Study of liquid viscosity dampers in octo-strut platform for whole-spacecraft vibration isolation

Whole-spacecraft vibration isolation is a direct and effective technique toward improving the dynamic environment that a spacecraft experiences during its journey to the orbit. Liquid viscosity dampers are the major component of an octo-strut vibration isolation platform for isolating the vibration of the whole spacecraft. To study the model and influence factors of the damper on the performance of the platform, a three-parameter dynamic model of the single strut is built, in which the effective elasticity of the liquid volume as a part of the strut is represented by a spring in series with the damper. By modeling the vibration isolation platform with Newton–Euler method, the design parameters of a single strut are defined by achieving optimal isolation performance along the longitudinal direction. From numerical analysis results with a rigid spacecraft and a flexible spacecraft on the top of the platform, it is found that the elasticity of the liquid volume is a key factor in defining the transmissibility. With a proper choice of the effective elasticity of the liquid volume, a better isolation performance than the commonly used two-parameter strut can be obtained.