JP2000131290A - Nondestructive test device of concrete - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nondestructive test device of concrete capable of detecting precisely and surely an internal crack of a concrete product. SOLUTION: An external force applied to an ALC board 1 by a hammer 2 for generating a hammering sound is detected by an exciting force sensor 11, and the ratio thereof to an external force reference value is determined by a ratio computing unit 15. The hammering sound generated on the ALC board 1 is detected by a microphone 3, and separated into time series signals in each frequency zone by an analog BPF 5, and rectified and instantaneous maximum values in each frequency zone are extracted by a peak hold 7. The maximum values are corrected based on the ratio calculated by the ratio computing unit 15, and compared with a vibration reference value set up beforehand by a comparator 9. When the result is out of the prescribed relation, comparison result signals are issued, and if the number of the comparison result signals is, for example, three or more, an alarm unit 18 gives the alarm. As the maximum values of the time series signals in each of the plural frequency zones are extracted and compared, reliability of the determination is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting internal cracks in concrete, and more particularly to a non-destructive inspection apparatus for concrete capable of improving inspection reliability.

[0002]

2. Description of the Related Art As a conventional non-destructive inspection apparatus for concrete, there is one disclosed in, for example, Japanese Patent Application Laid-Open No. 5-20097. This is a method of tapping an ALC product with a striking device, detecting the striking sound generated by a sound level meter, reading the peak value of a voltage signal corresponding to the magnitude of the sound pressure output from the sound level meter, and performing a fast Fourier transform. A predetermined frequency component is extracted by a filter (hereinafter, referred to as FFT). Then, the extracted waveform is displayed on the display device.

When the ALC product to be inspected is hit in order from the end to the center, if there is a crack inside, the sound pressure waveform changes. The change in the sound pressure waveform is determined, and the presence or absence of a product caressing defect is determined.

[0004]

The conventional non-destructive concrete inspection apparatus as described above is characterized by a composite frequency because it only compares the maximum value of the sound pressure signal generated by impact. In the inspection of the hammering sound, when the characteristic of the abnormality appeared in the frequency other than the main component, the abnormality could not be detected accurately.

[0005] Further, since the maximum level of the frequency band is evaluated, it is not possible to discriminate between a sound pressure that is instantaneously generated greatly and a sound pressure that has a long lingering sound and a low level, which is a characteristic of the tapping sound. was there.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to obtain the following nondestructive concrete inspection apparatus. a. The reliability of the inspection can be improved by comparing the state of the vibration generated by the impact with the reference state. b. Inexpensive and high-speed processing is possible. c. It can be downsized and can flexibly respond to changes in conditions.

D. The influence of the variation of the external force applied to the object can be prevented. e. Noise from the surroundings and the effects of noise can be prevented.
Further, as further improvements, f. It is possible to know that an external force outside the proper range is applied or that the input has exceeded the proper range. g. The amplification factor of the amplifier can be easily set to an appropriate value. h. The vibration reference value can be set easily and accurately, and the reliability of the inspection can be improved.

[0008]

In order to achieve the above object, a concrete non-destructive inspection device according to the present invention provides a signal for detecting a vibration generated from concrete to which an external force is applied as a vibration signal. Detecting means, converting means for converting the vibration signal into a time series signal for each of a plurality of predetermined frequency bands, extracting means for extracting the maximum value of the time series signal for each frequency band, and setting each maximum value in advance And a comparing means for comparing with a vibration reference value for each frequency band. The vibration signal is converted into a time-series signal for each of a plurality of frequency bands, and the maximum value in each of the time-series signals is extracted. Thus, the frequency resolution of the vibration signal is improved, and the maximum value from the time-series signal is improved with high sensitivity. Can be extracted. Therefore, the characteristics of the loud sound or vibration immediately after the occurrence, which is also the characteristic of the impact, can be accurately grasped and compared.

The converting means is a plurality of band filters for passing a frequency component of a predetermined frequency band of the vibration signal. The extracting means rectifies the frequency components passing through each band filter, and converts each of the rectified frequency components. It is characterized in that the largest one of the peak values is extracted as the maximum value. If the conversion means is a bandpass filter, the processing can be performed at a high speed, and the apparatus is simple and inexpensive. In particular, if an analog bandpass filter is used, the processing can be speeded up. If a digital bandpass filter is used, the size can be reduced, and the condition can be flexibly changed. Further, since the extracting means extracts the maximum value from the rectified frequency components, it is possible to detect even when the maximum value is present in the negative sign part of the vibration signal, and to accurately compare even when the vibration signal is rapidly attenuated.

Further, the conversion means is a wavelet conversion means for performing a wavelet conversion of the vibration signal, and the extraction means extracts a maximum value for each frequency band based on a result of the conversion by the wavelet conversion means. If the wavelet transform means is used, the characteristics at the time of separating the signal into time-series signals for each frequency band can be improved, and the reliability of inspection can be improved.

The converting means is a short-time fast Fourier transform means for short-time fast Fourier transform of the vibration signal,
The extracting means extracts the maximum value for each frequency band based on the conversion result by the short-time fast Fourier transform means. The use of the short-time fast Fourier transform means improves the frequency resolution.

Further, an external force detecting means for detecting the magnitude of the applied external force is provided, and at least one of a vibration signal, a time-series signal, a maximum value, and a vibration reference value is corrected according to the magnitude of the external force. A correction means is provided. Correction is made in accordance with the magnitude of the external force to prevent the comparison means from being affected by variations in the magnitude of the external force. Also, for example, by performing different corrections according to the external force for each frequency band, it is possible to compare with high reliability even an object with a complicated structure in which the distribution of frequency components changes according to the applied external force. it can.

In addition, an external force detecting means for detecting the magnitude of the applied external force is provided, and at least one of a signal detecting means, a converting means, an extracting means, and a comparing means when the magnitude of the external force exceeds a predetermined value. Command means for commanding the start of operation is provided. Since the operation is not started until a command is issued, there is no possibility that noise, vibration, noise, or the like in the surroundings when no command is issued is erroneously processed as a vibration signal. Therefore, the influence of these can be prevented, and the reliability of the inspection is improved.

Further, there is provided external force detecting means for detecting the magnitude of the applied external force as an external force signal, and a ratio calculating means for obtaining a ratio obtained by dividing the external force signal by a preset external force reference value; Correction means for correcting the relationship between the maximum value and the vibration reference value in the comparison means by correcting at least one of the vibration signal, the time-series signal, the maximum value and the vibration reference value based on the ratio; And a ratio determining means for determining whether the value is within the range. The ratio calculating means determines whether or not the ratio between the external force and the external force reference value is within a predetermined range, that is, whether the external force applied to the object, that is, the exciting force is not too small or too large. Make sure that you have applied an inappropriate external force such as If the excitation force is too small or too large, erroneous determination can be prevented, for example, when the frequency characteristics of the vibration generated by the object are different. If you know that you have applied an inappropriate external force, you can apply the external force again,
It can be operated without using much nerves, and operability is also improved.

Further, there are provided external force signal amplifying means for amplifying the external force signal and outputting it as an amplified external force signal, and vibration signal amplifying means for amplifying the vibration signal and outputting it as an amplified vibration signal. It shall be used as an external force signal, the converting means shall use the amplified vibration signal as a vibration signal, and a range over detecting means for detecting that at least one of the peak values of the amplified external force signal and the amplified vibration signal has exceeded a predetermined value. It is characterized by having been provided. In order to ensure the reliability of the measurement, it is detected that the amplified external force signal or amplified vibration signal has exceeded a predetermined value, that is, that a large signal has been input that saturates the external force signal amplification means or vibration signal amplification means. I do.

Further, the present invention is characterized in that amplification factor automatic setting means for automatically setting the amplification factor of at least one of the external force signal amplification means and the vibration signal amplification means is provided. The amplification factor can be easily set so that the amplified external force signal and the amplified vibration signal are in an appropriate output range, and the operability is improved. Further, a decrease in the S / N ratio can be prevented, and the reliability of the inspection can be improved.

[0017] The comparison means is characterized in that the comparison is performed based on a vibration reference value set based on a vibration signal obtained when the state of the concrete is in a predetermined state. Vibration reference values can be easily set according to the condition of the concrete, and the reliability of inspection can be increased.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 Hereinafter, an embodiment of the present invention will be described with reference to the configuration diagram of FIG. In the figure, reference numeral 1 denotes a concrete ALC plate as an object,
Reference numeral 11 denotes a hammer which strikes the ALC plate 1 to generate a hitting sound, and 11 denotes an exciting force sensor which is attached to the hammer 2 and serves as external force detecting means for converting the exciting force applied to the ALC plate 1 into an electric signal. . Reference numeral 12 denotes an amplifier for amplifying the electric signal converted by the excitation force sensor 11, and reference numeral 13 denotes a rectifier for converting the signal amplified by the amplifier 12 to DC.

Reference numeral 14 denotes a peak hold that holds the maximum value of the DC signal output from the rectifier 13, and 15 denotes a ratio calculator that calculates the ratio between the output of the peak hold 14 and the external force reference value stored in the reference value setting device 16. It is. Reference numeral 17 denotes a trigger detector that detects a trigger from a DC signal output from the rectifier 13.

Reference numeral 19 denotes a ratio determiner for determining the ratio obtained by the ratio calculator 15. Reference numeral 20 denotes an automatic range setting device that automatically sets the amplification factor of the amplifier 12 from the maximum value output from the peak hold 14. Reference numeral 21 denotes a range over detector that detects range over from the maximum value output from the peak hold 14.

Reference numeral 3 denotes an A attached to the hammer 2
A microphone 4 as a signal detecting means for converting a tapping sound generated by the LC plate into an electric signal, and an amplifier 4 for amplifying the electric signal converted by the microphone 3. Reference numeral 5 denotes an analog BPF as conversion means for separating a signal obtained from the amplifier 4 for each frequency band. The analog BPF 5 covers nine octaves from 31.25 Hz to 16 kHz so as to cover, for example, almost 20 Hz to 20 kHz, which is a human audible range, and provides a total of 28 bands to provide a resolution of 1/3 octave.

Reference numeral 6 denotes a rectifier for rectifying a signal for each frequency band obtained from the analog BPF 5 and converting the signal to a direct current.
Reference numeral 7 denotes a peak hold as extraction means for holding the maximum value of the output from the rectifier 6, and reference numeral 8 denotes a corrector for correcting the maximum value output from the peak hold 7 based on the ratio obtained from the ratio calculator 15. 9 is the output of the compensator 8 and the reference value setting device 1
The comparator compares the sound pressure reference value as the vibration reference value stored in 0 with a predetermined method, that is, a predetermined comparison reference. Reference numeral 18 denotes an alarm device as determination means for performing an overall determination based on the comparison result from each of the comparators 9 and outputting an alarm when it is determined to be abnormal.

A rectifier 31 converts a signal amplified by the amplifier 14 into a direct current. Reference numeral 32 denotes a peak hold that holds the maximum value of the output from the rectifier 31, and reference numeral 33 denotes an automatic range setting device that automatically sets the amplification factor of the amplifier 4 based on the maximum value output from the peak hold 32. Numeral 34 is a range over detector for detecting range over from the maximum value output from the peak hold 32.

Next, a reference value setting mode for setting an external force reference value and a sound pressure reference value using a reference object as an operation will be described. First, the amplification factors of the amplifiers 4 and 12 are minimized. In this state, a sound ALC board 1 having no defect, which is an object, is hit with a hammer 2, and the generated hitting sound is converted into an electric signal by a microphone 3.
The rectifier 6 and the peak hold 32 determine the maximum value of the sound pressure signal that does not pass through the analog BPF. The soundness of the ALC plate 1 is confirmed by an X-ray inspection, a hitting inspection by a skilled person, or the like.

The maximum value is input to the automatic range setting unit 33, and the gain of the amplifier 4 is set so as to have an appropriate measurement range. Similarly, after the vibration generated in the hammer due to the impact is converted into an electric signal by the excitation force sensor 11, the maximum value of the vibration signal is obtained by the amplifier 12, the rectifier 13 and the peak hold 14. To set the gain of the amplifier 12 so as to have an appropriate measurement range.

The appropriate measurement range is, for example, corrected by the difference in the exciting force as in this embodiment. If the range is 1/2 to 2 times, the range is at most 2 times larger than the reference value. Since it is necessary to accept twice the input, the signal level input in this reference value setting mode is 5 times the measurement range.
The gain is set to be 0%.

In this way, the amplification of both vibration and sound is set by the first hit in the reference value setting mode.

Next, the sound ALC board 1 is hit by the hammer 2 as a reference object. At this time, the vibration generated in the hammer 2 is converted into an electric signal by the excitation force sensor 11, and the amplifier 12 gives the gain set by the first hit in the reference value setting mode. This amplified signal is converted into a direct current by the rectifier 13. The trigger detector 17 compares the DC signal from the rectifier 13 with a preset reference value, and outputs a trigger when the DC signal exceeds the reference value.

The peak hold 14 records the maximum value of the DC signal input from the rectifier 13. At this time, the operation of the peak hold 14 is started by a trigger signal from the trigger detector 17. The recording of such a maximum value is performed for a certain period of time until the sound pressure generated by the impact on the target object attenuates to some extent, and then the output from the peak hold 14 is stored in the reference value setting device 16 as an external force reference value.

Similarly, the sound wave generated by the impact is converted by the microphone 3 into an electric signal, and the amplifier 4 gives the gain set by the first impact in the reference value setting mode. A plurality of amplified sound pressure signals are provided to the analog BPF 5 set to pass different frequency bands, and are separated into time-series signals for each frequency band.

The time series signal separated for each frequency band by the analog BPF 5 is converted into a DC signal by the rectifier 6 and input to the peak hold 7. The maximum value recording operation of the DC signal from the rectifier 6 of the peak hold 7 is performed by the trigger detector 7.
, And is carried out for a certain period of time until the sound pressure of the object is attenuated in the same manner as the peak hold 14 for vibration. In this way, the instantaneous maximum value for each frequency band is recorded.

After a certain period of time until the sound pressure decay, the maximum value recorded by the peak hold 7 is stored in the reference setting device 10 as a sound pressure reference value. By the operation in the reference value setting mode, the reference value setting device 16 stores the external force reference value, which is information indicating the strength of the impact, and the reference value setting device 10
Stores a sound pressure reference value which is information indicating an instantaneous maximum sound pressure in each frequency band of the tapping sound.

Next, an inspection mode for inspecting an object will be described. First, ALC which is the object by the hammer 2
Hit plate 1. At this time, similarly to the case of the reference value setting mode, the vibration generated in the hammer 2 is converted into an electric signal by the excitation force sensor 11, amplified by the amplifier 12, and
Is converted to DC.

The trigger detector 17 similarly outputs a trigger from the DC signal from the rectifier 13 and
Records the maximum value of the DC signal for a certain period of time from the trigger output to the sound pressure decay. In the case of the inspection mode, the maximum value recorded in the peak hold 14 is input to the ratio calculator 15 after a fixed time until the sound pressure decay, and the ratio calculator 15 sets the maximum value from the peak hold 14 and the reference value. It calculates and outputs the ratio with the external force reference value stored in the container 16.

Similarly to the reference value setting mode, the sound wave generated by the impact is converted into an electric signal by the microphone 3 and amplified by the amplifier 4, separated into a time series signal for each frequency band by the analog BPF 5, and The signal is converted into a DC signal and input to the peak hold 7. The peak hold 7 records the maximum value of the DC signal for a fixed time from the trigger output to the sound pressure decay.

In the case of the inspection mode, the maximum value recorded by the peak hold 7 is input to the compensator 8 after a certain period of time until the sound pressure decay, and the corrector 8 determines an appropriate value from the ratio obtained from the ratio calculator 15. The correction value is calculated, corrected to the maximum value obtained from the peak hold 7, and output.

At this time, for example, assuming that the correction of the vibration level and the sound pressure is performed in proportion, if a ratio twice as large as the reference value is obtained by the calculation, the maximum value recorded in the peak hold 7 is calculated. Divide by two. That is, if the excitation force in the inspection mode is twice as large as the excitation force in the reference value setting mode, the maximum sound pressure obtained assuming that the sound pressure for each frequency band generated is also doubled Divide the value by 2 to convert the value to the excitation force in the reference value setting mode.

The maximum value corrected in this manner is compared by the comparator 9 with the sound pressure reference value stored in the reference value setting unit 10 based on a predetermined method or a predetermined comparison reference.
In this embodiment, a comparison result signal is output to the alarm 18 when the relationship deviates from a predetermined relationship set in advance.

At this time, the predetermined relationship is, for example, that when a corrected maximum value is within a range of, for example, 80% to 120% with respect to a sound pressure reference value of the band in a certain band, it is normal. When the value is out of the range, the value is out of the range and a comparison reference is set so as to output a comparison result signal. In another band, the comparison result signal is not output when the sound pressure reference value of the band is within a range of, for example, 70% to 110%, and is output when the sound pressure reference value is out of the range. Set the reference for comparison.

Further, when the sound pressure reference value is smaller than the overall sound pressure, by taking measures such as canceling the lower limit of the range, a comparison result signal is not erroneously output in a frequency band that is not the main component. I do.

The alarm device 18 receives the comparison result signal from the comparator 9 in each frequency band, and a criterion is determined so that if the number of comparison result signals exceeds a preset number, for example, two, it is determined to be abnormal. When an abnormality is determined, an alarm is output to the outside.

The ratio judging device 19 outputs an out-of-correction range alarm when the ratio calculated by the ratio calculator 15 exceeds a predetermined relationship. The predetermined relationship at this time is set to, for example, 1/2 to 2 times. Then, if there is an input less than や or more than twice, an out-of-correction-range alarm is output.

By limiting the range of the correction by the exciting force in this way, it is possible to reliably determine even an object whose frequency characteristic of a striking sound generated when the exciting force changes extremely is changed. In addition, it is possible to prevent erroneous determination due to an extreme change in the excitation force.

In the correction, the relationship between the waveform analysis result and the sound pressure reference value, that is, the sound pressure reference value stored in the reference value setting unit 10 in the comparator 9 is corrected according to the magnitude of the vibration signal. The output of the amplifier 12 and each analog B
One or more of the output of the PF 5, the output of the rectifier 6, or the sound pressure reference value stored in the reference value setting device 10 may be corrected.

When the magnitude of the vibration detected by the excitation force sensor 11 exceeds a predetermined value, the peak hold 1
4. Since the trigger detector 17 for instructing the start of the operation is provided to the peak hold 7 as the extracting means, the influence of noise from the surroundings can be reduced, and the reliability of the inspection can be improved.

Although the trigger signal from the trigger detector 17 is given to the peak hold 7, the microphone 3, the amplifier 4, the analog BPF 5 as the conversion means, the rectifier 6, the corrector 8 as the correction means, and the comparison means The same effect can be obtained by giving the maximum value to the comparator 9 or the like to start the storage operation of the maximum value or the comparison operation.

In each of the reference value setting mode and the inspection mode, the range over detector 21 inputs the maximum value obtained from the peak hold 14 for the vibration signal, and when the maximum value exceeds a predetermined relationship, the range over is detected. Output an alarm. The range over detector 34 inputs the maximum value of the sound signal obtained from the peak hold 7, and outputs a range over alarm when the measurement signal exceeds a predetermined relationship.

The predetermined relationship at this time is set, for example, as 99% of the measurement range. In this case, when a signal exceeding 99% is input, an overrange alarm is output.

Further, by setting an appropriate measurement range at the first hit in the reference value setting mode, the trouble of manually setting the measurement range is eliminated, and the operability is improved. Further, when the range is not appropriate when setting manually, the S / N ratio is lowered and the reliability of the inspection is lowered. However, such a problem does not occur because the range is automatically set to an appropriate value. In addition, it is possible to obtain a hammering inspection apparatus with improved inspection reliability.

Also, by outputting a range over alarm immediately before the input of each signal is saturated, it is possible to prevent a false judgment due to the saturation of the amplifier and to obtain a tapping sound inspection apparatus with improved inspection reliability. Becomes The inspection can be performed at high speed by using the analog BPF.

Embodiment 2 FIG. 2 is a configuration diagram of an ALC plate nondestructive inspection apparatus showing another embodiment of the present invention. In FIG. 2, the following points are different from those shown in FIG. 1, but the other configuration is the same as that shown in FIG. The maximum value of the sound pressure for each frequency band extracted by the peak hold 7 is corrected by the corrector 8 and then input to the reference setting device 10, and the reference setting device 10 determines the maximum value of the input maximum value. The difference is that an average value is obtained, this is used as a sound pressure reference value, a range of variation of the maximum value is determined, and a comparison reference is determined based on the range of variation.

Next, the operation will be described. First, a center portion of the surface of a sound ALC plate 1 is hit with a hammer 2.
At this time, the vibration generated in the hammer 2 is detected as an external force applied to the ALC plate 1 by the excitation force sensor 11, converted into an electric signal, and the maximum value is extracted by the peak hold 14. The maximum value extracted by the peak hold 14 is determined by the reference setter 16
Is stored as an external force reference value. At this time, the ratio calculator 1
5 outputs the ratio 1. These are the same as those shown in the embodiment of FIG. Note that the soundness of the ALC plate 1 is confirmed by a hitting sound inspection or an X-ray inspection by a skilled person.

On the other hand, the maximum value of the sound pressure signal extracted by the peak hold 7 passes through the compensator 8 as it is because the ratio output by the ratio calculator 15 is 1, and is input to the reference setter 10 to be sounded. It is stored as a pressure reference value.

Next, the average value of the maximum value of the sound pressure signal for each frequency band is obtained and set as the sound pressure reference value. Further, the variation of the maximum value is obtained. For example, hitting is performed while sequentially moving 100 different places on the surface of a sound ALC plate by a predetermined dimension from the end to the center. The maximum value of the sound pressure obtained for each impact, that is, the maximum value of each frequency band extracted by the peak hold 7, is calculated by the compensator 8 by the ratio calculator 1
The value is corrected by the ratio calculated by 5, and stored in the reference value setting unit 10. In other words, if the ratio is 1.2, it is assumed that the external force applied this time is 1.2 times the external force when the external force reference value was previously stored in the reference setting device 16 and divided by 1.2. To normalize. In this way, one for each frequency band
Obtain 00 data.

Then, an average value of the maximum values is obtained and used as a sound pressure reference value. In addition, a range of variation of the maximum value is obtained for each frequency band. For example, frequency band number A1
In the above, the sound pressure reference value is set to 100, 90 to 110,
In the frequency band number A2, like 80 to 120,
Hereinafter, the range of the variation is obtained for all 28 bands.
Then, the comparator 9 does not output a comparison result signal within the range of the variation determined as described above, and determines that the comparison result signal is output to the alarm device 18 when it exceeds the range. In consideration of the possibility of uncertain variation in the impact sound emitted from the normal ALC board, an additional 5 to 10
A margin of about% may be provided.

In the alarm device 18, even if it is normal, there is a possibility that it goes outside the data obtained from the above 20 places. In the case of, it is determined to be abnormal and an alarm is issued.

As described above, by hitting a sound ALC plate, the maximum value of the time-series signal in each frequency band of the vibration signal is obtained.
Since the comparison is performed on the basis of this, if there is an appropriate defect in the ALC plate, an abnormality appears in any of the above-mentioned frequency bands and the error is protruded from the comparison standard, so that the defect can be detected reliably. The comparison criterion set by the above-described method can be modified and learned based on data obtained in a later actual test.

Embodiment 3 FIG. In the first embodiment, an analog BPF is used to determine the maximum value for each frequency band, but a digital BPF may be used. In this embodiment, a case where a digital BPF is used will be described with reference to the configuration diagram of FIG. In FIG. 3, reference numeral 51 denotes an A / D converter for converting an analog signal from the rectifier 13 into a digital signal, and reference numeral 52 denotes an A / D converter for converting an analog signal from the amplifier 4 into a digital signal. 53 is an A / D converter 5
This is a maximum value calculator for calculating the maximum value of the output of No. 1.

Reference numeral 61 denotes a digital BPF as conversion means for converting a digital signal into a time series signal for each frequency band. The digital BPF 61 is, for example, 9 to 31.25 to 16,000 Hz in order to cover almost 20 to 20,000 Hz which is a human audible range similarly to the embodiment of FIG.
For 28 octaves, a total of 28 bands are provided with a resolution of 1/3 octave. Reference numeral 62 denotes a rectifier for rectifying an AC signal from the digital BPF, and reference numeral 63 denotes a maximum value calculator as extraction means for extracting a maximum value from the rectified digital signal.

Reference numeral 64 denotes a corrector which corrects the maximum value output from the maximum value calculator 63 based on the ratio obtained from the ratio calculator 15 and outputs a correction value. A comparator 65 compares the output of the compensator 64 with the sound pressure reference value stored in the reference value setting device 66 by a predetermined method. The rectifier 62, the peak hold circuit 63, the compensator 64, the comparator 65, and the reference value setter 66 are digital BPs provided for all 28 bands.
28 are provided corresponding to F61, respectively.

A maximum value calculator 41 extracts the maximum value from the digital signal from the A / D converter 52 rectified by the rectifier 31. Other configurations are the same as those shown in FIG. 1, and the corresponding components are denoted by the same reference numerals and description thereof is omitted.

Next, the operation will be described. First, a reference value setting mode for setting each reference value using a reference target object will be described. The A / D converter 51 converts an analog DC signal from the rectifier 13 into a digital signal. At this time, the A / D converter 51 starts operation in response to the trigger signal from the trigger detector 17, and continuously performs the operation for a certain period of time until the sound pressure generated by the impact on the object attenuates to a predetermined value or less. Will be The maximum value calculator 53 extracts the maximum value of the digital signal from the A / D converter 51, and the maximum value is stored in the reference value setting device 16 as an external force reference value.

Similarly, the sound wave generated by the impact is converted into an electric signal by the microphone 3, given an appropriate gain by the amplifier 4, and then converted into a digital signal by the A / D converter 52. At this time, the A / D converter 52 starts operating in response to a trigger signal from the trigger detector 17 and operates for a certain period of time until the sound pressure generated by the impact on the target object attenuates below a predetermined value. This converted digital signal is
The signals are input to 28 digital BPFs 61 set so as to pass through different frequency bands, and separated into time-series signals for each frequency band.

The time-series signal separated for each frequency band by the digital BPF 61 is converted into a DC signal by the rectifier 62 and input to the maximum value calculator 63. Maximum value calculator 63
Extracts the maximum value of this DC signal,
To be stored. In this way, the instantaneous maximum value of each frequency band is extracted, and the reference value setting unit 66 is used as the sound pressure reference value.
Is stored in

By such an operation in the reference value setting mode, the reference value setting device 16 stores the external force reference value which is information indicating the strength of the hitting, and the reference value setting device 66 stores each frequency band of the striking sound. The sound pressure reference value, which is information indicating the instantaneous maximum sound pressure at the time, is stored.

Next, an inspection mode for inspecting an object will be described. First, the ALC plate 1 as an object is hit with the hammer 2. At this time, similarly to the case of the reference value setting mode, the vibration generated in the hammer 2 is converted into an electric signal by the excitation force sensor 11, amplified by the amplifier 12, and
To convert to DC. Similarly, the trigger detector 17 is connected to the rectifier 1.
The A / D converter 51 converts the DC signal into a digital signal for a certain period of time from the trigger output to the sound pressure attenuation. The maximum value calculator 53 extracts and outputs the maximum value of the digital signal.

In the case of the inspection mode, the maximum value extracted by the maximum value calculator 53 is input to the ratio calculator 15, and the ratio calculator 15 calculates the maximum value and the external force reference value stored in the reference value setter 16. Calculates and outputs the ratio.

Similarly to the reference value setting mode, the sound wave generated by the impact is converted into an electric signal by the microphone 3, amplified by the amplifier 4, and converted into a digital signal by the A / D converter 52. At this time, the operation of the A / D converter 52 is started by a trigger signal from the trigger detector 17, and is performed for a certain period of time until sound pressure decay. The digital signal is separated into a time series signal for each frequency band by a digital BPF 61, converted into a DC signal by a rectifier 62, and input to a maximum value calculator 63. The maximum value calculator 63 extracts and outputs the maximum value of the DC signal.

In the case of the inspection mode, the maximum value extracted by the maximum value calculator 63 is input to the corrector 64,
Reference numeral 4 calculates an appropriate correction value based on the ratio obtained from the ratio calculator 15, corrects the maximum value obtained from the maximum value calculator 63, and outputs the corrected value.

The corrected maximum value is compared by a comparator 65 with a sound pressure reference value stored in a reference value setting device 66. If the reference value deviates from a predetermined relationship set in advance, a comparison result signal is output to the alarm 18. Is output to The predetermined relationship to set is
As in the embodiment shown in FIG. 1, for example, in a certain band, when the corrected maximum value is within the range of 80% to 120% with respect to the sound pressure reference value of the band, the comparison result signal is regarded as normal. Is set to output a comparison result signal when the value is out of this range, that is, when it is less than 80% and more than 120%, as an abnormality. Also, other,
In a certain band, it is set so that the comparison result signal is output as out of the range when it deviates from 70% to 110% with respect to the sound pressure reference value of the band.

If the sound pressure reference value is smaller than the overall sound pressure, a comparison result signal is not erroneously output in a frequency band that is not the main component by taking measures such as canceling the comparison on the lower limit side. To When the number of input comparison result signals exceeds a preset number, for example, two, the alarm device 18 sounds a buzzer as a notification need and flashes a lamp to give an alarm.

As described above, by using the digital BPF 61 as a method for obtaining a time series signal for each frequency band, the size of the apparatus can be reduced, and since the processing is performed by software (S / W), the filter characteristic is changed or the frequency band to be diagnosed is changed. It is possible to flexibly cope with the addition of, for example.

Embodiment 4 FIG. 4 is a configuration diagram of a non-destructive inspection apparatus for an ALC plate showing still another embodiment of the present invention. Although the digital BPF is used to find the maximum value for each frequency band in the embodiment of FIG. 3, wavelet transform (Wavelet Transform) may be used. Hereinafter, the case where the wavelet transform is used will be described based on the configuration diagram of FIG.

In this embodiment, a wavelet transform calculator 71 is provided to obtain a time-series signal for each frequency band.
This is the same as the embodiment. In the wavelet transform, an effective value is calculated by the analysis operation, so that it is not necessary to provide a rectifier.

In the figure, reference numeral 71 denotes a wavelet transform (WaveletTransform) as a transforming means.
An arithmetic unit that separates a digital sound pressure signal into a time series signal for each frequency band by expanding or reducing a basis function (mother wavelet). The wavelet-transformed signal is supplied to a maximum value calculator 6 provided in 28 sets.
3, input to the corrector 64 and the comparator 65.

The comparator 65 is compared with the sound pressure reference value stored in the reference value setting device 66 in the same manner as shown in FIGS. 1 and 3, and when a predetermined relationship is established, The comparison result signal is output to the alarm 18.

At this time, by selecting an appropriate basis function in accordance with the measured waveform and the phenomenon to be observed, the frequency separation characteristics can be improved, and the reliability of the inspection can be improved. In addition, the size of the apparatus can be reduced by using the wavelet transform operation unit.

Embodiment 5 FIG. FIG. 5 is a configuration diagram of a non-destructive inspection apparatus for an ALC plate showing still another embodiment of the present invention. In the embodiment of FIG. 3, the digital BPF is used to find the maximum value for each frequency band.
FT may be used. Hereinafter, the case where the short-time FFT is used will be described with reference to FIG. In this embodiment, a short-time FFT calculator 81 is provided to obtain a time-series signal for each frequency band.

Other operations are the same as those of the embodiment shown in FIG. In the short-time FFT, an effective value is calculated by the analysis operation, so that it is not necessary to provide a rectifier. In FIG. 5, reference numeral 81 denotes a short-time FF as a conversion unit.
T (SFFT: Short-Time Fast Fo)
uri-Transform) computing unit, which obtains a time-series signal for each frequency band.

As described above, the short-time F which is a Fourier transformer
By providing the FT calculator 81 and obtaining a time-series signal for each frequency band, the frequency resolution can be improved.

Therefore, the reliability of diagnosis can be improved in the case where a characteristic appears in a change in frequency due to the properties and configuration of concrete by utilizing the excellent resolution of short-time FFT. Further, the size of the apparatus can be reduced by using the short-time FFT operation unit.

In each of the above-described embodiments, a method in which an external force is applied by a hammer has been described. However, a method in which an external force is applied by other means, or a method in which an exciting force is applied by an electromagnetic wave, a cylinder, or the like, can also be used. .

In each of the above embodiments, the external force is detected by the excitation force sensor 11 and the striking sound is detected by the microphone 3, but the striking sound is detected by using a vibration detector instead of the microphone. Is also good. In the above embodiments, the audible frequency is referred to as sound, and the frequency range wider than the audible frequency is referred to as vibration. However, in the present invention, the inspection apparatus is not limited to sound, but may be referred to as sound. Are not distinguished, and include those caused by vibration.

Although the alarm device 18 is shown to warn, each signal in such a determination and the calculated value, for example, each sound pressure reference value stored in the setting device 10 in the embodiment of FIG. And a range serving as a reference for determining whether or not to output a comparison result signal set in the comparator 9, a correction value calculated by the ratio calculator 15, a corrected maximum value from each corrector 8 in determination, and the like. Those that are displayed on the CRT in a band shape and are out of the range are color-coded with red or the like, so that they can be easily confirmed, and the operability can be improved.

The maximum value corrected by the corrector 8 may be superimposed on a normal range and displayed so as to be visually grasped. At this time, if the comparison result deviates from the predetermined relationship, the maximum value detected at that time may be displayed in red, or the like.

[0086] In such an inspection apparatus, the object is AL.
The present invention is not limited to the C plate, and can be used for inspection of internal defects of other concrete plates, concrete walls, and the like.

Instead of the sound pressure reference value and the comparison reference shown in the third to fifth embodiments, the sound pressure reference value and the comparison reference obtained in the same manner as in the second embodiment are used. You can also.

[0088]

Since the present invention is configured as described above, it has the following effects.

Signal detecting means for detecting vibration generated from concrete to which an external force is applied as a vibration signal, converting means for converting the vibration signal into a time series signal for each of a plurality of predetermined frequency bands, The extraction means for extracting the value for each frequency band and the comparison means for comparing each maximum value with the vibration reference value for each preset frequency band are provided. Can be accurately grasped, and the reliability of comparison can be improved.

The converting means is a plurality of band filters for passing the frequency components of a predetermined frequency band of the vibration signal. The extracting means rectifies the frequency components passing through each band filter, and converts each of the rectified frequency components. Since the maximum value among the peak values is extracted as the maximum value, if the converting means is a band-pass filter, the processing can be performed at high speed, and the apparatus is simple and inexpensive.
Further, since the extracting means extracts the maximum value from the rectified frequency components, it is possible to detect even when the maximum value is present in the negative sign part of the vibration signal, and to accurately compare even when the vibration signal is rapidly attenuated.

Further, the transforming means is a wavelet transforming means for wavelet transforming the vibration signal, and the extracting means extracts the maximum value for each frequency band based on the result of the conversion by the wavelet transforming means. It is possible to improve characteristics at the time of separating into time-series signals for each frequency band, and to improve the reliability of comparison and inspection.

Since the converting means is a short-time fast Fourier transforming means and the extracting means extracts the maximum value for each frequency band based on the result of the conversion by the short-time fast Fourier transforming means, the frequency resolution is improved. be able to.

Further, external force detecting means for detecting the magnitude of the applied external force is provided, and at least one of a vibration signal, a time-series signal, a maximum value, and a vibration reference value is corrected according to the magnitude of the external force. Since it is characterized by the provision of a correction means, by correcting according to the magnitude of the external force,
In the comparison by the comparison means, the influence of the variation in the magnitude of the external force can be prevented, and the reliability of the comparison is improved.

Further, an external force detecting means for detecting the magnitude of the applied external force is provided, and at least one of a signal detecting means, a converting means, an extracting means, and a comparing means when the magnitude of the external force exceeds a predetermined value. A command means for commanding the start of operation is provided. Since the operation is not started until a command is issued, the surrounding noise, vibration, noise, etc. when there is no command may be erroneously processed as a vibration signal. There is no. Therefore, the influence of these can be prevented, and the reliability of the inspection is improved.

Further, there is provided external force detecting means for detecting the magnitude of the applied external force as an external force signal, and a ratio calculating means for calculating a ratio obtained by dividing the external force signal by a preset external force reference value; Correction means for correcting the relationship between the maximum value and the vibration reference value in the comparison means by correcting at least one of the vibration signal, the time-series signal, the maximum value and the vibration reference value based on the ratio; It is characterized in that it is provided with a ratio determining means for determining whether or not it is within the range. it can.

Further, external force signal amplifying means for amplifying the external force signal and outputting it as an amplified external force signal and vibration signal amplifying means for amplifying the vibration signal and outputting it as an amplified vibration signal are provided. It shall be used as an external force signal, the converting means shall use the amplified vibration signal as a vibration signal, and a range over detecting means for detecting that at least one of the peak values of the amplified external force signal and the amplified vibration signal has exceeded a predetermined value. Since it is characterized in that it has been provided, it is detected that the amplified external force signal or the amplified vibration signal exceeds a predetermined value, that is, it is detected that a large signal is input such that the external force signal amplifying means or the vibration signal amplifying means is saturated. As a result, the reliability of the inspection can be ensured.

[0097] Further, since amplification factor automatic setting means for automatically setting the amplification factor of at least one of the external force signal amplifying means and the vibration signal amplifying means is provided, the amplified external force signal and the amplified vibration signal are output. The amplification factor can be easily set so as to be in an appropriate output range, and operability is improved.
Further, a decrease in the S / N ratio can be prevented, and the reliability of the inspection can be improved.

The comparison means is characterized in that the comparison is performed based on a vibration reference value set based on a vibration signal obtained when the state of the concrete is in a predetermined state. Therefore, it is possible to easily set the vibration reference value according to the above, and it is possible to improve the reliability of the inspection.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an ALC plate non-destructive inspection apparatus according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of an ALC plate non-destructive inspection apparatus according to another embodiment of the present invention.

FIG. 3 is a diagram showing another embodiment A of the present invention.
It is a lineblock diagram of a nondestructive inspection device of an LC board.

FIG. 4 is a diagram showing another embodiment A of the present invention.
It is a lineblock diagram of a nondestructive inspection device of an LC board.

FIG. 5 is a diagram showing another embodiment A of the present invention.
It is a lineblock diagram of a nondestructive inspection device of an LC board.

[Explanation of symbols]

1 ALC board, 2 hammer, 3 microphone, 4 amplifier, 5 analog BPF, 6 rectifier, 7 peak hold circuit, 8 corrector, 9 comparator, 10 reference value setting device, 11 excitation force sensor, 12 amplifier, 13 rectifier , 14 Peak hold, 15 Ratio calculator, 16
Reference value setting device, 17 trigger detector, 18 alarm device, 1
9 Ratio judgment device, 20 range automatic setting device, 21 range over detector, 31 rectifier, 32 peak hold, 33 range automatic setting device, 34 range over detector, 41 maximum value calculator, 51, 52 A / D converter ,
53 maximum value calculator, 61 digital BPF, 62 rectifier, 63 maximum value calculator, 64 corrector, 65 comparator, 66 reference value setter, 71 wavelet transform calculator, 81 short-time FFT calculator.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2G047 AA10 BA04 BC04 BC07 CA03 CA07 EA01 EA04 EA11 EA12 GA18 GF11 GG08 GG12 GG15 GG17 GG24 GG33 GG41 GH05

Claims (10)

[Claims] 1. A signal detecting means for detecting a vibration generated from concrete to which an external force is applied as a vibration signal, a converting means for converting the vibration signal into a time series signal for each of a plurality of predetermined frequency bands, A concrete non-destructive inspection device, comprising: extracting means for extracting a maximum value of a series signal for each frequency band; and comparing means for comparing each of the maximum values with a preset vibration reference value for each frequency band. 2. The converting means is a plurality of bandpass filters for passing a frequency component of a predetermined frequency band of the vibration signal,
2. The method according to claim 1, wherein the extracting means rectifies the frequency components passing through the band-pass filters, and extracts a maximum value among peak values of the rectified frequency components as maximum values. Non-destructive inspection equipment for concrete as described. 3. The method according to claim 1, wherein the transforming means is a wavelet transforming means for performing a wavelet transform on the vibration signal, and the extracting means extracts a maximum value for each frequency band based on a result of the transformation by the wavelet transforming means. Item 2. The nondestructive inspection device for concrete according to item 1. 4. The short-time fast Fourier transform means for short-time fast Fourier transform of the vibration signal, and the extracting means extracts a maximum value for each frequency band based on a result of the conversion by the short-time fast Fourier transform means. The non-destructive concrete inspection device according to claim 1, wherein 5. An external force detecting means for detecting the magnitude of the applied external force, and correcting at least one of a vibration signal, a time-series signal, a maximum value, and a vibration reference value according to the magnitude of the external force. The concrete non-destructive inspection device according to claim 1, further comprising a correction unit. 6. An external force detecting means for detecting the magnitude of the applied external force, and at least one of a signal detecting means, a converting means, an extracting means, and a comparing means when the magnitude of the external force exceeds a predetermined value. 2. The concrete non-destructive inspection device according to claim 1, further comprising command means for commanding the start of operation. 7. An external force detecting means for detecting the magnitude of the applied external force as an external force signal, and a ratio calculating means for calculating a ratio obtained by dividing the external force signal by a preset external force reference value; Correcting means for correcting at least one of the vibration signal, the time-series signal, the maximum value, and the vibration reference value based on the relationship to change the relationship between the maximum value and the vibration reference value in the comparing means; The non-destructive concrete inspection apparatus according to claim 1, further comprising a ratio determination unit configured to determine whether the ratio is within the range. 8. An external force signal amplifying means for amplifying an external force signal and outputting it as an amplified external force signal, and a vibration signal amplifying means for amplifying a vibration signal and outputting the amplified vibration signal as an amplified vibration signal, wherein the ratio calculating means comprises the amplified external force signal. Is used as an external force signal, the converting means uses the amplified vibration signal as a vibration signal, and a range for detecting that the peak value of at least one of the amplified external force signal and the amplified vibration signal exceeds a predetermined value. The non-destructive concrete inspection device according to claim 7, further comprising an over-detection unit. 9. The concrete non-destructive method according to claim 8, further comprising automatic gain setting means for automatically setting at least one of the external force signal amplifying means and the vibration signal amplifying means. Inspection equipment. 10. The comparison means according to claim 1, wherein the comparison is performed based on a vibration reference value set based on a vibration signal obtained when the state of the concrete is in a predetermined state. Item 10. The nondestructive inspection device for concrete according to any one of items 9.