JPS5925182B2 - AE monitoring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an AE that can remove the influence of noise.
Relating to a monitoring device.

When a solid object breaks, the energy that has been stored up to that point is released into a unique sound wave (acoustic/engineering wave, hereinafter abbreviated as AE wave).

). Therefore, by measuring AAE waves, it is possible to evaluate the health of a structure and predict its destruction. In this way, a so-called AE monitoring device that examines the state of a structure by measuring AE waves is generally configured as shown in FIG. That is, a plurality of acoustic sensors 2-1,
2-2, ... 2-n are attached, and the output signals of these acoustic sensors 2-1, 2-2, ... 2-n are connected to amplifiers 3-1, 3-2, ... 3-n, respectively. It is introduced into the signal processing device 4 via. The signal processing device 4 calculates the number of events, event rate, ringdown count, amplitude distribution, source, etc. from the magnitude and time difference of the output signals of each acoustic sensor 2-1, 2-2, ... 2-n. It is configured to perform position determination, etc. The information calculated and organized by the signal processing device 4 is displayed on the display device 5 in the requested format. However, the conventional device configured as described above has the following problems.

That is, the sound waves that propagate through the structure 1 and enter the acoustic sensors 2-1, 2-2, . . . 2-n are not necessarily AE waves. For example, when the structure 1 is in contact with a fluid or connected to a mechanical vibration system, these sound waves also enter the acoustic sensors 2-1, 2-2, . . . 2-n. Furthermore, if the distance between the acoustic sensors 2-1, 2-2, . The conventional device is AE
Since signals other than waves are also introduced into the signal processing device 4, it is difficult to obtain accurate defect information, and this method has the disadvantage that it can only be used in places with favorable conditions, such as a laboratory. The present invention has been made in view of the above circumstances, and its purpose is to be able to prevent noise signal components other than AE waves from being introduced into a signal processing device, and to be able to prevent noise signal components other than AE waves from being introduced into a signal processing device. An object of the present invention is to provide an AE monitoring device that can accurately monitor the health of a structure.

Hereinafter, details of the present invention will be explained with reference to illustrated embodiments.

FIG. 2 shows the device according to the present invention in a plotted manner.
The same parts as in FIG. 1 are designated by the same reference numerals.

Therefore, the explanation of the overlapping parts will be omitted. The difference between the device of the present invention and the conventional device is that the acoustic sensors 2-1, 2-2
, . . . A time difference signal detection device U is connected to the output line of 2-n,
This is because the waveform analysis device J is interposed. The time difference detection device includes acoustic sensors 2-1, 2-2,...2-
n output lines, especially amplifiers 3-1, 3-2, . . .
Gate circuits 12-1, 12-2, . -n
are interposed in series, and these gate circuits 12-1, 12-
The output signal of the time difference detector 13 is commonly applied to the terminals 2, . . . , 12-n in a closed operation.

The time difference detector 13 includes each gate circuit 12-1, 12
-2, . . . 12-n input end signals are introduced as input signals, and only when the respective input signals are introduced at almost the same time, the gate circuits 12-1, 12-2, . 12
-n for a predetermined period of time. First, the waveform analysis device J includes the gate circuit 1
Analyzer units 22-1, 22-2, . . . 22-n are connected to the lines between the output ends of the signals 2-1, 12-2, . It has become something that has been mediated.

The above analysis device units 22-1, 22-2,...22
-n are configured equally, and taking the unit 22-1 as an example, the signal passing through the gate circuit 12-1 is sent to the signal processing device 4 via the delay circuit 23 and the gate circuit 24 in series. The signal that has passed through the gate circuit 12-1 is also introduced into the waveform analyzer 25. The waveform analyzer 25 analyzes the waveform of the input signal and determines whether the input signal is caused by an AE wave or not.
It is configured to apply an open control signal to the gate circuit 24 for a predetermined period of time when it is determined that the input signal is caused by an AE wave. Note that the waveform analyzer 25 determines whether the input signal is caused by an AE wave in the following manner. In other words, according to experiments, the AE wave is
They often have a unique shape. For example, if the rise time is the Trl duration and τ is the peak value, then the majority of AE waves have values of Tr/τ, Tr/A, and τ/N within a certain range. Therefore, each time an output signal is sent out from an acoustic sensor, the above values are determined and whether or not these are within a known range is determined to determine whether the signal is caused by an AE wave. You can know whether it is or not. The waveform analyzer 25 performs at least one of the calculations described above to determine whether the signal is caused by an AE wave or not. With such a configuration, if a defect occurs in the structure 1, for example, at a position indicated by P in the figure, an AE wave will be emitted at this position.

This AE wave propagates through the structure 1 and reaches the acoustic sensor 2-1.
, 2-2, . . . 2-n. Therefore, the output signal power from the acoustic sensors 2-1, 2-2, ... 2-n {
Sent out. In this case, the distances between the AE wave generation position and each acoustic sensor 21, 2-2, ... 2-n are not equal, so from each acoustic sensor 2-1, 2-2, ... 2-n No output signals are sent out at the same time. Therefore, the signals amplified by the amplifiers 3-1, 3-2, . . . 3-n are sent to the gate circuits 12-1, 12-2, .
12-n, and is introduced into analyzer units 22-1, 22-2, . . . 22-n inserted in each line. Each analysis device unit 22-1, 22-2,...22
Since the signal introduced into the analyzer units 22-1 and 22-n satisfies the conditions caused by the AE wave,
The signal passes through 22-2, . . . 22-n and is introduced into the signal processing device 4. In addition, when mechanical noise such as vibration propagates to the structure 1, this noise is also transmitted to the acoustic sensors 2-1, 2-2,
. . 2-n, but the analyzer units 22-1, 22-2, . . . 2-n determine that the signal is not caused by an AE wave, and the gate circuit 24 is closed. , after all, such a signal is not conducted to the signal processing device 4. Furthermore, when noise signals are induced in the output lines of the acoustic sensors 21, 2-2, . , the time difference detection device 11 detects these, and the gate circuits 12-1, 12-2, . . .
Since 2-n is closed, such signals are also processed by the signal processing device 4.
As a result, only the signals caused by the AE waves are introduced into the signal processing device 4.

Therefore, even when used in a so-called adverse environment where mechanical vibrations and induction disturbances occur, the health of the structure to be measured can be accurately evaluated, and the range of use can be greatly expanded.

Further, according to the present invention, since the time difference detection device u is interposed in particular at the front stage of the waveform analysis device, there are also the following advantages.

In other words, according to the inventors' experiments, 90% of the noise component
It has been confirmed that the above is an electromagnetic induction signal induced in the signal line.

If this electromagnetic induction signal also enters the waveform analyzer 21 as an input signal, it will take a long time to analyze in the waveform analyzer because of its high frequency. Therefore, in the present invention, focusing on the fact that electromagnetic induction signals appear simultaneously on each output line, a time difference detection device 1 is provided at the front stage of the waveform analysis device J, and as described above, electromagnetic induction signals appear on each output line simultaneously. The guidance signal is cut by the time difference detection device 11. ing. Therefore, the waveform analysis device 2
1 receives as input signals only AE wave signals, mechanical vibration sound signals, and fluid sound signals that do not include electromagnetic induction signals. For this reason, unlike the case where electromagnetic induction signals are included, analysis by the waveform analyzer J becomes easier, and it is possible to perform a highly reliable analysis that can significantly shorten the analysis time. can. As described in detail above, according to the present invention, it is possible to provide an AE monitoring device that can be used satisfactorily even under adverse environments.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional device, and FIG. 2 is a block diagram of an embodiment of the present invention. 1... structure, 2-1, 2-2,...2-n
...Acoustic sensor, 4 ... Signal processing device, 5 ... Display device, 11 ... Time difference detection device, 21 ... Waveform analysis Device.

Claims (1)

[Claims] 1 A plurality of acoustic sensors that are attached to a structure and detect sound waves that have arrived through the structure, a signal processing device that introduces the output signals of these acoustic sensors and performs the necessary processing, and a signal processing device that is organized by this device. a display device that displays the information in a required format; and a time difference detection device that is inserted into the output lines of each of the acoustic sensors and turns off all the output lines when signals appear on each output line at approximately the same time. and a waveform analysis device that is inserted in a line between the time difference detection device and the signal processing device and allows only signals that satisfy the conditions of an AE wave to pass among the signals that have passed through the time difference detection device. An AE monitoring device characterized by: