Study On Loss Analysis And Thermal Characteristics Of Giant Magnetostrictive Transducers

As a strategic functional material with superior performance,the giant magnetostrictive material has become one of the research hotspots in all walks of life since it was discovered because of its large strain,high energy density and fast response speed.Giant magnetostrictive transducers with giant magnetostrictive rods as the driving components have played an important role in many fields such as hydroacoustics,precision machining and medicine.However,the transducer structure is compact and airtight,and the heat dissipation capacity is poor.The heat generated inside the transducer during high-power continuous operation will affect the magnetostriction coefficient of the giant magnetostrictive rod,speed up the aging speed of the driving coil,reduce the working efficiency of the transducer,and then affect the stability and reliability of the transducer.It can be seen that the in-depth research on the loss and thermal characteristics of giant magnetostrictive transducers has important academic value and engineering significance.The main research contents of this paper are as follows:(1)Aiming at the heating problem of the giant magnetostrictive transducer,the main heat source of the transducer is analyzed,and the corresponding heat loss is estimated according to the working principle of the transducer.Starting from Maxwell's equations,the magnetic field distribution characteristics inside the giant magnetostrictive rod are studied,and the classical eddy current loss of the rod is solved on this basis.Considering that giant magnetostrictive materials are different from traditional magnetic materials,the dynamic effects of the transducer will affect its material parameters,so an electromechanical conversion model is constructed to study the effects of the resonance frequency,prestress and load of the transducer on the permeability and eddy current loss of the rod.Then,the hysteresis loss of the rod is studied by the method of combining theoretical analysis with the experimental measurement.Finally,the equivalent model of the driving coil is established,and the resistance loss of the driving coil is analyzed respectively under the DC and AC conditions.(2)A longitudinal vibration giant magnetostrictive transducer experimental platform is built.The design theory and details of each component are explained in detail,which lays the foundation for the following experiments on the thermal characteristics of the transducer.The magnetic field and eddy current distribution of different rods are analyzed by finite element simulation,and it is pointed out that slitting the rod has a good suppression effect on the eddy current.Based on the theoretical analysis and calculation of the heat loss of the transducer,the temperature field of the transducer experimental platform is simulated to study the temperature distribution and temperature rise changes of the transducer under different excitation conditions and heat dissipation conditions,and the influence of slitting the rod on the temperature rise of the transducer is analyzed.(3)The thermal characteristics experiment system of the transducer is designed and built,and the temperature rise experiment of the transducer is carried out under different excitation conditions.By comparing the experimental results with the temperature field simulation results,the accuracy of the thermal loss theoretical model is verified.Then the output characteristics of the transducer at different temperatures are studied through experiments,and the conclusion that temperature rise will seriously reduce the output capacity of the transducer is obtained,which emphasizes the importance and necessity of suppressing the heat of the transducer.Finally,some methods for suppressing the eddy current loss and accelerating the heat dissipation of the transducer are proposed and verified through experiments,which provides a certain reference and guidance for the structure optimization and heat dissipation design of the low-frequency and high-power giant magnetostrictive transducer in the future.