The Effect Of Temperature On The Output Features Of Rare Earth Magnetostrictive Transducer

With the development of science and technology, research and application aboutintelligent materials brought more and more attention in all areas. Rare earth giantmagnetostrictive material (GMM) with great strain, great potential energy, large band width,rapid respond speed, high reliability and high precision, is the ideal choice to made transducer,such as nondestructive testing transducer, actuator, drive actuator and so on. GMM issensitive to temperature in practical application, which has a significant impact on outputcharacteristic of actuator. This thesis analyzed the temperature effect on transducer from twosides of environment temperature and interior thermal effect. The main content and relativeresults are as follows:(1) The fundamental characteristic of the giant magnetostrictive transducer was analyzed.Finite element model was established by the COMSOL Multiphysics, and then steady-stateanalysis, parametric sweep feature analysis and transient analysis were given. The resultsshows that the uniformity of axis magnet field reduces and the output displacement increasesfirstly and then reach saturation with the increasing of loading current; The uniformity of axismagnet field and the output displacement increases with increasing coil turns, but the outputdisplacement also reach saturation at last.(2) Influence of ambient temperature on the output performance of giantmagnetostrictive transducer was studied. The magnetostrictive strain curves at differenttemperatures were synthesized to functions of magnetic and strain using curve fitting software1stOpt, then they were imported to finite element software to research the effect oftemperature. It was found that at the temperature of20℃the first wave amplitude increasesfirstly and then decreases with the increasing of loading time, while the residual oscillationsignificantly enhances, which indicates that the resolution of the transducer reduces; Theoutput displacement amplitude lower significantly with the rising environment temperatureand the residual oscillation and the difference between them also reduce at the same loadingtime; after Fourier Transform, the output frequency distribution is more uniform, and theoperating frequency is within7.5kHz and the output energy decreases with the temperatureincreasing. Whatsmore, the relation about young’s modulus of GMM varing with theenvironment temperature were also imported to finite element software, and the results showsthat the downward trends of amplitude become more obviously, residual oscillation issmaller and attenuates quickly and natural frequency of the transducer decreases with theincreasing of temperature. (3) The impact of thermal field caused by hysteresis losses, eddy-current losses and coilheat to the dynamic output performance of the transducer were studied. Firstly, it was foundthat the heat generated by hysteresis losses, eddy-current losses is greater than the coil heat byintroducing thermal stress module. After that, the magneto-elastic-thermal coupled model wasestablished by PDE module, and the results shows that under constant temperature theamplitude of output displacement reduces and the equilibrium position also has a slightdecline at higher temperature; when the transducer operated at a transient state temperaturefield, the peak of transducer vibration reduces with the temperature increasing. At last, peakvalue of the output waveform relatively increased with enhancing compressive pre stresswhile the amplification decreased, and the percentage error declined.This thesis is focused on the influence of environment temperature and internal heatsource on the output performance, which can provide assistance for the development andapplication of transducer.