SU1229686A1 - Apparatus for determining coordinates of sources of acoustic emission signals - Google Patents

Abstract

The invention relates to non-destructive testing of materials by acoustic emission. The aim of the invention is to improve the accuracy of calculating coordinates due to the possibility of calculating coordinates using a digital method. The signals from the outputs of the four transducers arrive at the block for determining the time differences, where rectangular pulses are produced, the durations of which are proportional to the time intervals between the instants of the appearance of the signals on the glands. These pulses are filled with clock pulses from the generator of overlapping pulse sequences using eight circuits I. The outputs of the AND circuits are connected in pairs with the inputs of the three OR circuits. In the OR circuits, non-overlapping sequences are superimposed so that the number of pulses at the outputs of these OR circuits corresponds to the pairwise sums of the pulse durations coming from the output of the time difference measurement unit. The pulse sequences from the outputs of the four OR circuits are fed to the corresponding summing and subtracting inputs of two reversible counters, in which the values are obtained that are proportional to the X and Y coordinates, respectively. To determine the sign of the magnitude of the coordinates, there are two signs of determining the sign, analyzing the overflows of the counters in the forward count and zero crossing in the reverse count. Information from the meter outputs goes to the recorder. 1 il. with S GO 10 Yu Od 00 O5

Description

The invention relates to the field of non-destructive testing of materials and can be used to determine the coordinates of defects in materials and structures by the method of location of acoustic emission (AE).

The purpose of the invention is to increase the accuracy due to the possibility of calculating the coordinates by a digital method.

The drawing shows a block-: device for determining the coordinates of the source of AE signals.

The device contains channels 1 - 4 receiving signals, block 5 for determining time differences, the inputs of which are respectively connected to the outputs of channels 1 - 4, the first circuit AND 6, the first circuit OR 7, the first input of which is connected to the outputs of the first circuit AND 6, the second circuit AND 8, the output of which is connected to the second input of the first circuit OR 7, the third circuit And 9, the second circuit OR 10, the first input of which is connected to the output of the third circuit And 9, the fourth circuit And 11, the output of which is connected to the second input of the second OR 0, the fifth circuit And 12, the third circuit OR 13, the first input of which is Connected to the output of the fifth circuit And 12, the sixth circuit And 14, the output of which is connected to the second input of the third circuit OR 13, the seventh circuit And 15, the fourth circuit OR 16, the first input of which is connected to the output of the seventh circuit And 15, the eighth circuit And 17 whose code is connected to the second input of the fourth circuit OR 16, a series-connected pulse generator 18 and three identical delay lines 19-21, the output of the ijropa 18 pulses is connected to the second inputs of the fourth 11 and eighth 17 And circuits, the output of the delay line 19 is connected to the second inputs of the third 9 and seventh 15 circuits And, you the course of the delay line 20 is connected to the second inputs of the second 8 and sixth 14 And circuit, the output of the delay line 2 is connected to the second inputs of the first 6 and fifth 12 And circuits,

The device also contains the first reversible counter 22, the summing input of which is connected to the output of the first IDN circuit 7, and the subtractive input to the code of the second OR circuit 10, the second reversible counter 23, the summing input of which is connected to the output of the third IH 13 circuit, and the subtractive input to the output of the fourth circuit OR 16, the registrar 24, the first 25

and the second 26 character determination units whose inputs are connected respectively to the transfer outputs of the first 22 and second 23 reversible counters,

the information outputs of the reversible counters 22 and 23 and the outputs of the sign determining units 25 and 26 are connected to the inputs of the recorder 24.

Each of the channels 1–4 for receiving signals can contain a serially connected receiving electroacoustic transducer, an amplifier, and a driver. The time difference determination unit 5 may produce

verification of signals in channels for belonging to one source.

The pulse generator 18 and the three delay lines 19-21 produce four (by the number of outputs) continuous sequences of pulses of the same exemplary follow frequency, having the property that, being combined through the OR circuit into one channel, can be transmitted

along this channel without imposing the pulses of these sequences on top of one another.

The device works as follows

AE signals, emitted by defects of the monitored product when it is loaded, propagate through the product and reach the locations of the receiving electroacoustic transducers of channels 1-4 at different points in time, respectively. Corresponding normalized square-wave pulses corresponding to these signals are formed at the outputs of channels 1–4.

Block 5 for determining the time differences produces square-wave pulses, the durations of which are AT, -TT correspond to the time intervals between the instants of the signal

fishing, respectively, at the outputs of the channels,, fishing 1-4.

15 if, for example, the signal appears last at the output of channel 3, then we get

T. -t ,; iX t -

DT t, - t, 0;

uT t, - C.

From the generated dT pulses, the coordinates X and Y of the sources of the signals are determined by the formulas

X KCuT ,, +

Y K (iT, +

ATe dT - AT, - dT);

where K is the proportionality coefficient.

This happens as follows.

The pulses d T from the output of block 5 are filled with circuits AND 6.8.9,

12296864

Lt, - t); the time differences of arrival of signals, the inputs of which are respectively connected to the outputs of the channels, and the recorder, characterized in that 5, in order to ensure accuracy, the first AND scheme, the first OR scheme, the first input of which is connected to the output of the first AND scheme, the second scheme are entered into it And, the output of which is connected

11,12,14,15 and 17 pulses of the sample - 10 to the second input of the first circuit OR,

howling frequency from generator 18 and delay lines 19-21. The OR 7 scheme imposes non-overlapping pulse sequences from the output of the delay line 21 and from the output of the delay line 20, therefore the total number of pulses of the reference frequency at the output of this circuit corresponds to the total long duration of these pulses dTj and uTg. The OR 10 circuit imposes non-overlapping pulse sequences from the output of the delay line 19 and from the generator 18, so the total number of pulses of the reference frequency at the output of this circuit corresponds to the total duration of the impulses dT. and dtd.

The pulse sequences at the outputs of the OR circuit 7 and 10 are also non-overlapping and, therefore, they are subtracted in the reversible counter 22. As a result, the value in the reversible counter 22 is stored in a digital code corresponding to the X coordinate of the source. In order to determine the sign of the magnitude of the X coordinate, the sign determining unit 25 analyzes the overflows in the forward count and zero crossings in the countdown of the reversible counter 22. Similarly, in the reverse counter 23, the value corresponding to the Y coordinate of the source is stored in a digital code. Counter Information

the third circuit AND, the second circuit OR, the first input of which is connected to the output of the third circuit AND, the fourth circuit AND, the output of which is connected to the second

f5 to the input of the second circuit OR, the fifth circuit AND, the third circuit OR, the first input of which is connected to the output of the fifth circuit AND, the circuit AND, the output of which is connected to the second input of the third

2Q circuit OR, the seventh circuit AND, the fourth circuit OR, the first input of which is connected to the output of the seventh circuit AND, the eighth scheme AND, the output of which is connected to the second input of the fourth.

25 OR circuits, the first inputs of the first and sixth AND circuits are connected to the second output of the time difference determination unit, the first output of which is connected to the first input of the third and fifth AND circuits, to the third output the first inputs of the second and seventh AND circuits, to the fourth output - the first the inputs of the fourth and eighth circuits And, serially connected pulse generator and three identical delay lines, the output of the generator is connected to the second inputs of the fourth and eighth circuits And, the output of the first delay line is connected to the second inputs of the third and seventh circuits And, you the stroke of the second delay line is connected to the second inputs of the second and sixth And circuits, the output of the third delay line is connected to the second inputs of the first and fifth And circuits, the first reversible counter, summed30

40

22 To 23 To blocks 25 and 26, the post-abatement input of which is connected to the output of the recorder 24. of the first OR circuit, and the subtractor

input - to the output of the second circuit OR, the second reversible counter, the summation Using the proposed device will improve the accuracy of determining the coordinates of AE sources

input input of which is connected to the output

due to the replacement of operations in the analogue third circuit, and the subtracting input to the digital output of the fourth OR circuit, the first and second sign determining units, the invention's inputs are connected to the transfer outputs of the first and second receivers, respectively. counter counters, and the informational data of the sources of the signals from the acoustic outputs of the reversible counters and the emission outputs containing four channels for determining the sign are connected to the reception of signals, the detection unit to the inputs of the recorder.

the third circuit AND, the second circuit OR, the first input of which is connected to the output of the third circuit AND, the fourth circuit AND, the output of which is connected to the second

the input of the second circuit OR, the first circuit AND, the third circuit OR, the first input of which is connected to the output of the fifth circuit AND, the circuit AND, the output of which is connected to the second input of the third

the OR circuit, the seventh circuit AND, the fourth circuit OR, the first input of which is connected to the output of the seventh circuit AND, the eighth scheme AND, the output of which is connected to the second input of the fourth.

the OR circuit, the first inputs of the first and sixth circuits AND are connected to the second output of the time difference determination unit, the first output of which is connected to the first input of the third and fifth AND circuits, the first output of the second and seventh I circuits to the third output, and the first inputs to the fourth output fourth and eighth circuits And, serially connected pulse generator and three identical delay lines, the output of the generator is connected to the second inputs of the fourth and eighth circuits And, the output of the first delay line is connected to the second inputs of the third and seventh circuits And, out d second delay line connected to the second inputs of the second and sixth AND gates, the third delay line output is connected to second inputs of the first and fifth AND gates, the first reversible counter, summing

the input of which is connected to the output of the first OR circuit, and the subtractive

input input of which is connected to the output

the third schema is BIT, and the subtracting input is to the output of the fourth circuit OR, the first and the second

Mon

Editor A. Kozornz

Compiled by V.Rzhevkin Tehred L.Oleinik

Order 2446/45 Circulation 778 Subscription

VNIIGGI USSR State Committee

on affairs invented: iy and discoveries 113035, Moscow, Zh-35, Raushsk nab, d.4 / 5

Production and printing company, Uzhgorod, Projecto st., 4

Proofreader L. Patay

Claims (1)

Claim A device for determining the coor- ^5S dinatics of acoustic emission signal sources, containing four signal reception channels, a determination unit 1229686 4 time differences of the arrival of signals, the inputs of which are respectively connected to the torus, which, to the outputs of the channels, are registered in order to increase accuracy, in not, the first circuit of which the first input is connected to the first circuit whose output And, the second ^{one is} connected to an OR circuit, an OR circuit, the first circuit is introduced OR ma OR, to the output circuit And, to the second input of the first third circuit And, the second first input of which is connected to the output of the third circuit And, the fourth circuit And, the output of which is connected to the second input of the second OR circuit, the fifth AND circuit, the third OR circuit, whose first input is connected to the output of the fifth AND circuit, the sixth circuit AND, whose output is connected to the second input of the third OR circuit, the seventh circuit AND, the fourth OR circuit, the first input of which is connected to the output of the seventh circuit And, the eighth circuit And, output d is connected to the second input of the fourth. OR circuits, the first inputs of the first and sixth circuits AND are connected to the second output of the time difference determination unit, the first output of which is connected to the first inputs of the third and fifth circuits AND, the third output is the first inputs of the second and seventh circuits AND, the fourth output is the first inputs of the fourth and the eighth circuit And, connected in series with the pulse generator and three identical delay lines, the output of the generator is connected to the second inputs of the fourth and eighth circuits And the output of the first delay line is connected to the second inputs of the third and seventh circuit And, the output the second delay line is connected to the second inputs of the second and sixth circuits AND, the output of the third delay line is connected to the second inputs of the first and fifth circuits AND, the first reversible counter, the summing input of which is connected to the output of the first OR circuit, and the subtracting input - to the output of the second OR circuit , the second reversible counter, which sums the input of which is connected to the output of the third OR circuit, and subtracts the input to the output of the fourth OR circuit, the first and second sign determination blocks, whose inputs are connected respectively to the transfer outputs of the first and second roars sive counter and down counter output information and outputs the character determining unit are connected to the inputs of the recorder.