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Abstract

With the maturity of manufacturing process for the giant magnetostrictive material called Terfenol-D, high force and high precision actuators can now be realized at a reasonable cost. These actuators can be used in many applications, one of them being the control of machine chatter vibration. This violent phenomenon is one of the limiting factors on how fast a metal-cutting operation can proceed. In chapter 1 a discussion of chatter vibration is presented. Terfenol-D possesses some unique properties that affect actuator design; therefore an understanding of the magnetoelastic mechanism is essential. A basic discussion of magnetic material is first presented in appendix A; then properties unique to Terfenol-D are discussed in chapter 2. The design of the actuator at UBC is presented in chapter 3. It incorporates many features not found in existing designs. In particular, the push-pull configuration makes it suitable for applications requiring bi-directional movements. Preliminary test results of the device built are presented in chapter 4. Before Terfenol-D can be widely used, however, the problem of modelling and control has to be solved. Because of hysteresis and other nonlinearities, ordinary linear design techniques may not be applicable. Some promising nonlinear control strategies based on Preisach model and neural networks are discussed in the last chapter.