SU1442905A1 - Method of measuring coordinates of sources of acoustic emission signals - Google Patents

Abstract

The invention can be used in determining the coordinates of the sources of acoustic emission signals in thin-walled structures when they are in a complicated stress state. The aim of the invention is to increase the credibility of determining the coordinates of the sources of acoustic emission signals by taking into account the influence of the anisotropic properties of the material, the design on the magnitude of the propagation speed of the acoustic signal. Acoustic emission transmitters using two acoustic conversion channels are used as receivers of acoustic emission signals. for example, converters made in the form of a disk of ferroelectric material to which two potential electrodes are connected. A group consisting of four such transducers is placed on a controlled area of the structure. When the latter is loaded, acoustic emission signals are received, differences in arrival times of signals to transducers are measured, as well as differences in arrival times of signals from the channels of each transducer. For each transducer, the speed of propagation of the received mode of the acoustic signal is determined. The obtained values of the speed of propagation of acoustic signals are used to determine the coordinates of the sources, according to the relationship between arrival times, the speed of the received modes of acoustic signals and the distance to the source, signals. 1 il. with s

Description

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The invention relates to the field of non-destructive testing and can be used in determining the coordinates of the sources of acoustic emission signals in thin-walled structures in their complex tension state.

The purpose of the invention is to increase the reliability of determining the coordinates of the sources of acoustic emission signals by taking into account the influence of the anisotropic properties of the material of the structure on the value of the speed of propagation of the acoustic signal.

The drawing shows devices for determining the coordinates of the sources of acoustic emission signals.

The device for determining the coordinates of the sources of acoustic emission signals contains four identical processing channels, one of which is shown in the drawing. The first channel of the device contains a transducer with a sensitive element 1, the first 2 and second 3 potential electrodes, the first 4 and second 5 amplifiers, the first 6 and second 7 blocks of pulse shapers, the first 8 and second 9 blocks for determining the arrival time difference, and also block 10 accumulation and calculation of coordinates. The converter is made in the form of a disk made of thin ferroelectric material to which the first electrode 2 is connected in the form of a ring ka to the edge of the converter and the second electrode 3 in the form of a disk located in the center of the converter. The potential electrodes 2 and 3 of the converter are connected to the first amplifier 4 in series . the first block 6 pulse generator and to the second amplifier 5 with the second block 7 pulse generator. The outputs of blocks 6 and 7 of pulse formers are connected respectively to the first and second inputs of the first block 8 for determining the arrival time difference, the output of which is connected to the first input of the first accumulation channel 10 and calculating the coordinates. The output of the second pulse generator unit 7 is connected to the input of the first channel of the second block 9 for determining the arrival time difference, the output of which is connected to the second input of the first channel of the accumulation unit 10 and calculating the coordinates.

The second block 9 for determining arrival time differences and block 10 for accumulating and calculating coordinates are common for the channels of the device.

The method is implemented as follows.

During loading of the structure, acoustic emission signals reach sensing element 1 of the transducer in the first channel of the device. The electrical signals generated from the first potential electrode 2 of the converter are amplified by the first amplifier 4 and are fed to the pulse shaper unit 6, where a positive pulse is generated when the leading edge of the signal reaches a certain threshold level. After time ut (determined by the acoustic properties of the construction material and the distance between the potential electrodes of the converter, the acoustic emission sins reach the location of the potential electrode 3 of the converter, from which the electrical signal amplified by the second amplifier 5 enters the second pulse generator unit 7. Positive the pulses that occur at the output of blocks 6 and 7 of the pulse shaper, in block 8, determine the difference between the arrival times of the acoustic emission signals to the electrodes photoelectret in the first channel, buyout to a first input of the first channel unit 10 .nakopleni and calculating coordinates.

To the second input of the first channel of this block from block 9, the difference in arrival times of the acoustic emission signals is transmitted to different converters of the device. At the same time, the same information comes from other channels of the device and is transmitted to the corresponding inputs of the accumulation and calculation unit 10, At the moment when the differences in the arrival times of acoustic emission signals are transmitted to the converters in all four channels and potential the electrodes of the transducers, in this block, the coordinates of the signal source are determined by the ratios

1442905

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X, Y - the desired coordinates of the source of acoustic emission signals. .

Claims (1)

After TOGO, the coordinates of the source — the formula of the invention of acoustic emission signals is determined by the method of determining the coordinates of the source divided, the results of calculations from the block of NOIC acoustic emission signals, 10 of the accumulation and calculation of coordinates resulting in that the group is transferred to the display device for educational purposes and placed on the control analysis (not shown) of the design area, the design The method allows to determine the coordinate-load, receive signals from the acoustic sources of acoustic emission signals, measure emission times in the structures from the input material of the signals to the transducers and with anisotropic acoustic properties according to the relationship between the times at the expense of the fact that - the speed, the speed of acoustic signals, the determination of the velocity of the spreads in the construction material and the distance of the received mode - by acoustic signal to the source of signals determined for each Atel vyut coordinates acousto source signals separately. In this case, the transducer emissions, the rationalizers accept acoustic signals and so that, with the aim of increasing, the reliability of the coordinate determination designs with different speeds, dinat sources due to the consideration of influences - 50 depending on the location of the predominantly anisotropic material properties. distributors relative to the source structure on the magnitude of the speed of signals. Separately determining the propagation of the received acoustic-speed mode of the received acoustic signal mode, a signal transform is used for each transducer containing two channels of conversion — it improves the accuracy of the coordination determination, during loading of the structure, and thus the accuracy of measuring the difference in the arrival times of the division of the coordinates of the sources of the acoustic emission signals from the canal — acoustic emission. 51A429056 for the coordinates of the sources of signals of the aux- for each converter for the dependence of the emission, use the speeds of the symmetry between the velocity and the propagation difference of the received modes, the acoustic times of arrival of signals from the channels converter which signal for each predominance between the speeds of arrival of si converter v zzzzz zz // z / z / . eight / 2L i-3 / T ff 75 -