Development Of Magnetostriction Coefficient Measuring Instrument Based On Optical Fiber Displacement Sensor

Gaint magnetostrictive material is a new kind of functional material developed from 1970s, which was regarded as the strategic functional material in twenty-first century to improve national competition. Since it has some excellent performances such as high conversion rate of mechanical energy and electrical energy, high energy density, high response speed, and good reliability and so on at room temperature, it leads revolutionary changes to the traditional electronic information system, sensor system and vibration system. Thus, it is important to obtain accurate performance parameters of GMM for the application and development of the material, especially for magnetostriction coefficient. Terfenol-D is typical GMM, and its magnetostriction coefficient in this paper is in micron level, so its measurement is micro-displacement measurement.With the development of modern industrial technology, more and higher requirments to the accuracy and mothod of micro-displacement measurement was requested. At the same time, fiber sensor was applicated to every aspect with the fiber sensor technology developing. A light stress fiber micro-displacement sensor based on the development of the fiber micro-displacement sensor was designed in this paper, the overall design scheme and all the modules such as the probe, the modulation and driver of the light, the photoelectric conversion and receiving, the weak signal processing and so on were introduced dividedly also. The output characteristic curve of the sensor was given at last. The experimental results indicated that the best distance from the fiber probe to the measured surface was 370μm-470μm for the good linearity, and this range was selected to measure the magnetostriction coefficient in the paper.A instrument for measuring magnetostriction coefficient was designed using fiber micro-displacement sensor with the micro-controller and data processing and so on. AT89C52 is the core of the equipment, and AD574 is the data collecting unit. Magnetostrictive coefficient changed when the magnetic field educed by micro machine changed, then magnetostriction coefficient of the sample was detected by micro-displacement sensor, and the results were showed on the LCD. The software was written by C language, including data collecting, data display, data processing and other related subprograms.The magnetostriction coefficient of the sample was given in this paper and the experimental results showed that the equipment had a good performance for magnetostriction parameter measurement and reached the expected goals.