Research on nonlinear stiffness and damping of bellows-type fluid viscous damper

Abstract

Micro-vibrations in satellites mainly originate from the control moment gyroscope because of its mass imbalance, which seriously affect the image accuracy of high-resolution optical payload, so it must be isolated. Bellows-type fluid viscous damper (FVD) can be used to isolate micro-vibrations. In this paper, a simplified model of the damping element in bellows-type FVD under medium- and high-frequency excitation is proposed according to the concept of bellows effective area. Based on this theoretical model, nonlinear stiffness and damping at different design parameters are extracted by nonlinear fitting method. Then, the main cause of nonlinear stiffness and damping is analyzed by the velocity distribution in the cross section of damping orifice. The factors that affect the intensity of nonlinear stiffness and damping are discussed by using the flow resistance. The results show that the velocity term in the corrected hydraulic resistance is the cause of nonlinear damping and stiffness. Damping orifice diameter, length and silicone oil viscosity will affect the intensity of nonlinear characteristics of this damper. At low viscosity, the nonlinear damping is more obvious. The larger the diameter, the more obvious the nonlinear damping. In the frequency domain between 1 and 200 Hz, the velocity index is not a constant, but changes with frequency. Hydraulic stiffness can be divided by linear stiffness and nonlinear stiffness; both of them can affect the elastic force.