Hydrodynamics and energy dissipation in a ferrofluid damper

Abstract

A ferrofluid damper with a simple structure is proposed. Hydrodynamics and energy dissipation in the damper are studied theoretically and experimentally. This is applied to the study of damping of a cantilever whose free extremity is installed with the ferrofluid damper. The dependences of the decrement of the oscillations on the geometrical characteristics of the damper are described by a theoretical model and are shown to predict the experimental result well under some conditions.

Damping Applications of Ferrofluids: A Review

“…Researchers from China [50][51][52] have shown great interests in ferrofluid dynamic vibration absorbers, and one of their proposed structures is shown in Fig. 18.…”

A novel magnetic fluid shock absorber with levitating magnets

“…But more interestingly, in order to eliminate the local oscillation of the solar panels and antennae, several shock absorbers using the unusual self-levitation of an immersed magnet are proposed in [15][16][17][18]. The unique buoyancy phenomenon is defined as the second kind levitation principle of ferrofluid in [19,20].…”

“…In particular, a magnetic fluid shock absorber is presented in [15], which exploits a magnetic fluid drop with a self-levitating permanent magnet as a dissipating element when the external oscillations are applied. Its excellent performance with small amplitude (less than 1mm) and small frequency (less than 1 Hz) is best for removing the vibration problems in spacecraft technologies.…”

Magnetic levitation force exerted on the cylindrical magnet in a ferrofluid damper

“…The self-levitation technique is the base of many applications like sensors (He and Li, 2009), dampers (Berkovsky et al., 1993), bearings (Masafumi et al., 2000), microactuators (Assadsangabi et al., 2014) and some types of seals (Ravaud et al., 2010) using ferrofluid. Especially in the field of ferrofluid dampers, the principle depends completely on the magnetic levitation force exerted on the magnets immersed in ferrofluid (Yang et al., 2013). Take the ferrofluid damper proposed by us in (Yang et al., 2013) for example, it consists of ferrofluid around a cylindrical permanent magnet (or an annular permanent magnet) placed in a cylindrical nonmagnetic tube as shown in Figure 1 where the magnet is magnetized with a constant magnetization in its axial direction.…”

“…Especially in the field of ferrofluid dampers, the principle depends completely on the magnetic levitation force exerted on the magnets immersed in ferrofluid (Yang et al., 2013). Take the ferrofluid damper proposed by us in (Yang et al., 2013) for example, it consists of ferrofluid around a cylindrical permanent magnet (or an annular permanent magnet) placed in a cylindrical nonmagnetic tube as shown in Figure 1 where the magnet is magnetized with a constant magnetization in its axial direction. It is because of the levitation force exerted on the magnet that the levitation can be stable.…”