Analysis Of Output Characteristics Of Double Rod Magnetostrictive Actuator Under Multi Field Coupling

Magnetostrictive materials have been widely used in the fields of actuators,sensors,transducers and so on.A new type of double rod structure magnetostrictive actuator was designed based on the Fe-Ga magnetostrictive material to extend the applied range of the actuator.The output of the actuator could be realized simultaneously in the axial and radial output displacement.The actuator has simple structure and low working resonance frequency,which is of practical value.Firstly,the mechanism parameters of the designed actuator were determined.Based on the magnetic circuit analysis,we could get that the magnetic field strength of the magnetostrictive rod was related to the number of turns,the input current,and the length of the magnetostrictive rod,the cross section area of rod and the relative permeability of the magnetic yoke.In order to make magnetic field strength become larger,the magnetostrictive rod diameter was chosen to 10 mm,the length of the coil was 50 mm,the magnetic yoke material was chosen to the silicon steel sheet which had strong magnetic conductivity,and the width of the yoke was 12 mm.Then,the finite element software was used to analyze the magnetic field and temperature field of the actuator.When the reverse current was applied to the two driving coil,the magnetic flux on the magnetostrictive rod was larger than that of the same direction current,and the magnetic field distribution in the magnetostrictive rod was relatively uniform in the two cases.The temperature rise characteristics of GMA under DC and AC input conditions were analyzed based on multi field coupling model of material considering temperature.The higher the DC current,the higher the temperature of the device was.When the sliced magnetostrictive rod was cooled by air cooling device,the GMA temperature change was controlled below 4 degrees,and the device temperature remained was not increased with the increase of time.The GMA could meet the design requirements.Finally,the dynamic output characteristics of magnetostrictive actuator were studied.It was found that when the two driving coils of the actuator were connected to the opposite current,the resonant frequency of the system were 981.79 Hz,4280Hz,7898.2Hz.The output displacements of the radial and axial were 52μm,16μm,8μm and 1.8μm,2.4μm,2μm respectively.The actuator can be applied to the precision machining of the workpiece and other fields.When the same direction current was applied to the two driving coils of the magnetostrictive actuator,the actuator had only one resonant frequency which was 7898.2Hz in the axial direction.The axial output displacement at the resonant frequency was 14μm.In this case the actuator can be applied to high frequency vibration exciter and other fields.The output characteristic of the magnetostrictive actuator was studied by experiments,and the experimental result was in agreement with the simulation results.It is proved that the developed actuator was of practical value.