Coupled Magneto-elastic Theory Of Giant Magnetostrictive Transducer And Application In Cutting Machining

The giant magnetostrictive transducer used in non-circular section machining system provided with a lot of advantages such as a simple and compact structure, high repetitious accuracy, seamless, good stiffness, minor driving inertia, better working stability and so on, and high-precision processing without profile modeling could be achieved. So not only the shortcomings of the traditional method but also the method of flexible model promoted by electromagnetic force can be overcomed, which could be applied to processing of complicated or hard-substrate workpiece. Therefore, the method can bring a major change for high-precision manufacture. However, in the practical application of GMM micro-actuator, it involves in non-linear vibration, magneto-elastic dynamics, precision machining, automatic control, and many other disciplines. The key technical problems of the giant magnetostrictive actuator on theoretical study and practical application have been restricted by some factors such as the nonlinear relation and magnetic machine coupling between the magnetic field strength and magnetostriction of the transducer, the internal nonlinear properties of the giant. magnetostrictive material, hysteresis characteristics, eddy current losses and heat phenomenon with the magnetic field and so on, which result in the low accuracy of the actuator.Although in the efforts of researchers, the theoretical research of the giant magnetostrictive material devices has achieved certain results. But most of the studies mainly concentrated in magnetization and control theory research of the magnetostrictive component. And the relevant theoretical modeling mainly concentrated in the phenomenon of the micro-mechanical properties, nonlinear hysteresis characteristics approaches, and domain theory based upon mean field equilibrium thermodynamics, and so on. In recent years, the magnetostrictive models are mainly based on either the typical basic energy theory that quantify the interaction between atomic moments in a crystal lattice, or polynomial expansions constructed to quantify the phenomenological behavior of the magnetostriction. And the few results is universally used to describe the nonlinear coupling magneto-elastic properties of the magnetostrictive materials. The nonlinear model of the magnetostrictive strain, which is described by the input magnetic field and used to describe the coupling magneto-elastic of the magnetostrictive material, has been mentioned in relevant literatures. But it is lacking in the strain model and approaches used to describe the turning of magnetostrictive transducer. Based on the above reasons, the paper carried on the study on the nonlinear properties inside the giant magentostrictive material and the magneto-elastic coupling of the giant magnetostrictive transducer. Major researches are as follows,1. Through the performance experiments of the giant magnetostrictive cutting tool holder, the effect of current intensity (magnetic field intensity) and the pressure on the magnetostriction was analyzed, and the mutual relations of current intensity, pressure and magnetostriction was founded.'2. Through the analysis on molding theoretical of the varying ellipse section and middle-convex curve of the piston skirt, the second derivative problems of the endpoint in the interpolation process was resolved. Through the synthesis of the elliptical cross-section and the middle-convex surface processing trajectory, the simulation machining track of the cutting system was received. The cutting mechanism of the middle-convex was expounded, and the required format data-processing documents ware established.3. According to the first piezomagnetic theory, the transducer system under static magnetic field was analyzed. Through the introduction of the nonlinear characteristics of the prestressed spring, the mechanical model of the transducer system with square and cubic nonlinear terms was established, and the chaotic phenomena, which maybe exist in the system, was discussed. Through dynamic simulation and numerical simulation for the transducer system, the main factors affecting the non-linear character of the transducer system were established.4. Based on Maxwell's equations, the internal magnetic field distribution function containing material parameters was established. And internal magnetic field expression of the giant magnetostrictive material was founded. The main factors influencing the internal magnetic field distribution of the material was discussed. The characteristic parameters of the material were introduced in the analysis process of the internal magnetic field of the material.5. Based on the distribution function of the magnetic field inside the material, the Jiles-Atherton nonlinear hysteretic non-linear model is improved. The characteristic of the magnetic field inside the giant magnetostrictive material was introduced to the hysteresis analysis. And influence of material parameters and eddy current on the hysteresis characteristics was discussed. Results indicated that it should take full account of the internal distribution of the magnetic field in higher incentives frequency.6. In accordance with magneto-elastic theory, considering the characteristics of giant magnetostrictive material parameters, internal magnetic field distribution of the materials and the influence of bias magnetic field, the coupling magneto-elastic model of the giant magnetostrictive transducer was founded. A displacement distribution coefficient equation with virtual coefficient was established. In different boundary conditions, the theoretical model was discussed. Through comparing the simulation results with the experimental results of the literature, it was shown that the theoretical model was reasonable. The influence of the various factors on the output performance of the transducer was discussed with the different parameters.7. Based on the assumptions of the output displacement of the giant magnetostrictive material, through analyzing on the output mandrel, the nonlinear dynamic model of the transducer considering internal characteristics of the giant magenitostrictive material and the spring was founded. Through dynamic simulation, the influence of the main structure parameters of the transducer on the nonlinear dynamic model was discussed. According to the demand of the actual processing for the output displacement, with the linear theory, the required input of the transducer was confirmed. In the analysis methods, the Simulink was introduced to dynamics simulation analysis process of the giant magnetostrictive transducer system, and achieved nicer analysis results.