Magnetostrictive Actuators

This article demonstrates that materials that change their shapes when exposed to magnetic fields can now be used to drive high-reliability linear motors and actuators. The concept of magnetostriction effect has been the focus of efforts by engineers at ETREMA Products Inc. in Ames, Iowa, to device simple, high-reliability linear motors and actuators. The development of compact, low-voltage motors will offer advantages in applications in which high-force, extended-stroke, high-precision, and fail-safe-operating characteristics are required. ETREMA researchers are looking to improve Terfenol-D using material characterization methods, schemes to enhance the available strain, and better magnetomechanical design techniques. In the Terfenol-D-actuated device, an advanced-design wing flap incorporates multiple deployment segments that would smooth the airflow over the upper surface. During manufacture, Terfenol-D is melted, cast, and directionally solidified to provide the crystalline microstructure required to produce large strains. The strain and actuation force available from Terfenol-D are superior to those of other smart shape-change materials.