JP2003270221A - Apparatus and method for measuring properties of substance - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for measuring properties of a substance or the like suitable for measuring a sound velocity of a substance having a large attenuation, measuring values corresponding to a sound velocity simply with high precision, and measuring properties of a substance including the degree of compaction of the ground and a layer thickness or the like. <P>SOLUTION: The apparatus comprises a detector 21 detecting the vibration of a substance to be measured 1 and gaining a signal representing the vibration, an amplifier 22 amplifying the signal gained by the detector 21, a vibrator 23 vibrating the substance to be measured 1 by the amplified signal, a resonance circuit 20 gaining a resonance signal by positioning the substance to be measured 1 between the vibrator 23 and the detector 21, and a signal processing unit 30 determining the properties of the substance to be measured 1 based on the resonance frequency of the resonance signal on the resonance circuit 20. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material characteristic measuring apparatus and a material characteristic measuring method suitable for measuring the sound velocity of a material having large attenuation, and further the material characteristic such as strength and thickness of the material according to the measured sound velocity. TECHNICAL FIELD The present invention relates to a material property measuring device and a material property measuring method suitable for measuring a substance.

[0002]

2. Description of the Related Art Conventionally, in order to obtain the speed of sound propagating in a substance, a substance whose length or distance is known in advance is continuously vibrated by some method to cause resonance, and the resonance frequency is measured. The resonance method is known. Since the resonance method uses the vibration of a standing wave composed of a traveling wave and a reflected wave, the vibration mode and frequency are determined by the shape and size of the elastic body. Therefore, unless the elastic body has a simple shape such as a rod shape, there are many vibration modes, which makes measurement difficult. Moreover, an elastic body with large attenuation such as soil is difficult to generate a standing wave and is difficult to measure.

Further, conventionally, in order to measure the strength and hardness of the ground, when the compaction layer thickness is 50 to 60 cm, a density measuring device using a vibrator or a frame type RI (radioisotope) density / moisture meter is used. The quality of the compaction layer is confirmed by the In the frame type RI densitometer, it is necessary to embed a steel conduit frame in the compaction layer in advance.
Since it is a non-destructive method, it is effective for detecting the density change of the ground at a fixed point.

[0004]

When the sound velocity of a material having a large attenuation such as the ground is measured by using a normal resonance measuring method, the Q of the resonance mode is small and the S / N ratio cannot be made large. The accuracy is poor and the measurement itself is very difficult.

On the other hand, in order to measure the strength and hardness of the ground,
In the density measuring device using the exciter, the weight of the exciter must be set to the optimum weight for each ground measurement area, and the spectrum must be measured to determine the optimum vibration frequency. There is a problem that the shape and weight are large.
Further, it is necessary to correct the vibration frequency measured by detecting the exciting force and to adjust the timing of taking in the vibration frequency, which makes it difficult to perform accurate measurement. Further, the frame type RI density / moisture meter uses radiation called gamma rays, which is problematic in managing radioactive substances. Furthermore, since the conduit frame must be left buried, it is very costly.

The present invention has been made to solve the above problems, and an object of the present invention is to measure a value corresponding to the speed of sound propagating through an elastic body easily and accurately, and measure the measured value. The object of the present invention is to provide a material property measuring device and a material property measuring method for measuring the property of a material including the degree of compaction of the ground, the layer thickness and the like.

[0007]

Means for Solving the Problems A substance property measuring apparatus of the present invention which achieves the above object is provided by a detector for detecting the vibration of a substance to be measured and obtaining a signal representing the vibration, and the detector. An amplifier for amplifying the signal and an exciter for exciting the substance to be measured with the signal amplified by the amplifier are provided, and the substance to be measured is interposed between the exciter and the detector. A resonance circuit for obtaining a resonance signal, and a signal processing unit for obtaining the characteristic of the substance to be measured based on the resonance frequency of the resonance signal on the resonance circuit.

Here, the above-mentioned "resonance frequency" is a value corresponding to the speed of sound in the substance to be measured, and here, the value corresponding to this speed of sound and the speed of sound are simply referred to as "speed of sound". Sometimes.

The sound velocity measuring method of the present invention is a sound velocity measuring method suitable for measuring the sound velocity of a substance having a large attenuation. In this sound velocity measuring method, resonance including a signal in an electronic circuit is used. That is, unlike a general resonance method, it is not necessary to scan a specific frequency or a frequency and add it to the exciter. At the start of the measurement, if necessary, for example,
If white noise is added to the exciter, resonance will occur naturally due to a phenomenon such as howling. Therefore, the propagation of oscillatory waves in a material is unidirectional. There are also resonances with frequencies different from the general resonance mode of the elastic body. However, even if there are a plurality of resonance modes, it is easy to analyze because it resonates in the mode that is most likely to resonate. Further, even a substance having a large attenuation of a vibration wave resonates if the amplification degree of the electronic circuit is increased, so that almost all substances can be measured.

Here, in the above-mentioned material property measuring apparatus of the present invention, the signal processing unit may be one that obtains the speed of sound in the substance to be measured, but is not limited to one that obtains the speed of sound, or obtains the speed of sound. In addition, the signal processing unit may be one that obtains the thickness of the substance to be measured, or this device for measuring the material properties is the resonance frequency of the resonance signal on the resonance circuit or the sound velocity obtained from the resonance frequency. The signal processing unit may include a storage unit that stores the relationship with the intensity of the substance to be measured, and the signal processing unit may refer to the storage unit to obtain the intensity of the substance to be measured. Further, in the material property measuring apparatus of the present invention, a storage unit for storing the relationship between the resonance frequency of the resonance signal on the resonance circuit or the sound velocity obtained from the resonance frequency and the moisture content of the measured substance. The signal processing unit may be configured to obtain the water content of the substance to be measured with reference to the storage unit, and further, it is obtained from the resonance frequency of the resonance signal on the resonance circuit or the resonance frequency thereof. The signal processing unit may include a storage unit that stores the relationship between the sound velocity and the fat percentage of the substance to be measured, and the signal processing unit may refer to the storage unit to obtain the fat percentage of the substance to be measured.

Further, the substance property measuring method of the present invention which achieves the above object, a detector for detecting a vibration of a substance to be measured to obtain a signal representing the vibration, and an amplifier for amplifying the signal obtained by the detector. A resonance circuit including an amplifier and an exciter that excites the substance to be measured with a signal amplified by the amplifier is used, and the substance to be measured is placed between the exciter and the detector of the resonance circuit. It is characterized in that a resonance signal is obtained through the interposition and the characteristic of the substance to be measured is obtained based on the resonance frequency of the resonance signal.

Here, in the method for measuring material properties of the present invention,
All aspects corresponding to the various aspects of the above-mentioned material property measuring apparatus of the present invention are included.

That is, the material property measuring method of the present invention is
The speed of sound in the substance to be measured may be determined, or the thickness of the substance to be measured may be determined. Furthermore, the material property measuring method of the present invention, the resonance frequency of the resonance signal on the resonance circuit or the relationship between the sound velocity obtained from the resonance frequency and the strength of the measured substance is obtained in advance, and the relationship is referred to. The strength of the substance to be measured may be obtained, and the relation between the resonance frequency of the resonance signal on the resonance circuit or the sound velocity obtained from the resonance frequency and the moisture content of the substance to be measured is obtained in advance, and the relation is referred to. The moisture content of the substance to be measured may be calculated,
Alternatively, the relation between the resonance frequency of the resonance signal on the resonance circuit or the sound velocity obtained from the resonance frequency and the fat percentage of the substance to be measured is obtained in advance, and the fat percentage of the substance to be measured is obtained by referring to the relation. Good.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION In the following, first, theoretical consideration will be given to sound waves in a substance, and then embodiments of the present invention will be described.

[0015] The sound waves have transverse wave, each of the propagation velocity V _P, V _S Accordingly, different depending on the material is V _P and V _S in a material (raw materials and water, impurities, the presence or absence of cracks) . If an object of finite size is vibrated, V _P and V _S are generally
Becomes a mixed wave, and the analysis of the propagation velocity is very complicated.
Therefore, if V _P and V _S of the object can be individually measured without vibrating the object, the characteristics such as the physical quantity or the physical property of the measurement target can be accurately analyzed and determined.

Young's modulus E is a physical quantity representing the strength of an object.
Where ρ is the density and σ is the Poisson's ratio, there is the following relationship with the propagation velocity of the sound wave propagating in the object.

[0017]

[Equation 1]

Α and β are expressed by Poisson's ratio,
It is a constant determined by the material.

On the other hand, if the density of the substance is constant, the strength increases as the Young's modulus E increases, so √ (E / ρ)
Determines the strength of the material. (1)-(2)
The formula shows that the higher the propagation speed, the greater the strength (hardness) of the substance, and conversely, the slower the propagation speed when the water content in the substance is large or the hardness is insufficient. .

The propagation velocity of a sound wave is defined as follows: where the distance between the exciter and the detector is L, the longitudinal fundamental resonance frequency is f _P , and the transverse fundamental resonance frequency is f _S. When the vibration is in phase (that is, when the vibration of the exciter is outward, the vibration of the detector is also outward), if the exciter and the detector are perpendicular to the ground, then V _P = f _P · L (3) V _S = f _S · L (4)

The feature of the present invention is that the resonance fundamental frequency f of the longitudinal wave is
_P and the resonant fundamental frequency f _S of the transverse wave are measured separately and accurately,
The purpose is to determine the propagation velocity of each from the equations (3) to (4) and determine the strength and hardness of the substance. Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of the entire material property measuring apparatus according to the first embodiment of the present invention.

The material property measuring apparatus 10 shown in FIG.
The resonance circuit 20, the signal processing unit 30, a personal computer 40, and a printer 50 are further provided.

The resonance circuit 20 is composed of a detector 21, a vibrator 23, and an amplifier 22, which are arranged with the substance to be measured 1 interposed.

The detector 21 detects the vibration of the substance 1 to be measured and obtains a signal representing the vibration, and a small microphone or an acceleration pickup is used. The signal obtained by the detector 21 is input to the amplifier 22. The amplifier 22 includes a preamplifier 221, a buffer amplifier 222, and an output amplifier 223. The signal input from the detector 21 to the amplifier 22 is a preamplifier 221, a buffer amplifier 222, and an output amplifier 2.
It is amplified by 23 and applied to the vibrator 23. Shaker 23
Has a role of vibrating the substance to be measured 1 with the signal amplified by the amplifier 22, and a small speaker or a piezoelectric element is used.

In the resonance circuit 20, when the substance to be measured 1 is interposed between the detector 21 and the vibration exciter 23, the substance to be measured 1 is generated spontaneously or by applying some vibration stimulus to the substance to be measured 1. The substance to be measured 1 is placed on the resonance circuit 20.
A resonance signal having a resonance frequency according to various characteristics of the is generated. The substance to be measured 1 placed between the detector 21 and the vibrator 23 behaves as if it were one circuit element, and the closed system as a whole constitutes a positive feedback circuit. The frequency of the output amplifier 223 includes many frequency components such as white noise. If the output of the output amplifier 223 is gradually increased, the strength / solidity of the measured substance 1, moisture content, fat content, etc. Resonance occurs at a frequency corresponding to the physical characteristics.

The output signal of the buffer amplifier 222 is also transmitted to the signal processing section 30, and the resonance frequency is analyzed in the signal processing section 30 to evaluate the substance 1 to be measured.

The evaluation result of the substance 1 to be measured in the signal processing unit 30 is input to the personal computer 40 and stored as data in the personal computer,
If necessary, the printer 50 connected to the computer 40 prints out the stored data.

FIG. 2 is a block diagram showing the configuration of the signal processing unit 30 shown by one block in FIG.

From the resonance circuit 20 of FIG. 1 to the signal processing unit 3
The resonance signal input to 0 is input to the frequency counter 31, and the frequency counter measures the resonance frequency of the resonance signal by counting the number of pulses of the resonance signal.

The count value representing the resonance frequency obtained by the frequency counter 31 is input to the CPU 32 and its CP
At U32, the speed of sound in the substance to be measured 1 is obtained from the count value. In the memory 33, each correspondence relationship (each calibration curve) between the sound velocity of the substance to be measured 1 and the characteristics of the substance to be measured, for example, strength (firmness), thickness, moisture content, fat content, and the like. Is stored, and CPU3
In step 2, after obtaining the sound velocity, the target characteristic of the substance 1 to be measured is obtained by referring to the correspondence table in the memory 33. The memory 33 stores the correspondence between the count value of the resonance frequency (frequency counter 31) and the material property, instead of the correspondence between the sound velocity and the material property.
In 32, the material characteristic may be directly obtained from the count value without converting the count value of the frequency counter 31 into the sound velocity.

The measurement data representing the characteristics of the substance 1 to be measured, obtained as described above, is displayed on the display 34, and the measurement data is transferred to the personal computer 40 via the interface 35. The measurement data is accumulated. Here, as the data transfer interface 35, for example, RS232C, GP-
IB, USB device, etc. are used.

FIG. 3 is a block diagram showing a resonance circuit portion of the material property measuring apparatus according to the second embodiment of the present invention.

Circuit elements corresponding to those of the first embodiment shown in FIG. 1 are designated by the same reference numerals as those used in FIG. 1, and the differences will be described.

The detector 21 and the vibrator 23 enter the cylindrical cases 211 and 231 whose mutual distances are kept constant, and are embedded in the substance 1 to be measured. Tubular cases 211,2
31 has a tip 211a, 231a that is tapered, and has a structure that easily enters the substance to be measured 1.
The vibration direction A represents the longitudinal wave of the sound wave, and the vibration direction B represents the transverse wave of the sound wave.

In this embodiment, the detector 21 is provided with both an acceleration pickup for detecting acceleration in the vibration direction of longitudinal waves and an acceleration pickup for detecting acceleration in the vibration direction of transverse waves. The transverse wave can be detected separately. By separating the longitudinal wave component and the transverse wave component in this manner, accurate measurement can be performed. Since the averaged longitudinal and transverse waves of the substance to be measured 1 between the detector 21 and the vibrator 23 are to be measured, there is a feature that even if there is some foreign matter, the measurement is not hindered. ing.

FIG. 4 is an explanatory diagram of a method of separating the resonance frequency (signal) from the noise.

The fundamental wave 61 and the higher harmonic waves 62 and 63 of the resonance frequency f ₀ and the low frequency noise 64 and the high frequency noise 65 generated by the sneak are separated by providing the band pass filter 70.

FIG. 5 is a correlation diagram between the degree of compaction of the ground and the resonance frequency.

FIG. 5 shows the resonance circuit 2 having the structure shown in FIG.
The sound velocity when measuring the sound velocity of the ground by using the material property measuring apparatus having the value 0 as an embodiment of the present invention (horizontal axis)
FIG. 3 is a correlation diagram between the compaction degree of the ground and the compaction degree (vertical axis) when the compaction degree of the ground is measured by a surface RI density moisture meter.

If the resonance frequency is high (if the speed of sound is high)
The degree of compaction of the ground becomes large, and conversely, when the amount of water in the ground is large or the soil is not sufficiently compacted, the resonance frequency becomes low (the sound velocity becomes slow), which is a clear correlation.

Based on such a correlation, data representing the resonance frequency or sound velocity measured by the material property measuring apparatus 10 to which the present invention is applied, and data obtained by a reference measuring apparatus, for example, an RI density / moisture meter. And a calibration curve is created in advance. This calibration curve is stored in the memory 3 of the signal processing unit 30.
3 (see FIG. 2) and can be used to measure the degree of compaction of the ground using average soil. In order to measure with even higher accuracy, it is sufficient to measure in advance with the material property measuring apparatus of the present invention during test construction, and create a correction calibration curve separately based on the consolidation test data.

In addition, GPS (Global Position)
If a satellite receiver for an ionizing system) is connected to the personal computer 40 via the interface 35 (see FIG. 2), it is possible to acquire sound position data and position information data at the same time.

In the personal computer 40, it is possible to plot sound velocity data on the Z axis and position information data on the XY axes to create a three-dimensional graphic image. In this way, the ground management data can be provided as visual information.

FIG. 6 is a block diagram of a material property measuring apparatus according to the third embodiment of the present invention. The above first and second
Differences from the embodiment will be described.

In the third embodiment shown in FIG. 6, the amplifier 22 and the signal processing section 30 of the resonance circuit 20 are the same as those in the first and second embodiments. In the third embodiment,
This is a device in which the detector 21 and the vibration exciter 23 are arranged toward the substance to be measured 1 and the sound velocity therebetween is measured.

As described above, when the detector 21 and the vibrator 23 are arranged toward the substance to be measured and the output of the output amplifier 223 is gradually increased, resonance occurs between the detector 21 and the vibrator 23. Occur. The resonance frequency can be measured, and the sound velocity can be measured from the distance between the detector 21 and the vibrator 23.

Once the speed of sound of the substance to be measured is obtained, physical properties such as strength and hardness or water content and fat percentage of the substance to be measured are measured by the speed of sound as in the case of the first and second embodiments. It is possible. In the case of the third embodiment, it is not necessary to puncture the substance to be measured with the detector 21 and the vibrator 23, and the shape of the measuring device and the preparation for the measurement are very simple.

FIG. 7 shows the sound velocity (horizontal axis) and T when the sound velocity of the ground is measured by using the material property measuring apparatus as one embodiment of the present invention having the resonance circuit 20 having the configuration shown in FIG.
It is a correlation diagram with the content rate when measuring the water content of the ground with the soil moisture meter by the DR method. There is a correlation that when the water content of the ground is low, the resonance frequency is high (the sound speed is high), and conversely, when the water content of the ground is high, the resonance frequency is low (the sound speed is slow).

Although the above-described first to third embodiments have been described here, the present invention is not limited to these embodiments, and various modifications may be made without departing from the spirit of the invention. Is possible.

[0051]

As described above, according to the present invention,
Even a substance with large attenuation can accurately measure the sound velocity of the substance, and the sound velocity can be used to accurately measure the properties of the substance such as the strength, hardness, and thickness of the substance, or the water content and the fat percentage. can do. The device can be small and lightweight, and the operability is greatly improved. INDUSTRIAL APPLICABILITY The present invention can contribute to improving the quality of civil engineering work as a whole and reducing the cost of civil engineering work in Japan. Further, it is possible to meet various industrial demands for easily measuring the water content and the fat percentage on site.

[Brief description of drawings]

FIG. 1 is a block diagram of an entire material property measuring apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a signal processing unit shown by one block in FIG.

FIG. 3 is a block diagram showing a resonance circuit portion of a material property measuring apparatus according to a second embodiment of the present invention.

FIG. 4 is an explanatory diagram of a method of separating a resonance frequency (signal) and noise.

[Fig. 5] Sound velocity when the sound velocity of the ground is measured (horizontal axis)
FIG. 3 is a correlation diagram between the compaction degree of the ground and the compaction degree (vertical axis) when the compaction degree of the ground is measured by a surface RI density moisture meter.

FIG. 6 is a block diagram of a material property measuring apparatus according to a third embodiment of the present invention.

[Fig. 7] Sound velocity when the sound velocity of the ground is measured (horizontal axis)
FIG. 4 is a correlation diagram with the water content when the water content of the ground is measured with a soil moisture meter by the TDR method.

[Explanation of symbols]

1 Substance to be measured 10 Material property measuring device 20 resonance circuit 21 detector 22 Amplifier 23 shaker 30 signal processor 31 frequency counter 32 CPU 33 memory 34 Display 35 Interface 40 personal computer 50 printers 221 Preamplifier 222 buffer amplifier 223 output amplifier

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Sohei Kawabata             40, 1-2-1, Takamori, Izumi-ku, Sendai City, Miyagi Prefecture             21st Century Plaza IT Re Co., Ltd.             Within the search (72) Inventor Sanbe Masuichi             40, 1-2-1, Takamori, Izumi-ku, Sendai City, Miyagi Prefecture             21st Century Plaza IT Re Co., Ltd.             Within the search (72) Inventor Hideki Takahashi             1-7-22 Miyagino, Miyagino-ku, Sendai City, Miyagi Prefecture               Business Support System Co., Ltd.             Within (72) Inventor Yoshiyasu Matsumura             5-9-10 Nagamachi, Taihaku-ku, Sendai City, Miyagi Prefecture             1003 F term (reference) 2G047 AA10 AB05 BA04 BC02 BC04                       BC15 CA01 CA03 CA07 CB01                       CB02 EA10 EA14 GD02 GG20                       GG33 GJ21                 2G064 AB05 BA02 BA23

Claims (7)

[Claims] 1. A detector for detecting a vibration of a substance to be measured to obtain a signal representing the vibration, an amplifier for amplifying a signal obtained by the detector, and a signal after being amplified by the amplifier. A resonance circuit that includes a vibrating device that vibrates a measurement substance, obtains a resonance signal by interposing the measurement substance between the vibration device and the detector, and a resonance frequency of the resonance signal on the resonance circuit. A material property measuring apparatus comprising a signal processing unit for determining the property of the material to be measured based on the above. 2. The substance characteristic measuring apparatus according to claim 1, wherein the signal processing unit obtains a sound velocity in the substance to be measured. 3. The substance characteristic measuring apparatus according to claim 1, wherein the signal processing unit obtains a thickness of the substance to be measured. 4. A storage unit for storing the relationship between the resonance frequency of the resonance signal on the resonance circuit or the speed of sound obtained from the resonance frequency and the strength of the substance to be measured, wherein the signal processing unit comprises: The strength of the substance to be measured is obtained by referring to a storage unit.
The described material property measuring apparatus. 5. A storage unit for storing the resonance frequency of the resonance signal on the resonance circuit or the relationship between the sound velocity obtained from the resonance frequency and the moisture content of the substance to be measured, the signal processing unit comprising: The substance property measuring apparatus according to claim 1, wherein the moisture content of the substance to be measured is obtained by referring to the storage unit. 6. A resonance frequency of a resonance signal on the resonance circuit or a storage section for storing a relationship between a sound velocity obtained from the resonance frequency and a fat percentage of the substance to be measured, the signal processing section comprising: The substance property measuring apparatus according to claim 1, wherein the fat content of the substance to be measured is obtained by referring to the storage unit. 7. A detector for detecting a vibration of a substance to be measured to obtain a signal representing the vibration, an amplifier for amplifying the signal obtained by the detector, and a signal after being amplified by the amplifier. A resonance circuit including a vibration exciter for vibrating a substance to be measured is used to obtain a resonance signal by interposing a substance to be measured between the vibration exciter and the detector of the resonance circuit. The material property measuring method, wherein the property of the material to be measured is obtained based on the resonance frequency of the resonance signal.