Magnetostrictive elastic wave-type linear motion with Terfenol-D

Abstract

Magnetostriction means change of shape of material in the presence of a magnetic field, with the degree of this change proportional to the strength of the magnetic field. The magnetostrictive TERFENOL-D expands in length and contracts diametrically, thereby conserving the volume of an essentially incompressible material. The magnetostrictive effect generates the elastic forces in accordance with a generalized Hooke's law. The principle of magnetostriction of TERFENOL-D can be used in the development of linear motion devices. In an elastic wave type linear motion, the `smart material' TERFENOL-D is enclosed with an interference fit in a stator tube which is enclosed in a series of coils that generate the magnetic field when power is applied. The pattern of activation of these fields is controlled by a digital controller which will enable the TERFENOL-D `smart material' to move inside the stator tube like a worm. During this motion, the TERFENOL-D rod can push and pull loads. When power is turned off this device will lock itself in the stator tube without any slippage. Some of the important applications are nano positioning, aircraft wing warping, airplane/helicopter flap/tab positioning and control, automobile brakes, controlled delivery of fluids, and space applications.