Semi-active particle-based damping systems controlled by magnetic fields

This paper reports the design of a semi-active particle-based damping system in which a dry magnetic particle bed is used to dissipate the energy of a vibrating piston. The system is magnetized by a magnetic field generated by an electromagnetic coil. Hysteresis-free, ferromagnetic materials are selected for both the piston and particles. The damping efficiency increases as the magnetization of the piston and particles increases up to saturation. Semi-active control is achieved by varying the electric current supplied to the coil, which changes the magnetization and allows for real-time tunability of the damping rate. During the process of magnetization and demagnetization, the damping is reversible and temperature-independent over a wide temperature range. This system can be useful in aerospace, automobile and structural engineering applications, particularly in harsh environments.