SU1201747A1 - Method of measuring ultrasound damping ratio - Google Patents

Abstract

A METHOD FOR MEASURING THE ULTRASONIC Damping Factor, which implies that ultrasound pulses are emitted into the test medium using resonant transducers, receive reflected echo pulses and determine the attenuation coefficient of ultrasound in their parameters, which is different in that radiation within each pulse periodically changes the frequency of filling in the range corresponding to the frequency response of the transducer, and the attenuation coefficient of the ultrasound determined by the extremes of the echo pulse amplitudes.

Description

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ABOUT

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tpuf.l The invention relates to non-destructive testing and can be used to determine the physicomechanical properties of materials by the attenuation coefficient of ultrasound. The aim of the invention is to shorten the measurement time. Figure 1 shows the structure-g on the device; 2, an exponential comparison signal combined with extreme values of reflected echo pulses. A device for measuring the attenuation coefficient of ultrasound includes a pulsed transmitter 1, a resonant ultrasonic transducer 2, a test sample 3, an amplifier 4, whose input is connected to the output of a pulsed transmitter 1 and to a resonant ultrasonic transducer 2, which has acoustic contact with a 1 m sample. 3, two-channel oscilloscope 5, exponent generator 6, synchronizer 7, the first input of which is connected to the first input of the pulse transmitter 1, the second output of the synchronizer 7 is connected to the input of the generator the exponent, the third output of the synchronizer 7 is connected to the input of a two-channel oscilloscope 5, the input of the first channel of the oscilloscope 5 is connected to the output of the amplifier 4, and the input of the second channel of the oscilloscope 5 is connected to the output of the generator 6 of the exponent, block 8 of the modulating voltage, the input of which is connected to the fourth the output of the synchronizer 7, and the frequency modulator 9, the input of which is connected to the output of the modulating voltage block 8, and the output to the second input of the frequency modulator 9. The method of measuring the ultrasound attenuation coefficient t as follows. The high-frequency radio pulses produced by the pulsed transmitter 1 are fed to a resonant ultrasonic transducer 2, which converts them into ultrasonic waves, propagates in the test sample 3. The ultrasonic transducer 2 is excited by a square radio pulse, the filling frequency of which, within its pulse v, periodically changes 47 For example, according to a linear law. The maximum and minimum pulse filling frequency is determined by frequencies corresponding, for example, to a level of 0.5 of the frequency response of the ultrasonic transducer. In this case, in the test sample 3, ultrasonic signals are excited, enveloping which correspond to the frequency response of the converter. Ultrasonic oscillations are taken in by resonant ultrasonic transducer 2. Each received echo signal corresponding to an ultrasonic signal. Having twice passed through the sample under study, also has a similar shape. The frequency characteristics of the transducers commonly used to measure the attenuation of ultrasound in weakly absorbing single-crystal solids have distinct maxima. The peak values of these maxima correspond to the resonant frequency of the converter, at which the damping is minimal and there is no monotonic shift or conversion of the spectral distribution of the signal. The received ultrasonic echo pulses are converted into electrical signals, which, after amplification in amplifier 4, are fed to the input of one of the channels of a two-channel oscilloscope 5 and are observed on a CRT screen as a series of descending radio pulses. The input of the second channel of the two-channel oscilloscope 5 is supplied with a calibrated exponential comparison signal from the generator 6 of the exponent. The time constant of the comparison signal is selected so that the latter is compatible with the extremes of the pulses of a series of reflections. By the constant time of the exponential comparison signal, the attenuation of ultrasound is judged. The synchronizer 7 provides the triggering of the pulse transmitter 1, the generator 6 of the exponent, the scan generator of the two-channel oscilloscope 5 and the block 8 of modulating voltage. The modulating voltage unit 8 generates a corresponding voltage, for example, a linearly varying voltage, which is supplied to the frequency modulator 9 connected to the pulse transmitter 1. Varicaps which are connected to the inductance of the master oscillator of the pulse generator can be used as the frequency modulator 9. of the transmitter The attenuation of ultrasound in a gluing-sample system is judged by the time constant of the exponential comparison signal combined with the extreme values of the amplitudes of the reflected echo pulses. (figure 2). At this time, the measurement of the attenuation coefficient is reduced to 15-35 seconds. 747 Thus, the method of measuring the attenuation coefficient of ultrasound reduces the measurement time, because with an additional periodic change in the filling frequency within each pulse in the range corresponding to the frequency response e of the converter and the analysis of the received signals from the experimental amplitudes pulses there is no need to measure 5-7 times and build a plot of attenuation versus frequency.

Claims (1)

METHOD FOR MEASURING THE ULTRASONIC ATTENUATION FACTOR, which consists in the fact that ultrasonic pulses are emitted into the test medium using resonant transducers, receive reflected echo pulses and determine the ultrasound attenuation coefficient from these parameters, characterized in that, in order to reduce the measurement time, in the radiation process within each pulse periodically change the frequency of filling in the range corresponding to the frequency response of the Converter, and the attenuation coefficient of ultrasound is determined elyayut of extreme values of the amplitudes of the echo pulses. SU .... 1201747 Φ <ι ·· 1>