Force Optimization and Damping Performance of a Novel Ferrofluid Inertial Damper Based on the Levitation Principle of Ferrofluids

Background Flexible aerospace structures present dynamic characteristics of low natural frequency. For a long-term free-floating spacecraft, theses flexible aerospace structures are prone to vibrate due to various excitation. However, it is extremely difficult to eliminate these low-frequency vibrations. Purpose The main aim of this paper is to verify the damping performance of a novel ferrofluid inertial damper with the optimal stiffness in reducing the low-frequency free vibration of structures. Methods The ferrofluid inertial damper consists of an inertial mass block, ferrofluids, and two magnetic field sources. The inertial mass block is levitated in two layers of ferrofluid absorbed on magnetic field sources. When the main system vibrates, the ferrofluid can generate a very small restoring force and damping force between the inertial mass block and the main system. A series of simulations and experiments are used to optimize the restoring force. Furthermore, the influence of the ferrofluid mass on the restoring force is studied. The damping performance is verified by the free oscillation of a flexible copper plate. Results Two sets of geometric parameters whose restoring forces meet the requirement of the optimal stiffness are obtained. Compared to the copper plate damped by itself, the oscillation time of the copper plate with the ferrofluid inertial damper can be reduced by 97.73%. Conclusion The inertial mass block has a fast response to external vibrations. The ferrofluid inertial damper has very excellent performance for damping the free oscillations of a copper plate.