Nonlinear dynamic characteristics of a micro-vibration fluid viscous damper

This study is concerned with the nonlinear dynamic characteristics of a micro-vibration fluid viscous damper used in a satellite. When a control moment gyroscope is working, it produces micro-vibrations, which is a disadvantage for imaging equipment. Taking a single-tube micro-vibration fluid viscous damper as our research subject, a nonlinear dynamic model of the micro-vibration fluid viscous damper under harmonic excitation is proposed. Then, the analytical form of the pressure gradient force is derived. Considering the entrance effect in the orifice, the nonlinear elastic force and nonlinear damping force are analyzed. The results reveal that if the entrance effect is not considered, the elastic force and damping force are linear forces. When the entrance effect is considered, the damper has a nonlinear elastic force and a nonlinear damping force. These nonlinear forces are related to the orifice length, diameter, fluid viscosity, excitation amplitude and frequency. In the low-frequency domain, the differences between the two cases are small, while in the high-frequency domain, they are considerable.