Modeling and parametric research of a bellows-type fluid viscous damper with annular damping gap for spacecraft micro-vibration suppression

Micro-vibration is an important issue that affects the observation accuracy and imaging quality of spacecraft. The micro-vibration of spacecraft has the characteristics of wide frequency (1–300 Hz) and low amplitude (μm level). Installing a micro-vibration isolation device on a disturbance source or precision payload is an effective method to suppress micro-vibration. In this paper, we propose a novel modeling method for a micro-vibration isolator with annular damping gap. Firstly, by cleverly utilizing the principle of effective area of bellows, the complex bellows are simplified into a single tube. Based on the axial vibration of the bellows, springs are used to equivalent the elasticity of the bellows, and the interaction between the fluid and bellows is considered in the model. Through this method, we greatly simplify the isolator and constructed a semi-analytical model. Then, we use the fluid–structure coupling analysis to evaluate the difference in describing the volume deformation between the single tube and the bellows with different wall thicknesses, and then propose a novel solution. We introduce the bellows volume deformation correction coefficient to modify the model. The effectiveness of the correction method for isolators with different wall thicknesses is discussed. Next, we conduct parametric research to analyze the influences of different wall thicknesses, viscosity, damping gap width and length, and excitation force amplitude on the isolation performance. Through our research, it is found that this annular damping gap has better adjustability for isolation performance than the damping orifice, which may help propose more combinations of design parameters suitable for different isolation performance requirements. Our proposed model is suitable for fluid viscous damper working at the frequency of 1–300 Hz, that used for spacecraft micro-vibration suppression (including magnetorheological dampers and adjustable damping orifice fluid viscous damper).