Research on the Influence of Mechanical Characteristics of a Ferrofluid Inertial Damper on the Vibration-Damping Performance

The low-frequency vibration is one of the main issues in developing loading Aerospace. Using ferrofluid inertial dampers (FIDs) is an effective method to inhibit these low-frequency vibrations. However, the mechanical characteristics of FIDs need to be better understood.

The main aim of this paper is to design a new FID and propose a suitable method for calculating the ferrofluid buoyant and damping forces.

The FID consists of an inertial mass block (IMB), a nonmagnetic shell, and ferrofluids. The ferrofluid buoyant forces can be calculated by obtaining the profile of ferrofluids based on the Bernoulli equation. The damping forces can be calculated using an expression deduced from the Navier–Stokes and continuity equations. The effect of the ferrofluid mass on the equivalent stiffness and the damping coefficient of FID is investigated by experiment and calculation. A free vibration test of a cantilever beam is used to investigate the vibration-damping performance of FID.

Errors exist between the calculation and experiment of the stiffness and the maximum error is about 30%. The equivalent damping coefficient of FID decreases with the increase of the ferrofluid mass and the maximum is 0.72 kg/s. The vibration attenuation time of initial amplitude with 1 mm can be shortened by 94% when the height inside the shell is 38 mm and the ferrofluid mass is 5.5 g.

Although this calculation method has errors, it is very suitable for preliminary design and optimization of structures due to a small computational complexity. Furthermore, the FID has very excellent performance for damping the free oscillations of a copper plate.