| Since magnetostrictive effect was found, magnetostrictive materials have grown by leaps and bounds, and have been applied in a wide range of fields, and on this basis a large number of practical devices have been developed. This requires we have a deeper understanding of the characteristics of magnetostrictive materials and should measure their unique parameters more accurately and simply. As magnetostriction measurement progressing, the emphasis is put on sensitivity, precision and automatic. In this paper, based on the current status of development of magnetostrictive materials, I made a device which can be used to measure the material properties of AC and DC parameters. The measurement of the parameters is related to the theory of calculation and application of chip microcomputer. The control technology, communications technology, automatic data collection technology and computer technology in modern measurement techniques are combined closely with it.The core of the device is AT89C52 and the data acquisition unit is AD7731. They respectively collect and measure the data in the AC and DC magnetic field, AC and DC variables as well as magnetic flux signal and then send the data to chip microcomputer to be analyzed.This paper introduces the magnetostrictive contents measuring instrument by means of hardware and software structure. The hardware system mainly includes Control circuit board, the system power supply board, integrator plate and audio amplifier plate, etc.Control circuit board includes the Hall probe circuit, magnetic-flux meter circuit, extension measurement circuit, data capture circuit, the parameters storage circuit, display and keyboard circuit, serial communication controller circuit etc and other related circuit design. The Hall probe measurement circuit is mainly composed by the Hall probe, the non-idiostatic offset circuit, the signal amplification circuit, the automatic range conversion circuit and the A/D transducer circuit. The apparatus use constant voltage source, and it been converted to constant– current source by amplification, which provide current for the Hall probe. The non-idiostatic offset circuit use the bridge method to offset the circuit.So while the magnetic density is null, the output voltage of Hall probe is null too. Measurement of alternating magnetic field is in accordance with the formula of the solenoid magnetic field, by measuring the solenoid current to deduce the size of an alternating magnetic field. In accordance with a powerful phase-locked amplification principle, the spontaneous development of a strain sensor to measure the decline of the overall DC Magnetostrictive material volume, with the corresponding strain gauge to measure the volume of the AC magnetostriction and cleverly using the same measurement circuit solved DC magnetostriction can be measured, but also the problem of measuring the AC magnetostriction. This is the device most important innovation. All artificial circuit and microcomputer is isolated with photocoupler. The low-frequency control lines use TPL521, the high ones use 6N137. Isolation circuit restrains the keen-edged impulse and other kinds of noise, and increases the radio of signal. In order to measure automatic.system use X24C45 to store the parameters. The X24C45 is a serial 256 bit NOVRAM featuring a static Ram configured 16×16, overlaid bit-by-bit with a nonvolatile EEPROM array. It can automatically perform a store operation when Vcc falls below a preset threshold. The instrument read the parameters when the power is turn on by program, so the instrument can return to the state which used last time. Low cost MAX232 is used in the serial communication controller circuit,function of which is to convert voltage from TTL to RS232 and communicate with PC. On the front panel of the apparatus were installed an LCD screen, thin-film buttons as well as the power switch to operate the instrument visualized. System power control board is used for system to provide the required number of voltage +5 V and +5 V,-5V analog voltage.Audio amplifier plate uses Pressure, high temperature operation of integrated power amplifiers for the exchange of signals, power amplifier, and through the provision of the AC magnetic field solenoid.integrator plate is mainly used to measure the magnetic characteristic of sample, using B-coil or coil-coil around the M in the sample system.The integrator includes the chopper-stabilized amplifier ICL7650, and it has high precision because of using exact input resistance and integral capacitance.The software design of the system is divided into two parts: single-chip machine programming and PC. 51 assembly language is adopted in the single-chip programming while VB is used in PC machine programming.single-chip machine programming includes the main program segment, the initialization program segment, the A/D convert program segment, X24C45 program e segment, the key interrupt program segment, the serial port interrupt program segment, data communication program segment, the display program segment and data-processing program segment.The instrument'PC software is program by VB 6.0 and Measurement Studio.Experimental and theoretical results show that the measurement system work well on the test accuracy, stability, resolving power etc.It achieved the desired results.With the development of researching on the ferromagnetic material characteristics the application of magnetostriction on the engineering technology is also developing. It is particularly essential to study on the measurement methods of magnetostriction and it can promote not only the study of the material.but also the application of magnetostrictive effect in the production and life . The instrument which we have designed has an extremely far-reaching significance.
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