Magnetic Circuit for Stress-Based Magnetic Force Control Using Iron-Gallium Alloy

We propose a stress-based magnetic force control method using the inverse magnetostrictive effect. A basic magnetic circuit consists of iron yokes, permanent magnets, and magnetostrictive material by which compressive stress applied to the material is converted to variations in the magnetic force. The characteristics of the force, such as bias, variation and sensitivity, depend on the inverse magnetostrictive properties of the material. In this paper we investigate the suitability of Galfenol, iron-gallium alloy, which has large permeability and high saturation. Measurements of the relations between stress and strain, flux density, and magnetic force in series and parallel magnetic circuit with a rod of Galfenol or Terfenol-D under compression show the advantages of Galfenol and clarify the design criteria for the magnetic circuit in future applications