Study On Dynamic Model Construction And Characteristic Analysis Of Giant Magnetostrictive Actuator

As an efficient intelligent material for electro-magnetic-mechanical conversion,Giant Magnetostrictive Material(GMM)has the advantages of high magnetic-mechanical conversion rate,large saturation magnetostriction coefficient,short response time,high frequency response characteristics and large output force GMM.There is a huge market in the fields of sensors,transducers,aerospace,intelligent manufacturing,active vibration control,etc.,and it has attracted many scientists,scientific research institutions and universities in various countries.Therefore,Giant Magnetostrictive Actuator(GMA)based on GMM has become a hot research topic for researchers.On the basis of mastering the basic characteristics of GMM and the design principle of GMA,this paper designs a GMA which can work for a long time and has large output force.The main contents are as follows:First of all,after mastering the basic characteristics of GMM,the basic structure and working principle of GMA.The geometric parameters of GMM rod are selected and determined.The geometric parameters of electromagnetic coil are determined according to the size of GMM rod.Pre-pressure mechanism and cooling device are designed in order to improve the output performance and working temperature of actuator.Secondly,in order to optimize the working characteristics of GMA,the problems of internal magnetic field strength and uniformity of GMA are solved.Starting from the structure and working principle of GMA,the equivalent magnetic circuit model of GMA is established and the internal magnetic circuit is analyzed.Combined with Maxwell’s basic theory of electromagnetism,the finite element model of GMA is established in ANSYS software.The effects of open magnetic circuit,closed magnetic circuit,relative permeability of magnetizer material and thickness of magnetizer on magnetic field intensity,magnetic induction intensity and uniformity on GMM rod are analyzed by simulation.Thirdly,in order to obtain the dynamic characteristics of GMA theoretically.The equivalent parameters of mass,stiffness and damping of GMM bar are solved by using vibration theory analysis method.In order to effectively establish the dynamic model of the GMA,the equivalent dynamic model of the GMA is established under the premise of six assumptions.At the same time,combined with the D ’Alembert principle and Newton’s second law and other physics theories,the system transfer function of the GMA is derived.The dynamic simulation model of GMA is built in MATLAB,and the time domain analysis method and frequency analysis method are used to qualitatively and quantitatively analyze the system equivalent mass,system equivalent stiffness,system equivalent damping and the number of electromagnetic coil turns.The influence of the parameters on the overall performance of the GMA system.Finally,through the existing integrated test platform,the characteristics test of pre-pressure and driving current on output force is carried out.It is found that when the preloading is 10 MPa,the giant magnetostrictive rod exerts better performance,and the output force of the GMA is also the largest,about 1420 N,which is consistent with the overall maximum saturation magnetostrictive coefficient of the giant magnetostrictive material when the preloading stress is 10 MPa.When the driving current is 3.5A,the output force of the GMA at unit current is up to 383 N/I,and the efficiency is higher.