Inducing rotation and levitation in magnetostrictive wires and rods: correlated amplitude and frequency of exciting ac axial magnetic field

摘要

Magnetostrictive wires and ribbons spontaneously rotate under the excitation of an alternating axial magnetic field of suitable frequency and amplitude. This surprising effect is here exploited to induce high-speed rotation (several tens of Hz) in wires and rods. It is shown that the values of frequency and amplitude of the exciting field, that determine the rotation of the sample, are correlated. In particular, a shift of the resonance frequencies is observed when the field amplitude increases. This shift seems to be related to the change of the Young's modulus with the applied field induced magnetostrictively. This induced rotation is also studied in samples that levitate under the action of the non-homogeneous exciting field. (C) 2003 Elsevier B.V. All rights reserved. [References: 11]