JP4025005B2 - Nondestructive inspection method and nondestructive inspection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a nondestructive inspection method and nondestructive inspection apparatus for detecting nondestructively exfoliation tiles being used for walls of buildings.
[0002]
[Prior art]
Conventionally, a method for detecting in advance an accident in which a tile used for a wall of a building is peeled and dropped due to a change with time or the like has been desired, and for example, Japanese Patent Application Laid-Open No. 07-209262 or There are some which are indicated by JP, 2000-131290, A.
[0003]
Japanese Patent Application Laid-Open No. 07-209262 discloses a method in which an object to be inspected is hit with a hammer, and the hitting sound at that time is converted into a digital signal and analyzed by a computer.
[0004]
More specifically, the object to be inspected is hit with a hammer or other hitting means, the crest factor is calculated from the reflected sound obtained at that time, and the object to be inspected is healthy when the crest factor is equal to or greater than a first predetermined value. When the crest factor is less than the first predetermined value, the expected frequency is calculated from the reflected sound. When the deviation between the expected frequency and the expected frequency of the sound object to be inspected is smaller than the second predetermined value, the target frequency is calculated. The inspection object is determined to be healthy, and when the deviation is greater than or equal to a second predetermined value, it is determined that the inspection object is defective.
[0005]
Japanese Patent Application Laid-Open No. 2000-131290 discloses a method of analyzing the frequency of impact sound using a plurality of bandpass filters.
[0006]
More specifically, the external force when an external force is applied to the object to be inspected with a hammer to generate a hitting sound is detected by an excitation force sensor, and the ratio between the result and the external force reference value is obtained while the object to be inspected is detected. The sound generated by an object is detected by a microphone, and the result is separated into time-series signals for each frequency by a bandpass filter, and further rectified to extract the instantaneous maximum value in each frequency band by peak hold. To do. The maximum value is corrected based on the ratio calculated earlier, and compared with the vibration reference value set in advance in the comparator, when the result is out of the predetermined relationship, a comparison result signal is issued, and the alarm device counts the number of comparison result signals. However, for example, when there are three or more, an alarm is given. That is, the maximum value of time series signals for each of a plurality of frequency bands is extracted and compared.
[0007]
On the other hand, there is one in which an object to be inspected is hit using a vibrator instead of hitting with a hammer. For example, in the one disclosed in Japanese Patent Application Laid-Open No. 59-94062, an object to be inspected is hit by driving an exciter with an alternating current generated by an oscillator. In the apparatus disclosed in this publication, a vibration having a continuously changing frequency is applied to an object to be inspected by a vibration exciter, and a resonance point at the natural frequency is measured by a vibration sensor.
[0008]
[Problems to be solved by the invention]
By the way, the conventional nondestructive inspection method has the following problems. That is, the inspector is beating tile surface at etc. Han Ma, its judges sensitive test the difference between hitting sound when is the primary, it is difficult to quantitatively determine the individual difference or skills of the examiner in this manner Also, the accuracy and reproducibility were incomplete.
[0009]
In addition, there are some attempts to mechanically and electrically process this determination, but all of them require a large-sized apparatus or an expensive measuring instrument. For example, the method disclosed in Japanese Patent Application Laid-Open No. 07-209262 requires a device and a computer for hitting a tile to be inspected with a hammer and for processing the hitting sound with a computer. Further, in the method disclosed in Japanese Patent Laid-Open No. 2000-131290, the structure is complicated because a plurality of bandpass filters are prepared in order to analyze the frequency. In addition, since the hammering sound is collected by a microphone, accurate measurement cannot be performed if there are other noise sources.
[0010]
In the method disclosed in Japanese Patent Application Laid-Open No. 59-94062, the object to be inspected is vibrated and only the resonance frequency at that time is measured. More accurate determination is difficult, and extra inspection costs such as labor costs are required.
[0011]
The present invention has been made in view of such circumstances, and an object thereof is to provide a nondestructive inspection method and a nondestructive inspection apparatus that can perform a measurement with a simple structure and high accuracy.
[0012]
[Means for Solving the Problems]
Non-destructive inspection method of the present invention, to generate a sine wave signal whose frequency varies continuously within a predetermined range, direct contact with the predetermined point tile converts the sinusoidal signal to mechanical vibration while applying Te, detected by contacting the mechanical vibration generated by the tile at a point spaced from the point of applying the mechanical vibrations directly converts the mechanical vibrations the detected into an electric signal, further By multiplying the converted electrical signal by the sine wave signal and obtaining a frequency characteristic of an output voltage obtained by removing a predetermined frequency component with a low-pass filter from the multiplication result , the building from the tile is obtained. when there is exfoliation, wherein the frequency characteristic detecting the exfoliation of the tiles differ greatly as compared with the case of normal.
[0013]
According to this method, a sine wave signal whose frequency continuously changes in a predetermined range is used as the excitation signal, and reception in which the frequency continuously changes in a predetermined range is the same as this sine wave signal. The frequency characteristics of the output voltage obtained by multiplying the signal and removing the specified frequency component from the multiplication result by the low-pass filter is compared with the frequency characteristics in the normal case where there is no tile peeling . It can be done easily .
[0014]
The nondestructive inspection apparatus of the present invention includes an excitation signal generating means for repeatedly generating a sine wave signal whose frequency continuously changes within a predetermined range, and a sine wave signal generated by the excitation signal generating means. converted into mechanical vibration, mechanical vibration applying means for applying direct contact the mechanical vibrations at a predetermined point of tile, with the tile at a point spaced from the point of applying the mechanical vibrations Mechanical vibration detection means for detecting the generated mechanical vibration by direct contact and outputting an electrical signal corresponding to the detected value; the sine wave signal generated by the excitation signal generating means; and the machine Signal multiplying means for multiplying the electrical signal detected by the mechanical vibration detecting means and outputting the result, and a low-pass filter for removing a predetermined frequency component from the output signal of the signal multiplying means. lowpass, characterized Characterized by comprising data and, a.
[0015]
According to this configuration, a sine wave signal whose frequency continuously changes in a predetermined range is used as the excitation signal, and reception in which the frequency continuously changes in the predetermined range similarly to this sine wave signal. Since the frequency characteristics of the output voltage obtained by multiplying the signal and passing the output signal of the multiplication result through the low-pass filter are compared with the frequency characteristics in the normal case where there is no tile peeling, tile peeling detection is possible. This simplifies and simplifies the apparatus, and enables highly accurate measurement.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of a nondestructive inspection apparatus according to an embodiment of the present invention. In this figure, the nondestructive inspection apparatus according to the present embodiment includes a sine wave oscillator 1, first and second amplifiers 2 and 3, a multiplier 4, an excitation piezoelectric speaker 5, and a reception piezoelectric element. A speaker 6 and a low-pass filter 7 are provided.
[0017]
The sine wave oscillator 1 repeatedly generates a sine wave signal whose frequency continuously changes in a predetermined frequency range (for example, 1 kHz to 20 kHz). The first amplifier 2 amplifies the sine wave signal from the sine wave oscillator 1 to a level at which the excitation piezoelectric speaker 6 can be driven, and outputs it as an excitation signal Vr. The second amplifier 3 amplifies the sine wave signal from the reception piezoelectric speaker 5 to a level that can be used by the multiplier 4 and outputs the amplified signal as a reception signal Vi. The multiplier 4 multiplies the excitation signal Vr from the first amplifier 2 and the reception signal Vi from the second amplifier 3 and outputs the result.
[0018]
The excitation piezoelectric speaker 5 converts the excitation signal Vr from the first amplifier 2 into mechanical vibration and applies it to the tile 10 to be inspected. The receiving piezoelectric speaker 6 uses a piezoelectric element, converts a mechanical signal into an electric signal, and outputs it. The vibrating piezoelectric speaker 5 and the receiving piezoelectric speaker 5 are spaced apart from each other on the tile 10 to be inspected. The low-pass filter 7 removes an amount of cos (2ωt + α + β) described below from the output signal from the multiplier 4.
[0019]
In such a configuration, the sine wave signal generated by the sine wave oscillator 1 is amplified by the first amplifier 2 and output to the excitation piezoelectric speaker 5 as the excitation signal Vr. Mechanical vibration is applied to the substrate. The excitation signal Vr is also output to the multiplier 4. When mechanical vibration is applied to the tile 10 to be inspected, the vibration is received by the receiving piezoelectric speaker 6, and a signal having a level corresponding to the magnitude of the vibration at that time is output to the second amplifier 3. The The received signal Vi is amplified by the second amplifier 3, and the received signal Vi is multiplied by the excitation signal Vr from the first amplifier 2 by the multiplier 4. Then, the output of the multiplier 4 is sent to the low-pass filter 7, and the cos (2ωt + α + β) component is removed by the low-pass filter 7 to obtain the output voltage Vo.
[0020]
The output voltage Vo is a signal reflecting the amplitude and phase of the reception signal Vi with respect to the frequency change of the excitation signal Vr. Therefore, this output voltage Vo represents a simple frequency characteristic of the tile 10 to be inspected. Since the frequency characteristics of the normal tile and the peeled tile are greatly different, it is possible to easily distinguish the peeled tile.
[0021]
The above operation principle is expressed as follows using mathematical formulas.
Vr = sin (ωt + α)
Vi = sin (ωt + β)
Where ωt is the frequency and α and β are the phase shifts.
Vr × Vi = sin (ωt + α) × sin (ωt + β)
= 1/2 [cos (β−α) −cos (2ωt + α + β)] (1)
[0022]
The cos (β−α) portion of the above equation (1) is a direct current component that changes in accordance with the phase difference, and includes the amplitude component of the reception signal Vi. The portion of cos (2ωt + α + β) is a signal having a frequency twice that of the original excitation signal Vr and the reception signal Vi. Since the required frequency characteristic information is the amplitude (magnitude) of the received signal Vi, only cos (β−α) in the equation (1) is sufficient. Therefore, the component of cos (2ωt + α + β) may be removed by passing through the low-pass filter 7. In this way, frequency characteristics appear in the form of voltage in the output voltage Vo.
[0023]
Here, FIG. 2 is a diagram showing a waveform of the output voltage Vo of a normal tile and a tile having a peeling portion. In this case, (a) is an output voltage waveform in a normal tile, and (b) is an output voltage waveform in a tile having a peeled portion. A normal tile is entirely in contact with the building, so the excited energy is absorbed and does not return to the receiver side very much, but only a part of the tile with the peeled part is in contact with the building. The peeled portion does not absorb the excited energy, and the frequency characteristics of the vibration of the tile itself can be observed. Therefore, it is possible to determine the separation of tiles by observing the difference in frequency characteristics appearing in the output voltage Vo.
[0024]
As described above, according to the nondestructive inspection apparatus of the present embodiment, the sinusoidal excitation signal Vr whose frequency continuously changes is used for the excitation of the tile 10 to be inspected. In addition, the normal tile and the peeled tile can be distinguished with high accuracy. Further, by multiplying the excitation signal Vr and the reception signal Vi and sending the multiplication result to the low-pass filter 7, a noise component unrelated to the excitation signal Vr can be removed from the reception signal Vi, and a simple signal High-precision measurement can be performed by processing. Furthermore, since the process is simple, the apparatus can be simplified. In particular, amplifiers and multipliers to be used can be easily realized with inexpensive semiconductors currently on the market, and can be manufactured at low cost. In addition, since it is not necessary to measure a large amount of basic data, labor costs can be saved.
[0025]
In the above embodiment, a sine wave having a single frequency range is used. However, a frequency range switch (not shown) for switching the frequency range is provided to selectively select a sine wave having a plurality of frequency ranges. You may be able to do it. In this case, the sine wave oscillator 1 has a function of repeatedly generating a sine wave signal in the frequency band in the range switched by the frequency range switch. As described above, by selecting a sine wave having a plurality of frequency ranges, the optimum frequency range for measurement is selected according to the physical characteristics such as the structure and material of the tile 10 to be inspected. This allows for more accurate measurements.
[0026]
【The invention's effect】
As described above, according to the present invention, by using the sinusoidal signal frequency in a predetermined range in excitation changes continuously in tiles, continuous frequency sine wave signal as well as a predetermined range Multiply by the received signal that changes periodically, send the multiplication result to the low-pass filter, remove the predetermined frequency component from the output signal of the multiplication result, and the frequency characteristic of the output voltage obtained by this is normal without tile peeling since determining the presence or absence of peeling in comparison with the frequency characteristics of the case, possible to provide a non-destructive inspection method and device structure suitable for peeling Hanareken査tiles can simple accurate measurements.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a nondestructive inspection apparatus according to an embodiment of the present invention.
2A and 2B are diagrams illustrating an example of measurement results obtained by the nondestructive inspection apparatus in FIG. 1, wherein FIG. 2A is an output voltage waveform diagram in a normal tile, and FIG. 2B is an output voltage waveform diagram in a tile having a peeled portion. is there.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Sinusoidal oscillator 2,3 Amplifier 4 Analog multiplier 5 Piezoelectric speaker for vibration 6 Piezoelectric speaker for vibration 7 Low-pass filter 10 Inspected tile

Claims (2)

By generating a sine wave signal whose frequency varies continuously within a predetermined range, while applied in direct contact with the predetermined point of tile converts the sinusoidal signal to mechanical vibration, the mechanical vibration mechanical vibration generated by the tile detected in direct contact at a point spaced from the point of applying the, converts the mechanical vibrations the detected into electrical signals, Furthermore, the electrical signals mentioned above converting said sinusoidal multiplying the wave signal, by determining the frequency characteristics of the output voltage obtained by removing a predetermined frequency component from the multiplication result by a low pass filter, the frequency when there is peeled away from the building of the tile non-destructive inspection method characterized by characteristic detecting the exfoliation of the tiles differ greatly as compared with the case of normal. Excitation signal generating means for repeatedly generating a sine wave signal whose frequency continuously changes within a predetermined range, and converting the sine wave signal generated by the excitation signal generation means into mechanical vibration, vibration and mechanical vibration applying means for applying in direct contact with the predetermined point of tiles and the mechanical vibration generated by the tile directly contact at a point spaced from the point of applying the mechanical vibrations Mechanical vibration detection means for detecting and outputting an electric signal corresponding to the detected value, the sine wave signal generated by the excitation signal generation means and the mechanical vibration detection means detected by the mechanical vibration detection means as a result a signal multiplier means for outputting, non-destructive testing equipment, characterized by comprising a low-pass filter, the removal of the predetermined frequency component from the output signal of said signal multiplying means multiplies the electric signal.

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