SU590657A1 - Device for measuring ultrasonic vibration propagation velocity - Google Patents

Description

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The invention relates to the field of ultrasound technology and is intended to determine the elastic characteristics of solid media by measuring the speed of propagation of ultrasonic vibrations in them.

A known device for measuring the speed of propagation of ultrasonic vibrations comprises a generator of video pulses, a variable delay line, an attenuator, two selective amplifiers and an indicator 1.

The determination of the propagation velocity of oscillations is carried out by combining the leading edges of the received and reference signals. The combination, as a rule, is carried out by visual inspection on the screen of the cathode ray tube of the indicator, which limits the accuracy of measurement by the thickness of the lines combined on the screen. In addition, the lack of a sufficiently reliable pulse does not allow automating the measurement process.

The closest to the invention to the technical essence is a device for measuring the speed of propagation of ultrasonic vibrations, which contains a generator of video pulses, two channels of the test and reference signals, a transmitter and a receiver of ultrasonic vibrations in the channel of the test signal, and a selective amplifier and limiter connected in series to the receiver. pulse duration, variable delay line in the reference signal channel, as well as a delay line control unit and register An alternating device associated with a variable delay line 2.

The disadvantage of such a device is that the standard control signal is formed from an electric exponential signal. In this case, the ignoring caused by the normalization of the leading edge of the received signal is not taken into account, which with a decrease in the frequency of the used oscillations increases significantly and in some cases makes the use of the device uninterrupted.

The purpose of the invention is to increase the accuracy of measurements of the speed of propagation of ultrasonic vibrations.

This is achieved by the fact that a selective amplifier and a pulse width limiter are connected in series to the output of a variable delay line in the channel of the reference signal, and an adder, to the inputs of which two-channel pulse width limiters are connected, and the output connected to a delay line control unit. associated with a recording device.

The drawing shows a block diagram of a device for measuring the speed of propagation of ultrasonic vibrations.

Two channels of the studied and reference signals are connected to the video pulse generator 1. In the channel of the signal under study, with the output of the generator 1, the emitter 2 of ultrasonic vibrations is connected, the acoustic oscillations of which passed through the test environment 3 are perceived by the receiver 4. In the channel of the reference signal, a variable delay line 5 is connected to the output of the generator 1. The outputs of the oscillation receiver 4 and the delay lines are connected, respectively, to the inputs of the selective amplifiers 6 and 7, to which the pulse width limiters 8 and 9 connected to the adder 10 are connected. A delay line control unit 11, connected to the output of the adder 10, is mechanically connected a system that changes the distance between the receiving and the radiating sensors of the delay line 5. Registering; its device 12 is connected by its inputs with a time delay line 5 and with a AND control unit for a delay line.

The device works as follows.

From the generator 1 video pulses, the signal is fed to the emitter 2 and to the input of the alternating line 5 of the delay. The mechanical vibrations that have passed the test medium 3 from the radiator 2 to the receiver 4 kOv of ebnia are converted by it into an electrical signal, which is fed to the input of the selective amplifier 6 and then to the limiter 8 of the pulse duration. From the output of the delay lines, the signal passes through the selective amplifier 7 and the limiter 9 of the pulse duration, respectively. From the outputs of the limiters 8 and 9, the signals, which are the first half-waves of radio pulse oscillations, arrive at the inputs of the adder 10, from which the half-difference of the received signals is fed to the input of the delay line control unit 11.

The change in holding time continues until a unipolar pulse is obtained. A signal from the output of the delay line 5, corresponding to the measured time interval, is fed to the input of the recording device 12, which is triggered by a signal from the delay line control unit 11. At a certain delay time, the propagation velocity of the ultrasonic vibrations is calculated. As a recording device, a recorder or a digitizer can be used together with a block for entering information into a computer.

The proposed device allows to increase the accuracy in the automatic mode of measuring the speed of propagation of ultrasonic vibrations. The measurement results can be used to calculate the elastic parameters of materials directly during the process, for example, in the production of building materials. The device can also be used to study the physical characteristics of materials when exposed to various external factors and internal factors or to monitor changes in internal stresses in the material during its operation.

Claims (2)

1. USSR author's certificate No. 466441, cl. G ORS 29/00, 05.31.72. 2. USSR author's certificate number 304448 Cl. G 01I 5/00, 05.29.69.