JP5507267B2 - Method and apparatus for calculating thickness of damping material - Google Patents

Description

  The present invention relates to a method and apparatus for calculating the thickness of an attenuation material used in a composite structure.

  In general, when measuring the thickness of a steel material, a probe that oscillates ultrasonic waves and a processing device that processes data from the probe are used. A probe is placed on the base plate, an ultrasonic wave of several MHz is oscillated, a bottom reflection echo reflected from the bottom surface of the steel material is obtained, and various analyzes are performed to measure the thickness of the steel material (for example, Patent Documents) 1 and 2).

  In addition, there are specific devices and devices that use a composite structure in which a metal material such as steel and a damping material such as resin are laminated. When such devices and devices are used or operated Is required to observe the wear of the damping material by appropriately measuring the thickness of the damping material.

JP-A-7-198362 JP 2004-163250 A

  However, when measuring the thickness of an attenuation material by oscillating several MHz ultrasonic waves to a composite structure including a metal material and an attenuation material, the reflection echo becomes multiple reflections due to the metal material, and low There is a problem that the ultrasonic wave is greatly attenuated by the density attenuation material, and the reflection echo of the attenuation material cannot be acquired appropriately.

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide a damping material thickness calculation method and apparatus capable of appropriately measuring the thickness of the damping material used in the composite structure. And

According to the attenuation material thickness calculation method of the present invention, ultrasonic waves are oscillated from the metal material by an ultrasonic probe to a composite structure including the metal material and the attenuation material, and a reflection echo from the composite structure is used. A method for calculating the thickness of the damping material by measuring the thickness of the damping material,
The frequency of the ultrasonic wave oscillated from the ultrasonic probe is made lower than the frequency at which multiple reflection from the metal material is reduced,
When measuring the thickness of the damping material, wavelet analysis is performed on the reflected echo signal from the ultrasonic wave to extract the specific frequency component, and the correlation between the multiple thicknesses of the damping material and the signal at the specific frequency component is calculated. Correlation data to be shown is prepared in advance, and a signal at a specific frequency component is converted from the correlation data into the thickness of the attenuation material to calculate the thickness of the attenuation material.

According to the attenuation material thickness calculation method of the present invention, ultrasonic waves are oscillated from the metal material by an ultrasonic probe to a composite structure including the metal material and the attenuation material, and a reflection echo from the composite structure is used. A method for calculating the thickness of the damping material by measuring the thickness of the damping material,
The frequency of the ultrasonic wave oscillated from the ultrasonic probe is set to be equal to or lower than the frequency at which the multiple reflection from the metal material is reduced, and the frequency f (Hz) of the ultrasonic wave oscillated from the ultrasonic probe is reduced.
f ≦ v / 8T
v: Sound velocity of metal material (m / s)
T: Metal material thickness (m)
In the condition of
When measuring the thickness of the attenuation material, wavelet analysis is performed on the reflected echo signal from the ultrasonic wave to extract a specific frequency component, and the thickness of the attenuation material is calculated based on the signal at the specific frequency component. It is.

  In the damping material thickness calculation method of the present invention, it is preferable to monitor the thickness reduction of the damping material by measuring the thickness of the damping material over time.

An attenuation material thickness calculation apparatus according to the present invention includes an ultrasonic probe that transmits ultrasonic waves from a metal material to a composite structure including a metal material and an attenuation material, and a signal from the ultrasonic probe. A damping material thickness calculation device comprising: a signal calculation unit that processes the data; and a thickness calculation unit that processes data from the signal calculation unit,
The ultrasonic probe oscillates an ultrasonic wave at a frequency equal to or lower than a frequency at which multiple reflection from a metal material is reduced,
The signal calculation unit, when measuring the thickness of the attenuation material, wavelet analysis of the reflected echo signal by the ultrasonic wave, to extract a specific frequency component,
The wall thickness calculation unit includes correlation data indicating a correlation between a plurality of wall thicknesses of the attenuation material and a signal at a specific frequency component in advance, and the signal at the specific frequency component is converted from the correlation data to the wall thickness of the attenuation material. The thickness of the damping material is calculated in terms of conversion .

An attenuation material thickness calculation apparatus according to the present invention includes an ultrasonic probe that transmits ultrasonic waves from a metal material to a composite structure including a metal material and an attenuation material, and a signal from the ultrasonic probe. A damping material thickness calculation device comprising: a signal calculation unit that processes the data; and a thickness calculation unit that processes data from the signal calculation unit,
The ultrasonic probe oscillates an ultrasonic wave at a frequency equal to or lower than a frequency at which multiple reflection from a metal material is reduced, and sets a frequency f (Hz) of the oscillating ultrasonic wave.
f ≦ v / 8T
v: Sound velocity of metal material (m / s)
T: Metal material thickness (m)
In the condition of
The signal calculation unit, when measuring the thickness of the attenuation material, wavelet analysis of the reflected echo signal by the ultrasonic wave, to extract a specific frequency component,
The wall thickness calculation unit is configured to calculate the wall thickness of the damping material based on a signal with a specific frequency component.

  In the damping material thickness calculation apparatus according to the present invention, it is preferable that the thickness calculation unit is configured to monitor the thickness reduction of the damping material by measuring the thickness of the damping material over time.

  According to the attenuation thickness calculation method and apparatus of the present invention, the frequency of the ultrasonic wave oscillated from the ultrasonic probe is controlled to reduce multiple reflections from the metal material, and the attenuation material has a low density. Since the reflection echo of the attenuation material is acquired by suppressing the attenuation of the ultrasonic wave, and the specific echo component is extracted by wavelet analysis of the reflected echo signal, the thickness of the attenuation material used in the composite structure is measured appropriately. can do. Further, even when the S / N ratio decreases due to the frequency of the ultrasonic wave being reduced to a frequency that reduces the multiple reflection from the metal material, a specific frequency component having a strong frequency component can be extracted by wavelet analysis. It is possible to obtain an excellent effect that the thickness of the damping material can be appropriately measured by improving the ratio.

It is a block conceptual diagram which shows the example of a form of this invention. It shows the ultrasonic original signal, the wavelet transform result, and the extraction result of the specific frequency component in the composite structure of the steel plate and the rubber plate. It is a graph of the correlation data which shows the correlation with the thickness of the damping material of a rubber material, and peak time. It is a graph which shows the data output of implementation at the time of monitoring the thinning of a damping material. It is a graph for selecting the upper limit of the frequency of an ultrasonic wave. It is another graph for selecting the upper limit of the frequency of an ultrasonic wave. It is a graph for selecting the lower limit of the frequency of an ultrasonic wave. It is another graph for selecting the lower limit of the frequency of an ultrasonic wave.

  DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a damping material thickness calculation method and apparatus according to the present invention will be described below with reference to FIGS.

The method and apparatus for calculating the thickness of the damping material according to the embodiment is applied to the composite structure 3 in which the metal material 1 and the damping material 2 are laminated. The metal material 1 is a material such as a steel material or an aluminum material. And a density of 2.0 [g / cm ³ ] or more and 22.0 [g / cm ³ ] or less. The damping material 2 is made of rubber, plastic, or other non-metallic material having a density of 0.1 [g / cm ³ ] or more and 3.0 [g / cm ³ ] or less. Compared to 1, the attenuation rate of the ultrasonic waves for flaw detection is high.

  The attenuation-material thickness calculation apparatus includes a transmitting-side ultrasonic probe 4a that oscillates ultrasonic waves, a receiving-side ultrasonic probe 4b that receives reflected echoes, and a transmitting-side ultrasonic probe 4a. And the ultrasonic transmitter / receiver 5 connected to the ultrasonic probe 4b on the receiving side, the signal sampling unit 6 connected to the ultrasonic transmitter / receiver 5, and the signal calculation connected to the signal sampling unit 6 to process signals A thickness calculating unit (thinning amount calculating unit) 8 connected to the signal calculating unit 7 for processing data, and a signal storing unit 9 connected to the thickness calculating unit 8 for storing signals such as data. And. Here, the ultrasonic probe 4a on the transmission side and the ultrasonic probe 4b on the reception side may be constituted by one ultrasonic probe. The ultrasonic transmitter / receiver 5 may be configured by a pulsar receiver or a burst wave generator. Furthermore, the ultrasonic transmitter / receiver 5, the signal sampling unit 6, the signal calculation unit 7, the thickness calculation unit 8, and the signal storage unit 9 may be integrally configured by a processing unit such as a PC, or may be configured separately. It may also be configured in various parts. Further, the attenuation-material thickness calculation device may include a display unit for displaying each data.

The ultrasonic probe 4a on the transmission side and the ultrasonic probe 4b on the reception side are arranged on the surface of the metal material 1 such as a steel material at a predetermined interval. Here, the ultrasonic probe 4a on the transmission side sets the frequency f (Hz) of the oscillating ultrasonic wave to f ≦ (v / 8T)
v: Sound velocity of metal material (m / s)
T: Metal material thickness (m)
More specifically, the frequency of the oscillating ultrasonic wave is 20 kHz to 500 kHz, preferably 40 kHz to 200 kHz. Further, the material sound speed and thickness of the metal material 1 are not particularly limited as long as the above equation is followed. A range of 3000 m / s to 8000 m / s and a thickness of 2 mm to 10 mm are preferable. Moreover, the material sound velocity of the damping material 2 is preferably in the range of 1000 m / s to 3000 m / s, and the thickness is preferably in the range of 5 mm to 100 mm.

  The ultrasonic transmitter / receiver 5 is configured to receive a reflected echo as a waveform by the ultrasonic probe 4b on the receiving side, and the signal sampling unit 6 converts the waveform from the ultrasonic transmitter / receiver 5 into a digital signal. It is supposed to convert.

  The signal calculation unit 7 includes a time frequency analysis unit and a specific frequency extraction unit, and acquires a specific frequency component by performing signal extraction and wavelet analysis on the signal from the signal sampling unit 6.

  The wall thickness calculation unit 8 includes in advance correlation data indicating a correlation between a plurality of wall thicknesses of the attenuation member 2 and a signal at a specific frequency component, and the signal at the specific frequency component is supplied from the correlation data to the attenuation member 2. It is to be converted to the wall thickness. Moreover, when observing the thinning of the damping material 2 of the composite structure 3, the thickness of the damping material 2 is measured every time.

  The signal storage unit 9 stores all data used in the wall thickness calculation unit 8. As the data stored here, only desired data such as the thickness of the damping material 2 and the thickness reduction of the damping material 2 may be stored, or the data values of the respective processes may be stored. .

  Hereinafter, the operation of the embodiment for carrying out the damping thickness calculation method and apparatus according to the present invention will be described.

  When measuring the thickness of the attenuation member 2 of the composite structure 3, the transmitting-side ultrasonic probe 4a and the receiving-side ultrasonic probe 4b are arranged on the surface of the metal material 1, and the transmitting-side ultrasonic probe 4b is arranged. An ultrasonic wave is oscillated from the ultrasonic probe 4a, and a reflected echo is received by the ultrasonic probe 4b on the receiving side.

  Next, the reflected echo from the ultrasonic probe 4 b on the receiving side is received as a waveform by the ultrasonic transmitter / receiver 5, converted into a digital signal via the signal sampling unit 6, and transmitted to the signal calculation unit 7.

  Subsequently, the signal calculation unit 7 performs signal extraction and wavelet analysis on the signal from the signal sampling unit 6 to acquire a specific frequency component. Here, the wavelet analysis is to obtain a specific frequency component by a wavelet function without losing time domain information in a wide frequency domain.

  The thickness calculator 8 calculates the thickness of the damping material 2 by converting the signal at the specific frequency component into the thickness of the damping material 2 from the correlation data prepared in advance. Further, when observing the thinning of the damping material 2 of the composite structure 3, the thickness of the damping material 2 is measured every time and the thinning data of the damping material 2 is observed.

[Test 1]
Hereinafter, a specific example of measuring the thickness and thickness reduction of the damping material will be shown. In one example, a composite structure made of a steel plate and a rubber plate is used, and the composite structure has a thickness of 4 mm and a thickness of three types of rubber plates of 50 mm, 30 mm, and 15 mm. I prepared something. The excitation on the transmitting-side ultrasonic probe 4a and the receiving-side ultrasonic probe 4b was a rectangular wave having a frequency of 110 KHz, 80 V, and one cycle.

  As a result, the upper part of FIG. 2 shows the respective ultrasonic original signals having a rubber thickness of 50 mm, a rubber thickness of 30 mm, and a rubber thickness of 15 mm. Here, in the original ultrasonic signal, the signal indicated by the arrow is a reflected signal from the back surface of the rubber plate via the steel plate, and the reflected signal (echo signal) has a wider wave width than the signals of other parts. It is clear that the frequency is low. Next, when performing continuous wavelet transform (CWT), the fourth-order signal of the Gauss function is processed as a mother wavelet. In the middle of FIG. 2, the horizontal axis represents time, the vertical axis represents frequency, and the intensity of frequency components. Shows the wavelet transform result with the brightness (color). Here, it is clear from the wavelet transform result that there is a strong frequency component in a predetermined range corresponding to the reflection signal from the back surface of the rubber plate. Subsequently, when extracting a specific frequency component from the wavelet transform result, a desired frequency (50 kHz in FIG. 2) is extracted from a predetermined range having a strong frequency component. The result of a frequency component is shown. From this result, when the ultrasonic original signal and the arrow portions of the specific frequency component are compared with each other, it is clear that the signal-to-noise ratio is improved in the wavelet transform processed signal compared with the ultrasonic original signal.

  Next, when the thickness of the rubber plate obtained from the specific frequency component of FIG. 2 and the peak time are plotted, as shown in FIG. 3, the thickness of the rubber plate (attenuating material) and the signal at the specific frequency component are plotted. Correlation data in which the correlation is located on a straight line can be obtained. Here, the correlation data is not created by plotting the thickness of the attenuation material and the peak time, but may be created by plotting the thickness of the attenuation material and the rise time of the peak. Alternatively, the time difference may be obtained by calculating the cross-correlation with the echo and the thickness of the damping material and the time difference may be plotted. Further, in the wall thickness calculation unit (thickness reduction calculation unit) 8 in FIG. 1, various correlation data of the damping material are input in advance before measuring the thickness and thickness reduction of the damping material. Correlation data may be changed according to the above.

  Subsequently, when measuring the thickness of an attenuation material such as a rubber plate, the ultrasonic original signal is wavelet transformed to obtain a signal such as a peak time at a specific frequency component, and from the correlation data, A signal such as a peak time is converted into a thickness of the attenuation material to calculate the thickness of the attenuation material. On the other hand, when measuring the thickness reduction of the damping material due to wear or burnout in the damping material of the composite structure, the thickness of the damping material is measured over time by performing the same processing, and FIG. As shown, it is possible to monitor the amount of thinning of the damping material.

[Selection example 1]
Hereinafter, a first example of frequency selection is shown so that the frequency oscillated from the ultrasonic probe can be specified. The signal sampling pitch Δt (s) when the sampling frequency of the ultrasonic signal is Fs (Hz) is Δt = 1 / Fs.
The resolution Δd (m) of the thinning measurement at this time is defined as v (m / s) as the sound velocity of the material.
Δd = vΔt / 2 = v / (2Fs)
Fs = v / (2Δd)
It becomes. Since the sampling frequency for signal processing is generally 10 times or more the frequency to be analyzed,
f <v / (20Δdr)
It is necessary to measure at a frequency of. (Δdr: required resolution (m))
Therefore, as an example, the sampling frequency can be selected based on f <v / (20Δdr).

[Selection example 2]
Hereinafter, a second example of frequency selection is shown so that the upper limit value of the frequency oscillated from the ultrasonic probe can be specified. In the second example, a composite structure made of a steel plate and a rubber plate is used, and the composite structure is a steel plate having a thickness of 4 mm. Further, the sound pressure reflectance at the boundary surface between the steel plate and the rubber plate was set to 0.87, and the frequency was changed and measured. In this selection example and the embodiment, only the acoustic impedance of the metal material and the attenuation material is considered, and it does not depend on the thickness of the attenuation material.
As a result, as shown in FIG. 5, at a frequency of 500 kHz or higher, multiple reflections on the steel sheet were observed, making it difficult to apply to thickness measurement of the damping material and monitoring of thinning. On the other hand, at a frequency of 200 kHz or less, multiple reflection on the steel sheet occurs under the condition that the wavelength of the ultrasonic wave in the steel sheet is 29.6 mm or more and the wavelength (λ) / metal material thickness (T) is 7.4 or more. Reduced. From this, it is clear that when the upper limit value of the frequency is 200 kHz, it can be applied to the measurement of the thickness of the damping material and the monitoring of the thinning.

[Selection Example 3]
Hereinafter, a third example of frequency selection will be shown so that the upper limit value of the frequency oscillated from the ultrasonic probe can be specified. In the third example, a composite structure composed of a steel plate and a rubber plate is used, and the composite structure having a thickness of 3.7 mm is used. Further, the sound pressure reflectance at the boundary surface between the steel plate and the rubber plate was set to 0.87, and the frequency was changed and measured. Similarly, in this selection example, only the acoustic impedance of the metal material and the attenuation material is considered, and it does not depend on the thickness of the attenuation material.
As a result, at a frequency of 500 kHz or more as shown in FIG. 6, multiple reflections on the steel plate were observed as in the second example, making it difficult to apply to thickness measurement of the damping material and monitoring of thinning. On the other hand, at a frequency of 200 kHz or less, multiple reflection on the steel sheet is reduced under the condition that the wavelength of the ultrasonic wave in the steel sheet is 29.6 mm or more and the wavelength (λ) / metal material thickness (T) is 8 or more. It was. From this, it is clear that when the upper limit value of the frequency is 200 kHz, it can be applied to the measurement of the thickness of the damping material and the monitoring of the thinning.

Further, since λ / T is 8 at 200 kHz, it is necessary to select a frequency at which λ / T is 8 or more.
λ / T ≧ 8
Here, λ is the wavelength of ultrasonic waves in the metal material (= sound velocity (v (m / s)) / frequency (f (Hz))), and T is the thickness (m) of the metal material.
That is,
v / (fT) ≧ 8
f ≦ v / (8T)
It is preferable to measure at a frequency of.

[Selection Example 4]
Hereinafter, a fourth example of frequency selection is shown so that the lower limit value of the oscillating frequency can be specified. In the fourth example, a convolution of echoes (corresponding to a standard value of about 50 mm as the sound speed of the material 1800 m / s) at a frequency of 200 kHz and 40 kHz is calculated. As a result, when the frequency is 200 kHz and the frequency is 40 kHz, the peak exists at the position of 55 μs. In the case of a frequency of 200 kHz, if the error is in the range of 99% of the peak, the width is ± 0.1 μs as shown in FIG. 7, resulting in an error of 0.2%. Further, in the case of a frequency of 40 kHz, if the error is set to a height range of 99% of the peak, the width is similarly ± 0.5 μs as shown in FIG. 8, resulting in an error of 0.9%. Therefore, in order to suppress the error to 2%, it is preferable to analyze a frequency component of 20 kHz or more.

  As described above, according to the attenuation material thickness calculation method and apparatus of the embodiment, multiple reflections from the metal material 1 by controlling the frequency of the ultrasonic wave oscillated from the ultrasonic probe 4a on the transmission side. In addition, the attenuation of ultrasonic waves by the low-density attenuation material 2 is suppressed, the reflection echo of the attenuation material 2 is acquired, and the signal of the reflection echo is further wavelet analyzed to extract a specific frequency component. The thickness of the damping material 2 used for the body 3 can be appropriately measured.

  In addition, even when the SN ratio is reduced due to the frequency of the ultrasonic wave being reduced to a frequency that reduces multiple reflections from the metal material 1, a specific frequency component having a strong frequency component can be extracted by wavelet analysis. The SN ratio can be improved and the thickness of the damping material 2 can be measured more appropriately.

  In the damping material thickness calculation method and apparatus according to the embodiment, correlation data indicating a correlation between a plurality of thicknesses of the damping material 2 and a signal at a specific frequency component is prepared in advance and specified from the correlation data. Since the signal of the frequency component is converted into the thickness of the attenuation member 2 and the thickness of the attenuation member 2 is calculated, the thickness of the attenuation member 2 can be suitably measured from the signal of the specific frequency component.

  In the method and apparatus for calculating the thickness of the damping material according to the embodiment, the thickness of the damping material 2 is measured every time and the thinning of the damping material 2 is monitored. Therefore, not only the thickness of the damping material 2 but also the thickness reduction of the damping material 2 can be monitored appropriately. When solid fuel is used as the damping material, the consumption of fixed fuel can be continuously monitored.

In the attenuation member thickness calculation method and apparatus according to the embodiment, the frequency f (Hz) of the ultrasonic wave oscillated from the ultrasonic probe 4a on the transmission side is expressed as f ≦ v / 8T.
v: Sound velocity of metal material (m / s)
T: Metal material thickness (m)
With this condition, the reflection echo of the attenuation material 2 is appropriately acquired while suppressing the double reflection on the metal material 1, so that the thickness of the attenuation material 2 can be measured appropriately.

  In the thickness calculation method and apparatus of the attenuation member 2 of the embodiment, when the frequency of the ultrasonic wave oscillated from the ultrasonic probe 4a on the reception side is set to 20 kHz or more and 500 kHz or less, overlapping reflection on the metal material 1 is caused. Since the reflection echo of the attenuation material 2 is appropriately acquired by suppressing the thickness, the thickness of the attenuation material 2 can be suitably measured. In addition, when the frequency of the ultrasonic wave oscillated from the ultrasonic probe 4a on the receiving side is set to 40 kHz or more and 200 kHz or less, the reflection echo of the attenuation material 2 is acquired more appropriately, so that the thickness of the attenuation material 2 is measured extremely suitably. can do

  It is needless to say that the damping material thickness calculation method and apparatus according to the present invention can be variously modified without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Metal material 2 Attenuating material 3 Composite structure 4a Ultrasonic probe 4b Ultrasonic probe 7 Signal calculation part 8 Thickness calculation part (thickness reduction calculation part)

Claims (6)

An attenuating material that oscillates ultrasonic waves from the metal material with a ultrasonic probe to a composite structure including a metal material and an attenuation material, and measures the thickness of the attenuation material using a reflection echo from the composite structure. A thickness calculation method,
The frequency of the ultrasonic wave oscillated from the ultrasonic probe is made lower than the frequency at which multiple reflection from the metal material is reduced,
When measuring the thickness of the damping material, wavelet analysis is performed on the reflected echo signal from the ultrasonic wave to extract the specific frequency component, and the correlation between the multiple thicknesses of the damping material and the signal at the specific frequency component is calculated. Correlation data to be shown is prepared in advance, and from the correlation data, a signal at a specific frequency component is converted to the thickness of the attenuation material to calculate the thickness of the attenuation material. An attenuating material that oscillates ultrasonic waves from the metal material with a ultrasonic probe to a composite structure including a metal material and an attenuation material, and measures the thickness of the attenuation material using a reflection echo from the composite structure. A thickness calculation method,
The frequency of the ultrasonic wave oscillated from the ultrasonic probe is set to be equal to or lower than the frequency at which the multiple reflection from the metal material is reduced, and the frequency f (Hz) of the ultrasonic wave oscillated from the ultrasonic probe is reduced.
f ≦ v / 8T
v: Sound velocity of metal material (m / s)
T: Metal material thickness (m)
In the condition of
When measuring the thickness of the attenuation material, wavelet analysis is performed on the reflected echo signal from the ultrasonic wave to extract a specific frequency component, and the thickness of the attenuation material is calculated based on the signal at the specific frequency component. A method for calculating the thickness of a damping material characterized by the following.   3. The attenuation material thickness calculation method according to claim 1, wherein the thickness of the attenuation material is measured over time to monitor the thickness reduction of the attenuation material. An ultrasonic probe that transmits ultrasonic waves from the metal material to a composite structure including a metal material and an attenuation material, a signal calculation unit that processes a signal from the ultrasonic probe, and the signal calculation unit A thickness calculating device for a damping material, comprising a thickness calculating unit for processing data from
The ultrasonic probe oscillates an ultrasonic wave at a frequency equal to or lower than a frequency at which multiple reflection from a metal material is reduced,
The signal calculation unit, when measuring the thickness of the attenuation material, wavelet analysis of the reflected echo signal by the ultrasonic wave, to extract a specific frequency component,
The wall thickness calculation unit includes correlation data indicating a correlation between a plurality of wall thicknesses of the attenuation material and a signal at a specific frequency component in advance, and the signal at the specific frequency component is converted from the correlation data to the wall thickness of the attenuation material. A damping material thickness calculating apparatus characterized in that the thickness of the damping material is calculated by conversion . An ultrasonic probe that transmits ultrasonic waves from the metal material to a composite structure including a metal material and an attenuation material, a signal calculation unit that processes a signal from the ultrasonic probe, and the signal calculation unit A thickness calculating device for a damping material, comprising a thickness calculating unit for processing data from
The ultrasonic probe oscillates an ultrasonic wave at a frequency equal to or lower than a frequency at which multiple reflection from a metal material is reduced, and sets a frequency f (Hz) of the oscillating ultrasonic wave.
f ≦ v / 8T
v: Sound velocity of metal material (m / s)
T: Metal material thickness (m)
In the condition of
The signal calculation unit, when measuring the thickness of the attenuation material, wavelet analysis of the reflected echo signal by the ultrasonic wave, to extract a specific frequency component,
The thickness calculating unit of the attenuation material is configured to calculate the thickness of the attenuation material based on a signal with a specific frequency component. 6. The damping material according to claim 4, wherein the thickness calculation unit is configured to monitor the thickness reduction of the damping material by measuring the thickness of the damping material over time. Thickness calculation device.

Images