Actuation with Terfenol-D

Abstract

The magnetomechanical properties of Terfenol have been determined by two independent experimental techniques. Measurements on several samples of the same nominal compositions made by free-float zoning reveal variations in quality. With a novel technique for scanning along the length of a Terfenol rod, structural defects can be detected which may explain these variations. A difference between magnetostrictive surface and bulk strains has been observed, and the frequency response of the former is substantially different from theoretical predictions, casting doubt on techniques for the characterization of Terfenol which involve the use of dynamic (AC) fields to measure the magnetostrictive strain coefficient. A description of the control strategies used to implement the actuation of Terfenol-based transducers is given.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>