of satellite branches (satellite, satellite brackets, transition brackets) and the entire launch vehicle with a remarkably increase in satellite vibration displacement. The former seriously affects the flight stability of launch vehicle, especially the stability of final stage, while the latter greatly reduces the dynamic clearance between satellite and fairing, which may lead to collision between satellite and fairing in severe cases. In order to solve the problem of series whole-satellite vibration isolation, this paper presents a whole-satellite vibration isolation scheme with parallel dampers in the original main bearing structure (transition support). This scheme does not change the form and connection relationship of satellite branch structure, and does not affect the strength and stiffness of satellite branch main bearing structure. According to the characteristics of flexible spacecraft, a multi-degree-of-freedom system dynamics model is established. The effects of different damping characteristics on the transmission characteristics near the resonance frequencies of the system are analyzed by simulation. It is concluded that increasing damping can effectively improve the vibration transmission characteristics near the resonance frequencies of the system. A viscous damper and its mounting bracket are designed according to the external excitation characteristics of a launch vehicle, the structural form of transition support and vibration reduction requirement of satellite. By evenly distributing eight vibration reduction units in the transition support, a whole satellite vibration isolation scheme with Parallel bearing and vibration reduction is constructed. Finite element analysis and experimental results show that the variation of satellite branch frequencies is less than 5％ and the transmission characteristics at resonance frequencies are improved by 30％~40％ compared with the non-vibration state.