JP2000088819A - Ultrasonic detecting device and computer-readable record medium memolizing program for supersonic detection - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a deep position of a material to be detected and a detection and a flaw- detection of a porous material at a high accuracy by setting a transmitting and receiving ultrasonic wave strength to a predetermined value or more and sweeping-processing and then, natural number-multiplicating a time series wave. SOLUTION: A transmitting probe 2a transmits a ultrasonic wave to a substance to be detected by a pulse wave from a pulse generating device 1 and a reflection wave is received by a receiving probe 2b to convert it to an electric signal. The electric signal is amplified by an external amplifier 3 and is analyzed by an analyzer 4. That is, the electric signal inputted is further amplified by an amplifier circuit 4a and is filtered by a filter circuit 4b. The signal is A/D converted by an ADC 4c and an addition average of a received wave at the same point is calculated by a gate array 4d. At this time, the transmitting/receiving original wave is converted to an input ultrasonic wave and a received ultrasonic wave of a high strength very broad band area by a first processing filter with a processing program of a memory device connected to CPU or DSP 4e. A time series wave obtained by a sweeping calculation processing the ultrasonic wave by a second processing filter is natural number- multiplicated by a third processing to remove a scattering wave, etc. Thereby, a significant reflection wave is clearly obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic detecting apparatus and a computer-readable recording medium for storing an ultrasonic detecting program used for detecting an internal defect of a steel material or the like using ultrasonic waves. In particular, the present invention relates to an ultrasonic detection device capable of detecting a reinforcing bar and a crack depth, etc., which are arranged in a concrete structure in a complicated manner, and a computer-readable recording medium storing an ultrasonic detection program.

[0002]

2. Description of the Related Art High-precision, rapid, and easy techniques for detecting internal defects in steel or the like and the presence or absence of flaws in welds using ultrasonic waves are being studied. Many of these studies and inventions are directed to the detection of minute flaws based on the straightness of ultrasonic waves, their high directivity, Huygens' principle, and Snell's theorem.

In a conventional general flaw detection method, a wideband ultrasonic wave is selected from a frequency of 1 to 100 MHz, input from a surface of steel or the like, and is transmitted from the inside of the steel at another point at or near the same point. A reflected wave (often a horizontal wave) is acquired, and a transmission path length between an ultrasonic input point and a receiving point and an internal defect is calculated from the time of occurrence of the reflected wave and the sound speed of the object to be inspected. The position of an internal defect or the like is determined by the input direction of the ultrasonic wave and its straightness.

[0004] Such a conventional method for detecting an internal defect using high-frequency broadband ultrasonic waves detects a flaw or the like in steel at a position where the transmission distance is short, and can be regarded as microscopic detection. .

However, recently, there has been a demand for a detection method and a detection device for macroscopically detecting the inside of an elastic body. This macroscopic detection enables detection of a reflector present at a position extremely distant from the ultrasonic transmission and reception positions, for example, at a position 10 m away. When a plurality of reflected waves are obtained, the meaning of each is specified. Further, it is desired that the object to be detected is not limited to iron, steel, plastic and the like.

In addition, it is possible to measure the position and size of a reinforcing bar or a steel frame which is arranged in a complex structure in a complicated manner, and to detect the state of cracks and their depth, the internal voids and the thickness of the concrete with ultra-high accuracy. There is a need for macroscopic detection that is possible and can also be used for internal exploration of castings, soil, and ground. That is, even if the object to be detected is porous or a composite of several different materials or an ingot in which the crystal of the material particles is in one direction, it is desirable that the inside can be detected.

[0007]

However, as described above, the conventional detecting device and the conventional detecting method are characterized in that the ultrasonic waves travel straight in the input direction and have high directivity, and the ultrasonic waves are based on Huygens' principle. Because it utilizes only the property of reflecting, bending, and modulating at different boundaries based on Snell's theorem, it can improve the microscopic inspection of homogeneous elastic materials such as steel and iron. Although it can be performed with high precision, it is difficult to detect the interior of a concrete or the like with a porous material having a large amount of fine stones of about 1 to 2 cm and an infinite number of fine voids called an aggregate, which is difficult. If not possible. FIG. 113A is a cross-sectional view showing the straightness and directivity of ultrasonic waves in a homogeneous elastic body, and FIG. 113B is a cross-sectional view showing the straightness, directivity and scattering of ultrasonic waves in a porous elastic body.

As shown in FIG. 113 (a), when detecting a homogeneous elastic body such as steel, a vertical wave input immediately below travels straight in the input direction and has high directivity. However, FIG.
As shown in FIG. 13B, in a porous elastic material such as concrete, ultrasonic waves are scattered due to the presence of fine stones and voids therein, and the straightness and directivity thereof are extremely low. For this reason, the input ultrasonic wave, as shown in FIG.
It is diffused into the porous elastic material in a fan shape. This phenomenon is
The same applies to the case where the input wave is a horizontal wave.

As described above, in the detection and flaw detection of the porous elastic material, the directivity and directivity of the ultrasonic wave are reduced, and the intensity of the ultrasonic wave on the path reaching the detection target is greatly attenuated. In some cases, they may disappear in appearance.
Furthermore, a surface wave having a large power and a direct wave of a large power due to the scattering phenomenon are generated near the measurement point, and the reflected wave from the detection target is buried in these waves. Further, the surface wave and the direct wave may be erroneously recognized as a reflected wave from the detection target. Furthermore, a reflected wave or the like having a short transmission path that is not in the directivity direction also occurs. Mode conversion and the like also occur at the time of reflection and bending contact by a large number of fine stones. Even if a vertical wave is input directly below the transmitter, not only a vertical wave in the porous elastic material, A wide wave of waves is emerging. When a reverse zigzag wave is input, a strong wave is generated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and is an ultrasonic detecting apparatus capable of detecting and detecting flaws of a detection target material at a deep position and detecting and detecting a porous material with high accuracy. And a computer-readable recording medium storing an ultrasonic detection program.

[0011]

SUMMARY OF THE INVENTION An ultrasonic detecting apparatus according to the present invention is an ultrasonic detecting apparatus for transmitting an ultrasonic wave and analyzing the received ultrasonic wave. A first process for applying a first filter to the sound wave so that the intensity of the ultrasonic wave is equal to or more than a predetermined value in a predetermined frequency band or more, and a second filter for the ultrasonic wave subjected to the first process. Arithmetic processing unit for executing a process including a second process of performing the sweep process of the ultrasonic wave by applying the second process, and a third process of raising the time-series wave of the ultrasonic wave subjected to the second process to a natural number. It is characterized by having.

Another ultrasonic detecting apparatus according to the present invention is an ultrasonic detecting apparatus for transmitting an ultrasonic wave and analyzing the received ultrasonic wave, wherein the transmitted ultrasonic wave is divided by the transmitted ultrasonic wave. A first process of applying a first filter to the received ultrasonic wave divided by the received ultrasonic wave to make the intensity of the ultrasonic wave not less than a predetermined value in a predetermined frequency band or more; A second process of performing a sweep process of the ultrasonic wave by applying a second filter to the ultrasonic wave subjected to the first process, and raising a time series wave of the ultrasonic wave subjected to the second process to a natural number power And a processing device that executes a process including the third process.

In the present invention, the transmitted transmitted ultrasonic waves and the received received ultrasonic waves are converted into high-intensity and ultra-wideband ultrasonic waves by the first processing. Next, a sweep process is performed by the second process, and a wideband ultrasonic wave is extracted in an arbitrary frequency band. Then, when this is raised to a natural number power, a desired wave appears sharply.

The arithmetic unit includes a fourth process for correcting the occurrence time of the reception ultrasonic wave in association with the transmission time of the transmission ultrasonic wave changed by the second process; A fifth process of selecting a predetermined area of the time-series wave of the received ultrasonic wave in association with the approximate value when the approximate value of the birth time from the target detection object is known; and A sixth process for obtaining a difference between an ultrasonic wave received when the target object is affected by the target object and an ultrasonic wave received when the target object is not affected by the target object, and measurement at a plurality of points. A seventh process for obtaining an average of a plurality of received waves obtained, an eighth process for obtaining an average of a plurality of received waves obtained by performing a plurality of measurements at the same point, Ninth processing for determining whether the sound wave is appropriate or inappropriate It is desirable to perform processing including.

Since an error may occur due to the environment of the detection and the flaw detection, the error is eliminated by the processing by the fourth to ninth programs, and the detection and the flaw detection with high accuracy are performed.

A transmitter connected to the arithmetic unit for transmitting ultrasonic waves to the object to be detected; and a receiver connected to the arithmetic unit for receiving ultrasonic waves from the object to be detected.
The transmitter may have a plate-shaped substrate and electrodes formed at the center of both surfaces of the substrate. Further, the receiver may have a plate-shaped base material and electrodes formed at central portions of both surfaces of the base material.

[0017] Further, there is provided a transmission / reception probe connected to the arithmetic unit for transmitting ultrasonic waves to the detection target material and receiving ultrasonic waves from the detection target material. The substrate may have a shape of a base, and electrodes formed at the center of both surfaces of the base. By using such a transmitter, a receiver, and a transmitter / receiver probe, unnecessary vibration such as buckling is suppressed, so that transmission and reception of ultrasonic waves are performed with high accuracy.

The first filter may include a third filter represented by a product of an m-order sine function and an n-order cosine function, where m and n are integers of 0 or more. desirable. Further, it is preferable that the first filter includes a fourth filter that removes a wave having a frequency not included in the transmitted ultrasonic wave from the received ultrasonic wave.

Still further, the second filter has a fifth filter represented by a product of an m-order sine function and an n-order cosine function, where m and n are integers of 0 or more. It is desirable to have a sixth filter in which, when m and n are integers greater than or equal to 0, the frequency giving the maximum value represented by the product of the m-th sine function and the n-th cosine function is the desired frequency. Is even more desirable.

The computer-readable recording medium storing the ultrasonic detection program according to the present invention includes first and second transmission ultrasonic waves transmitted from the ultrasonic detection apparatus and reception ultrasonic waves received by the ultrasonic detection apparatus. A first process of making the intensity of the ultrasonic wave equal to or more than a predetermined value in a predetermined frequency band or more by applying a filter, and applying a second filter to the ultrasonic wave subjected to the first process. And causing the computer to execute a process including a second process of performing the ultrasound sweep process and a third process of raising the time-series wave of the ultrasound that has undergone the second process to a natural number. I do.

A computer-readable recording medium storing another ultrasonic detecting program according to the present invention is a computer-readable recording medium obtained by dividing an ultrasonic wave transmitted from an ultrasonic detecting device by the transmitted ultrasonic wave and the ultrasonic detecting method. A first process in which the intensity of the ultrasonic wave is equal to or more than a predetermined value in a predetermined frequency band or more by applying a first filter to a signal obtained by dividing the received ultrasonic wave received by the device by the received ultrasonic wave; A second process for performing a sweep process of the ultrasonic wave by applying a second filter to the ultrasonic wave subjected to the first process, and converting a time-series wave of the ultrasonic wave subjected to the second process into a natural number. And causing the computer to execute a process including a third process of riding.

The ultrasonic detection program includes a fourth processing for correcting the occurrence time of the reception ultrasonic wave in association with the transmission time of the transmission ultrasonic wave fluctuated by the second processing; When the approximate value of the birth time from the target object in the object to be detected is known, a predetermined area of the time-series wave of the received ultrasonic wave is selected in association with the approximate value.
And a sixth process of calculating a difference between an ultrasonic wave received when the ultrasonic wave is affected by the target object in the object to be detected and an ultrasonic wave received when the ultrasonic wave is not affected by the target object. And a seventh process for calculating an average of a plurality of received waves obtained by measuring a plurality of points, and an eighth process for obtaining an average of a plurality of received waves obtained by performing a plurality of measurements at the same point. And a ninth process of determining whether the transmitted ultrasonic wave is appropriate or inappropriate.

The first filter may include a third filter represented by a product of an m-th sine function and an n-th cosine function, where m and n are integers of 0 or more. desirable. Further, it is preferable that the first filter includes a fourth filter that removes a wave having a frequency not included in the transmitted ultrasonic wave from the received ultrasonic wave.

Still further, the second filter has a fifth filter represented by a product of an m-th sine function and an n-th cosine function, where m and n are integers of 0 or more. It is desirable to have a sixth filter in which, when m and n are integers greater than or equal to 0, the frequency giving the maximum value represented by the product of the m-th sine function and the n-th cosine function is the desired frequency. Is even more desirable.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION As a result of intensive experiments and research conducted by the present inventors in order to solve the above-mentioned problems, in addition to the two ultrasonic transmission characteristics used in the conventional ultrasonic detection device, three new ultrasonic transmission characteristics are used. It has been found that macroscopic detection and flaw detection can be performed by also utilizing the ultrasonic transmission characteristics. The two ultrasonic transmission characteristics used in conventional ultrasonic detection devices are the characteristics that ultrasonic waves travel straight in the input direction and have high directivity, and are based on Huygens' principle and Snell's theorem. Ultrasound is reflected at different boundaries of
This is a characteristic of bending and mode conversion. In addition, the three newly added ultrasonic transmission characteristics are as follows: ultrasonic waves are diffused in a porous material in a fan-like manner by a scattering phenomenon to generate vertical waves and side waves in the porous material, and the intensity of the diffused ultrasonic waves. Is a property that changes greatly depending on the frequency of the ultrasonic wave. The change in the ultrasonic intensity greatly depends on the transmission distance d and the frequency f, and the attenuation rate α is a function α that depends on the transmission distance d and the frequency f.
(D, f) and when a vertical wave and a transverse wave of an ultrasonic wave are inputted from the surface of the porous body, a direct wave, a vertical wave, a transverse wave and a surface wave are generated due to a scattering phenomenon, and the transmission speed of these waves is It is the nature of being different.

FIG. 1 is a diagram showing the intensity of a fan-shaped diffused ultrasonic wave due to a change in frequency in a porous elastic body.
Is a schematic diagram at a low frequency, and (b) is a schematic diagram at a high frequency. FIG. 2 is a diagram showing the intensity of fan-shaped diffused ultrasonic waves due to a change in frequency in a homogeneous elastic body,
(A) is a schematic diagram at a low frequency, and (b) is a schematic diagram at a high frequency. When the ultrasonic wave is input directly below the surface of the homogeneous and porous elastic body, the intensity in the directing direction is expressed by a vector of 1.0, and the ultrasonic intensity in the direction inclined by θ degrees from the directing direction is transmitted as a solid line envelope. It is represented by P (θ) by an arc drawn at a distance d. The intensity P (θ) of the homogeneous elastic body becomes negligibly small as the angle θ approaches 90 degrees, but an ultrasonic wave having a very large power remains in the porous elastic body. This tendency is particularly remarkable at low frequencies.

FIG. 3 is a graph schematically showing the attenuation rate of ultrasonic waves in the porous elastic material with the transmission distance on the horizontal axis. As the frequency increases and the transmission distance increases, the attenuation rate α (d, f) increases at an accelerated rate.

Hereinafter, an ultrasonic detecting apparatus according to an embodiment of the present invention will be specifically described with reference to the accompanying drawings.
FIG. 4 is a block diagram illustrating an ultrasonic detection device according to an embodiment of the present invention.

The ultrasonic detecting apparatus according to the present embodiment includes a voltage pulse generator 1, a transmitting probe 2 which receives a pulse wave generated from the pulse generator 1 and transmits an ultrasonic wave to an object to be detected.
a, a receiving probe 2b that receives a reflected wave or the like from the inside of the object and converts it into an electric signal, an external amplifier 3 that amplifies the electric signal obtained by the receiving probe 2b, An analysis device 4 for analyzing the electric signal amplified by the amplifier 3 and a display device 5 for displaying an analysis result by the analysis device 4 and a pulse wave generated by the pulse generator 1 are provided.

The pulse generator 1 includes a pulse generation circuit 1a for generating a pulse wave, a pulse interval change circuit 1b for changing the generation interval of the pulse wave, and a pulse wave connected to these and sending out the pulse wave to the outside of the pulse generator 1. A pulse drive circuit 1c is provided.

The analyzer 4 further includes an amplifier circuit 4a for further amplifying the input electric signal, a filter circuit 4b for filtering the amplified signal, and an analog / digital converter (A / D converter) for converting the filtered signal. AD
C) 4c and gate array 4d and CPU or DSP
4e is provided. The gate array 4d calculates the average of the received waves at the same point.

Further, a readable storage device (not shown) is connected to the CPU or the DSP 4e, and the following nine processing programs are stored in the storage device. The pulse generator 1, the amplifier circuit 4a, the filter circuit 4b, and the ADC 4c are controlled by a CPU or a DSP 4e. Note that an external amplifier 3 is provided outside the main body in order to remove or reduce electric noise mixed into the received wave.

Although the ultrasonic detector according to the present embodiment shown in FIG. 4 is represented by the two-probe method, the one-probe method may be employed. FIG. 10 is a schematic diagram showing an example in which the one-probe method is adopted. In this case, one probe functions as a transmission probe and a reception probe.

The first processing program applies a low-pass filter, a high-pass filter, a special filter represented by a sine function or a cosine function to the transmission source wave and the reception source wave, and divides the transmission source wave by the transmission source wave. High-intensity ultra-wide band by applying a low-pass filter, a high-pass filter, or a special filter (third filter) represented by a sine function or a cosine function to the filtered signal and the received signal divided by the received signal. To obtain the input ultrasonic wave and the received ultrasonic wave.

The second processing program is a sweep calculation processing for extracting a time series wave in an arbitrary frequency band by further filtering the ultrasonic wave obtained by the first processing program.

The third processing program removes a scattered wave and the like and removes a significant reflected wave by raising the time series wave obtained by the first processing program and the second processing program to the m-th power (m: natural number). And so on to obtain such information clearly.

The fourth processing program is to correct the occurrence time of the reflected wave by using the transmission time that changes with the change of the center frequency of the input ultrasonic wave in the second processing program.

[0038] The fifth processing program is used to generate the approximate time of occurrence of the reflected wave or the like from the detection target object when the time of occurrence can be estimated in advance or when the approximate value of the time of occurrence is found. The necessary part of the time-series wave is cut out in association with the raw time.

The sixth processing program calculates a difference between a reception wave at a position where the detection target is located and a reception wave at a position where the detection target is not located where the detection target is located relatively shallow from the surface. It is.

The seventh processing program is for obtaining a composite wave from the received waves obtained by the multi-point measurement.

The eighth processing program eliminates the influence of disturbance at the site or the like.

In the ninth processing program, when extracting a reflected wave or the like in a broadband frequency band having an arbitrary center frequency, an input ultrasonic wave is obtained at the same center frequency and frequency band, and the waveform of the input ultrasonic wave is examined. By doing
This is to exclude a reception wave corresponding to an inappropriate input ultrasonic wave from an analysis target.

Next, the transmitting probe 2a and the receiving probe 2b
Will be described. 5A is a plan view showing a ceramic probe used in the embodiment of the present invention, FIG. 5B is a cross-sectional view showing the same probe, and FIG. 5C is a conventional ceramic probe commercially available. FIG. 3D is a plan view showing the probe, FIG. 4D is a cross-sectional view showing the same probe, FIG. 4E is a plan view showing another conventional ceramic probe on the market, and FIG. It is sectional drawing which shows a child.

The probe 11 used in this embodiment
Has a diameter of 30 m as shown in FIGS. 5 (a) and 5 (b).
m, and has a shape in which the edge 12 is provided in a disk shape having a thickness of 2 mm. The diameter of the region where the edge 12 is not provided is 23 mm. Then, platinum is baked as the electrode 13 only on both surfaces of the region where the edge 12 is not provided.

On the other hand, the conventional ceramic probe 21a
Or, 21b has a disk shape with a diameter of 30 mm and a thickness of 2 or 3 mm, as shown in FIGS. Then, platinum is baked on the entire surface as electrodes 23 on both surfaces thereof.

The operation of the probe thus configured will be described. 6A to 6C are cross-sectional views showing the operation of the ceramic probe used in the embodiments of the present invention in various vibration modes, and FIGS. 6D to 6G are conventional sectional views in various vibration modes. FIG. 5 is a cross-sectional view showing the operation of the ceramic probe of FIG.

In the probe 11 used in the present embodiment, the occurrence of abnormal vibration is suppressed by the edge portion 12. That is, it is possible to obtain an input ultrasonic wave in which vibration due to buckling and vibration in the circumferential direction are restricted.

On the other hand, in the conventional probe 21a or 21b, as shown in FIGS. 6 (d) and 6 (e), vibration in the circumferential direction is likely to occur, and when the load voltage exceeds the critical value, Buckling occurs suddenly beyond its structural and physical limits. This buckling occurs slightly later than the vibration in the radial direction or the thickness direction. Therefore, when the load voltage is high, a problem may occur in the transmitted ultrasonic waves.

FIG. 7A is a graph showing a spectrum obtained by the probe 11, FIG. 7B is a graph showing a time-series waveform, and FIG. 8A is a graph showing a spectrum obtained by the probe 21a. 9B is a graph showing a time-series waveform, FIG. 9A is a graph showing a spectrum obtained by the probe 21b, and FIG. 9B is a graph showing a time-series waveform. . 7 to 9 show that the transmitted ultrasonic wave (collected by the AE sensor) when a voltage of 500 V is loaded on the probe for a short time is sin ³ ((π / 2) ×
^{(F / (2.5 × 10 6} )) multiplied by the filter, which was a _{X · exp (iω x t)} , X / X · exp (iω
_x t) is obtained by applying a C ₁ · C ₂ filter according to a fourth example of a first processing program described later.

The wave transmitted from the probe 11 has a small wave number and is suitable as an input ultrasonic wave. On the other hand, in the transmitted wave from the probe 21a or 21b, since a plurality of waves are superimposed, it is not suitable for the input ultrasonic wave.

In FIGS. 5 (a) and 5 (b),
Although the edge portion 12 is provided, even if the ceramic plate is flat without such an edge portion 12, a sufficient effect can be obtained if the electrode is provided only in the center portion of the ceramic plate. That is, it is only necessary that the electrode is not formed on the peripheral portion of the ceramic plate.

Next, for each of the above-described processing programs,
A specific description will be given using actual measurement data as appropriate. FIG.
(A) And (b) is sectional drawing which shows the concrete block in which the rebar used for actual measurement was embedded. The concrete mass 31 used for the actual measurement has a square pillar shape with a side length of 500 mm and a height of 300 mm. Among them, six diameters are 19 mm at a position 50 mm away from the front or back surface.
Reinforcing bars 32 of mm are embedded at intervals of 150 mm. Further, a crack having a width of 2 mm is formed from the surface to a depth of 200 mm.

When the ultrasonic detection measurement of such a concrete mass 31 is performed, the vertical wave, the side wave and the direct wave 33 on the reinforcing rod path, the vertical wave and the surface wave 34 on the cracking path, and the reflection path from the reinforcing rod. The vertical waves 35a and 35b, the vertical wave 36 of the reflection path from the bottom of the concrete block, and the vertical waves 37 of the reflection path from the corner of the bottom of the concrete block are received. FIG. 12A is a graph showing the Fourier spectrum of the transmitted ultrasonic original waveform measured by the AE sensor, and FIG.
FIG. 4 is a graph showing a time-series waveform. FIG.
3 (a) is a graph showing a Fourier spectrum of an original waveform of a received ultrasonic wave measured by arranging a transmitting probe and an AE sensor as a receiving probe with a crack interposed therebetween in a measurement directly above a reinforcing bar, and (b). FIG. 4 is a graph showing a time-series waveform.

First, the first processing program will be described using a received wave at a position immediately above a reinforcing bar. As described above, the first processing program applies a special filter represented by a low-pass filter and a high-pass filter, or a sine function and a cosine function to the transmitted original wave and the received original wave,
By applying a low-pass filter and a high-pass filter, or a special filter represented by a sine function and a cosine function, to the transmission original wave divided by the transmission original wave and the reception original wave divided by the reception original wave , For obtaining input ultrasonic waves and received ultrasonic waves or nearly received ultrasonic waves of high intensity and ultra-wide band. The first processing program has the following five types.

In the first example, general low-pass filters and high-pass filters are applied to an input wave and a received original wave. FIG. 14A is a graph showing a high-pass filter, and FIG. 14B is a graph showing a low-pass filter.
In FIGS. 14A and 14B, the maximum value on the vertical axis of the filter is normalized to 1.0. As shown in FIG. 14A, the high-pass filter F _H is, for example, 110
It increases monotonically up to kHz and remains constant above that frequency.
On the other hand, the low-pass filter F _L, as shown in FIG. 14 (b), for example, is constant until 120 kHz, monotonically decreasing at higher. By applying such a high-pass filter and a low-pass filter to the input ultrasonic waves and the received ultrasonic waves, it is possible to obtain the received ultrasonic waves corresponding to the input ultrasonic waves in an arbitrary frequency band. FIG. 15A shows that after the filters F _H and F _L have been subjected to input ultrasonic waves,
FIG. 7 is a graph showing a Fourier spectrum of an input ultrasonic wave obtained by applying a high-pass filter _H1 , and FIG. 7B is a graph showing a time-series waveform. FIG. 16A is a graph showing a Fourier spectrum of a received wave obtained by the same filtering process, and FIG. 16B is a graph showing a time-series waveform. However, FIGS. 15B and 16
(B) is displayed by applying a third processing program (m = 6) described later.

As shown in FIG. 15B, the input ultrasonic waves are steep and have a small wave number. Then, FIG.
In the received waves shown in (1), the occurrence of reflected waves with a steep and low wave number is confirmed, but vertical waves (not reflected waves), surface waves, direct waves, etc. that pass through the reinforcing bar directly under the probe (not reflected waves) are apparent. Has disappeared above. Further, a peak A1 indicating a vertical wave bypassing the bottom of the crack and a peak E1 indicating a surface wave are significantly prominent. Further, the reflected wave B1 from the reinforcing bar on the bottom side of the concrete and the peak D1 indicating the reflected wave from the bottom of the concrete are slightly smaller than the other generated waves. This is because the ultrasonic waves were cut off by the reinforcing bar on the concrete surface side. Furthermore, a peak C1 indicating a reflected wave reflected from the oblique reinforcing bar on the bottom side of the concrete is large. This is because the directivity direction of the ultrasonic wave was changed by the front-side rebar.

The second example is a filter using a special function composed of a sin curve and a cos curve (third filter).
Is applied to the input wave and the received original wave. The special function filter, when the constant that specifies the filter is _fHL ,
For example, it is represented by the following Equation 1.

[0058]

## EQU1 ## sin ((π / 2) × (f / ( _fHL / 2)))
= 2 × sin ((π / 2) × (f / f _HL )) · cos
((Π / 2) × (f / f _HL ))

FIG. 17 is a graph showing an example of a special function filter.
It is a rough figure. In FIG. 17, the constant f _HLIs 2.5 × 10⁶
(Hz), and a spectrum of 1.0 in all frequency bands
Functions with special values are filtered by a special function
You. The curve shown in FIG. 17 is standardized. Ma
Further, as another example of the special function filter, the above function is represented by n
Multipliers can also be used. In other words,
The number is represented by the following equation (2).

[0060]

## EQU2 ## sin ⁿ ((π / 2) × (f / ( _fHL / 2)))

FIG. 18 is a graph showing another example (n = 8) of the special function filter (third filter). By applying such a special function filter to the input ultrasonic wave and the received ultrasonic wave, it is possible to obtain a received ultrasonic wave corresponding to the input ultrasonic wave in an arbitrary frequency band. Below, sin
((Π / 2) × (f / f _HL )) is _converted to C ₁ , cos ((π /
2) × a (f / f _HL)) referred to as C _2.

[0062] The third example, the input wave X · exp (iω _x t)
And instead of the received original wave Y · exp (iω _y t), X /
X · exp (iω _x t) and _{Y / Y · exp (iω y} t)
Are the input wave and the substantially received wave, respectively.
A pass filter or a high-pass filter is applied on the frequency axis. Note that the substantially received wave is the received wave Y · exp
We shall refer to a _{Y / Y · exp (iω y} t) relative (iω _y t). FIG. 19A is a graph showing the input ultrasonic wave X and the received original wave Y in the measurement directly above the reinforcing bar, and FIG. 19B is a graph showing the input ultrasonic wave X and the transfer function Y / X in the measurement just above the reinforcing bar. As shown in FIGS. 19A and 19B, when the received original wave Y is divided by the input wave X, many spectra having sharp peaks occur in the frequency band corresponding to the valley of the input wave spectrum X. ing. This is an erroneous spectrum necessarily resulting from the calculation of the transfer function Y / X. This wrong spectrum has a bad influence on the identification of the reflected wave. Therefore, the occurrence time of the reflected wave is specified by obtaining a substantially received wave from which the erroneous spectrum has been removed.

Therefore, by dividing the transfer function by the transfer function Y / X, the input ultrasonic wave X / X · exp (iω _x
The substantially received wave corresponding to t) is set to Y / Y · exp (iω _y t), and a general low-pass filter / high-pass filter is applied to these, and a substantially received wave corresponding to a high-intensity broadband input ultrasonic wave in an arbitrary frequency band is obtained. Think about getting. In this case, the wave Y / X · exp (iω _y t) and the wave Y / Y · exp (iω _y
In t), although the amplitudes of the reflected waves are different, the birth times coincide, so that the birth times can be specified without any problem.

Next, a fourth example will be described. In the fourth example, instead of the low-pass filter and the high-pass filter in the third example, the sine function and the co function described in the second example are used.
A special function composed of the s function is used as a filter (third filter). FIG. 20A shows AE
(Acoustic emission) A graph showing FY / Y obtained by applying the fourth example of the first processing program to the spectrum Y of the wave received by the sensor, and (b) is a graph showing the time-series waveform. is there. As shown in FIG. 20, the received original wave has a large number of standing spectral components.
These spectral components correspond to the resonance frequency corresponding to the transmission distance of the reflected wave or the like. However, in the fourth example, Y · exp (iω _y t) is changed to Y / Y · exp (iω _y
t), both the spectrum value at the resonance frequency and the spectrum value at the non-resonance frequency are 1.0. For this reason, in the broadband substantially received wave spectrum (FY / Y), non-resonant waves are recognized more prominently, and the amplitudes of reflected waves having a late onset time and reflected waves from a distance are reduced. FIG. 1 using the resonance wave of the first example.
The analysis result of No. 6 differs from the occurrence of reflected waves.

That is, the peak A1 of the vertical wave bypassing the bottom of the crack is dominant, and the reflected waves from farther than this are all except that the peak C1 of the vertical wave reflection from the path 35b remains. Has disappeared. The peak F1 of the direct wave of the path 33 via the reinforcing bar among the waves of the short-range path emerges.

The fifth example is to improve the accuracy of the third or fourth example. FIG. 21 (a) graph showing the spectrum of ultrasonic waves amplify a high frequency component by multiplying the filter C ₁ of the second example in the recorded input wave X by the AE sensor, indicating the (b) is also a time-series waveform FIG. FIG. 22A is a graph showing an X / X spectrum, and FIG. 22B is a graph showing a time-series waveform. Comparing the time-series waveforms of FIG. 21B and FIG. 22B, in the latter case, a wave generated by the calculation of X / X occurs before and after the actual input wave.

The wave subjected to the calculation of X / X contains a large amount of waves of frequency components which are hardly contained in the input wave. Therefore, the substantially received wave Y / Y · exp (iω
_yt ) also contains a large amount of this frequency component wave. If the wave of such a frequency component can be substantially removed from the received wave as much as possible, the extraction accuracy of the reflected wave and the like can be improved. The fifth example is to remove such a frequency component wave. FIG. 23 (a) shows a spectral component which was originally not included in the input ultrasonic wave or was minute by removing unnecessary generated waves artificially by cutting out a time-series wave by a fifth processing program described later. Is a graph showing a spectrum in which is smaller and the contained component is larger, and FIG. 4B is a graph showing a time-series waveform. Function function represented by X / X = 1.0 This process is somewhat similar to C ₁ · X, such as F _e (Fourth
Filter). That is, a function is obtained in which the frequency component not included in the input ultrasonic wave is smaller and the component included therein is larger.

Therefore, Y / Y in the third and fourth examples
・ F _e・ Y / Y ・ exp instead of exp (iω _y t)
Assuming that (iω _y t) is a substantially received wave, a frequency component that the input ultrasonic wave does not have or a minute frequency component that does have is removed from the substantially received wave.

The actual processing method in the analyzer 4 is as follows.
This function F _e is prepared in advance as a filter with numerical data for each ultrasonic transmission probe used in the detection, and F _{e.
X / X · exp (iω y} t) and F _e · Y / Y · exp
The calculation of (iω _y t) is performed by the CPU or the DSP 4e.

The first processing program is arranged as follows. Here, the input ultrasonic wave is X · exp
(Iω _x t), the received original wave and _{Y · exp (iω y t)} .

[0071] The first _{example, X · exp (iω x t} ) and Y
A low-pass filter or a high-pass filter is applied to exp (iω _y t).

[0072] The second _{example, X · exp (iω x t} ) and Y
A filter (third filter) composed of a sin function or a cos function is applied to exp (iω _y t).

[0073] The third example is intended to apply a low-pass filter or high pass filter to the _{X / X · exp (iω x} t) and _{Y / Y · exp (iω y} t).

In the fourth example, the sine function or cos is used for X / X · exp (iω _x t) and Y / Y · exp (iω _y t).
This is to apply a filter composed of functions (third filter).

[0075] The fifth example, the fourth filter obtained using _{F E F E · X / X} · exp (iω x t) and F _E · Y /
In Y · exp (iω _y t), for example, sin function or co
A filter (third filter) composed of an s function is applied.

Next, the second processing program will be described. The second processing program is a sweep processing as described above. The second processing program has the following four types.

[0077] The first example, enter a common low-pass and high-pass filters HaraNami X · exp (iω _x t) and the reception HaraNami Y · exp (iω _y t) or the input original waves in this original input wave subjected to dividing the _{X / X · exp (iω x} t) and substantially received wave _{Y / Y · exp (iω y} t), it is to change the starting frequency of these filters sequentially. FIG. 24 is a graph showing a high-pass filter and a low-pass filter. Note that the start frequency of the filter is arbitrarily determined.

In the second example, the value is 1.0 in the entire frequency range.
Sin to a function with spectral values ^k((Π / 2) ×
(F / f_HL)) And cos^k((Π / 2) × (f /
f_HLThe maximum value of the function obtained by multiplying by)) is normalized to 1.0.
sin^k((Π / 2) × (f / (f_HL/ 2)))
This, this is cosⁿ((Π / 2) × (f / f_HL)) Or
sinⁿ((Π / 2) × (f / f_HL)) Multiplied by
Filter the function shown in Equation 3 or Equation 4 (fifth filter
To use as

[0079]

## EQU3 ## sin ^k ((π / 2) × (f / (f _HL /
2))) · cos ⁿ ((π / 2) × (f / f _HL ))

[0080]

## EQU4 ## sin ^k ((π / 2) × (f / (f _HL /
2))) · sin ⁿ ((π / 2) × (f / f _HL ))

FIG. 25 is a graph showing a filter based on the function shown in Equation 3, with the maximum value being normalized to 1.0. In FIG. 25, k is 4, f _HL is 2.5
× 10 ⁶ Hz. Also, the filter function is shifted from the high frequency side to the low frequency side by arbitrarily changing n between 1 and 405. Using Expression 4, the filter function is shifted from the low frequency side to the high frequency side. Then, by applying the above-described filter function on the frequency axis to the input wave obtained by the first processing program and the corresponding received wave and substantially received wave, a high-intensity and wide-band input ultrasonic wave in an arbitrary frequency band is obtained. And (substantially) a received wave.

Although the above-described filter function can be obtained for each measurement by the CPU or the DSP 4e, the following method is desirably employed to reduce the processing time. A filter function FiLT (j) is prepared for about 1 to 30 j in advance. Next, for a broadband input ultrasonic wave, FiLT (j) · X · exp (iω
_{x t), FiLT (j)} · for broadband receiving ultrasonic
Y · exp (iω _y t), F for broadband substantially received waves
iLT (j) · Y / Y · exp sweep calculations represented by (iω _y t) to be calculated in CPU or DSP4e. Then, these time series waves are displayed in real time.

In the third example, a function having a spectrum value of 1.0 in the entire frequency range is multiplied by a function expressed by the following equation (5).
A function whose maximum value is normalized to 1.0 is filtered (No. 5).
Filter).

[0084]

## EQU5 ## sin ⁿ ((π / 2) × (f / f _HL )) · co
s ⁿ ((π / 2) × (f / f _HL ))

In the third example, it is possible to sweep from the high frequency side to the low frequency side or the opposite direction by changing the value of f _HL . FIG. 26 is a graph showing filter functions at various f _HL when n is 2.

In the fourth example, a function having a frequency at which a local maximum value is arbitrarily given at a desired frequency is extracted from the filter functions described in the second and third examples, and the function (sixth filter) is extracted from the high frequency side. Sweep is performed by freely moving in the direction on the low frequency side or in the opposite direction. FIG. 27 is a graph showing sweeping of the filter function.

In the second, third and fourth examples, s
Since the sweep is performed by the special function including the in function or the cos function, a wave having a large number of peaks and valleys does not occur before and after the reflected wave. Or, even if it has occurred, its number is small. This phenomenon will be described.

The input ultrasonic wave and the reception wave and the substantially reception wave are:
It can also be obtained by addition and subtraction on a time series. Here, the description will be made using a time-series wave y (t) represented by the following Expression 6.

[0089]

Y (t) = a ₀ + Σ _{n = 1} ^k a _n cos (nωt) +
^{_{Σ n = 1 k b n sin}} (nωt)

[0090] However, t is time, ω is the angular velocity, is a _0, a _n and b _n coefficient, k and n is a positive number. Then, addition and subtraction of the following equations 7 and 8 are performed on the function y (t).

[0091]

G ₁ (t) = １ ／ × (y (t) −y (t + Δt))

[0092]

G ₂ (t) = １ ／ × (y (t) + y (t−Δt))

Further, for simplicity, a component in which nω is R is extracted, and Expression 6 is converted to y (t) = a _R cos (Rt) + b _R s
in (Rt). Furthermore, Δt is set to 1 / 2f _HL = 1
Assuming /(2×2.5×10 ⁶ ), Equations 7 and 8 are represented by Equations 9 to 12 below.

[0094]

G ₁ (t) = C ₁ (a _R cos (Rt) + b _R si
n (Rt))

[0095]

G ₂ (t) = C ₂ (a _R cos (Rt) + b _R s
in (Rt))

[0096]

C ₁ = sin ((π / 2) × (R / (2.5
× 10 ⁶ )))

[0097]

C ₂ = cos ((π / 2) × (R / (2.5
× 10 ⁶ )))

C ₁ and C ₂ are the filter functions shown in the second, fourth, and fifth examples of the first processing program and the second, third, and fourth examples of the second processing program. It is.

Next, the characteristics of the input ultrasonic wave and the substantially received ultrasonic wave obtained by using the C ₁ and C ₂ functions will be described on a time-series wave. FIG. 28A is a graph showing a function y (t), FIG. 28B is a graph showing a function y (t−Δt),
(C) is a graph showing the sum of the function y (t) and the function y (t−Δt).

When applying a 2C ₂ filter to the function y (t), in the calculation of the waveform, the sum of the function y (t) and the function y (t−Δt) shifted to the right by a small time (Δt) is used. G (t) = y (t) + y (t- [Delta] t) may be calculated. Although Δt is preferably as small as, here, for simplicity, has a Δt period of the wave as t ₀ and t _0/4.

FIG. 29A is a graph showing a function g (t), FIG. 29B is a graph showing a function g (t + Δt),
(C) is a graph showing the sum of the function g (t) and the function g (t + Δt).

Further, applying a 2C ₂ filter to the function y (t) is equivalent to the sum of a function g (t) and a function g (t + Δt) obtained by shifting the function g (t) to the left by a short time (Δt).
This means calculating (t) = g (t) + g (t + Δt).

When the operation for obtaining the function h (t) is repeated n times, the function represented by y (t) having a period of t ₀ becomes a low-period wave in which the period of t ₀ + 2n · Δt is dominant. And its amplitude is amplified.

[0104] Furthermore, applying a 2C ₁ filter instead of 2C ₂ filter performs subtraction instead of addition of the wave above, g (t) = y ( t) -y (t-Δt) and h
This means calculating (t) = g (t) -g (t + Δt).

In this case, the operation for finding the function h (t) is n
When it is repeated twice, the wave y (t) changes sequentially to a high-frequency wave, and its amplitude is amplified.

Next, an example in which Δt is made extremely small will be described. FIG. 30A shows that the center frequency is 1.25.
FIG. 4 is a graph showing a spectrum of a reflected wave having a wide frequency band of MHz, and FIG. 4B is a graph showing a time-series waveform. H when a C ₂ function is used as a filter for this wave
The calculation for (t) is performed a plurality of times with Δt = 0.2 μsec. FIG. 31 is a graph in which the calculations of FIGS. 28 and 29 are performed n times on the reflected wave of FIG. 30 as one set, where (a) is n = 0 times, (b) is n = 5 times, c) is n = 20 times,
(D) is obtained by performing n = 100 calculations. FIG.
As shown in FIGS. 1 (a) to 1 (d), as the number of operations n increases, the period of the reflected wave gradually transitions to the longer period side such as t ₀ + n · Δt, and the time of occurrence thereof becomes earlier.

FIG. 32 is a graph showing the spectrum of the reflected wave of the time-series waveform shown in FIG.
In the spectrum corresponding to (a), C ₂ ²ⁿ = cos ²ⁿ ((π
/2)×(f/(2.5×10 ⁶ ))). Therefore, between Δt and f _HL , Δt = 1
0 ⁶ / relationship 2f _HL (μ s) is established.

FIG. 33A shows that the reflected wave shown in FIG.
FIG. 6 is a graph showing a spectrum obtained by applying a low-pass filter of 5 MHz, and FIG. 7B is a graph showing a time-series waveform. FIG. 34A is a graph showing a spectrum obtained by cutting the reflected wave shown in FIG. 30 at 625 MHz, and FIG. 34B is a graph showing a time-series waveform. According to these processes, a waveform having one cycle at the beginning is changed into a wave having many peaks and valleys. On the other hand, such a phenomenon did not occur in the sweep of the special function described above. In addition, as the center frequency of a reflected wave of high frequency initially shifted to the lower frequency side, the reflected wave gradually changed to a lower frequency wave and the amplitude thereof was amplified.

However, the above does not mean that a general low-pass / high-pass filter cannot be used. By applying a third processing program described later, a general low-pass / high-pass filter can be used. FIG. 35 is a graph showing a time-series waveform y ^m (t) when a low-pass filter is used.
= 1, (b) is m = 2, and (c) is m = 4. Also,
FIG. 36 shows a time-series waveform y ^m when cutting is used.
It is a graph which shows (t), (a) is m = 1,
(B) is m = 2, and (c) is m = 4.

As shown in FIGS. 35 and 36, as m becomes larger, apparently smaller waves appear. In other words, a general low-pass filter / high-pass filter can be sufficiently used for detection that does not require the accuracy of millimeters such as concrete thickness.

Next, the third example of the second processing program is used.
A measurement example used will be described. Here, FIG.
Third example of the second processing program for the reflected wave shown in FIG.
Apply FIG. 37 shows a substantially received wave spectrum in the third example.
FIG. FIG. 38 corresponds to FIG.
FIG. 7 is a graph showing a time-series waveform of the waveforms shown in FIG. _HL
Is 1.25 × 10⁶, (B) is f_HLIs 0.625 × 1
0⁶, (C) is f_HLIs 0.3125 × 10⁶It is. What
Note that the values displayed in the figure are corrected by the ultrasonic transmission time.
It is a thing.

At f _HL = 1.25 × 10 ⁶ Hz, 75.
There is a large amplitude wake wave peak at 9 μs and a small amplitude wake wave peak immediately 89.0 μs behind it. The former is a peak F2 indicating a wave 33 detouring through a penetrating rebar, and the latter is a peak A2 indicating a wave 34.
It is.

[0113] In the ^{_{f HL = 0.625 × 10 6 Hz}} , the amplitude is reversed between the peaks F2 and A2, f _HL =
At 0.3125 × 10 ⁶ Hz, the peak F2 has disappeared. This is because, as described above, the high-frequency wave greatly reduces the amplitude of the wave transmitted from a far distance, and the amplitude of the wave transmitted from the near field is amplified relatively large even if it is a little. This is because waves from far away, where power is originally large, emerge without attenuation.

Next, the third processing program will be described. As described above, the third processing program is for raising the time-series wave obtained by the second processing program to the m-th power.

FIG. 39 (a) is a graph showing the Fourier spectrum of a broadband received wave having a center frequency around 300 kHz filtered by the second example of the first processing program and the second example of the second processing program. Figure, (b)
Is a graph showing the time-series waveform. Here, the received wave Y in rebar position directly above, the first processing filter C ₁ ⁴ according to the second example of the program ^{_{(f HL = 2.5 × 10 6}} H
Filter C ₂ ⁶⁰ according to a second example of z) and a second processing program ^{_{(f HL = 2.5 × 10 6}} Hz) is applied.
In FIG. 39B, generation of a wave having a large amplitude can be confirmed. These waves are reflected waves or detour waves from either boundary. In addition, since the wave is extracted at a relatively low frequency of 300 kHz center frequency, each reflected wave or the like is a wave that is repeated several times, and is generated as a superposition of these waves.

FIGS. 40A to 40C are graphs showing time-series waveforms obtained as a result of processing by the third processing program. FIG. 40A shows a case where m is 2, and FIG. Is 4
, (C) shows the case where m is 6. As shown in FIGS. 40 (a) to 40 (c), as the value of m increases, the wave having a large amplitude in FIG. 39 (b) is amplified, and the wave having a small amplitude disappears. In particular,
The result is remarkable when m is 6, the peak F3 indicating the direct wave 33 in the reinforcing bar path, the peak A3 indicating the bypass wave 34 in the cracked path, and the reflected wave (vertical wave) from the reinforcing bar. A peak B3 indicating 35a and a peak C3 indicating a reflected wave (vertical wave) 35b from a reinforcing bar are clearly identified. It should be noted that the numerical values (occurrence times) in the figure are corrected by the transmission times of the ultrasonic waves.

FIG. 41A shows the Fourier spectrum of a broadband received wave centered around 300 kHz filtered by the fourth example of the first processing program and the second example of the second processing program. Graph diagram,
(B) is a graph showing the time-series waveform. Here, the filter sin ⁴ ((π / π) according to the fourth example of the first processing program is added to the substantially received wave Y / Y at the position immediately above the reinforcing bar.
2) × (f / 2.5 × 10 ⁶ )) and the filter cos ¹³⁰ ((π / 2) ×
(F / 2.5 × 10 ⁶ )). And
FIGS. 42A to 42C are graphs showing time-series waveforms obtained as a result of processing the time-series wave shown in FIG. 41B by the third processing program, and FIG. At some point, (b) shows when m is 4, and (c) shows when m is 6. As in the case of FIGS. 40A to 40C, as the value of m increases, the wave having a large amplitude in FIG. 41B is amplified and the wave having a small amplitude disappears.

As described above, according to the third processing program, a reflected wave or a detour wave having a large power can be raised clearly. That is, even if there is a scattered wave that hinders the detection inside the concrete, the amplitude is smaller than that of the significant reflected wave and the detour wave. As a result, the reflected wave, the bypass wave, and the like to be detected are amplified and become remarkable.

In the above description, the received wave or the substantially received wave filtered by the combination of the second example or the fourth example of the first processing program and the second example of the second processing program is referred to as the second example. Although the processing is performed by the processing program of No. 3, the present invention is not limited to this, and can be realized by a combination of other examples.

Next, the fourth processing program will be described. The fourth processing program corrects the birth time as described above.

For example, the input ultrasonic wave X.exp (iω
applying filters _{^{C 1 2 · C 2 2 (}} f HL = 2.5 × 10 6 Hz) by the fourth example of the first processing program _x t), according to the second example of the second processing program to Filter C ₂ ⁿ
Is applied, a spectrum represented by the following Expression 13 is obtained.

[0122]

[Number 13] _{^{C 2 n · C 1 2 ·}} C 2 2 · X / X

Here, assuming that n is 0, 2, 12, or 92, 1.25 MHz, 0.98 MHz, 0.57M
Hz, a broadband input ultrasonic spectrum having a center frequency of 0.23 MHz is obtained. FIG. 43 is a graph showing a spectrum of a broadband input ultrasonic wave. Table 1 below shows the occurrence times of the time series waves in these broadband input ultrasonic waves.
Shown in

[0124]

[Table 1]

As shown in Table 1, as the value of n increases and the center frequency becomes lower, the generation time of the input ultrasonic wave is advanced. For example, 1.25 MHz (n =
0) and 0.23 MHz (n = 92) have a difference of 3.2 μs. Therefore, assuming that the propagation speed of the ultrasonic wave in the concrete is 4 (mm / μsec), an error of 12.8 mm occurs in the transmission length.

Therefore, in the fourth processing program, the input ultrasonic wave transmission time at the center frequency of each filter is calculated in advance for each ultrasonic transmitter used in the present embodiment, and the reflected wave and the like of the received wave are calculated. Is corrected. This correction when the input ultrasonic wave transmission time CAL value t _cal calculated values, the measured Okoshisei time of the reflected waves and the like were set to t _h, (t _h -
t _cal ). This correction is performed as follows.

As a first method, a CAL value is calculated for each ultrasonic transmitter and for each center frequency of each filter, and the corresponding CAL value is applied to a received wave extracted at the same center frequency to obtain a reflected wave. And the like.

As a second method, there is a method of recognizing and correcting a CAL value by extracting an input wave at the same time when a received wave is extracted at each center frequency.

Next, a fifth processing program will be described. As described above, the fifth processing program cuts out only the necessary portion of the time-series wave using the approximate occurrence time of the reflected wave or the like from the detection target.

In the fifth processing program, the following equation 14
A time-series filter corresponding to any one of formulas (1) to (17) is applied to the received wave. The time-series filter is a function that changes continuously on the time axis.

[0131]

Sin ((π / 2) × ((t−a ₁ ) / (a ₁ −a ₂ ))

[0132]

Cos ((π / 2) × ((t−a ₁ ) / (a ₁ −a ₂ ))

[0133]

Sin ² ((π / 2) × ((t−a ₁ ) / (a ₁ −a ₂ ))

[0134]

Cos ² ((π / 2) × ((t−a ₁ ) / (a ₁ −a ₂ ))

Here, the approximate birth time from the detection target is t
_h , when an arbitrary value is α, a ₁ = t _h −α, a ₂ = t _h
+ Α. Hereinafter, the function represented by Expression 14 is referred to as E ₁ , and the function represented by Expression 15 is referred to as E ₂ . The time-series filter E ₁ is 0 under t ≦ a ₁ and 1.0 under t ≧ a ₂ . On the other hand, the time series filter E ₂ is 1 under t ≦ a _1.
0, and becomes 0 under t ≧ a ₂ .

Next, a description will be given of an example of detecting a concrete thickness or the like to which the fifth processing program is applied. FIG.
(A) And (b) is sectional drawing which shows the concrete block in which the rebar used for actual measurement was embedded. The concrete mass 71 used for the actual measurement has a square pillar shape with a side length of 500 mm and a height of 300 mm. Among them, six diameters are 19 mm at a position 50 mm away from the front or back surface.
Reinforcing bars (round steel) 72 mm are embedded at intervals of 150 mm.

First, a description will be given of an embodiment for obtaining an approximate value of the occurrence time of the vertical wave reflection from the concrete bottom.
A transmitting probe 73a for transmitting an ultrasonic wave having a frequency component of 50 to 1500 kHz and a receiving probe or an AE sensor 73b are placed on the surface of the concrete block 71 by 300 mm.
At intervals. FIG. 45 (a) is a graph showing a Fourier spectrum of a wave received by the AE sensor, and (b)
FIG. 4 is a graph showing a time-series waveform. It should be noted that the numerical values displayed in the figure are corrected by the transmission time of the ultrasonic wave.

The waveform obtained by the measurement includes a direct wave including a wave generated by a disturbance caused by traffic conditions around the measurement location, a bending wave transmitted through a reinforcing bar, and a reflected wave from a reinforcing bar. A generated wave having a relatively small amplitude on which the superimposed wave is superimposed first appears.

At the time indicated by the leftmost dotted-line cursor, the amplitude suddenly increases. This time is specified as an approximate value of the time of occurrence of the reflected wave from the concrete bottom.

By applying the processing according to the third processing program to the time-series waveform shown in FIG. 45B, it is possible to more easily and visually obtain the approximate value of the occurrence time. FIG. 46 is a graph showing a time-series waveform processed by the third processing program, where m is 2. In addition,
The numerical values displayed in the figure are those corrected by the transmission time of the ultrasonic wave. Visually, it can be determined that the occurrence of the reflected wave from the concrete bottom portion is near 177 μsec.

The speed of sound in the concrete mass 71 is 3.85 mm / μsec. Therefore, the thickness of the concrete is obtained by the following equation (18).

[0142]

(18) ((3.85 × 177/2) ² −150 ² )
^1/2 = 306mm

It can be said that this value is close to the actual value of 300 mm. However, since there are reflected waves from the reinforcing bar on the concrete bottom side and reflected waves from the corners of the concrete bottom near this area, the value of 306 mm is the time when these waves are superimposed. Nothing else. Therefore, a fifth processing program is required. FIG. 47 is a graph showing the extracted time-series waveform.

In the time series waveform shown in FIG.
After multiplying by a function E ₁ · E ₂ obtained by multiplying the expressions represented by Expressions 14 and 15 as 0, the processing of the fourth example of the first processing program is performed, and the second example of the second processing program is performed. C _{1 ²} · C ^{2 44} sweeps over the filter ^{_{(f HL = 1.25 × 10 6}} Hz) to the low frequency side, finally a third processing example program was due to treatment is described as. FIG.
(A) is a graph showing a time-series waveform when m is 1;
(B) is a graph showing a time-series waveform when m is 4. It should be noted that the numerical values displayed in the figure are corrected by the transmission time of the ultrasonic wave. In addition to the peak E4 indicating a reflected wave from the concrete bottom, a peak A4 indicating a wave from the upper end of the lower reinforcing bar, a peak B4 indicating a wave from the lower end thereof, and a reflection in which the wave from the reinforcing bar and the wave from the concrete bottom overlap. A peak C4 indicating a wave and a peak D4 indicating a wave from a corner of the concrete can be read.

In the above processing, the center frequency is set to 488 kHz.
In this case, a wave in a frequency band of 0 to 1000 kHz is extracted in a state where non-resonant waves are dominant. Then, since 175 μs is obtained as the birth time, the thickness of the concrete block is obtained by the following equation (19).

[0146]

(19) ((3.85 × 175/2) ² −150 ² )
^1/2 = 301.5mm

Therefore, it can be said that the measurement was performed with higher accuracy.

In the above example, the center frequency is 488.
kHz, but the center frequency is, for example, 200, 3
It may be 00 or 600 kHz. In these cases,
Although a slight variation appears in the amplitude of each reflected wave, similar results can be obtained as the thickness of the concrete block. However, when the center frequency is shifted to the high frequency side, the reflection from the reinforcing bar emerges. This is due to the fact that the reflected wave from the concrete bottom having a long transmission path is acceleratedly attenuated as the frequency becomes higher in the high frequency region due to the transmission characteristics of the ultrasonic waves described above. FIG. 49A shows that the center frequency is 1250.
FIG. 5B is a graph showing a time-series waveform when the frequency is kHz, and FIG.
Is a graph showing a time-series waveform when the center frequency is 1090 kHz, (c) is a graph showing a time-series waveform when the center frequency is 980 kHz, and (d) is a graph when the center frequency is 900 kHz. FIG. 7E is a graph showing a series waveform, FIG. 9E is a graph showing a time series waveform when the center frequency is 833 kHz, and FIG.
FIG. 5 is a graph showing a time-series waveform when the frequency is 0 kHz. In FIGS. 49 (a) and (b) in which the center frequency is 1250 or 1090 kHz, the peak B5 of the vertical wave reflection from the back surface of the reinforcing steel on the lower surface side of the concrete is dominant, but the center frequency is swept to a low frequency. Therefore, peak B5
Etc. gradually disappear, and in the case of FIG. 49 (f), only the peak E5 of the vertical wave reflection from the concrete bottom surface is obtained. This phenomenon is due to the fact that by sweeping in the low frequency direction, the attenuation of reflected waves from more distant places is alleviated,
The reflected waves from the bottom of the concrete have become dominant.

As described above, it is possible to judge whether the obtained reflected wave is from the reinforcing bar or the bottom of the concrete from the change in the occurrence of the reflected wave in the frequency band from which the reflected wave is extracted. .

Although not particularly shown as an analysis example, the first
A similar detection result can be obtained by using another example of the second processing program. Further, in the above-described actual analysis example, the processing by the above-described third processing program (m = 4) and the later-described eighth and ninth processing programs are also performed.

Furthermore, the present processing program is also effective for detecting a diameter of a reinforcing bar or the like with high accuracy as described later.

Next, the sixth processing program will be described. As described above, the sixth processing program calculates the difference between the waveform when the detection target object is near the measurement point and the waveform when the detection target object does not exist. By taking this difference, it is possible to exclude the direct wave and the surface wave to some extent from the time-series waveform.

FIG. 50 is a sectional view showing a concrete block in which a reinforcing bar used for actual measurement is embedded. In a concrete block 81 used for actual measurement, a reinforcing bar (round steel) 82 having a diameter of 19 mm is embedded at a position 50 mm away from the surface. And the transmitter 83a having a diameter of 20 mm
And the receiver 83b are arranged on the reinforcing bar 82 at an interval of 30 mm. In such a concrete mass 81, a reflected wave 84 from the upper end of the reinforcing bar 82, a reflected wave 85 from the lower end thereof, a direct wave 86 and a surface wave 87 are received by the receiver 83b as significant reflected waves and the like.

FIG. 51A is a graph showing a time-series waveform when a reinforcing bar in a concrete block is embedded near a measuring point, and FIG. 51B is a graph when a reinforcing bar is not embedded near a measuring point. FIG. 4 is a graph showing a sequence waveform. And
FIG. 52 is a graph showing a difference between the time series wave of FIG. 51 (a) and the time series wave of FIG. 51 (b). The transmission time of the ultrasonic wave is 86.8 μsec. FIG. 53 is a graph showing a Fourier spectrum at this time. In the time-series waves described above, relatively low frequencies are dominant.

In the wave of FIG. 52 showing the difference between the time series wave when the reinforcing bar in the concrete block is embedded near the measurement point and the time series wave when it is not embedded, the time indicated by the cursor is 116.7 μm. The second (not considering the CAL value) is the approximate occurrence time of the reflected wave from the reinforcing bar, and α = 10
After multiplying by the time series filters E ₁ and E ₂ , the filter C ₁ ⁿ (f _HL = 2.5) according to the second example of the second processing program
When (10 ⁶ Hz) is applied, the reflected wave from the rebar surface emerges as the value of n increases. FIG.
FIG. 4 is a graph showing the filter C ₁ ⁿ . FIG.
(A) is a graph showing a time-series waveform when n is 12,
(B) is a graph showing a time-series waveform when n is 18;
(C) is a graph showing a time-series waveform when n is 32,
(D) is a graph which shows the time-sequential waveform when n is 52.

When n is 12 or 18, the direct wave 86
And the peak B6 indicating the reflected wave 85 from the lower end of the reinforcing bar are dominant. On the other hand, when n becomes large and is swept toward the high frequency region, the peak A6 indicating the reflected wave 84 from the upper end of the reinforcing bar becomes prominent.

This phenomenon is a phenomenon that the above-mentioned ultrasonic waves generate a vertical wave and a transverse wave when diffused in a fan shape by a scattering phenomenon, and the intensity thereof largely changes depending on the frequency of the ultrasonic waves. The change in strength varies greatly depending on the transmission distance d and the frequency f, and not only the property that the attenuation rate α becomes a function α (d, f) depending on the transmission distance d and the frequency f, but also that the reinforcing bar has a circular cross section. However, the theoretical reason is unclear.

Referring to FIG. 54, the generated wave when n = 52 shown in FIG. 55 (d) is the received wave of the conventional ultrasonic flaw detector which is a broadband input wave having a frequency of 2.5 MHz.
This corresponds to processing performed by the third and fifth processing programs provided in the present apparatus. Therefore, in the detection of the reinforcing bar using the high-frequency broadband input ultrasonic wave according to the conventional method, even if the reflected wave from the front surface of the reinforcing bar is obtained, it is difficult to obtain the reflected wave from the back surface.

When the occurrence times of the peaks A6 and B6 of the reflected waves obtained in FIG. 55 are corrected using the transmission time of the ultrasonic wave of 86.8 μs, the occurrence time of the reflected wave from the upper end of the reinforcing bar becomes 11
0.5-86.8 = 23.7 μsec, and the originating time from the lower end is calculated as 117.1-86.8 = 30.3 μsec.

The velocity of the ultrasonic wave (vertical wave) of the concrete block obtained by a separate measurement was 4.3 mm / μsec. Therefore, the path length from the probe drawn by Snell's theorem to the upper end of the rebar is 4.3 × 23.7 / 2 = 5.
1.0 mm, and the path length from the front side to the back side of the reinforcing steel is 6 × (3
0.3−23.7) /2=19.8. Than this,
The cover thickness and the reinforcing bar diameter of the concrete are obtained as the following Expressions 20 and 21.

[0161]

(51.0 ² − (30/2) ² ) ^1/2 = 49.0

[0162]

(19.8 ² − (15−9.5) ² ) ^1/2 = 19.0

In Equation 21, 15 is a half value of the inter-probe distance, and 9.5 is the horizontal distance from the transmitter to the incident point of the wave incident on the reinforcing bar.

Since the actual cover thickness is 50 mm and the rebar diameter is 19 mm, it can be said that the measurement is performed with extremely high accuracy.

In general, in the two-search method, it is necessary to set the distance between the probes to an appropriate value. If the distance between the probes is too large, the intensity of the reflected wave (vertical wave) from the upper end or the lower end of the reinforcing bar becomes small, which may make it difficult to detect. As an empirical value in many measurement experiments, when the cover thickness of the rebar is about 3 to 10 cm, the distance between the probes is preferably about 0.5 to 0.8 times the cover thickness.

Next, the seventh processing program will be described. As described above, the seventh processing program is for obtaining a composite wave from the received waves obtained by the multipoint measurement. That is, k received waves obtained by the multi-point measurement are represented by y
_{When i} (t) (i = 1, 2,..., k), a composite wave y (t) represented by the following Expression 22 is obtained.

[0167]

Y (t) = (1 / k) × Σ _{i = 1} ^k y _i (t)

As described above, by taking the average of the received waves as the composite wave, the reflected waves and scattered waves from the fine stones in the concrete block disappear from the time-series waveform.

FIG. 56 is a sectional view showing a concrete block containing large fine stones. Concrete mass 9 to be detected
If a large stone 92 or the like is unfortunately present in 1 as shown in FIG. 56, a direct wave (a vertical wave and a side wave reflected on the surface of the stone) passing through the stone is transmitted to the receiver. For this reason, the transmission path may be short and the power may be much larger than the reflected wave from the reinforcing bar 93 which is the detection target.
In such a case, it is extremely difficult to detect the detection target.

It should be noted that in various types of flaw detection using a conventional flaw detector, there is a case in which an average of a plurality of received waves obtained by measuring a plurality of points is obtained. For example, although it cannot be considered successful, the purpose is to use the concrete thickness measurement by amplifying the reflected wave from the concrete bottom by adding a plurality of received waves in concrete thickness measurement.

However, the function of this averaging in the present apparatus is different. The purpose is to remove the direct waves that hinder the internal detection of the porous elastic body. In particular, it is for removing reflected waves from fine stones and the like shown in FIG.

In the actual analysis, for example, the fourth example of the first processing program is applied to the synthesized wave obtained by the present processing program. Then, this is ^{converted to} a filter C ₁ ⁿ¹ C ₂ ⁿ² (f _HL = 2.5 × 10 ⁶ ) by the second processing program.
To FIG. 57 shows that n1 is 2, n2 is 20 (center frequency; 480 kHz), 30 (center frequency; 400 kHz).
FIG. 7 is a graph showing a spectrum when z) or 50 (center frequency; 315 kHz). As the value of n2 becomes higher, the spectrum is swept toward the lower frequency side. Further, the value of m is set to 4 and the processing by the third processing program is performed. FIG. 58A is a graph showing a time-series waveform when n2 is 20, FIG. 58B is a graph showing a time-series waveform when n2 is 30, and FIG.
FIG. 7 is a graph showing a time-series waveform when. In addition,
The numerical values displayed in the figure are those corrected by the transmission time of the ultrasonic wave. The dotted line cursor in the figure indicates the time of occurrence of the superimposed wave of the reflected wave from the front side and the back side of the reinforcing bar immediately below, the early time side indicates a vertical wave (31.6 μsec after transmission of the ultrasonic wave), and the late time The side shows the surf. The speed ratio of the latter is about 63% of the former. In addition, as shown in FIG.
When n is 50, not only the reinforcing bar immediately below the probe but also a peak A7 indicating a reflected wave as a vertical wave from a reinforcing bar embedded at a position shifted from immediately below is clearly shown. In addition, a peak B7 indicating a vertical wave from a reinforcing bar immediately below the probe,
A peak C7 indicating a transverse wave, D7 indicating a surface wave, and E7 indicating a direct wave appear. This calculation can be said to be the extraction of a reflected wave at a center frequency of 500 kHz or less. Since the low frequency is taken out, the reflected waves from the upper and lower ends of the reinforcing bar are superimposed. As experience in many detection measurements, the birth time indicated by the dotted cursor in FIG. 58 is closer to the birth time of the reflected wave from the lower end of the reinforcing bar.

Next, a method for measuring the reinforcing bar immediately below with high accuracy will be described. First, the approximate value of the birth time of the reflected wave from the front side of the rebar was calculated using the input wave transmission time of 86.8 μs, the assumed value of the rebar diameter was 20 mm, and the sound speed was 6 mm / μ.
11 from 86.8 + 31.6-2 × 20/6 as seconds
It is determined as 0.0 μsec. Next, a time-series wave is cut out from the composite wave y (t) of Expression 22 by setting α to 20 by the above-described fifth processing program. Here, E ₁ and E ₂ are used.
Further, C ₁ ^{n is added to} this by the second example of the second processing program.
(However, f _HL = 2.5 × 10 ⁶ Hz)
The processing according to the third processing program is performed with m = 4.
FIG. 59 (a) is a graph showing a time series waveform when n is 6, (b) is a graph showing a time series waveform when n is 10, and (c) is a time series when n is 14. FIG. 4D is a graph showing a waveform, and FIG. 4D is a graph showing a time-series waveform when n is 20. It should be noted that the numerical values displayed in the figure are corrected by the transmission time of the ultrasonic wave.

As compared with FIG. 55, the peak C8 of the direct wave
Almost no occurrence has occurred. Also, n is 6 or 10
Is a relatively low-frequency region, a peak A8 indicating a reflected wave from the lower end of the reinforcing bar indicates that n is 14 or 20.
When the high frequency region is taken out, the peak B8 indicating the reflected wave from the upper end of the reinforcing bar is dominant.

Although such a recording method of the received wave by the multi-point measurement can be seen in the past, by producing these composite waves, the intensity from the large fine stone shown in FIG. There is no example of a method for removing reflected waves, direct waves, surface waves, and scattered waves. Furthermore, by using the processing of the first, second, and third processing programs in combination, it is possible to acquire a reflected wave from a reinforcing bar or the like in a wide frequency band at a low frequency. The onset time of this reflected wave is approximately equal to the onset time from the back side of the rebar according to many similar measurement examples.
Because it is a reflected wave at a low frequency, some accuracy problems remain,
Although it is not possible to detect the reinforcing bar diameter or the like, the second time after the processing by the fifth processing program is performed using the time of occurrence of the reflected wave.
If the time series extraction frequency is swept in the high frequency direction by the processing program of (1), reflected waves from the upper end and the lower end of a reinforcing bar or the like can be acquired with extremely high accuracy.

This measuring and analyzing method is also extremely effective for measuring a concrete thickness having a constant thickness.

Next, the eighth processing program will be described. As described above, the eighth processing program collects received waves many times continuously at the same point, and averages the received waves.

Note that some conventional ultrasonic flaw detectors also have a function of obtaining an average of received waves. However, these methods use ultrasonic waves having a frequency of 5 MHz or 10 MHz for the purpose of detecting minute flaws in steel. Therefore, the purpose of the averaging is to remove the electrical noise near the frequency.

On the other hand, the ultrasonic detecting device according to the present invention aims at macroscopic detection of waves, and uses low-frequency ultrasonic waves of about 0.1 to 2 MHz. For this reason, in the conventional apparatus, traffic noise and the like which would not have to be considered because the ultrasonic waves used are high frequencies cannot be ignored. That is, a disturbance having the same amplitude as the amplitude of the reflected wave or the like to be obtained is mixed in the reception wave measured by the present apparatus. The purpose of the eighth processing program is to eliminate such disturbances.

FIG. 60A is a graph showing a time-series waveform of a received wave affected by a disturbance, and FIG. 60B is a time-series waveform obtained by averaging 1000 times of the received wave affected by a disturbance. FIG. FIG. 61 is a graph showing a Fourier spectrum at this time. The received wave used here is 0 to 700 kHz as shown in FIG.
It is excited almost uniformly in the range of z. FIG.
As shown in (a) and (b), the influence of disturbance is almost eliminated by averaging 1000 times.

As another example, only the disturbance is received without inputting the ultrasonic wave to the object to be detected, and the processing is performed by the second example of the first processing program and the second example of the second processing program. The measurement in the broadband frequency band having the center frequency of 843 kHz will be described. FIG. 62A is a graph showing a Fourier spectrum of a received wave (disturbance) having a center frequency of 843 kHz, and FIG.
FIG. 6 is a graph showing m = 2 using the processing program of FIG. A disturbance having a large amplitude has occurred. FIG. 63 is a graph showing a time-series waveform obtained by averaging the disturbance of FIG. 62 1000 times. By the averaging of 1000 times, the disturbance having a large amplitude is completely removed from the time-series waveform. Therefore, even in a measurement at a site where an extremely large disturbance such as civil engineering or a building structure occurs, the internal detection is performed with high accuracy.

However, unlike the conventional averaging for removing electrical noise and the like, it is necessary to calculate a large amount of averaging at a very high speed.
d or the built-in CPU 4e performs the averaging process at an extremely high speed.

Conventionally, ultrasonic waves are scattered inside a porous material such as concrete, and scattered waves of large power are generated.
It was a common wisdom that its internal detection would be impossible. This phenomenon is true. However, it is true that the disturbance shown in FIG. 62 (b) was erroneously recognized as the occurrence of a scattered wave. Such erroneous recognition was one of the reasons why it was impossible to detect the inside of concrete or the like.

Further, in macroscopic detection, a low frequency ultrasonic wave of about 100 kHz may be used. Such low-frequency waves are hard to attenuate and last for a relatively long time. For this reason, it is necessary to set the ultrasonic transmission interval extremely long.
This is because, when performing the averaging process, it is necessary to transmit the next input ultrasonic wave when the wave generated inside the object to be detected has completely disappeared by the immediately preceding ultrasonic transmission. According to experience, the transmission interval is desirably about 5 to 10 msec. However, when detecting at a very high depth, it is necessary to further increase the transmission interval. Therefore, in this embodiment, the pulse generation circuit is made capable of loading the voltage at such a gradual time interval under the control of the computer.

Next, the ninth processing program will be described. As described above, the ninth processing program eliminates received ultrasonic waves corresponding to inappropriate input ultrasonic waves.

In the case where the probe 11 used in this embodiment is used, the input wave is 2 if the fundamental frequency is f _1.
have higher resonance frequencies of f ₁ , 3f ₁ ,... FIG.
FIG. 4 is a graph showing the Fourier spectrum of a wave having a higher-order resonance frequency. FIG. 64 illustrates waves having first to third-order resonance frequencies. FIGS. 65A to 65C are graphs showing time-series waveforms based on each resonance spectrum. As shown in FIGS. 65 (a) to 65 (c), 1
The occurrence times of the waves having the third to third resonance frequencies can be considered to be the same. FIG. 66 is a graph showing a composite wave on which the time-series waves shown in FIGS. 65A to 65C are superimposed. When waves having a plurality of types of resonance frequencies are superimposed, as shown in FIG. 66, there is a wave having a different birth time even though the respective birth times coincide with each other. Will be seen.

FIG. 67A shows the original wave X.ex of the input ultrasonic wave.
FIG. 7 is a graph showing a Fourier spectrum of a result of p (iω _x t) being filtered according to a second example of the first processing program, and FIG. 7B is a graph showing a time-series waveform. Here, as a filter of the second example of the first processing ^{_{program, C 1 5 (f HL =}} 2.5 × 10 6 Hz) is adopted. As shown in FIG. 67 (b), occurrence of two waves is confirmed in the time-series wave. Therefore, when such a wave is used as an input wave, two reflected waves are generated from one reflection boundary, and such a wave is inappropriate as an input ultrasonic wave and needs to be eliminated.

Therefore, in the ninth processing program, when a reflected wave in a wide band frequency band is extracted from a received original wave,
The suitability of the input ultrasound is checked. In this test, when two or more peaks are discretely generated in the time series wave, it is unsuitable, and other times are appropriate.

The input wave shown in FIGS.
₁ when multiplied by the filter ^{_{2 · C 2 6 (f HL}} = 2.5 × 10 6 Hz), it is possible to obtain a usable input wave.
Figure 68 (a) is a graph illustrating the filter and Fourier spectrum of the input ultrasound applied to the filter of C _{1 ²} · C ^{2 6,} is a graph showing (b) is also a time-series waveform. Note that the third processing program (m = 6) is applied to FIGS. 67 (b) and 68 (b).

In the case of the waveform shown in FIG. 68B, since two or more peaks do not appear discretely,
The input ultrasound is usable and qualified.

Note that, even when the center frequency band is swept to the high frequency side or the low frequency side by the second processing program,
This test is necessary.

As a test method, for example, each time a reflected wave is extracted, an input wave corresponding to the reflected wave is calculated and obtained.
There is a method of testing for inappropriateness. In addition, the suitability / inappropriateness of each center frequency and each frequency band is examined based on the input wave characteristics of the ultrasonic transmitter used for measurement, and when the input wave is inappropriate, the reflected wave corresponding thereto is extracted. It may be excluded from analysis.

Next, a description will be given of a method for detecting a reflection object in a concrete block using the detection apparatus according to the present embodiment, which is configured as described above and incorporates a processing program.

FIG. 69 is a cross-sectional view showing the detection target material. A reflector 42 is embedded in the porous elastic material 41.

When a wave is input immediately below the surface of the detection target material, as described above, the directivity of the ultrasonic wave is largely lost due to the scattering phenomenon. That is, as shown in FIG. 69, the directivity direction of the input wave expands in a fan shape, and a vertical wave and a side wave having a large power are generated also in a direction inclined from a direction directly below. That is, some reflected waves scattered at the boundary with fine stones or the like cause mode conversion, and are converted into side waves or vertical waves. Waves that have been repeatedly reflected, bent, and changed in mode by a myriad of fine stones and the like are transmitted from the transmitting point to the receiving point in an arc as direct waves from a shallow path to a deep path. Further, a surface wave is generated on the surface of the porous elastic material 41.

FIG. 70 (a) is a graph showing the Fourier spectrum of a received wave when the distance between the transmitting point and the receiving point is 35 mm when there is no reflector near the measuring point, and FIG. It is a graph which shows a waveform. FIG. 71
(A) is a graph showing a Fourier spectrum of a received wave when an interval between a transmission point and a reception point is set to 100 mm when there is no reflector near a measurement point, and (b) is a graph showing a time-series waveform. It is. However, the reflection object 42
Does not exist, but has a size of 1 to 2c as a reflection source.
There are many fine stones of about m. By comparing FIG. 70 (b) with FIG. 71 (b), it is possible to compare a surface wave transmitted between a transmission point and a reception point and a wave in which a direct wave is superimposed. It should be noted that the numerical values displayed in the figure are corrected by the transmission time of the ultrasonic wave.

When the distance between the transmitting point and the receiving point is 35 mm, the earliest wave generation occurs 15 μs after the input of the ultrasonic wave. Thereby, 35/15 = 2.3 (mm / μsec) is obtained as the equivalent sound speed of the first wave of the direct wave.
Note that the sound speed of the vertical wave of the detected material in this measurement is 4.
3 (mm / μsec). Further, since the surface wave has a sound velocity of about 60% of the vertical wave, the surface wave is generated behind the first wave of the direct wave.

On the other hand, the distance between the transmitting point and the receiving point is 100 m
m, the earliest wave onset is 5 from the ultrasonic input
It occurs after 1.3 μs. Therefore, the equivalent sound speed is 10
0 / 51.3 = 1.95 (mm / μsec). At this time, a direct wave having a large power is generated at a later time.

Therefore, by processing the received wave by the first, second and third processing programs while adjusting the distance between the transmitting point and the receiving point, the reflected wave from the detection target at a position close to the measuring point can be obtained. , Surface waves and direct waves can be measured without overlapping each other. FIG. 72 shows a surface wave,
FIG. 9 is a graph showing a time-series waveform in which a vertical reflected wave and a direct wave from a detection target appear without being superimposed.

Further, it has been confirmed in many measurement examples that although there is a limit, when the distance between the transmitting point and the receiving point is increased, the power of the direct wave becomes smaller than the power of the reflected wave. ing. This property can be said to be a very advantageous phenomenon in extracting reflected waves. In FIG. 69, such measurement can be performed by using a vertical wave generated in a direction slightly inclined from a direction directly below the input of the ultrasonic wave or a vertical wave input in an oblique direction.

Then, in a measurement in which a wave ultrasonic wave is input immediately below or slightly inclined from the transmission point and a reception wave is obtained at the reception point, the transition of the reception wave is immediately changed while gradually changing these intervals. When there is a reflection boundary such as a reinforcing bar near the transmission point or the reception point, the reflected wave from this reflection boundary always emerges before the generation of the direct wave. In addition, the time of occurrence of surface waves and direct waves can be predicted in advance based on the distance between the transmitting point and the receiving point and the sound speed of concrete, so that the rising waves are reflected waves from the reflection boundary such as reinforcing bars. It is very easy to discriminate between surface waves and surface waves or direct waves.

Further, in the detection of the reinforcing bars in the concrete, if the design concept of the concrete structure is utilized, the effect is great. That is, the arrangement direction of the concrete structure can be predicted in many cases. Therefore, using this prediction, the transmitting point and the receiving point are arranged in parallel with the direction of the reinforcement so that the length of the forward path and the return path of the reflected wave becomes the same in the vertical wave reflection.

Next, a specific analysis method will be described. FIGS. 73A and 73B are cross-sectional views showing the detection target material. The concrete mass 51, which is the material to be detected, has a square prism shape with a side length of 300 mm and a height of 350 mm. And 100mm from the surface
A rectangular column-shaped iron bar 52 having a width of 30 mm and a height of 20 mm is embedded at the position of the square. The reason why the rod-shaped iron rod was used instead of the round steel was to compare the analysis result and the actually measured value in detail.

FIG. 74 is a sectional view showing a main path of an ultrasonic wave. In FIG. 74, a solid line indicates a vertical wave, and a broken line indicates a transverse wave. The main paths of the ultrasonic waves transmitted through the concrete mass 51 configured as described above by measurement by the detection device having the transmission sensor and the reception sensor arranged at intervals of 100 mm are the following six paths.

A path 54 in which a vertical wave generated obliquely from the transmission sensor 53a due to the scattering phenomenon is reflected by the upper end of the iron bar 52 and transmitted to the reception sensor 53b by a vertical wave. A vertical wave generated obliquely from the transmission sensor 53a due to the scattering phenomenon bends at the upper end of the horizontal bar 52, reaches the lower end of the vertical bar 52 with the vertical wave, reflects the vertical wave here, and further at the upper end of the vertical bar 52. The sensor 53b squats and makes a vertical wave inside the concrete block 51.
Path 55 for transmission to A path 56 for transmitting waves within the iron rod 52 in the same reflection path as the path 55. A vertical wave and a wake wave generated in the oblique direction from the transmission sensor 53a due to the scattering phenomenon are reflected and changed in mode at the upper end of the iron bar 52,
Two paths 57 for transmitting the concrete block 51 to the receiving sensor 53b by means of a vertical wave and a vertical wave. Transmission sensor 53a
A path 58 through which a surface wave generated on the surface of the concrete mass 51 by the vertical wave transmitted from the surface is transmitted to the receiving sensor 53b. A path 59 of a direct wave transmitted from the transmission sensor 53a to the reception sensor 53b in a shallow path or a deep path. In addition, the sound velocity of a direct wave has a small amplitude but has an equivalent sound velocity close to a vertical wave on a shallow path, and a sound path with a large power on a deep path and has an equivalent sound velocity of about 1/4 to 1/2 of a vertical wave. Miscellaneous.

The following Table 2 shows an example of analysis described below.

[0207]

[Table 2]

In the first analysis example, first, a high-pass filter of 100 kHz is applied to the received original wave obtained by the reception sensor 53b. This is expressed as y ₁ (t) = Y ₁ · exp (iω
_y t).

Next, from FIG. 71 (b), the generation of the direct wave is 5
Since 1.3 + CAL value ≒ 133 μsec (CAL value = 81) or later, a wave after 133 μsec, that is, a direct wave is deleted and reduced by the fifth processing program. Specifically, by multiplying the function ^{_{E 2 2 (a1 = 133,}} a2 = 300) to y ₁ (t), a function to obtain y ₂ a (t).

[0210] Then, the filter of C ₁ ² · C ₂ ⁴ by the second example of the second processing program (f _HL = 2.5MHz) multiplied on the frequency axis, which is referred to as y ₃ (t). Thereby, the center frequency is 340 kHz and the frequency band is 0 to 62.
A broadband received wave of 5 kHz is obtained. FIG. 75 is a graph showing a Fourier spectrum obtained by the above processing.

Further, the function y is calculated by the third processing program.
Y ₃ ^m (t) (m = 4) is obtained from ₃ (t). FIG. 76 is a graph showing a time-series waveform obtained by the third processing program. It should be noted that the numerical values displayed in the figure are corrected by the transmission time of the ultrasonic wave. At t = 54.4 μs, a large amplitude generated wave is observed. This is the reflected wave from the rebar. However, this extraction has a center frequency of 340k
Since it is performed at a low frequency of Hz, it cannot be said that the accuracy is high. That is, the reflected waves of the paths 54, 55, 56, etc. are superimposed, and the analysis accuracy is poor. Further, the waves generated thereafter are the superimposition of the reflected waves of other paths and the remaining direct waves.

Therefore, in analysis example 2, y_Three(T)
From the fifth processing program to the time-series wave y_Four(T)
cut. From FIG. 76, 54.4 + 81 + 10 ≒ 145 μ
A reflected wave from the lower end of the iron bar 52 exists near the second.
And the wave of this part is a ₁= 145-α = 95, a_Two
= 145 + α (α = 50) is y _Four
(T). FIG. 77 shows y_Four ^m(T) (m = 4)
FIG. 4 is a graph showing a sequence waveform. Displayed in the figure
The numerical value is corrected by the transmission time of the ultrasonic wave. y_Four
(T) is a wave extracted at a center frequency of 340 kHz.
Therefore, there is a problem in the analysis accuracy. For this reason, the second processing
Apply the second example of the program again to increase the center frequency in the high frequency direction.
To 1.5 MHz. FIG. 78 shows the fifth processing procedure.
Fourier spectrum Y to which the gram is applied_FourThe second processing
Using the second example of the_Two ⁶(F_HL= 2.5 × 1
0⁶Hz) filtered Fourier spectrum Y_Five
FIG. FIG. 79 shows y_Five ^m(T) (m = 4)
3 is a graph showing a time-series waveform of FIG. It is displayed in the figure.
The value to be corrected is corrected by the transmission time of the ultrasonic wave.

According to the second analysis example, as shown in FIG.
The analysis accuracy is improved, and the iron rod 52 buried in the analysis example 1
The reflected wave from the lower end of is rising. And path 5
In FIG. 4, the time of occurrence of the reflected wave from the upper end of the iron bar 52 is 5
The occurrence time of the reflected wave from the lower end of the iron bar 52 in the path 55 is measured to be 57.6 μsec. Note that 7
The generated wave at 4.7 μs is also a significant reflected wave, which will be described later.

Next, analysis example 3 will be described. Analysis example
In the third example, as in the first analysis example, a 100 kHz
In the fifth processing program, the wave subjected to the
4th example of the first processing program after cutting out
X / X · exp (iω _xapproximately received wave y for t)_Two
(T) = Y_Two/ Y_Two・ Exp (iω_yFind t).

Then, C is obtained by the second processing program.₁ ^Two
・ C_Two ^FourFilter and C₁ ^Two・ C_Two ⁴⁴Filter (f_HL= 2.
5MHz) to Y_Two/ Y_TwoBy multiplying by_Three(T)
= C₁ ^Two・ C_Two ⁴⁴・ Y_Two/ Y_Two・ Exp (iω_yt) and y_Four
(T) = C₁ ^Two・ C_Two ^Four・ Y_Two/ Y_Two・ Exp (iω_yt)
Ask. FIG. 80 shows y_Three(T) and y_FourFouriers of (t)
Vector Y_ThreeAnd Y_FourFIG.

Next, using the third processing program,
From y ₃ (t) and y ₄ (t), y ₃ ^m (t) and y ₄ ^m (t)
(M = 4). Figure 81 (a) is a graph showing a time-series waveform of y ₃ ⁴ (t), is a graph showing a time-series waveform of (b) is y _{⁴ 4} (t). It should be noted that the numerical values displayed in the figure are corrected by the transmission time of the ultrasonic wave.

[0217] the center frequency of the y ₃ ⁴ (t) is 340 kHz, no significant difference was observed and analysis Example 1. On the other hand, y ₄ ⁴
The center frequency of (t) is 940 kHz, and y ₃ ⁴ (t)
A wake wave that does not appear in is observed. In FIG. 81 (b), the first earliest of the large generated waves is the input ultrasonic wave, and the second earliest generated wave is the surface wave of the path 58 transmitting between the transmitting sensor and the receiving sensor. The earliest generated wave is a reflected wave from the upper end of the rod 52 in the path 54, and the fourth earliest generated wave in the small path is a reflected wave from the lower end of the rod 52 in the path 55. The generated waves each indicate a direct wave remaining on the path 59.

In the analysis example 4, the fifth processing program is applied to the extracted wave Y ₄ having the center frequency of 940 kHz in the analysis example 3. Thereby, the input ultrasonic wave and the surface wave of the path 58 are removed from y ₄ (t), and the vicinity of the reflected wave from the lower end of the reinforcing bar 52 in the path 55 is amplified. That is, the same process as the second fifth process of the analysis example 2 shown in Table 2 is performed. Figure 82 (a) is a graph showing the Fourier spectrum Y ₅ in the analysis Example 4 is a graph showing the (b) is also a time-series waveform _{Y 5 · exp (iω y t} ). A peak A9 indicating a reflected wave from the upper end of the iron bar 52 and a peak B9 indicating a reflected wave from the lower end of the path 54 or 55 can be read clearly.

However, these reflected waves include the first
By the processing of the fourth example of the processing program, a large amount of waves having a frequency that is hardly included in the transmitted ultrasonic waves is included. This, in analysis example 5, using a fifth example of the first processing program, filters F _E for removing the unnecessary amplified waves Y _5, obtains the Y _6.

FIG. 83 (a) is a graph showing the Fourier spectrum Y ₆ in Analysis Example 5, and FIG. 83 (b) is a graph showing the time-series waveform Y ₆ · exp (iω _y t). In the analysis example 5, by removing the above-mentioned unnecessary waves, the reflected waves from the lower end of the iron rod 52, although fine, are removed.
A peak A10, which indicates a wave taking the path 56 that is transmitted by the transverse wave inside, is also confirmed.

In the analysis example 6, the second processing program is further applied to the Y ₆ spectrum of the analysis example 5. For example, using a ^{_{C 1 6 (f HL = 2.5}} × 10 6 Hz) filter. As a result, the center frequency shifts to a high frequency side near 1500 kHz.

FIG. 84 (a) is a graph showing the Fourier spectrum Y ₇ obtained by this processing, and FIG. 84 (b) is a graph showing the time-series waveform Y ₇ · exp (iω _y t). Here, the third processing program is applied with m = 4. In Analysis Example 6, the peak B11 indicating the reflected wave from the lower end of the reinforcing bar 52 in the path 55 is dominant, and the peak A11 indicating the reflected wave of the path 54 from the upper end of the reinforcing bar 52 is relatively reduced. This is because the inclination with respect to the vertical wave transmission direction is larger in the path 54. That is, even in the transmission of an ultrasonic wave having low directivity under the scattering phenomenon, the higher the frequency becomes, the higher the directivity becomes, as in the conventional ultrasonic theory. Therefore, the amplitude of the reflected wave on the path 54 having a large inclination is small. Further, a peak C11 indicating a wave taking the path 56 is also confirmed.

In Analysis Example 7, the fourth example of the first processing program is applied to the spectrum Y ₇ obtained in Analysis Example 6,
Furthermore C ₁ ¹⁰ · C ₂ ⁴ according to the second example of the second processing program
(F _{H L} = 2.5 × 10 ⁶ Hz) Use a filter. Accordingly, the resonance frequency component in analysis example 6 is non-resonant frequency component reflected wave Y ₇ which are distinguished converts the reflected wave Y ₈ to excellence. FIG. 85A is a graph showing the Fourier spectrum of the reflected wave Y ₈ in the analysis example 7, and FIG. 85B is a graph showing the time-series waveform Y ₈ · exp (iω _y t). FIG. 86 is an enlarged graph of FIG. 85 (b). It should be noted that the numerical values displayed in the figure are corrected by the transmission time of the ultrasonic wave.

In FIG. 86, a peak A12 (path 54) indicating a reflected wave reflected from the upper end of the reinforcing bar, a peak B12 indicating a reflected wave reflected in the path (path 55) from the lower end, and a horizontal wave transmitted only inside the reinforcing bar. A peak C12 indicating a reflected wave (path 56) from the lower end of the reinforcing bar, and a peak D12 indicating a reflected wave (path 57) reflected from the upper end of the rebar at the upper end of the reinforcing bar and converted from a vertical wave to a vertical wave or a vertical wave to a vertical wave. And peak E12,
Peaks indicating a total of seven generated waves of F12 and G12 are confirmed. These seven generated waves are all reflected waves from the iron bar 52. In addition to the main paths 54 to 57 shown in FIG. 74, the reflected wave from the horizontal bar 52 is transmitted as a vertical wave from the transmission sensor 53a to the horizontal bar 52, refracted at the upper end of the horizontal bar 52, and reflected at the lower end. And the receiving sensor 5
There are four paths 60a to 60d that transmit the waves up to 3b. FIG. 87 is a sectional view showing the path of the reflected wave. In addition, a vertical wave is indicated by a solid line and a horizontal wave is indicated by a dotted line. Also, due to the ultrasonic scattering characteristics of the concrete, the wave from the transmission sensor 53a to the iron bar 52 is changed by the horizontal wave.
There is also a wave that transmits from the second to the reception sensor 53b as a vertical wave. The wave of this path is obtained by turning over the paper surface of FIG. The time for these two types of reflected waves to reach the receiving sensor is the same. Accordingly, a total of thirteen paths of reflected waves, including five paths in FIG. 74 and 4 × 2 paths in FIG. 87, exist from the transmission sensor 53a to the reception sensor 53b via the iron bar 52.

In consideration of the fact that among the paths of these 13 reflected waves, there are waves arriving at the same time at the receiving sensor 53b, there are 7 reflected waves that occur. That is, the reflected wave of the path 60a has a peak E12.
The reflected waves on the paths 60c and 60d have a peak F12, and the reflected waves on the path 60b have a peak G12. Table 3 below shows a comparison between the measured value and the measured value of the occurrence time on each path.

[0226]

[Table 3]

Here, the sound velocity V ₁ of the vertical waves in the concrete block 51 is 4.3 mm / μsec, and the sound velocity of the side waves is 0.63
V _1, the acoustic velocity of the surface wave is 0.60 V _1, the acoustic velocity V ₂ of the vertical wave in the horizontal bar 52 is 6.0 mm / mu sec, the acoustic velocity of the transverse wave was 0.55 V _2. The calculation formulas in Table 3 above add the transmission time obtained by dividing the transmission path length in FIGS. 74 and 87 drawn using Snell's theorem by the ultrasonic speed of concrete or the ultrasonic speed of iron, respectively. It was done. In addition,
The values of 10 and 13 in the calculation formula of the path 58 in Table 3 are the diameters of the transmitter and the receiver, respectively.

As shown in Table 3, the occurrence time of each reflected wave is specified with an error within 1 to 2%, and it can be said that the measurement result is extremely accurate.

In addition to the reflection paths shown in the figure, there are a total of five reflection waves that are transmitted by both the forward path and the return path in the concrete lump 51 as a tortuous wave. However, these five reflected waves are buried in the direct waves because the time to reach the receiving sensor is significantly slower than other reflected waves. Therefore, it was excluded from the measurement target.

Next, a method for detecting the crack depth will be described. FIGS. 88 (a) and (b) are cross-sectional views showing concrete models simulating cracks to be measured. The concrete mass 61 to be measured includes the concrete mass 61
A total of six reinforcing bars 62 are embedded at an interval of 150 mm, three at a depth of 50 mm from the front surface and the rear surface, respectively, and one crack having a depth of 100, 150 or 200 mm is formed. 100mm crack and 15
The distance from a crack of 0 mm is 121 mm and 150 mm.
The distance between a crack of 200 mm and a crack of 200 mm is 13
5 mm. Also, a crack of 100 mm is formed at a position 104 mm from the end of the concrete mass 61, and a crack of 200 mm is 140 mm from the other end.
Is formed at the position.

First, 150 m was measured using three measurement types.
This shows a case where the depth of a crack having a depth of m was measured.
In the first type, the distance between the probes was 70 mm, and the probe was arranged so that a crack was located between the two probes. In the second type, the distance between the probes was 115 mm, and the probe was arranged so that a crack was located between the two probes. In the third type, the interval between the probes is 115 mm,
The receiver was placed near the crack, and the transmitter was placed away from the crack. FIG. 89 (a) is a graph showing a time-series waveform of a received original wave measured by the first type,
(B) is a graph showing a time-series waveform of the received original wave measured by the second type, and (c) is a graph showing a time-series waveform of the received original wave measured by the third type. It should be noted that the numerical values displayed in the figure are corrected by the transmission time of the ultrasonic wave.

FIG. 90 is a cross-sectional view showing a transmission path of vertical wave reflection from the concrete bottom in the first and second types. In these types, the reflected wave from the concrete bottom is directly transmitted to the receiving probe. For this reason, the received waves in the first and second types contain a large amount of reflected waves from the concrete bottom and reinforcing bars and the like in the vicinity thereof. In particular, in the first type, the inter-sensor distance is shorter than in other types, so that the strength of the reflected wave from the concrete bottom surface increases.

FIGS. 91 and 92 are sectional views showing transmission paths of vertical wave reflection from the concrete bottom surface in the third type. In FIG. 92, the input wave is reflected once at the adjacent cracked surface, and then reflected at the concrete bottom for the second time. However, the receiving probe is hidden by the shadow of the cracked surface to be measured, and the reflected wave from the concrete bottom is not directly transmitted to the receiving element. However, although the strength is small, there is a vertical wave on the path indicated by the broken line due to the scattering phenomenon of concrete.

FIG. 93 is a sectional view showing a direct wave, a reflected wave, and the like transmitted through a penetrating rebar in the third type.
In the third type, the intensity of the direct wave reaching the receiver becomes very small due to the presence of cracks. And the reflected wave from the rebar is also cut off at the cracked portion. However, in the first and second types, the intensity of the direct wave is higher than in the third type.

As described above, there is a difference between the first to third types in the received wave shapes. From the above, FIG.
In the vicinity of the position indicated by the cursor of the first, second and third types of received waves of No. 9, it can be expected that there is a vertical wave bypassing the bottom of the crack.

FIGS. 94 and 95 are cross-sectional views showing the path of a vertical wave diffracting and bypassing the crack bottom in the third type. In FIG. 95, the input wave is reflected once on a cracked surface outside the object to be measured, and the reflected wave is diffracted and bypassed at the bottom of the crack. On the other hand, the diffracted wave is a wave whose traveling direction changes by 90 ° with respect to the wave incident on the bottom of the crack, but is diffused in a fan shape due to the scattering phenomenon of concrete. Then, the waves whose directivity changes to the paths 111 to 113 are received by the receiver.
The corresponding paths in FIG. 94 are paths 101 to 103.

Using the third type of reception wave shown in FIG. 89 (c), paths 111 and 11 diffracting and bypassing the bottom of the crack are used.
The approximate value of the birth time of the second wave is 167 μsec (80+ (CA
L value 86)) and t _h in the fifth processing program
Is set to this approximate value +10, ie, 177 μsec, and the value of α is set to 5
0, and the processing of E _{1 ²} · E ^{2 2.} Then, the fourth example of the first processing program ^{_{C 1 2 · C 2 10 (}} f HL = 2.5
X 10 ⁶ Hz). Further, according to the second example of the second processing program, C ₂ ⁿ (f _HL = 2.5 × 10 ⁶
Hz). FIG. 96 is a graph showing a Fourier spectrum obtained by the above processing.

Next, the processing of the third processing program is performed with the value of m set to 4. FIGS. 97 (a) to 97 (f) are graphs showing time-series waveforms. FIG. 97 (a) shows a case where n is 0, FIG. 97 (b) shows a case where n is 4 and FIG. ,
(D) when n is 16; (e) when n is 32;
(F) shows the case where n is 60. In addition,
The numerical values displayed in the figure are those corrected by the transmission time of the ultrasonic wave.

When n shown in FIG. 97 (a) is 0 (center frequency: 980 kHz), the analysis accuracy is extremely high and 1
The detour wave of the path 101 detouring at the bottom of the 50 mm crack is a peak A13, and its occurrence time is 78.4 μsec.
The detour wave of the path 102 is a peak B13, its occurrence time is 81.6 μs, and after being reflected once by a crack of 200 mm, the wave of the path 111 detouring at the bottom of the crack of 150 mm is a peak C13. Birth time is 9
The wave on the path 112 is at a peak D13 for 0.1 μsec, and its onset time is measured as 93.3 μsec.

FIG. 97 (d) swept to the low frequency side.
Is 16 (center frequency; 490 kHz), the bypass wave (peak B13) of the path 102 and the path 10
Three detour waves (peak E13) appear. The respective birth times are measured as 81.6 μs and 103 μs.

Further sweeping to the low frequency side, the path wave 10 from the bottom of the crack having a depth of 150 mm, which is the object of measurement, was measured.
2 gradually disappears, and diffraction and detour waves on a long path reflected and transmitted by other cracks adjacent to the crack to be measured emerge. That is, a reflected wave (peak E13) of the path 103 that is detoured at the crack bottom having a depth of 150 mm and reflected at the bottom of the crack having a depth of 100 mm, and is reflected once by a crack having a depth of 200 mm.
A reflected wave (peak F13) of the path 113 that circumvents at the bottom of the crack having a depth of mm and is reflected by the crack having a depth of 100 mm emerges. The occurrence times are measured as 103 μsec and 122.1 μsec, respectively.

The above phenomenon occurs for the following reasons. The substantially received wave extracted in this detection example contains a large amount of non-resonant waves due to the use of the fourth example of the first processing program. As a result, the higher the frequency, the more
Long diffraction and detour waves in the transmission path are attenuated at an accelerated rate.
On the other hand, the low-frequency wave has an extremely small attenuation rate compared to the high-frequency wave. For this reason, even in the case of a wave in the low-frequency region, even when the transmission path is long, a wave that is originally strong is emerging without attenuation. In Table 4 below, the measurement results are compared with the transmission path lengths plotted in FIGS. 94 and 95 as theoretical values.

[0243]

[Table 4]

In the above-described analysis, the fourth example of the first processing program is used. However, the second example may be used. Figure 98 (a) is multiplied by C ₁ ⁶ · C ₂ ⁶ to receive the original wave by the second example of the first processing program, the second example of the second processing program, the Fourier spectrum obtained by multiplying the C ₂ ¹⁴ FIG. 7B is a graph showing a time-series waveform.

In this case, the reflected wave (peak B13) of the path detouring at the bottom of the crack having a depth of 150 mm
A reflected wave (peak D <b> 13) of a path that is reflected by a crack having a depth of 00 mm and diffracted and bypassed at the bottom of the crack having a depth of 150 mm appears. Each birth time is 81.0
μs, 93.0 μs. The peak D13
The reason why is clearly emerged is that a resonance wave is used.

To perform such an analysis, it is necessary that the ninth processing program has verified whether or not the input wave is appropriate. FIG. 99A shows FIG.
8 is a graph showing a Fourier spectrum of an input ultrasonic wave corresponding to the received wave No. 8, and FIG. These are obtained from the transmitted ultrasonic waves of the transmitting probe for the verification of the suitability of the input wave. It can be said that the shape is optimal for input ultrasonic waves. Therefore,
It can be confirmed that the above measurement results are appropriate.

Although not described, the fourth and eighth processing programs are appropriately used.

The analysis results shown in FIG. 97 were obtained by specifying the waves of a number of paths diffracting and bypassing at the bottom of the crack shown in FIGS. 94 and 95 by changing the analysis frequency band.
That is, the extraction of the high-frequency wave specifies the diffraction wave and the bypass wave of a shorter path, and the extraction of the low-frequency wave specifies the diffraction wave and the bypass wave of the longer path. From this, to specify which path the obtained detour wave etc. is,
Requires some engineering judgment. However, it is very difficult to incorporate engineering decisions into analytical software. Thus, the software for automated crack depth measurement uses the following clever analysis method to make the above engineering judgment unnecessary.

[0249] Such an analysis method will be described.

FIG. 114 shows the third type of measurement shown in FIG. 88.
It is a schematic diagram which shows the transmission path | route which reaches the point B of the ultrasonic wave which bypasses a rebar path | route and a crack bottom when transmitting an ultrasonic wave immediately below at the point A. FIG. 114 (a) shows a shallow path 201 and a deep path 202 passing through a reinforcing bar, and a shortest path 101 bypassing a crack bottom. According to the new ultrasonic transmission characteristics shown in FIGS. 1 to 3 which are not used in the conventional ultrasonic detection device, the ultrasonic intensity of the transmission paths of the paths 201 and 202 and the path 101 greatly changes depending on the frequency of the ultrasonic waves. .

FIG. 114 (b) shows the change in the intensity of the high-frequency ultrasonic wave as a vector for each path. The wave of the long path 101 is attenuated, and the strength of the waves of the short paths 201 and 202 is excellent. It will be.

FIG. 114 (c) shows the change in the intensity of the low-frequency ultrasonic wave as a vector for each path, and the wave on the long path 101 reaches point B without attenuation.

As described above, the intensity (vector) of the input ultrasonic wave at point A in FIGS. 114 (b) and (c) is qualitatively plotted according to FIG. 1 (a).

As described above, the reinforcing rod path 201 and the
When including the waves of the bypass route 202 and the bottom of the crack 101
The time of the rising edge of the minute amplitude of the received original wave
To t _sAnd the time at which the amplitude suddenly increases is t_cAnd t
_h= (T_s+ T_c) / 2 at this time t_hTo the fifth processing
Apply to the program, cut out the time series wave for analysis, and
Applying the first processing program to obtain a broadband ultrasonic wave
In addition, by using the second processing program,
The time series wave obtained by sweeping or sweeping to the high frequency side is
If the processing program displays m-th power, paths 201 and 20
2 and the waves on path 101 require any engineering judgment.
Can be determined without delay. FIG. 115 shows t_s, T_cAnd t_hconnection of
FIG.

FIG. 116 shows the result of analysis when the distance between the probes is 135 mm in the case of the third type shown in FIG.

[0256] read as indicating the t _s and t _c in Figure 115, a ₁ = t _h -50 using a fifth processing program, a ₂
= T _h +50, y ₁ (t) = Y ₁ · exp (iω _y t)
= E ₁ · E ₂ · y (t).

Next, the fourth example of the first processing program is used.
And the non-resonant wave is dominant y _1,1(T) = Y_1,1・
exp (iω_yt), Y_1,1= C₁ ⁿ¹・ C_Two ⁿ¹・ Y₁/ Y₁To
create. Where f_HL= 2.5 × 10⁶Hz.

[0258] Then, C ₁ where the second processing program used, C ₂ ⁿ³ · Y _{1, 1} were swept to a lower frequency, sweeping the frequency side
Extract the spectrum of ⁿ² · Y _1,1 . However, f _HL = 2.
5 × 10 ⁶ Hz.

Next, using the third processing program, y
_1,2 ^m = (C ₁ ⁿ² · Y _1,1 ) ^m · exp (imω _y t), y
_2,2 ^m = (C ₂ ⁿ³ · Y _1,1 ) ^m · exp (imω _y t) was calculated.

[0260] spectrum of FIG. 116 (a) is ^{_{Y 1,1, C 1 n2 · Y}} 1,1 and _{^{C 2 n3 · Y 1,1, (}} b) is y _{1, 2} ^m (frequency extraction waves), ( c) is y _2,2 ^m (low frequency extracted wave). In this figure, n1 = 1, n2 = 15, n3 = 2
0, m = 4. The numerical values in the figure are corrected based on the ultrasonic transmission time. As described above, the generation of the waves of the rebar paths 201 and 202 by the high-frequency extraction wave of FIG.
It has been shown that the origin of the shortest path 101 of the bypass wave at the bottom of the crack can be obtained without any engineering judgment from the low frequency extracted wave of (c).

Next, another method of detecting the crack depth will be described. Here, FIG. 8 shows two types of measurement.
8 (a) and 8 (b), the depth of the cracks in the concrete block 61 is measured at multiple points along the cracks on the surface.
In the fourth type, the interval between the probes was 115 mm, the receiver was arranged near the crack, and the transmitter was arranged at a position away from the receiver from the crack. In the fifth type,
The distance between the probes was set to 35 mm, and the probes were arranged so that a crack was located between the two probes. Then, the two probes are sequentially moved along the crack to individually measure the received original waves, and the fourth example of the second processing program is applied to these received waves to obtain a time-series wave. The first wake time of the wave was measured. FIG. 100 is a diagram in which the occurrence times in the respective time-series waves obtained by the fifth type of measurement are plotted (hereinafter, referred to as “the occurrence times”).
It is called the birth time chart. ).

In this analysis, the filter of the fourth example of the second processing program was obtained as follows. C ₂ ^{n 1} · C ₁ ^{n 2} · C ₂ ^{n 3} (where n 1 = 408, n 2 =
4, n3 = 4, f _HL = 1.25 × 10 ⁶ Hz).
In the fourth example of the second processing program, this filter can be freely moved in the frequency band.
Is obtained, the center frequency of this filter is 300 kHz.
z.

FIG. 100 shows a curve having a local maximum value at the received wave immediately above the penetrating rebar and a local minimum value at the midpoint of the penetrating rebar. These onset times at the respective measurement points indicate the onset times of the waves with the penetrating rebar as the path, and the crack depth exists at a depth deeper than the minimum value. Therefore, one of three types of occurrence time diagrams is obtained depending on whether the crack depth is shallow or deep. FIG. 101 (a) is an occurrence time diagram when the crack is deep, (b) is an occurrence time diagram when the depth of the crack is medium, and (c) is an occurrence time diagram when the crack is shallow. . If the occurrence time diagrams of FIGS. 101 (b) and (c) are obtained, the crack depth can be easily specified.

However, when the crack is deep or the interval between the penetrating rebars is narrow, the occurrence time chart shown in FIG. 101A is obtained, and the depth of the crack is not known. From this, conventionally, all the concrete crack depth measuring devices on the market are unreinforced concrete, even if there is a penetrating rebar, the arrangement interval of the rebar is extremely large such as 30 or 40 cm or extremely shallow. It can only be used to measure crack depth.

Therefore, the measured crack depth using the received wave immediately above the penetrating rebar as shown in FIGS.
Crack depth determined from the penetration wave at the midpoint of the penetrating rebar shown in
In some cases, with the approximate value of the crack depth in FIG. 89 (c) as an initial value, measurement of the crack depth at all measurement point positions measured at multiple points along the surface crack is considered. Of course, the received waveform may be analyzed by the above-mentioned automated measurement software, but here, an analysis example to which another analysis method is applied will be described.

The approximate occurrence time of the path wave bypassing the bottom of the crack is, for example, t _h = 80 μs from FIG. 89 (c), and E ₁ ^m · E ₂ ^m (m = 2,
α = 50) and cut out a time-series wave. Further, according to the fourth example of the first processing program, the filters C ₁ ⁿ¹ and C ₂ ⁿ² (n
1 = 1, n2 = 1, f _HL = 2.5 × 10 ⁶ Hz). Then, according to the second example of the second processing program, a filter C ₁ ⁿ³ (f _HL = 2.5 × 10 ⁶ Hz, n3 = 5) is applied, and a third processing program (m = 4) is applied.

FIG. 102 is a diagram showing the measurement results obtained by the above processing. The depth of the crack is completely measured along the measurement point. The values of n1, n2, and n3 are not limited to the above values. The value of this coefficient may be changed so that the change in the crack depth at each measurement point in FIG. 102 becomes smoother.

The above measurement is performed under the assumption that the crack depths at other measurement points adjacent to an arbitrary measurement point are almost the same. That is, the approximate birth time t adopted when analyzing a received wave at an arbitrary measurement point position
_h is the time t _h already obtained as the solution at the next position
It is a method. In the case of the fourth type, the direction of the wave diffracted at the bottom of the crack is directed to the receiver, so that the power of the detour wave increases. Therefore, measurement becomes easier than in the case of the fifth type.

[0269] Note that although only shown only Okoshisei detour wave from cracking bottom in FIG. 102, instead of the schematic Okoshisei time t _h = 80 [mu] s path wave bypassing cracking bottoms, for example, FIG. 116 Approximate occurrence time t _s of rebar path wave
If the same processing is performed by using, the occurrence time and the transmission distance of the rebar path wave at each measurement point can be obtained with high accuracy, needless to say.

Next, on the concrete surface, a width of 0.01
A method of detecting a crack depth as extremely small as about 0.1 mm to 0.1 mm will be described. FIGS. 103 (a) to 103 (c) are schematic diagrams showing concrete plates having extremely narrow cracks, in which the transmitting and receiving probes are arranged very close to each other with the cracks interposed therebetween.

Detected material 12 detected by the present detection method
No. 1 was produced as follows. Width 1
A deformed reinforcing bar D20 is placed on a concrete plate having a size of 00 cm, a thickness of 23 cm and a length of 420 cm in a length direction and a width direction by 15 cm.
The cover thickness from the upper surface and the lower surface was set to 3 cm at intervals of 2 cm, and two-step reinforcement was arranged.

Next, a load is repeatedly applied to the central portion of the concrete plate in a state where it is supported at two places in the longitudinal direction, thereby artificially having a fine width and deep cracks. The width of cracks on the plate surface is about 0.05 mm or less.

The detection of the crack thus formed is performed as follows.

First, the received wave y (t) = Y · exp (iω
Applying the fourth example of the first processing program to _y t), y
₁ (t) = Y / Y · exp (iω _y t) is obtained.

Next, by multiplying y ₁ (t) by a filter F having a center frequency of 730 kHz manufactured using C ₁ and C ₂ , y ₂ (t) = FY / Yexp ( i
ω _y t). Then, the third processing program (m
= 4) is applied. FIG. 104 (a) is a graph showing the Fourier spectrum of FYY / Y, and FIG. 104 (b) is a graph showing the time-series waveform.

In FIG. 104 (b), the first earliest generated wave is an input ultrasonic wave, the second earliest generated wave is a reflected wave from the rebar surface, and the third earliest generated wave is a back surface of the rebar. The fourth and fifth earliest generated waves are direct waves transmitted through the rebar and surface waves generated on the cracked surface. In addition, although two dotted-line cursors are displayed, a cursor at an earlier time indicates a vertical wave, and a cursor at a later time indicates an onset time of a surface wave. Here, the speed of the surface wave is set to be 0.6 times the vertical wave.

The sound velocities of the vertical waves in concrete and reinforcing steel were 4.15 (mm / μsec) and 6.0 (mm / μsec), respectively.
μs), the cover thickness and the rebar diameter of the rebar take the following values from the first or second earliest generated wave. The cover thickness is
32.3m from 4.15 x (28.8-13.2) / 2
m, the rebar diameter is 16 mm from 6.0 x (34.1-28.8) / 2. FIG. 105 is a schematic view showing the shape of the deformed reinforcing bar D20. On the surface of the deformed reinforcing bar D20, a plurality of ring-shaped convex portions are formed in the longitudinal direction, and the diameter of the convex portion at the tip is 20 mm, and the diameter of the concave portion is 16 mm.
Therefore, it can be said that the above measurement accuracy is extremely high. Also,
Since the actual measurement value of the cover thickness is 32 mm, this accuracy is also high.

However, the detour wave from the crack bottom and the generation of the reflected wave from the lower reinforcing bar and the concrete bottom are mixed in forests such as scattered waves and cannot be read from FIG. 104 (b).

Therefore, according to the second example of the second processing program, a filter F _i for frequency sweeping is used. FIG.
6 is a graph showing the filter F _i. Note that the filter F _i is a filter C ₁ · C ₂ ⁿ (f _{H L} = 2.5 × 10 ⁶ Hz) having a spectrum value of 1.0 in the entire frequency domain.
Multiplied by. FIGS. 107A to 107F show these filters as Y / Y · exp (iω
7A and 7B are graphs showing time-series waveforms obtained over _y t), where FIG. 7A shows a case where i is 1 and n is 4; FIG. 7B shows a case where i is 2 and n is 6; Is 3 and n is 10,
(D) is when i is 4 and n is 16, (e) is when i is 5 and n
Is 24, and (f) shows the case where i is 6 and n is 36, respectively.

In FIG. 107 (a) to FIG. 107 (f), the meaning of the generated wave is that the generated wave at the leftmost cursor position is a crack bypass wave (vertical wave), and the generated wave at the second cursor position. Waves are cracked detour waves (surface waves), X marks are reflected waves from the front side of the reinforcing bar below (vertical waves), ○ marks are reflected waves from the back side of reinforcing bars below (vertical waves), The mark Δ represents a reflected wave (vertical wave) from the concrete bottom surface. The amplitudes of these generated waves change in FIGS. 107 (a) to 107 (f). In addition, the scattered wave disappears by shifting to low-frequency extraction, and the leftmost cursor indicates the position of the scattered wave (vertical wave),
You can see how the vertical wave reflection from the back side of the lower reinforcing bar (marked by ○) and the vertical wave reflection from the concrete bottom (marked by Δ) are dominant.

Note that the vertical wave reflection (marked by “x”) from the front side of the lower reinforcing bar, which was outstanding in FIGS. 107 (a) and 107 (b), disappears due to the extraction of the low frequency, and the reflected wave from the rear side. (Circle ○)
Is amplified. In the detection of rebar in concrete, according to many similar measurements, the high frequency range (1.2
2 to 2.5 MHz), the reflected wave from the front side of the reinforcing bar is dominant, and the wave from the low frequency region (200 to 600 kHz) is dominant in the extracting side. Although this phenomenon is also shown in the analysis example of FIG. 55 used in the description of the sixth processing program, it has been clarified by various measurement experiments that the rebar has a circular cross section. However, its theoretical and physical grounds are unclear. This is one of the future research themes.

[0282] The reason that the reflected wave from the concrete bottom indicated by the mark "小 さ い" is small is that the ultrasonic wave is cut off by the reinforcing bar and the transmission is hindered by cracks because the main measurement was performed immediately above the reinforcing bar. Because.

As described above, the crack depth is determined by the time indicated by the leftmost cursor (99.2 μsec) and the ultrasonic wave transmission time (1
3.2 μs) and the concrete sound velocity of this model (4.
Using 15 mm / μsec), 4.15 × (99.2-1)
3.2) / 2 = 178 mm. Note that the actually measured value was 175 mm.

Further, the substantially received wave y ₁ (t) = Y / Y · ex
If a third example of the first processing program of multiplying p (iω _y t) by a high-pass filter having a start frequency of 185 kHz and a relatively gentle low-pass filter having a start frequency of 340 kHz is applied, as shown in FIG. FIG.
A spectrum similar to the peak F6 at 06 is obtained. Thus, when the third processing program (m = 4) is applied, a result similar to FIG. 107 (f) is obtained as shown in FIG. 108 (b). FIG. 108 (a) is a graph showing a Fourier spectrum of a wave obtained by the third example of the first processing program, and FIG. 108 (b) shows a corresponding time-series waveform by applying the third processing program. FIG. Although the number of waves slightly increases, it can be said that it is almost the same as FIG. 107 (f).

[0285] In Fig. 107 (f), the reflected wave from the upper end of the lower reinforcing bar has disappeared. Therefore, a method for clearly confirming the reflected wave will be described.

First, the fifth processing program is applied to the time series wave shown in FIG. 107 (f). FIG. 109 is a graph showing a time series filter according to the fifth processing program. FIG. 110 is a graph showing a Fourier spectrum of a wave obtained by the fifth processing program. Here, a ₁ was set to 66 μs and a ₂ was set to 166 μs.

[0287] Then, by the second example of the second processing program to filter ^{_{C 1 4 (f HL = 2.5}} × 10 6 Hz), sweeps to the high frequency side. FIG. 111A is a graph showing a Fourier spectrum of a wave swept by the second processing program, and FIG. 111B is a graph showing a time-series waveform.

Thus, the peak A14 indicating the reflected wave from the upper end of the lower reinforcing bar can be clearly confirmed. Further, a peak B14 indicating a reflected wave from the lower end of the lower reinforcing bar and a peak C14 indicating the crack depth are also confirmed.

In the above-described embodiment, each processing program is stored in the storage device provided in the analyzer 4, but each processing program is configured as a routine in a computer-readable storage medium. A program may be stored.

Also, a plurality of receiving probes and transmitting probes may be arranged in series. Thereby, multipoint measurement can be performed collectively. FIGS. 112A to 112C are cross-sectional views showing examples of detection by the multipoint measurement probe. FIG.
In 2 (a), the ultrasonic wave transmitted from one transmission / reception probe 131 is received by the adjacent transmission / reception probe 131. In FIG. 112B, the ultrasonic wave transmitted from one transmission / reception probe 132 is received by the transmission / reception probe 132 located at the second position. In FIG. 112 (c), 1
The ultrasonic waves transmitted from the transmission / reception probes 133 are received by the transmission / reception probe 133 located at the third position.

[0291]

As described in detail above, according to the present invention,
Detection and flaw detection at a deep position of the detection target material can be performed. Also, even when a plurality of reflected waves are obtained,
The individual meanings can be easily specified. Furthermore, the detectable material to be detected is not only a homogeneous elastic body such as iron, steel and plastic, but also the position and size measurement of a reinforcing bar or a steel frame that is intricately arranged in a concrete structure. It is also possible to detect the crack status and its depth, the presence or absence of internal voids, and the thickness of the concrete with ultra-high accuracy. Furthermore, it can also be used for internal exploration of castings, soil or ground. In other words, even if the material to be detected is porous or a composite of a plurality of different materials or an ingot in which the crystal of the material particles is in one direction, the inside can be detected.

[Brief description of the drawings]

FIGS. 1A and 1B are diagrams showing the intensity of fan-shaped diffused ultrasonic waves due to a change in frequency in a porous elastic body. FIG. 1A is a schematic diagram at a low frequency, and FIG. 1B is a schematic diagram at a high frequency.

FIGS. 2A and 2B are diagrams showing the intensity of fan-shaped diffused ultrasonic waves due to a change in frequency in a homogeneous elastic body, wherein FIG. 2A is a schematic diagram at a low frequency, and FIG.

FIG. 3 is a graph schematically showing the attenuation rate of ultrasonic waves in a porous elastic material, with the transmission distance on the horizontal axis.

FIG. 4 is a block diagram illustrating an ultrasonic detection device according to an embodiment of the present invention.

5A is a plan view showing a ceramic probe used in the embodiment of the present invention, FIG. 5B is a sectional view showing the same probe, and FIG. 5C is a conventional commercially available probe. A plan view showing a ceramic probe, (d) is a sectional view showing the same probe, (e) is a plan view showing another conventional ceramic probe on the market, and (f) is the same. It is sectional drawing which shows a probe.

6A to 6C are cross-sectional views showing the operation of the ceramic probe used in the embodiment of the present invention in various vibration modes, and FIGS. 6D to 6G are various vibration modes. FIG. 6 is a cross-sectional view showing the operation of the conventional ceramic probe in FIG.

7A is a graph showing a spectrum obtained by a probe 11, and FIG. 7B is a graph showing a time-series waveform.

8A is a graph showing a spectrum obtained by a probe 21a, and FIG. 8B is a graph showing a time-series waveform.

9A is a graph showing a spectrum obtained by a probe 21b, and FIG. 9B is a graph showing a time-series waveform.

FIG. 10 is a schematic view showing an example in which the one-probe method is adopted.

FIGS. 11 (a) and 11 (b) are cross-sectional views showing a concrete mass in which a reinforcing bar used for actual measurement is embedded and a crack is simulated.

12A is a graph showing a Fourier spectrum of an input ultrasonic original waveform measured by an AE sensor, and FIG.
FIG. 4 is a graph showing a time-series waveform.

13A is a graph showing a Fourier spectrum of a received ultrasonic original waveform measured by an AE sensor in a measurement directly above a reinforcing bar using the concrete model of FIG. 11; FIG.
FIG. 4 is a graph showing a time-series waveform.

FIG. 14A is a graph showing a high-pass filter;
(B) is a graph showing a low-pass filter.

FIG. 15A is a graph showing a Fourier spectrum of input ultrasonic waves obtained by applying filters F _H and F _L to input ultrasonic waves and then applying a high-pass filter F _H1 to the input ultrasonic waves;
(B) is a graph showing a time-series waveform in the same manner.

16A is a graph showing a Fourier spectrum of a received wave obtained by the same filtering processing as that shown in FIG. 15, and FIG. 16B is a graph showing a time-series waveform.

FIG. 17 is a graph showing an example of a special function filter (third filter).

FIG. 18 is a graph showing another example (n = 8) of the special function filter (third filter).

FIG. 19A is a graph showing an input ultrasonic wave X and a received original wave Y just above a reinforcing bar, and FIG. 19B is a graph showing an input ultrasonic wave X and a transfer function Y / X just above a reinforcing bar.

FIG. 20A is a graph showing FYY / Y obtained by applying the fourth example of the first processing program to the spectrum Y of the received wave by the AE (acoustic emission) sensor, and FIG. FIG. 4 is a graph showing a time-series waveform.

[Figure 21 (a) is a graph showing the spectrum of the ultrasonic wave obtained by amplifying the high-frequency component is multiplied by a filter C ₁ of the second example in the recorded input wave X by the AE sensor, (b) the same time-series waveform FIG.

22 (a) is a graph showing an X / X spectrum, and FIG. 22 (b) is a graph showing a time-series waveform.

23A is a graph showing a spectrum (fourth filter) obtained by artificially removing unnecessary generated waves by extracting a time-series wave by a fifth processing program described later, and FIG. FIG. 4 is a graph showing a time-series waveform.

FIG. 24 is a graph showing a high-pass filter and a low-pass filter.

FIG. 25 is a graph showing a filter using a function (fifth filter) shown in Expression 3.

FIG. 26 is a graph showing filter functions at various f _HL when n is 2.

FIG. 27 is a graph showing sweeping of a filter function (fifth filter).

FIG. 28A is a graph showing a function y (t).
(B) is a graph showing the function y (t−Δt), and (c) is a graph showing the sum of the function y (t) and the function y (t−Δt).

29A is a graph showing a function g (t), FIG.
(B) is a graph showing the function g (t + Δt), and (c) is a graph showing the sum of the function g (t) and the function g (t + Δt).

FIG. 30 (a) is a graph showing a spectrum of a reflected wave having a broadband frequency with a center frequency of 1.25 MHz, and FIG. 30 (b) is a graph showing a time-series waveform.

31A and 31B are graphs showing a time-series waveform of a reflected wave on which calculation has been performed, where FIG. 31A is 0 times, FIG. 31B is 5 times, and FIG.
Is a calculation performed 20 times, and (d) is a calculation performed 100 times.

FIG. 32 is a graph showing a spectrum of a reflected wave indicated by the time-series waveform shown in FIG. 31;

FIG. 33 (a) shows 625 MHz for the reflected wave shown in FIG. 30;
FIG. 7B is a graph showing a spectrum obtained as a result of applying the low-pass filter of FIG.

FIG. 34 (a) shows the reflected wave shown in FIG.
FIG. 7B is a graph showing a spectrum as a result of cutting, and FIG. 7B is a graph showing a time-series waveform.

FIG. 35 is a graph showing a time-series waveform y ^m (t) when a low-pass filter is used.
1, (b) is m = 2, and (c) is m = 4.

FIG. 36 shows a time-series waveform y when cutting is used.
FIG. 8 is a graph showing ^m (t), where (a) is m = 1,
(B) is m = 2, and (c) is m = 4.

FIG. 37 is a graph showing a substantially received wave spectrum in a third example of the second processing program.

38 is a graph showing a time-series waveform corresponding to FIG. 37, where (a) shows that _fHL is 1.25 × 10 ⁶ Hz,
(B) is f _HL is ^{0.625 × 10 6 Hz, (c} ) is f _HL
Is 0.3125 × 10 ⁶ Hz.

FIG. 39 (a) is a graph showing a Fourier spectrum of a broadband received wave having a center frequency around 300 kHz filtered by the second example of the first processing program and the second example of the second processing program. And (b) are graphs showing the time-series waveforms.

40 (a) to (c) are graphs showing time-series waveforms obtained as a result of processing by the third processing program, where (a) is 2 and (b) is m When it is 4, (c) shows the case where m is 6.

FIG. 41 (a) is a graph showing a Fourier spectrum of a broadband reception wave having a center frequency around 300 kHz filtered by a fourth example of the first processing program and a second example of the second processing program. And (b) are graphs showing the time-series waveforms.

42 (a) to (c) are graphs showing time-series waveforms obtained by processing the time-series wave shown in FIG. 41 (b) by a third processing program. 2, (b) shows when m is 4, and (c) shows when m is 6.

FIG. 43 is a graph showing a spectrum of a broadband input ultrasonic wave.

FIGS. 44 (a) and (b) are cross-sectional views showing concrete blocks in which reinforcing steel used for actual measurement is embedded.

FIG. 45A is a graph showing a Fourier spectrum of a received wave in a low frequency region, and FIG. 45B is a graph showing a time-series waveform.

FIG. 46 is a graph showing a time-series waveform processed by a third processing program with m set to 2;

FIG. 47 is a graph showing cut-out time-series waveforms.

48A is a graph showing a time-series waveform when m is 1, and FIG. 48B is a graph showing a time-series waveform when m is 4. FIG.

49A is a graph showing a time-series waveform when the center frequency is 1250 kHz, FIG. 49B is a graph showing a time-series waveform when the center frequency is 1090 kHz, and FIG. Is a graph showing a time-series waveform when the frequency is 980 kHz, and FIG.
FIG. 5E is a graph showing a time-series waveform when the frequency is kHz.
7 is a graph showing a time-series waveform when the center frequency is 833 kHz, and FIG. 7F is a graph showing a time-series waveform when the center frequency is 740 kHz.

FIG. 50 is a sectional view showing a concrete mass in which a reinforcing bar used for actual measurement is embedded.

FIG. 51 (a) is a graph showing a time-series waveform when a reinforcing bar in a concrete block is embedded near a measuring point, and (b) is a time series when a reinforcing bar is not embedded near a measuring point. It is a graph which shows a waveform.

FIG. 52 is a graph showing a difference between the time series wave of FIG. 51 (a) and the time series wave of FIG. 51 (b).

FIG. 53 is a graph showing a Fourier spectrum corresponding to FIG. 52;

FIG. 54 is a graph showing a filter C ₁ ⁿ ;

FIG. 55 (a) is a graph showing a time-series waveform when n is 12, FIG. 55 (b) is a graph showing a time-series waveform when n is 18, and FIG. FIG. 8D is a graph showing a time-series waveform, and FIG. 9D is a graph showing a time-series waveform when n is 52.

FIG. 56 is a cross-sectional view showing a concrete block including large fine stones.

FIG. 57: n1 is 2, n2 is 20 (center frequency; 480)
kHz), 30 (center frequency; 400 kHz) or 50
It is a graph which shows the spectrum at the time of (center frequency; 315kHz).

58A is a graph showing a time-series waveform when n2 is 20, FIG. 58B is a graph showing a time-series waveform when n2 is 30, and FIG. FIG. 6 is a graph showing a time-series waveform at a certain time.

59A is a graph showing a time-series waveform when n is 6, FIG. 59B is a graph showing a time-series waveform when n is 10, and FIG. FIG. 4D is a graph showing a time-series waveform, and FIG. 4D is a graph showing a time-series waveform when n is 20.

60A is a graph showing a time-series waveform of a received wave affected by disturbance, and FIG. 60B is a graph showing a time-series waveform obtained by averaging 1000 times of a received wave affected by disturbance. FIG.

FIG. 61 is a graph showing a Fourier spectrum corresponding to FIG. 60;

62A is a graph showing a Fourier spectrum of a received wave (disturbance) having a center frequency of 843 kHz, and FIG.
Also uses the third processing program to convert the time-series waveform to m =
FIG. 2 is a graph diagram indicated by 2.

FIG. 63 is a graph showing a time-series waveform obtained by performing averaging 1000 times.

FIG. 64 is a graph showing a Fourier spectrum of a wave having a higher-order resonance frequency.

FIGS. 65 (a) to (c) are graphs showing time-series waveforms based on respective resonance spectra.

FIG. 66 is a graph showing a composite wave obtained by superimposing the time-series waves shown in FIGS. 65 (a) to (c).

FIG. 67 (a) is an original wave X · exp (iω) of an input ultrasonic wave;
_x t) is a graph showing the Fourier spectrum of the results of the filtered according to the second example of the first processing program, is a graph showing (b) is also a time-series waveform.

[Figure 68 (a) is a graph illustrating the filter and Fourier spectrum of the input ultrasound applied to the filter of C _{1 ²} · C ^{2 6,} is a graph showing (b) is also a time-series waveform.

FIG. 69 is a cross-sectional view showing a detection target material.

FIG. 70 (a) is a graph showing a Fourier spectrum of a received wave when the distance between the transmitting point and the receiving point is 35 mm when there is no reflector near the measuring point, and FIG. FIG.

FIG. 71 (a) is a graph showing a Fourier spectrum of a received wave when an interval between a transmitting point and a receiving point is set to 100 mm when there is no reflective object near a measuring point, and (b) is a time-series waveform; FIG.

FIG. 72 is a graph showing a time-series waveform in which a surface wave, a reflected wave reflected from a detection target, and a direct wave appear without being superimposed.

73 (a) and 73 (b) are cross-sectional views showing a detection target material.

FIG. 74 is a cross-sectional view showing main paths of ultrasonic waves.

75 is a graph showing a Fourier spectrum of Analysis Example 1 in Table 2. FIG.

FIG. 76 is a graph showing a time-series waveform of Analysis Example 1 of Vote 2.

FIG. 77 is a graph showing a time-series waveform indicating y ₄ ^m (t) (m = 4).

[Figure 78] The second example of the second processing program used in the Fourier spectrum Y ₄ which fifth processing program is applied, multiplied by ^{_{C 2 6 (f HL = 2.5}} × 10 6 Hz) becomes the filter FIG. 9 is a graph showing a Fourier spectrum Y ₅ (analysis example 2 in Table 2).

FIG. 79 is a graph showing a time-series waveform of y ₅ ^m (t) (m = 4) (analysis example 2 in Table 2).

FIG. 80 is a graph showing Fourier spectra Y ₃ and Y _{4 of} y ₃ (t) and y ₄ (t) (analysis example 3 in Table 2).

[Figure 81 (a) is ^{_{y 3 4 (t), (}} b) is y _{⁴ 4} (t)
FIG. 8 is a graph showing a time-series waveform of (Example 3 of Table 2).

[Figure 82 (a) is a graph showing the Fourier spectrum Y ₅ in the analysis Example 4 of Table 2 is a graph showing (b) is also a time-series waveform.

83 (a) is a graph showing a Fourier spectrum Y ₆ in Analysis Example 5 of Table 2, and FIG. 83 (b) is a graph showing a time-series waveform Y ₆ · exp (iω _y t).

84 (a) is a graph showing a Fourier spectrum Y ₆ before application of Analysis Example 6 in Table 2 and a Fourier spectrum Y ₇ after application thereof, and FIG. 84 (b) is a time series waveform Y ₇ · exp (iω
It is a graph showing _y t).

FIG. 85 (a) shows a reflected wave Y ₈ in Analysis Example 7 of Table 2;
FIG. 4B is a graph showing a time series waveform Y ₈ · exp (iω _y t).

FIG. 86 is an enlarged graph of FIG. 85 (b).

FIG. 87 is a cross-sectional view showing a path of a reflected wave in another path.

FIGS. 88 (a) and (b) are cross-sectional views showing concrete models simulating measured cracks.

89A is a graph showing a time-series waveform of a received original wave measured by the first type, FIG. 89B is a graph showing a time-series waveform of the received original wave measured by the second type, FIG.
(C) is a graph showing a time-series waveform of the received original wave measured by the third type.

FIG. 90 is a cross-sectional view showing a transmission path of vertical wave reflection from the concrete bottom surface in the first and second types.

FIG. 91 is a cross-sectional view showing a transmission path of vertical wave reflection from the concrete bottom surface in the third type.

FIG. 92 is a sectional view showing a transmission path of vertical wave reflection from the concrete bottom surface in the third type.

FIG. 93 is a cross-sectional view showing a direct wave, a reflected wave, and the like transmitted through a penetrating rebar in the third type.

FIG. 94 is a cross-sectional view showing a path of a vertical wave diffracting and bypassing a crack bottom in the third type.

FIG. 95 is a cross-sectional view showing a path of a vertical wave diffracting and bypassing a crack bottom in the third type.

FIG. 96 is a graph showing a Fourier spectrum obtained by sequentially applying a fifth processing program, a fourth example of the first processing program, and a second example of the second processing program to the third type of received wave; is there.

97 (a) to (f) show a time series waveform corresponding to the Fourier spectrum of FIG.
FIG. 7 is a graph showing the case where n is 0, (b) is when n is 4, (c) is when n is 8,
(D) when n is 16; (e) when n is 32;
(F) shows the case where n is 60.

FIG. 98 (a) is a graph showing a Fourier spectrum obtained by applying the fourth example of the first processing program to the received original wave and then obtaining the second example of the second processing program;
(B) is a graph showing a time-series waveform in the same manner.

FIG. 99 (a) is a graph showing a Fourier spectrum of an input ultrasonic wave corresponding to a received wave, and FIG. 99 (b) is a graph showing a time-series waveform.

FIG. 100 is a diagram in which the fourth example of the second processing program is applied to each of the received waves measured by the fifth type along the crack, and the first occurrence times of the obtained time-series waves are plotted. .

FIG. 101 (a) is an occurrence time diagram when a crack is deep, (b) is an occurrence time diagram when the crack depth is medium, and (c) is an occurrence time diagram when the crack is shallow. It is.

FIG. 102 is a diagram showing measurement results obtained for each of the measurement points along the crack, and a detour wave from the bottom of the crack is obtained.

FIGS. 103 (a) to (c) are schematic views showing concrete plates having extremely narrow cracks.

FIG. 104 (a) is a graph showing the Fourier spectrum of FYY / Y, and FIG. 104 (b) is a graph showing the same time-series waveform.

FIG. 105 is a schematic view showing the shape of a deformed reinforcing bar D20.

FIG. 106 is a graph showing a filter F _i .

[Figure 107] (a) to (f) is a filter F _i Y / Y
FIG. 7 is a graph showing a time-series waveform obtained over exp (iω _y t), where (a) shows a case where i is 1 and n is 4;
(B) when i is 2 and n is 6, (c) when i is 3 and n is 10, (d) when i is 4 and n is 16, (e)
Is when i is 5 and n is 24, (f) is when i is 6 and n is 36
Respectively.

FIG. 108 (a) shows y ₁ (t) = Y / Y · exp (i
( _y )) is a graph showing a Fourier spectrum obtained by applying the third example of the first processing program to (ω _y t), and (b) displays a time-series waveform corresponding thereto by applying the third processing program. FIG.

FIG. 109 is a graph showing a time-series filter according to a fifth processing program.

FIG. 110 is a graph showing a Fourier spectrum of a wave obtained by a fifth processing program;

FIG. 111 (a) shows the time series wave of FIG. 107 (f) in FIG.
09 is a graph showing a Fourier spectrum obtained by applying a fifth processing program and sweeping in the high frequency direction by a second example of the second processing program, and FIG. 9B is a graph showing a time-series waveform. It is.

FIGS. 112 (a) to (c) are cross-sectional views showing examples of detection by a multipoint measuring probe.

FIG. 113 (a) is a cross-sectional view showing the directivity and directivity of ultrasonic waves in a homogeneous elastic body, and FIG. 113 (b) is a cross-sectional view showing the directivity, directivity and scattering of ultrasonic waves in a porous elastic body. .

FIG. 114 is a schematic diagram showing a transmission path of the ultrasonic wave that reaches the point B when the ultrasonic wave is transmitted immediately below the point A in the third type measurement of FIG. 88 and bypasses the rebar path and the crack bottom.

[Figure 115] t _s, is a schematic diagram showing the relationship between t _c and t _h.

FIG. 116 shows an analysis result when the distance between the probes is 135 mm in the case of the third type shown in FIG. 88.

[Explanation of symbols]

Reference Signs List 1: pulse generator 1a; pulse generation circuit 1b; pulse interval change circuit 1c; pulse drive circuit 2a; transmission probe 2b; reception probe 3; external amplifier 4: analysis device 4a; amplifier circuit 4b; 4c; analog / digital converter 4d; gate array 4e; CPU or DSP 5; display device 11, 21a, 21b, 73a, 73b, 83a, 83
b; probe 12; edge 13, 23; electrode 31, 51, 61, 71, 81, 91; concrete mass 32, 62, 72, 82, 93; reinforcing bar 33.34, 35a, 35b, 36, 37 Wave 41; porous elastic material 42; reflector 52; iron bar 53a; transmission sensor 53b; reception sensor 54, 55, 56, 57, 58, 59, 60a, 60
b, 60c, 60d, 111, 112, 113; path 92; fine stone 121; detected material 131, 132, 133;

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Jinpei 3F, Nishi Shinjuku 3-chome, Shinjuku-ku, Tokyo 3-17-7 TOK Bldg. 9F F-term in etch and b system Shinjuku office (reference) 2F068 AA49 BB26 CC11 DD00 DD09 EE02 FF03 FF12 GG01 KK12 KK14 LL02 LL13 LL29 QQ12 2G047 AA10 BA04 BC03 BC04 BC07 BC10 EA10 GF06 GF11 GG09 GG12 GG17 GG19 GG24 GG33 GG34 GG38 GJ28

Claims (17)

[Claims] 1. An ultrasonic detecting apparatus for transmitting an ultrasonic wave and analyzing the received ultrasonic wave, wherein a first filter is applied to the transmitted transmitted ultrasonic wave and the received received ultrasonic wave, whereby the ultrasonic wave is detected. A first process for setting the intensity to a value equal to or more than a predetermined value in a predetermined frequency band or more, and a second process for performing the ultrasonic wave sweeping process by applying a second filter to the ultrasonic wave subjected to the first process. And a third process of raising the time-series wave of the ultrasonic wave subjected to the second process to a power of a natural number,
An ultrasonic detection device comprising an arithmetic device that executes processing including: 2. An ultrasonic detecting apparatus for transmitting an ultrasonic wave and analyzing the received ultrasonic wave, wherein the transmitted ultrasonic wave is divided by the transmitted ultrasonic wave and the received ultrasonic wave is received by the received ultrasonic wave. A first process for applying a first filter to the product divided by the sound wave to make the intensity of the ultrasonic wave equal to or more than a predetermined value in a predetermined frequency band or more; A second process for performing the ultrasonic sweep process by applying a second filter, and a third process for raising a time-series wave of the ultrasonic wave subjected to the second process to a natural number are described. An ultrasonic detection device having an arithmetic device for executing. 3. The processing device includes: a fourth process for correcting the occurrence time of the reception ultrasonic wave in association with the transmission time of the transmission ultrasonic wave that fluctuates by the second processing; A fifth process of selecting a predetermined area of the time-series wave of the received ultrasonic wave in association with the approximate value when the approximate value of the birth time from the target detection object is known; and A sixth process for obtaining a difference between an ultrasonic wave received when the target object is affected by the target object and an ultrasonic wave received when the target object is not affected by the target object, and measurement at a plurality of points. A seventh process for obtaining an average of a plurality of received waves obtained, an eighth process for obtaining an average of a plurality of received waves obtained by performing a plurality of measurements at the same point, A ninth process for determining whether the sound wave is appropriate or inappropriate. The ultrasonic detection device according to claim 1, wherein the ultrasonic detection device performs a process including the operation. 4. An oscillator connected to the arithmetic unit and transmitting an ultrasonic wave to the object to be detected, and a receiver connected to the arithmetic unit and receiving an ultrasonic wave from the object to be detected, 2. The transmitter according to claim 1, wherein the transmitter has a plate-shaped substrate and electrodes formed at central portions of both surfaces of the substrate.
The ultrasonic detection device according to any one of claims 1 to 3. 5. The ultrasonic detection device according to claim 4, wherein the receiver has a plate-shaped base material and electrodes formed at the center of both surfaces of the base material. . 6. A transmission / reception probe connected to the arithmetic unit for transmitting an ultrasonic wave to the detection target and receiving an ultrasonic wave from the detection target, wherein the transmission / reception probe has a plate shape. The ultrasonic detection device according to any one of claims 1 to 3, further comprising: a base material; and electrodes formed at central portions of both surfaces of the base material. 7. The method according to claim 1, wherein the first filter has a third filter represented by a product of an m-th sine function and an n-th cosine function, where m and n are integers of 0 or more. The ultrasonic detection device according to any one of claims 1 to 6, wherein: 8. The apparatus according to claim 2, wherein the first filter includes a fourth filter that removes a wave having a frequency not included in the transmitted ultrasonic wave from the received ultrasonic wave.
The ultrasonic detection device according to any one of claims 1 to 7. 9. The second filter has a fifth filter represented by a product of an m-th sine function and an n-th cosine function, where m and n are integers of 0 or more. The ultrasonic detection device according to any one of claims 1 to 8, wherein: 10. The second filter sets m and n to 0.
6. The method according to claim 1, wherein, when the integer is equal to or more than the integer, a sixth filter having a desired frequency, which is represented by a product of an mth-order sine function and an nth-order cosine function, and which gives a maximum value, is provided. 10. The ultrasonic detection device according to claim 9. 11. A first filter is applied to the transmission ultrasonic wave transmitted from the ultrasonic detection device and the reception ultrasonic wave received by the ultrasonic detection device so that the intensity of the ultrasonic wave is equal to or higher than a predetermined frequency band. A first process that is equal to or more than a predetermined value, and a second process that performs the ultrasonic sweep process by applying a second filter to the ultrasonic wave that has undergone the first process.
And a third process for raising the time-series wave of the ultrasonic wave subjected to the second process to a power of a natural number, and causing the computer to execute the process. A readable recording medium. 12. A first divided ultrasonic wave transmitted from the ultrasonic detection device by the transmitted ultrasonic wave and a divided ultrasonic wave received by the ultrasonic detection device by the received ultrasonic wave. A first process of making the intensity of the ultrasonic wave equal to or more than a predetermined value in a predetermined frequency band or more by applying a filter, and applying a second filter to the ultrasonic wave subjected to the first process. And causing the computer to execute a process including a second process of performing the ultrasound sweep process and a third process of raising the time-series wave of the ultrasound that has undergone the second process to a natural number. A computer-readable recording medium storing an ultrasonic detection program. 13. The ultrasonic detecting program according to claim 4, wherein the program corrects the occurrence time of the received ultrasonic wave in association with the transmission time of the transmitted ultrasonic wave which fluctuated by the second processing.
And selecting a predetermined area of the time series wave of the received ultrasonic wave in association with the approximate value when the approximate value of the birth time from the target object in the object to be detected is known. And calculating a difference between an ultrasonic wave received when the ultrasonic wave is not affected by the target object and an ultrasonic wave received when the ultrasonic wave is not affected by the target object in the object to be detected.
, A seventh process of calculating the average of a plurality of received waves obtained by measurement at a plurality of points, and obtaining an average of a plurality of received waves obtained by measurement of a plurality of times at the same point 12. The computer according to claim 11, further comprising: executing a process including an eighth process and a ninth process for determining whether the transmitted ultrasonic wave is appropriate or inappropriate.
3. A computer-readable recording medium storing the ultrasonic detection program according to 2. 14. The first filter sets m and n to 0.
14. The super filter according to claim 11, further comprising a third filter represented by a product of an m-th order sine function and an n-th order cosine function when the integers are equal to or larger than the integer. A computer-readable recording medium storing a sound detection program. 15. The apparatus according to claim 12, wherein the first filter includes a fourth filter that removes a wave having a frequency not included in the transmitted ultrasonic wave from the received ultrasonic wave. A computer-readable recording medium storing the ultrasonic detection program according to claim 1. 16. The second filter sets m and n to 0.
The super filter according to any one of claims 11 to 15, further comprising a fifth filter represented by a product of an m-th order sine function and an n-th cosine function when the integers are equal to or larger than the integer. A computer-readable recording medium storing a sound detection program. 17. The second filter sets m and n to 0.
12. The method according to claim 11, wherein, when the integer is equal to or greater than the integer, a sixth filter having a desired frequency whose frequency giving a local maximum value is represented by a product of an m-order sine function and an n-th cosine function is provided. A computer-readable recording medium storing the ultrasonic detection program according to any one of Claims 16 to 16.