Rotary magnetostrictive motor using helical magnetic field

This paper presents a proof-of-concept of a rotary magnetostrictive motor (MAGMOTOR) using helical magnetic field, BH. The helical magnetic field is made when a longitudinal magnetic field and a circumferential magnetic field are applied simultaneously to the Terfenol-D rod of length L, fixed at one end. The circumferential magnetic field is established by a current-carrying specimen on the axis of the rod specimen instead of being established by a toroid. The concept of the MAGMOTOR is the utilization of an intrinsic property of a giant magnetostrictive material, i.e., Terfenol-D. The magnetic circuit modeling is used to obtain the input values for the simulation. The simulation results clearly reveal the generation of the helical magnetic field along the Terfenol-D rod. In addition, the magnitude difference in BH between a current-carrying and a toroid MAGMOTORs is estimated to be 3 percent. The prototype is made and subjected to the experimental characterization. The rotational speed of the rotors increases with the increase of both current and frequency, and then decreases with further increase of the both. The peak rotational speed reaches 16 rpm at a frequency of 400 Hz with a rotor weight of 2.7 g.