| The development of national economy and high technology, are inevitably restricted and pushed by the development in material research. Fluid transmission and control technology, one main form of transmission and control, is no exception definitely. GMM (Giant Magnetostrictive Material) is a new type of function material appearing in recent years with giant strain, fast response speed, high energy density and large output force and so on. Utilizing GMM to design new-type actuator, replacing traditional actuator such as the torque motor or the force motor, will enhance the response speed and precision of electro-hydraulic servo valve.In the thesis, the nozzle flapper servo valve based on GMM actuator is systematically, deep analyzed and researched by combining theory analysis, computer simulation, finite element numerical computation and experimental study together. The scheme and concrete structure of the GMM actuator's nozzle flapper servo valve are presented for the first time, the GMM actuator's nozzle flapper servo valve is manufactured, the internal relationship among the nozzle flapper servo valve's drive current, dynamic offset and structure parameters, etc. is studied, matching relation of each structure parameter is defined, the field distribution and variant curves of magnetic flux density along the axial direction are determined by magnetic circuit computation, magnetic field finite element simulation and experimental verification, and the design and evaluation criterion of GMA nozzle flapper servo valve are created elementarily. The results show that the flapper structure driven by GMM actuator directly, has the characteristics that it is simple, reliable and controllable, and pressure control performance is improved by adopting the temperature compensation mechanism, the pre-pressure exerted organization, dynamically offset adjustment of the magnetic field controlled, additional magnetic ring and so on. In addition, the GMA nozzle-flapper servo valve has wide pressure control properties which are up to 0.52MPa, good linearity which is about 2.5%, fast response speed with rising time less than 1ms and 680 Hz frequency width (-3dB). On the basis of draw lessons from various kinds of existing GMM actuator's thermal compensation methods, combining the structure characteristic of GMM actuator's nozzle-flapper servo valve, self-adaptive thermal compensation mechanism of GMM actuator is brought forward, and theory analysis and experiment verification are finished. Then, the result shows that the thermal compensation mechanism can compensate the GMM rod's thermal deformation effectively. Magnetic flux change rate under different supply currents can be measured while control pressure under different supply currents is measured. The result of magnetic circuit simulation coincides with that of the experiments, which verifies the correctness of the magnetic circuit dynamic mathematical model.The main content of each chapter is summarized as following:In chapter 1, traditional and new-type actuators' functions, principles and their characteristics are introduced, and their performances are compared. GMM's performance superiority and development is given. Its applications in fluid components are presented in detail, and the latest research results and its applications are discussed. The significance, difficulties and main contents of research are summarized in brief.In chapter 2, the relation between production of magnetostrictive mechanism and physical property of magnetic crystal is presented systemically from GMM's phenomenological theory and practical project application. Based on magneto-mechanical theory, magnetostrictive equation is given. The characteristics of GMM's dilation mechanics, magneto-mechanical coupling, pressure and temperature, etc. are also introduced and analyzed. These lay the foundation for the application study of the next chapters.
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