Both magnetorheological (MR) fluid and ferrofluid, as the liquid magnetic material which can exist in the room temperature, are prospectively used in the field of vibration controls. MR fluid with the micrometre-scale particles greatly increases its apparent viscosity and becomes a viscoelastic solid in the presence of an external magnetic field.
Importantly, the yield stress of the fluid can be controlled very accurately by varying the magnetic field intensity. Hence there have been lots of attempts in using the fluid to develop the active damping devices, such as the vibration isolator of a vehicle suspension [1,2]