Research On The Giant Magnetostrictive Actuator Design And Optimization

With the rapid development of astronomical observation technology and space detection technology, there are more and more precision engineering applications in large astronomical telescope(LAT). For this reason, the segmented mirror active optics technology has been gradually and widely used in the LAT system. The core of this technology is the micro displacement actuator. The performance of the actuator is directly responsible for the precision of LAT system. The micro displacement actuators used today can't meet the need of large displacement, high precision control and large load simultaneously. To solve the problem, in this research, we have attempted to design and realize a novel displacement-amplified Giant Magnetostrictive Actuator (GMA) that may not only have large and precisice displacement but also large load capacity. Especially, we have focused on the work of modeling and then simulating the hysteretic-nonlinear drive beheavior of GMA through FEM by Comsol multiphysics?. This work may pave the basis of establishing a FEM-added optimal design system of GMA in the near future. The main research work of the thesis is presented as follows:In chapterâ… , we firstly introduce the composition of large astronomical telescope, the development of actuator used in LAT, and then the histories of giant magnetostrictive materials and GMA. The thesis research background and the research contents are introduced in the end of this chapter.In chapterâ…¡, we present the principle and property of GMM, especially some important parameters of GMM. Experimental work and the experimental setup for obtaining the optimal parameters which may be used in GMA optimal design are mainly introduced in this chapter.In chapterâ…¢, at first, we focus on establishing the magnetic circuit model of GMA. Secondly, we establish the axial magnetic field strength model of solenoid and the bias field strength model for the permanent magnet according to Biot-Savart law and ferromagnetic theory. The axial magnetic field strength has been worked out and illustrated through MATLAB. Because the model can't reflect the materials and structure sizes on electromagnetic properties of GMA adequately, we try to model it with ANSYS? in order to obtain the design criteria of GMA. The results play an important role for the electro-magnetic design of GMA.In chapterâ…£, the main content is to model the hysteresis nonlinearity of GMA . Firstly, the governmental differential equations for magnetic and structural field have been converted into weak form. At the same time, constitutive equation of GMM has been changed to adapt FEA solving. Magnetic hysteresis characteristics of GMM are described by Jiles-Atherton model. And then, the model is solved by COMSOL Multiphysics and proved to be valid.In chapterâ…¤, according to the optimal design method previously introduced, actuators with and without permanent magnet bias are designed to be applied to the project. And then, the displacement and load capacity is measured and proved to satisfy the need. At last, we assemble the actuators with displacement amplifier; a whole integrated large stroke actuator is thereby realized actually. Its performaces in terms of displacement and precision are tested, finally.In chapterâ…¥, all achievements of the dissertation are summarized and the further researches are dicussed.