SU1620934A1 - Method of determining coordinates of sources of acoustic emission - Google Patents

Abstract

The invention relates to non-destructive testing of materials and can be used to determine the coordinates of defects in oriented polymer fibers and filaments from acoustic emission signals (AE). The aim of the invention is to increase the reliability and accuracy of determining the coordinates of AE sources in oriented polymer fibers and threads by taking into account the change in the attenuation coefficient of ultrasound with the change in mechanical stresses in the sample. Acoustic oscillations are excited in a specially designated area of the sample and take them at two points of the selected area. According to their amplitudes, taking into account the amplitudes of the AE signals, the coordinates of the AE sources are determined in a controlled sample area. 1 il.

Description

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The invention relates to a technique for non-destructive testing of materials and can be used to determine the coordinates of defects in oriented polymer fibers and filaments from acoustic emission signals (AE).

The aim of the invention is to increase the reliability and accuracy of determining the coordinates of AE sources in oriented polymer fibers and threads by taking into account the change in the attenuation coefficient of ultrasound with the change in mechanical stresses in the sample.

The drawing shows a device for implementing a method for determining the coordinates of AE sources.

The device contains the first and second receivers 1 and 2 of the AE signals, the first and second receivers 3 and 4 of the acoustic signals, the emitter 5 of the acoustic signals, with

first to fourth meters 6–9 signal amplitudes, generator of 10 probe pulses, dampers 11–13 acoustic oscillations, and block 14 registration. The first and second receivers 1 and 2 of the AE signals, the emitter 5 of the acoustic signals, the first and second receivers 3 and 4 of the acoustic signals are located on the controlled sample 15 at points with XL x2, X4, Xs, Xs scradates, respectively.

The dampers 11-13 are made, for example, in the form of rubber strips measuring 10x5x5 mm.

The inputs of the meters 6-9 amplitudes of the signals are connected to the outputs of the first and second receivers 1.2 signals AE and the first and second receivers 3 and 4 acoustic signals, respectively, and their outputs with the first to fourth inputs of the block 14 registration, respectively

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Ca

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The output of the generator 10 probe pulses connected to the input of the emitter 5 acoustic signals.

The method of determining the coordinates of the AE sources is carried out as follows.

One end of sample 15 is fixed rigidly and motionless, the other end is connected to a loading unit (not shown). Choose the difference of distances | X4-Xs X5-Xs | such that it is equal to the distance Li2. Acoustic contact is made between sample 15 and the first and second receivers 1 and 2 of the AE signals, the first and second receivers 3 and 4 of the acoustic signals, and the emitter 5 of the acoustic signals, for example, by pressing or immersion method. The dampers 11-13 of acoustic oscillations are installed in the corresponding areas (first and second) of sample 15. Sample 15 is loaded, for example, at a constant speed. AE signals are registered by receivers 1 and 2 of AE signals and their amplitudes are measured using the first and second meters b and 7 signals amplitudes. The generator 10 and the emitter 5 excite acoustic signals, register their amplitudes by the first and second receivers 3 and 4 acoustic signals. A synchronous measurement of the amplitudes of the AE signals and the amplitudes of the acoustic signals is carried out using the recording unit 14. The amplitudes of the acoustic signals arriving at the third and fourth inputs of block 14 are recorded only when the AE signals arrive at the first and second inputs of the re-registration unit 14. The measured values of the amplitudes of the AE signals and acoustic signals determine the coordinates of the AE sources by the formula (U2 / UQ

L.1

-1I2G1 + PЈ

 2 11 + Shch1

(U5 / U4)

where C is the distance between the AE source and the point xi of the signal registration;

Li2 lX2-Xil is the distance between the points of registration of AE signals;

Ui and U2 are the amplitudes of the AE signals at the registration points HH and X2, respectively;

U4 and Us are amplitudes of signals of acoustic oscillations at points X and KhB, respectively.

Thus, the proposed method makes it possible to increase the reliability and accuracy of determining the coordinates of defects by taking into account changes in the attenuation coefficient of the sample material during its loading.

Claims (1)

The invention of the method for determining the coordinates of the acoustic-emission sources, which means that the sample is loaded with tensile force, the amplitudes of the acoustic emission signals are recorded in the first section of the sample at least two of its points with coordinates Xt and X2, according to the measured amplitudes, determines the coordinates of the acoustic emission sources, characterized in that, in order to increase the reliability and accuracy of determining the coordinates of acoustic emission sources in oriented polymer fibers and filaments, a second portion of the sample is acoustically insulated from the first portion at the time of registration of acoustic emission signals, acoustic oscillations are excited in the second section with coordinate Xs and their amplitudes are recorded at two points with coordinates X c and Xe, located data on the second section on opposite sides of the point excitation of acoustic oscillations so that the difference in the distances I S Xs-Xs I is equal to the distance IX2-Xil, and the coordinates of the sources of acoustic emission are determined by the ratio  -In (L 2 / UOl m 2 I ТГГ ГбТЩр where - the distance between the source of acoustic emission and the point Xi of signal registration; Li2 - distance between acoustic emission recording points; Ui and U2 are the amplitudes of the acoustic emission signals at the registration points Xi and X2, respectively; U4 and Us are the amplitudes of the signals of acoustic oscillations at the points XA and Xs, respectively.