- suspensions of magnetizable particles (iron) dispersed in a carrier liquid
- tangled chains of particles along the field lines
- reversible transition from a pourable liquid to a stiff paste within seconds
Materials of this type, whose properties can be controlled by applying a magnetic field, have a multitude of potential applications, including adaptive shock absorbers and vibration dampers, clutches and brakes.
The damping force in the MRF damper shown above can be switched to any intermediate state between liquid and solid via a magnetic field. The damper also includes a hybrid magnetic circuit with an electromagnet and a permanent magnet, which enables a special fail-safe behavior. Without supply of electric power the permanent magnet generates a medium damping force which can be increased or decreased on demand with the electromagnet.
With the MRF clutch a torque is transmitted via the MRF, whereas the maximum torque is limited by the preset strength of the magnetic field. At higher loads, the clutch slips easily without creating abrasion. The presented clutch in the test facility can transmit a torque up to 50 Nm, but it is possible to construct clutches for a higher torque.