Structure Design And Property Research Of Giant Magnetostrictive Actuators

Giant Magnetostrictive Materials (GMM) has the advantages of high resolution in displacement, great strain, quick response, high force output, energy density and so on, so it is treated as one of the most promising materials in the areas such as hyper-precision machining, electronic technology and bioengineering. GMM has two quite different effects, the Joule Effect and Vallari Effect, which transform energy in contrary directions. The Joule Effect can be applied to precision driver, hydro-controller (pump and valve), sonar system and active damping and noise suppressor, while the Vallari Effect can be applied to develop force sensor, torsion and magnetic field sensor. Nowadays, Giant Magnetostrictive Actuator (GMA) has been the center of research. However, there are still some difficulties in GMA design, as GMM has intrinsical hysteresis and is sensitive to temperature, stress and other factors.This thesis takes the smart materials and hyper-precision machining as the background, and summarizes the advantages and significance of novel micro-actuators applied in the field of hyper-precision machining. Magnetostrictive phenomenon and its reasons, the properties of GMM and its applications in micro-actuators are depicted, which is the necessary basis in the research and application of GMA.The key respects of GMA design is magnetic structure, temperature control structure and the method of designing the whole device. The related factors and designing rules with GMA structure is summarized, and the advantages of applying monolithic method in GMA design is analyzed as well. The research on the relation of GMM designing parameters, the coil's geometry factor and the optimized design of magnetic field is conducted. What's more, a novel water cooling structure consisting of two rooms is given in order to control the working temperature of GMA. The temperature control is achieved by using insulation materials to constrict the conducting of heat and multi cycling rooms to absorb heat outside, so the stability of GMA output is guaranteed. Linear Constitutive Piezomagnetic Equations is introduced into building the dynamic model of GMA. The affection of the system mass, damp and rigidity on step response in open-loop is simulated afterward. Simulation also includes the frequency analyzing. And these simulation results are useful in optimizing the structure design parameters and its applications.The performance of GMA has close relation with the working conditions, including the stress, bias magnetic field and the amplitude of drive magnetic field. The three factors' affecting on the strain, hysteresis, and linearity ofλ-H curve of GMA in quasi-static condition are analyzed respectively and then together. And the method of Orthogonal experimental design is introduced in finding the optimal working conditions of GMA.An integrated test and control system based on virtual instruments is built specially for GMA, and the multi threading programming is used to achieve real-timing control and data acquiring, analyzing and displaying, which meets the requirements of experiments in properties of GMA.