SU1583834A1 - Device for determining coordinates of source of signal of acoustic emission - Google Patents

Abstract

The invention relates to non-destructive testing of materials and products and can be used to determine the coordinates of developing defects mainly in products with large areas of the surfaces to be tested. The aim of the invention is to increase the monitoring efficiency by increasing the monitoring area without increasing the number of information receiving channels. The summing amplifier of each of the two information processing channels sums the signals of each of the group of receiving transducers with different weighting factors. In this case, the summation weight ratios for signals from different transducers are not equal to one another, the amplitudes of the summed signals are measured, and the addresses of the signals from the reception transducers are determined in the coordinate calculation unit by comparing the ratios of the weight summation factors and the ratios of the measured signal amplitudes. 1 il.

Description

The invention relates to the non-destructive testing of materials and products and to be used to determine the coordinates of developing defects mainly in products with large areas of the surfaces to be tested.

The aim of the invention is to increase the monitoring efficiency by increasing the monitoring zone without increasing the number of information receiving channels.

The drawing shows a block diagram of a device for determining the coordinates of the Acoustic emission signal bristle.

The device contains a group of receiving transducers 1, first 2 and second 3 information processing lavatories, each of which consists of series-connected preliminary 4 and main 5

amplifiers and filter 6, discriminator 7, serially connected unit 8 for measuring the difference in arrival time of signals and block S for calculating coordinates, first and second inputs of discriminator 7 are connected respectively to the outputs of filters 6 of the first 2 and second 3 channels of information processing, receiving converters 1 are connected with the inputs of the pre-amplifier of amplifiers, channels of information processing, the decoder 10 connected between the outputs of the discriminator 7 and the input of the unit 8 for measuring the difference in arrival time of signals, the preamplifiers filled in the form of multi-input by the number of receiving converters of adders with adjustable weighting coefficients for the inputs, and each receiving converter

ate

00

with

00 CJ

to

driver 1 is connected to one of the inputs of each of the two pre-amplifiers 4,

The device works as follows.

A group of receiving transducers is placed on the structure under study. Their number is chosen equal to the number of inputs of channels 2 and 3. Then each converter 1 is connected to one of the inputs of preamplifiers 4 so that

Aim GA | n

Afn

dl

 1 afr

where Aim, Ajm are the weighting factors of the summation of the inputs im and jm of the preamplifiers of 4 channels 2 and 3, respectively;

Jm is the input number of the preamplifier 4 channel 2, to which the corresponding converter 1 is connected,

The jm-number of the input of the preamplifier 4 channel 3, to which the converter 1 is connected under the same number. Thereafter, the values (Aim / Afm) for all transducers 1 are entered into the operational memory of the decoder 10, and the speed of sound in the material of the studied structure and the coordinates of the transducers 1 are entered into the operational memory of the coordinate calculation unit 9. The acoustic emission signals recorded by transducers 1 are summed in preamplifiers 4 with different weighting factors chosen arbitrarily in this device implementation. The signals obtained by summing are amplified in amplifiers 5. In filters b, the spectral components of the acoustic emission signals are distinguished. Then, in the discriminator 7, they are detected and fed to the input of the decoder 10. The amplitudes of the signals obtained by summing in the preamplifiers 4 EI and Ea are determined. A comparison is then made between Ei / E2 and Aim / Ajm. If these ratios match, i.e.

Ei / E2 Aim / Afm (1)

This means that the converter operated under the number t. Then, an electric pulse is applied to the m-th input of the arrival time difference measuring unit 8, which determines the time of arrival of the acoustic emission signal to the transducer 1. If these ratios do not match for all transducer numbers 1 , this means that either the signal came simultaneously to several transducers 1, or some or both of the receiving and transmitting channels and the signal amplification fix random

mechanical or electromagnetic interference. In this case, the information is discarded. In block 9 calculations on the arrival times of acoustic signals, sound speed and coordinates of transducers 1

the coordinates of the defects emitting the acoustic emission signals are calculated.

The device possesses, which is important in an industrial experiment, increased noise immunity, since

if one information channel 2 (3) or both of them immediately register electromagnetic interference, then condition (1) is not fulfilled and, therefore, the interference signals are not analyzed.

Thus, the invention makes it possible to increase the efficiency of determining the coordinates of the sources of acoustic emission signals while monitoring large area structures by expanding the control zone, increasing the reliability, reducing hardware costs and the number of communication lines.

Claims (1)

Claim Device the source of the acoustic emission signal containing a group of receiving transducers, the first and second channels of information processing, each of which consists of a series-connected preamplifier, a main amplifier and a filter, a discriminator, the first and second inputs of which are connected to the filter outputs, serially connected arrival time difference measuring unit signals and the unit for calculating the coordinates, and the receiving transducers are connected to the inputs of the preamplifiers of the information processing channels, so that, in order to increase the control efficiency, it is equipped with a decoder connected between the discriminator output and input unit measuring the difference in arrival times of signals, the preamplifiers are made in the form multiple input amplifiers with a number of receiving converters with adjustable weighting factors for the inputs, and each receiving converter is connected to one of the inputs of each preamplifier of the first and second information processing channels, SG-oh (-o