SU1670579A1 - Method of measuring the time of ultrasound propagation in a material over a fixed base - Google Patents

Abstract

The invention relates to non-destructive testing and can be used for ultrasonic monitoring of the physicomechanical characteristics of materials and products, in thickness measurement and for controlling the tightening torque of threaded connections. The aim of the invention is to improve the measurement accuracy by eliminating the discrete error associated with the uncertainty of the registration of the echo numbers. According to the method for measuring the propagation time of ultrasound, ultrasound pulses are emitted from a given base into the test item. Echo pulses are taken and T ₀ is the period of ultrasonic vibrations, T ₁ is the time interval between two adjacent echo pulses and T _M is the time interval for M periods of echo pulses. According to the measured parameters, the time of ultrasound propagation on a given base is determined using the formula given in the description. 1 il.

Description

The invention relates to non-destructive testing and can be used for ultrasonic monitoring of the physicomechanical characteristics of materials and products, in thickness measurement and for controlling the force of tightening of threaded connections.

The aim of the invention is to improve the measurement accuracy by eliminating discrete errors associated with the uncertainty in the registration of echo numbers.

The drawing shows a block diagram of an apparatus for implementing a method for measuring the propagation time of ultrasound in a material not specified in a base.

The device contains synchronizer 1 connected in series, probe pulse generator 2, piezoelectric transducer 3, receiving device 4 consisting of limiter 5, attenuator 6 and amplifier 7, limiter amplifier 8, key 9, selector 10, time converter 11 to code and a combined converter 3 connected to the generator 2 output of the probe pulses, gating circuit 12 by inputs connected to the synchronizer 1 and the output of the key 9, and an output to its control input, oscillographic indicator 13, inputs connected to the output receiver

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4 and the gating circuit 12, and the synchronization input to the synchronizer 1. In addition, the output of the synchronizer 1 is connected to the control inputs of the selector 10 and the converter 11, the time interval a to the code.

A method for measuring the propagation time of ultrasound in a material at a given base is carried out as follows.

Ultrasonic pulses are emitted into the controlled material by means of a transducer 3, echo signals are received, they are limited to amplifier-limiter 8 and then through a key 9 is fed to a selector 10, which forms an interval of two successive pulses. The time interval by the time interval converter 11 is converted into a code and indicated on an oscillographic indicator 13. The gating circuit 12 is tuned sequentially to measure the intervals To - the period of ultrasonic vibrations, TI - the interval between two adjacent echo pulses and Tt - the interval for m periods of echo following pulses. The gating circuit is triggered by synchronizer 1, which simultaneously excites a generator of 2 probe pulses. After a predetermined time interval, at the output of the gating circuit 12, a resolving potential appears, which opens the key 9. The first pulse at the output of the key 9 restarts the gating circuit 12 and after some time re-enters the resolving potential at the key 9. The selector 10 and the time converter 11 the interval in the code set by the pre-synchronizer 1 to the initial state, select the measured time interval and convert it into a digital code. On the screen of the oscillographic indicator 13, the sweep of which is triggered by synchronizer 1, echo pulses and a strobe pulse are simultaneously observed. From the measured values of T, T, and T0, the desired value of the time of ultrasound propagation on a given base is determined based on the following system of relations:

pG1 T + kTo; Y + PTo;

I I P I n; I KI p

where n is the maximum possible number of wave losses, determined by specific control features.

The system has the only solution.

subject to the condition m 2n.

From this system, it follows that the propagation time of ultrasound T is equal to:

T Ti + ENTIER (+0 5)

where ENTIER (X) is a whole part of the number X, i.e. maximum integer not exceeding X.

Claims (1)

Invention Formula A method for measuring the propagation time of ultrasound in a material on a given base, which consists in emitting ultrasound pulses into the material, receiving multiple reflected echo pulses, measuring the time interval Tt for the t follow periods of reflected echo pulses on a given base and taking into account the measured interval ultrasound propagation time in the material on a given base, characterized in that, in order to improve the accuracy of measurements, the time interval between two adjacent echo pulses TI and the period of ultrasonic oscillations are additionally measured. In this case, the value is chosen more than twice the maximum possible modulus of the difference between the wave numbers recorded by the echo signals n (m 2p) and the measured values of these quantities determine the time of propagation of ultrasound by the formula T Ti + ENTIER (+0.5) v m lo where ENTIER (X) is a whole part of the number X, i.e. maximum integer number, not exceeding X.