The Fundamental Theory And Experiments Study On Giant Magnetostrictive Actuator

Giant Magnetrictive Material(GMM) is a new functional material which has high transduction effects between magneic(electricity) and machinery(sound). Because GMM have lots of advantages such as higher strain, larger load capacity, higher precision, rapider response, higher reliability and so on compared with traditional technology, high technology and high precision fields have paid close attention to it, and it has a promising prospect in dual-purpose use. However, in the practical application of GMM, there are some problems such as nonlinear characteristics, hysteresis characteristics, eddy current losses and so on, and involve in non-linear vibration, magneto-elastic dynamics, automatic control, and many other disciplines, so that the theory research and widly used about GMM are difficult.At present, the scholars both at home and abroad have achieved certain results by studied on mechanism and the magnetization of GMM. Although some studies on nonlinear magnetic hysteresis characteristics, coupling magneto-elastic characteristics and magnetic field distribution have been done, it exist several problems such as some factors considered deficiency and with less actual working condition. And there are rarely reseaches on chatter of Giant Magnetostrictive Actuator(GMA). Therefore, in this paper, the hysteresis characteristics, nonlinear characteristics, theoretical model, non-circular process control and chatter turning were studied. And the results laid a foundation on theoretical model, machining and control applications of GMM. Main content as follows:1Through the static and dynamic experimental measurements of GMM which was producted by Shenyang Better Company, the function among the current, the axis-direction position of GMA and magnetic fields intensity was established, and the dynamic experiment datas of time domain and frequency domain were analyzed, and the output variations of GMA along with time and frequency were studied. Then, the relationships between input current and output displacement were discussed.2Based on the relationship between the exciting current, axial position of GMM and magnetic field intensity, which was obtained from the experiment of GMA, the theoretical formula between the current along the axis of the coil around the thick-wall hollow column and magnetic field intensity was corrected. And the correction factor was established. The dynamical model of GMA was analyzed theoretically to get the vibration responses of GMA. Then, the effects of related parameters on GMA were discussed.3Considering that the magnetic field distribution of GMM does not only relate to current, but also relate to the axis-direction position, so the coupling magneto-elastic dynamics model of the GMA were established by considering the bias magnetic field,pre-compression stress and material characteristic parameters. Then, the analytic expression was gained by using the methods on complex coefficient partial differential equation. And the effects of magneto-elastic parameters were analysed.4Based on the analysis on inner magnetic field, the Maxwell’s equation and the piezomagetic theory, the magnetic field distribution model of GMM is built, in which the permittivity, compressive prestress of the material were induced. And the influences of the material characteristic parameters on the material inner magnetic and hysteresis characteristics were discussed. Then, the Three-Dimension magnetic field distribution model was built by considering both radial direction and axis-direction. And the results were analysed correspondingly.5On the basis of constitutive equations of giant magnetostrictive material which took temperature and△E effect into account, the Turning dynamics model of GMA was established. And the vibration response and influences of parameters were analyzed. Then, the differences between the case of considering AE effect and ignoring△E werer discussed. Meanwhile, the dynamic temperature was induced, and the influences of dynamic temperature and effectively fuzzy PID control were studied.6Considering the effects of regenerative cutting chatter on both workpiece and GMA, the system dynamics model composed by GMA, turning tools and workpiece was built. And the stability was analyzed. According to the Hurwitz criterion, the effects of turning width, the equivalent rigidity and quality of workpiece on the stability of system were analyzed. Then, the effects of chatter were under control by using a simple adaptive control method.