Terfenol-D magnetostrictive linear motor

Actuators and linear motors are a common way to provide single axis motion and force. Rackand pinion, chain, belt, cable, screw, hydraulic and electric solenoid are a few of the manytypes of actuators available. All have inherent strengths and weakness such as powerconsumption, mechanical failure and usually a trade off with speed and resolution.The thesis investigation is to develop a linear motion actuator based on the magnetic material,Terfenol-D which alters its shape when subjected to a magnetic field. This phenomenon isknown as magnetostriction which can be defined as a changing of a material's physicaldimensions in response to its magnetization. Terfenol-D has the largest knownmagnetostriction, 2000ppm at ambient temperatures [1], of all commercially availablematerials. Because of these large strains it is given the term Giant Magnetostriction (GM).In Terfenol-D the GM is dependent on the direction of the applied magnetic field with respectto the direction in the crystal: the material elongates in the direction of the field and,orthogonal to this, the material contracts within the principal of constant volume.This property has been exploited by other researchers in the past resulting in Terfenol-D beingused as a short stroke conventional actuator in applications requiring large force at both highand low frequencies, generating a range of applications including surgical instruments,ultrasonic transducers and many others. It is this property of Terfenol-D that will be exploitedin this project in the development of the magnetostrictive linear motor.Stepping motors based upon Giant Magnetostrictive (GM) materials are more complexactuators than those based on a more conventional design. To get a long stroke, they use theaddition of several small steps, each produced by quasi static deformation of the GMmaterials.In this project the Kiesewetter Elastic Wave Motor using Terfenol-D, as referenced in theabstract, was used as the starting point for the design of a new Terfenol-D based motor. Inparticular, the project investigates different topologies of Terfenol-D in the design andconstruction of a Magnetostrictive Linear Moto