Structural damping and self-sensing actuation in Terfenol-D magnetostrictive materials

Terfenol-D magnetostrictive material has been used for actuation but rarely for "reverse" transduction from mechanical to electrical energy. A Terfenol-D transducer produces intense magnetic fields when compressed which are converted into electrical energy by a surrounding coil. This electrical energy can be dissipated in a coil shunt resistor to increase structural damping. During motion, the transducer coil produces a voltage that is proportional to velocity. High Terfenol-D energy density produces high modal damping, as well as high velocity sensor resolution. Terfenol-D has several benefits including low mass, stable properties, lack of fatigue, low operating voltages, and low temperature sensitivity. Models of transducer damping and velocity sensing performance are developed from Terfenol-D properties and transducer geometry. The models are validated by experiments showing modal loss factors up to 0.22, and velocity scale factors of 183 V/(m/s). Velocity sensing is demonstrated simultaneously with actuation, and during damping operation. The feasibility of Terfenol-D transducers for passive damping and selfsensing actuation is supported.