RU2069841C1 - Device measuring ultrasound velocity - Google Patents

Abstract

FIELD: measurement technology. SUBSTANCE: invention may find use in nondestructive ultrasound testing of metal structures. Article is probed with radio pulses and given device analyzes received echoes also in the form of radio pulses. Controlled delay element of probing signal changes its nominal dependance on its coincidence with value of time of propagation of ultrasound of each half-period of signal. Counters count time intervals and register displays order of half-wave. Ultrasound velocity is found by calculation formula. EFFECT: increased measurement precision due to exclusion of additional measurements of propagation time. 2 dwg

Description

 The invention relates to non-destructive tests and can be used for ultrasonic testing of metal structures subjected to mechanical loading.

A device for determining the speed of ultrasound containing a series-connected piezoelectric transducer, a probe signal generator, an amplifier, a time interval meter [1]
However, the known device has several disadvantages. It cannot be used for precision measurements of ultrasound velocity due to inaccurate measurements of the propagation time of elastic waves.

The closest technical solution is a device for determining the ultrasound speed in structural materials subjected to cyclic loading and containing a series-connected transducer, probe signal generator, amplifier, high-level comparator, low-level comparator, delay units, 3I element, switch, pulse counters, pulse shaper, RS time source trigger, integrator, adder, filter, inverter, recording unit, display unit [2]
The disadvantage of this device is that to measure the speed of ultrasound, at first, the constant component of the propagation time of ultrasound is measured, which then adds up to the measured variable component previously formed during cyclic deformation of the material. The phased measurement of the propagation time of ultrasound additionally leads to errors in the measurement of the speed of ultrasound.

 The aim of the invention is to improve the accuracy of measuring the speed of ultrasound.

 The goal is achieved by eliminating additional measurements of the propagation time, which reduce the accuracy of estimating the propagation velocity of ultrasonic waves. For this, the proposed device comprises a series-connected probe pulse generator, a piezoelectric transducer, an amplifier and a low level comparator, a high level comparator, the input of which is connected to the amplifier output, a first delay element, the input of which is connected to the second output of the probe pulse generator, a second delay element, the first element 2I, first and second counters, first and second square-wave formers, serially connected clock generator and key, the output of which connected to the counting input of the first counter, a third rectangular pulse shaper connected in series, the input of which is connected to the output of the first delay element, and a second element 2I, the second input of which is connected to the output of the second rectangular pulse shaper, and the output with the first key control input and the input the second delay element, the third element 2I, the first and second inputs of which are connected respectively to the first output of the first and the output of the third shaper of rectangular pulses, and the output to the second counter input, a register, the first input of which is connected to the output of the second counter, a third delay element, the output of which is connected to the second control input of the key, and a timer, the output of which is connected to the counter reset inputs, the register and the key, the output of the second delay element is connected to the input of the third delay element and the second input of the register, the output of the first counter is connected to the control inputs of the first delay element and the information inputs of the register, the output of the lower level comparator is connected to the first input of the first th element 2I connected to the input of the second output generator of rectangular pulses, and the output high-level comparator is connected with the input of the first generator of rectangular pulses, a second output connected to the second input of the first element 2I.

 Comparative analysis with the prototype shows that the proposed device is characterized by the presence of new units: the second and third elements 2I, the third shaper of rectangular pulses, a clock generator, key, register and timer.

 Figure 1 presents a functional diagram of a device for measuring the speed of ultrasound; figure 2 timing diagrams explaining his work.

 A device for measuring the speed of ultrasound contains (Fig. 1) a probe signal generator 1, a piezoelectric transducer 2 emitting ultrasonic waves into the test material 3, an amplifier 4, a high-level comparator 5, a low-level comparator 6, a first square-wave pulse shaper 7, a first element 8, second rectangular pulse shaper 9, first delay element 10, second 2I element 11, key 12, clock pulse generator 13, second delay element 14, third delay element 15, first counter 16, second counter 17, register 1 8, the third element 19 2I, the timer 20, the third driver 21 of the rectangular pulses.

 The signal from the first output of the probe signal generator 1 is fed to the piezoelectric transducer 2 and to the input of the amplifier 4, the output of which is connected to the inputs of the comparators 5 and 6. From the second output of the probe signal generator 1, the pulses go to the external trigger input of the first delay element 10. The input of the first driver 7 of the rectangular pulses is connected to the output of the high level comparator 5, and the first output to the second input of the first element 8 2I, and the second output to the first input of the third element 19 2I. The output of the comparator 6 low level connected to the first input of the first element 8 2I. The output of the element 8 2I is connected to the input of the shaper 9 of the rectangular pulses, the output of which is connected to the second input of the second element 11 2I. The input of the third rectangular pulse shaper 21 is connected to the output of the delayed signal of the delay element 10, and the output with the first input of the element 11 and with the second input of the third element 19 2I. The output of the second element 11 2I is connected to the first control input of the key 12 and to the input of the second delay element 14. The output 14 of the delay element is connected to the input of the delay element 15 and to the second input of the register 18, and the output of the delay element 15 to the second control input of the key 12. The third input of the key 12 is connected to the output of the clock generator 13, and the output to the counter input of the counter 16. C the output of the counter 16, the signals are fed to the information inputs of the register 18 and to the control inputs of the delay element 10. The first input of the register 18 is connected to the output of the second counter 17. The signals from the timer 20 go to the installation inputs of the register 18, the first and second counters 16, 17 and the key 12. The output of the third logic element 19 2I is connected to the counting input of the counter 17.

 A device for measuring the speed of ultrasound works as follows.

From the first output of the probe signal generator 1, the pulses are fed to a piezoelectric transducer 2 that emits ultrasonic pulses into the material 3 under study. Ultrasonic echo signals supplied to the piezoelectric transducer 2 are converted into electrical signals and, having passed the amplifier 4 (Fig. 2a), are fed to the inputs of the high and low level comparators 5 and 6. A high level comparator 5 is triggered (FIG. 2b) when the input signal reaches a voltage U _cm greater than the amplitude of random noise and structural acoustic noise. Comparator 6 is triggered when the input signal passes the zero potential. The signal from the output of the high-level comparator 5 is fed to the input of the first driver 7 of rectangular pulses, which generates at the first output signals of duration τ ₁ equal to the duration of the reflected pulses (Fig.2c), and at the second output, short pulses along the leading edge of the signals from its first output (Fig.2g). From the first output of the driver 7, the signals are fed to the second input of the first element 8 2I, the first input of which is the signals from the output of the comparator 6 low level. From the output of the first element 8 2I, the signals are fed to the input of the second rectangular pulse shaper 9, which generates short pulses at the output of the trailing edge (Fig. 2e), which go to the second input of the second element 11. The reference pulses from the second output of the probe signal generator 1 arrive at the input of the external start of the delay element 10. From the output of the first delay element 10, the pulses delayed for a time τ ′ (FIG. 2e) arrive at the input of the rectangular pulse shaper 21, which generates short pulses at the leading edge (FIG. 2g), which are transmitted to the first input of the 11I element 11 and to the second input element 19 2I.

 The change in the state of the counter 16 is carried out by signals from the generator 13 clock pulses supplied through the key 13 to the counting input of the counter 16.

With an increase in the number recorded by the counter 16, the delayed signal time τ ′ increases (FIG. 2e). If the signals from the second output of the first rectangular pulse shaper 7 coincide with the delayed signal from the output of the third rectangular pulse shaper 21 at the output of the third element 19 2I, a pulse arrives at the counting input of the second counter 17. At the moment of the coincidence of the signal from the output of the second rectangular pulse shaper 9 and the signal from the output of the shaper 21 of the rectangular pulses at the output of the element 11 2I there is a signal passing to the first control water key 12 and to the input of the delay element 14. The key 12 stops the supply of pulses from the clock generator 13 to the counter 16. The pulse delay element 14 from the second element 11 2I generates a pulse supplied to the second input of the register 18 and to the input of the delay element 15. When this signal arrives at register 18, information is recorded from the output of the first counter 16, the state of which determines the time of the first period in the first reflected signal, and from the counter 17, the state of which determines the number of the reflected signal. From the output of the delay element 15, the signal is supplied to the second control input of the key 12, which is opened for signals to pass through it from the output of the clock pulse generator 13 to the counting input of the counter 16. The counter 16 is filled until the next coincidence of the signals at the inputs of the second 11 11I element with subsequent recording the counters 16, 17 to the register 18. Reset counters 16, 17, switch 12 and register 18 is carried on a signal outputted from the timer 20. Thus, the register 18 are fixed values τ _m each time period in each of the K th expressions signal.

где N максимальный номер отраженного эхо-сигнала;
m_к количество синфазных точек в первом и К-м отраженных эхо-сигналах;
τ_ki измеренные значения в К-м эхо-сигнале.The propagation time of ultrasonic pulses τ is determined from the obtained data through the equation

where N is the maximum number of the reflected echo;
m _{to the} number of common-mode points in the first and K-th reflected echo signals;
τ _ki measured values in the K-th echo signal.

где l длина акустического пути.The propagation velocity of ultrasonic waves is determined through the measured time τ by the formula

where l is the acoustic path length.

 Thus, in the proposed device due to the elimination of additional errors in measuring the propagation time of ultrasound, the error in estimating the speed of ultrasound is reduced. In addition, due to the larger statistical volume recorded in the data register on the propagation time of the entire set of reflected ultrasonic signals, the measurement accuracy of the parameter significantly increases.

Claims (1)

 A device for measuring the speed of ultrasound, containing a series-connected probe pulse generator, a piezoelectric transducer, an amplifier and a low level comparator, a high level comparator, the input of which is connected to the output of the amplifier, the first delay element, the input of which is connected to the output of the probe pulse generator, the second delay element, the first element 2I, the first and second counters and the first and second formers of rectangular pulses, characterized in that, in order to improve accuracy, it is equipped with a connected by a clock generator and a key, the output of which is connected to the counting input of the first counter, connected in series with the third rectangular pulse shaper, the input of which is connected to the output of the first delay element and the second element 2I, the second input of which is connected to the output of the second rectangular pulse shaper, and the output with the first control input of the key and with the input of the second delay element, the third element 2I, the first and second inputs of which are connected respectively to the output of the tre the first and the first output of the first shaper of rectangular pulses, and the output to the counting input of the second counter, a register, the first input of which is connected to the output of the second counter, the third delay element, the output of which is connected to the second controlled key input, and a timer, the output of which is connected to the reset inputs counters, register and key, the output of the second delay element is connected to the input of the third delay element and the second input of the register, the output of the first counter is connected to the control input of the first delay element and inform with the register input, the output of the low-level comparator is connected to the first input of the first 2I element, connected by the output to the input of the second rectangular pulse shaper, and the output of the high level comparator is connected to the input of the first rectangular pulse shaper, connected by the second output to the second input of the first 2I element.

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