阅读说明：本技术 超声衰减系统的测量方法和测量装置 (Measuring method and measuring device for ultrasonic attenuation system ) 是由 张书增 张广栋 戴昭杰 李雄兵 于 2019-11-06 设计创作，主要内容包括：本发明公开了一种超声衰减系数的测量方法和测量装置,测量方法包括以下步骤：利用表面浸在水中的超声水浸探头向浸在水中的测试块发射超声波信号,其中,所述超声波信号为超声窄带脉冲正弦波信号；利用所述超声水浸探头接收所述超声波信号经所述测试块反射的回波信号；根据所述回波信号和所述超声波信号的频率计算所述测试块的超声衰减系数。该测量方法,通过超声水浸探头发射相应频率值的超声窄脉冲正弦波信号至测试块,测得该频率下测试块的超声衰减数系数,使得测得的超声衰减系数更加准确。(The invention discloses a measuring method and a measuring device of an ultrasonic attenuation coefficient, wherein the measuring method comprises the following steps: transmitting an ultrasonic signal to a test block immersed in water by using an ultrasonic water immersion probe with the surface immersed in water, wherein the ultrasonic signal is an ultrasonic narrow-band pulse sine wave signal; receiving an echo signal of the ultrasonic signal reflected by the test block by using the ultrasonic water immersion probe; and calculating the ultrasonic attenuation coefficient of the test block according to the frequencies of the echo signal and the ultrasonic signal. According to the measuring method, the ultrasonic narrow pulse sine wave signal with the corresponding frequency value is transmitted to the test block through the ultrasonic water immersion probe, and the ultrasonic attenuation coefficient of the test block under the frequency is measured, so that the measured ultrasonic attenuation coefficient is more accurate.)

1. A method for measuring an ultrasonic attenuation coefficient is characterized by comprising the following steps:

transmitting an ultrasonic signal to a test block immersed in water by using an ultrasonic water immersion probe with the surface immersed in water, wherein the ultrasonic signal is an ultrasonic narrow-band pulse sine wave signal;

receiving an echo signal of the ultrasonic signal reflected by the test block by using the ultrasonic water immersion probe;

and calculating the ultrasonic attenuation coefficient of the test block according to the frequencies of the echo signal and the ultrasonic signal.

2. The method of measuring an ultrasonic attenuation coefficient according to claim 1, wherein the echo signal includes a reflection signal of an upper surface of the test block and a reflection signal of a bottom surface of the test block, wherein the ultrasonic attenuation coefficient of the test block is calculated by the following formula:

wherein alpha is_L(f,2z) is the ultrasonic attenuation coefficient of the test block, f is the frequency of the ultrasonic signal, z is the thickness of the test block, d is the distance from the surface of the ultrasonic water immersion probe to the upper surface of the test block, S₁(f,2d) is a reflected signal of the upper surface of the test block, S₂(f,2D ') is a reflected signal from the bottom surface of the test block, D' is a propagation distance of the ultrasonic signal between the test block and water, D₁(f,2D) is a diffraction correction term for the ultrasonic signal as it propagates through the water, D₂(f,2d') is a diffraction correction term, T, of the ultrasonic signal as it propagates through the test block₁₂Is the transmission coefficient, T, of the ultrasonic signal when passing through the water interface₂₁Is the transmission coefficient, R, of the ultrasonic signal passing through the interface of the test block₂₁The reflection coefficient of the ultrasonic signal passing through the interface of the test block is shown.

3. The method for measuring the ultrasonic attenuation coefficient according to claim 1, wherein the surface of the ultrasonic water immersion probe is 20mm away from the upper surface of the test block, the test block is of a cuboid structure, and the measurement is carried outThe upper and lower surface areas of the test block are 50X 50mm²And the thickness of the test block is 20 mm.

4. The method of measuring an ultrasonic attenuation coefficient of claim 1, wherein the center frequency of the ultrasonic water immersion probe is 1MHz, 2.25MHz, or 5 MHz.

5. The method of measuring ultrasonic attenuation coefficient according to claim 4, wherein a plurality of ultrasonic signals of different frequencies are transmitted by one or more ultrasonic water immersion probes of different center frequencies, the method further comprising:

calculating to obtain a plurality of ultrasonic attenuation coefficients according to a plurality of different frequencies and corresponding echo signals;

and fitting the plurality of ultrasonic attenuation coefficients and the corresponding frequencies thereof to obtain an ultrasonic attenuation coefficient-frequency curve.

6. An ultrasonic attenuation coefficient measuring apparatus, comprising: the ultrasonic water immersion probe comprises an ultrasonic water immersion probe, a current probe, an amplifier, a function generator, an oscilloscope and an upper computer, wherein the surface of the ultrasonic water immersion probe is immersed in water, the current probe is respectively and electrically connected with the ultrasonic water immersion probe, the amplifier and the oscilloscope, the function generator is electrically connected with the amplifier, and the upper computer is electrically connected with the oscilloscope;

the ultrasonic water immersion probe transmits acquired echo signals reflected by the test block to the oscilloscope through the current probe for displaying on the oscilloscope, and the upper computer is used for acquiring the echo signals displayed by the oscilloscope and calculating the ultrasonic attenuation coefficient of the test block according to the echo signals and the frequency of the ultrasonic signals.

7. The apparatus of claim 6, wherein the echo signal includes a reflection signal of an upper surface of the test block and a reflection signal of a bottom surface of the test block, and the upper computer calculates the ultrasonic attenuation coefficient of the test block by the following formula:

wherein alpha is_L(f,2z) is the ultrasonic attenuation coefficient of the test block, f is the frequency of the ultrasonic signal, z is the thickness of the test block, d is the distance from the surface of the ultrasonic water immersion probe to the upper surface of the test block, S₁(f,2d) is a reflected signal of the upper surface of the test block, S₂(f,2D ') is a reflected signal from the bottom surface of the test block, D' is a propagation distance of the ultrasonic signal between the test block and water, D₁(f,2D) is a diffraction correction term for the ultrasonic signal as it propagates through the water, D₂(f,2d') is a diffraction correction term, T, of the ultrasonic signal as it propagates through the test block₁₂Is the transmission coefficient, T, of the ultrasonic signal when passing through the water interface₂₁Is the transmission coefficient, R, of the ultrasonic signal passing through the interface of the test block₂₁The reflection coefficient of the ultrasonic signal passing through the interface of the test block is shown.

8. The ultrasonic attenuation coefficient measuring device of claim 6, wherein the surface of the ultrasonic water immersion probe is 20mm away from the upper surface of the test block, the test block is of a cuboid structure, and the upper surface area and the lower surface area of the test block are both 50 x 50mm²And the thickness of the test block is 20 mm.

9. The apparatus for measuring ultrasonic attenuation coefficient of claim 6, wherein the center frequency of the ultrasonic water immersion probe is 1MHz, 2.25MHz or 5 MHz.

10. The apparatus for measuring ultrasonic attenuation coefficient according to claim 9, wherein the function generator is configured to output a plurality of narrow pulse sine wave signals with different frequencies, and transmit ultrasonic signals with corresponding frequencies by using an ultrasonic water immersion probe with corresponding center frequency, wherein the upper computer is further configured to obtain echo signals corresponding to the ultrasonic signals with different frequencies, calculate a plurality of ultrasonic attenuation coefficients according to the plurality of different frequencies and the corresponding echo signals, and perform fitting processing on the plurality of ultrasonic attenuation coefficients and the corresponding frequencies thereof to obtain an ultrasonic attenuation coefficient-frequency curve.

Technical Field

The invention relates to the technical field of ultrasound, in particular to a method and a device for measuring an ultrasonic attenuation coefficient.

Background

The attenuation coefficient is one of important parameters of material characteristics in ultrasonic application, so that the method is widely applied to quantitative nondestructive evaluation of microstructures such as material grain size, porosity and fatigue. The ultrasonic frequency domain attenuation coefficient curve can truly reflect the change of the microstructure in the material and can be used for accurately predicting the service state of the material. The accurate measurement of the frequency domain attenuation coefficient curve is crucial to the quantitative evaluation of the microstructure inside the material, so that it is necessary to provide a method for accurately measuring the frequency domain attenuation coefficient curve of the material.

Ultrasonic attenuation includes ultrasonic beam diffuse attenuation, material internal scattering attenuation, and medium absorption attenuation. The attenuation coefficient measured by practical experiments is the sum of two parts of internal scattering of the material and absorption attenuation of the medium. In most engineering applications, a convenient method is to measure the attenuation coefficient of a material with a contact type straight probe. Treiber et al showed that when the attenuation coefficient was measured with a contact probe, the result was a large error if the partial reflection coefficient at the interface of the ultrasound probe and the material was not considered. Most engineering application studies therefore only use the attenuation coefficient to roughly characterize the change in microstructure within the material, without regard to the accuracy of its value.

The other effective method for measuring the frequency domain attenuation coefficient of the ultrasonic longitudinal wave is an ultrasonic water immersion pulse echo method, and the method utilizes the ratio of primary bottom waves and secondary bottom waves or surface waves and the primary bottom waves returned by ultrasonic waves through a material interface to calculate, and obtains the frequency domain attenuation coefficient in the effective bandwidth of the probe after the diffraction correction of the ultrasonic waves in the material. Miguel et al obtained an attenuation coefficient calculation method suitable for a hydrophobic material by using an ultrasonic water immersion pulse method and correcting the reflection coefficient of ultrasonic waves passing through a material interface for the hydrophobic material. However, the above methods all use a single probe broadband pulse to transmit signals, and the frequency bandwidth of the pulse signals is limited and difficult to determine, so that an accurate relation curve between the attenuation coefficient and the frequency cannot be obtained.

Another key problem when measuring attenuation coefficients for wideband ultrasonic pulse signals is that the frequency spectrum of the signal shifts as the wideband pulse propagates through the attenuating medium, and secondly that the attenuation coefficient values are not accurately measured when the frequency values are far from the effective frequency band of the probe. This may cause deviations in the curve relationship between attenuation coefficient and frequency, thereby affecting the attenuation coefficient measurement.

Disclosure of Invention

The present invention is directed to solving, at least to some extent, one of the technical problems in the related art. Therefore, an object of the present invention is to provide a method for measuring an ultrasonic attenuation coefficient, so as to improve the accuracy of measuring the ultrasonic attenuation coefficient.

Another object of the present invention is to provide an apparatus for measuring ultrasonic attenuation coefficient.

In order to achieve the purpose, the invention provides a method for measuring an ultrasonic attenuation coefficient, which comprises the following steps: transmitting an ultrasonic signal to a test block immersed in water by using an ultrasonic water immersion probe with the surface immersed in water, wherein the ultrasonic signal is an ultrasonic narrow-band pulse sine wave signal; receiving an echo signal of the ultrasonic signal reflected by the test block by using the ultrasonic water immersion probe; and calculating the ultrasonic attenuation coefficient of the test block according to the frequencies of the echo signal and the ultrasonic signal.

According to the method for measuring the ultrasonic attenuation coefficient, the ultrasonic water immersion probe is used for transmitting the ultrasonic narrow pulse sine wave signal with the corresponding frequency value to the test block, the ultrasonic attenuation coefficient of the test block under the frequency is measured, and the measured ultrasonic attenuation coefficient is more accurate.

As an example, the echo signal includes a reflection signal of the upper surface of the test block and a reflection signal of the bottom surface of the test block, wherein the ultrasonic attenuation coefficient of the test block is calculated by the following formula:

wherein alpha is_L(f,2z) is the ultrasonic attenuation coefficient of the test block, f is the frequency of the ultrasonic signal, z is the thickness of the test block, d is the distance from the surface of the ultrasonic water immersion probe to the upper surface of the test block, S₁(f,2d) is a reflected signal of the upper surface of the test block, S₂(f,2D ') is a reflected signal from the bottom surface of the test block, D' is a propagation distance of the ultrasonic signal between the test block and water, D₁(f,2d)For a diffraction correction term, D, of the ultrasonic signal as it propagates through the water₂(f,2d') is a diffraction correction term, T, of the ultrasonic signal as it propagates through the test block₁₂Is the transmission coefficient, T, of the ultrasonic signal when passing through the water interface₂₁Is the transmission coefficient, R, of the ultrasonic signal passing through the interface of the test block₂₁The reflection coefficient of the ultrasonic signal passing through the interface of the test block is shown.

As an example, the surface of the ultrasonic water immersion probe is 20mm away from the upper surface of the test block, the test block is of a cuboid structure, and the upper surface area and the lower surface area of the test block are both 50mm multiplied by 50mm²And the thickness of the test block is 20 mm.

As an example, the ultrasonic water immersion probe has a center frequency of 1MHz, 2.25MHz, or 5 MHz.

As one example, a plurality of ultrasonic signals of different frequencies are transmitted using one or more ultrasonic water immersion probes of different center frequencies, the method further comprising: calculating to obtain a plurality of ultrasonic attenuation coefficients according to a plurality of different frequencies and corresponding echo signals; and fitting the plurality of ultrasonic attenuation coefficients and the corresponding frequencies thereof to obtain an ultrasonic attenuation coefficient-frequency curve.

In order to achieve the above object, the present invention provides an apparatus for measuring an ultrasonic attenuation coefficient, comprising: the ultrasonic water immersion probe comprises an ultrasonic water immersion probe, a current probe, an amplifier, a function generator, an oscilloscope and an upper computer, wherein the surface of the ultrasonic water immersion probe is immersed in water, the current probe is respectively and electrically connected with the ultrasonic water immersion probe, the amplifier and the oscilloscope, the function generator is electrically connected with the amplifier, and the upper computer is electrically connected with the oscilloscope; the ultrasonic water immersion probe transmits acquired echo signals reflected by the test block to the oscilloscope through the current probe for displaying on the oscilloscope, and the upper computer is used for acquiring the echo signals displayed by the oscilloscope and calculating the ultrasonic attenuation coefficient of the test block according to the echo signals and the frequency of the ultrasonic signals.

According to the device for measuring the ultrasonic attenuation coefficient, the function generator is used for driving the ultrasonic water immersion probe to emit the ultrasonic narrow pulse sine wave signal with the corresponding frequency value to the test block in a curved mode, the ultrasonic attenuation coefficient of the test block under the frequency is measured, and the measured ultrasonic attenuation coefficient is more accurate.

As an example, the echo signal includes a reflection signal of the upper surface of the test block and a reflection signal of the bottom surface of the test block, and the upper computer calculates the ultrasonic attenuation coefficient of the test block by the following formula:

wherein alpha is_L(f,2z) is the ultrasonic attenuation coefficient of the test block, f is the frequency of the ultrasonic signal, z is the thickness of the test block, d is the distance from the surface of the ultrasonic water immersion probe to the upper surface of the test block, S₁(f,2d) is a reflected signal of the upper surface of the test block, S₂(f,2D ') is a reflected signal from the bottom surface of the test block, D' is a propagation distance of the ultrasonic signal between the test block and water, D₁(f,2D) is a diffraction correction term for the ultrasonic signal as it propagates through the water, D₂(f,2d') is a diffraction correction term, T, of the ultrasonic signal as it propagates through the test block₁₂Is the transmission coefficient, T, of the ultrasonic signal when passing through the water interface₂₁Is the transmission coefficient, R, of the ultrasonic signal passing through the interface of the test block₂₁The reflection coefficient of the ultrasonic signal passing through the interface of the test block is shown.

As an example, the surface of the ultrasonic water immersion probe is 20mm away from the upper surface of the test block, the test block is of a cuboid structure, and the upper surface area and the lower surface area of the test block are both 50mm multiplied by 50mm²And the thickness of the test block is 20 mm.

As an example, the ultrasonic water immersion probe has a center frequency of 1MHz, 2.25MHz, or 5 MHz.

As an example, the function generator is configured to output a plurality of narrow pulse sine wave signals with different frequencies, and transmit an ultrasonic wave signal with a corresponding frequency by using an ultrasonic water immersion probe with a corresponding center frequency, wherein the upper computer is further configured to obtain echo signals corresponding to the ultrasonic wave signals with different frequencies, calculate a plurality of ultrasonic attenuation coefficients according to the plurality of different frequencies and the echo signals corresponding to the different frequencies, and perform fitting processing on the plurality of ultrasonic attenuation coefficients and the frequencies corresponding to the ultrasonic attenuation coefficients to obtain an ultrasonic attenuation coefficient-frequency curve.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

FIG. 1 is a schematic flow chart of a method of measuring an ultrasonic attenuation coefficient according to an embodiment of the present invention;

FIG. 2 is a schematic illustration of the propagation of an ultrasonic signal according to an example of the present invention;

fig. 3(a), fig. 3(b), and fig. 3(c) are time domain signal waveforms of ultrasonic signals with frequencies of 2.25MHz, 5MHz, and 10MHz, respectively, when propagating in an acrylic material;

FIG. 4(a), FIG. 4(b), and FIG. 4(c) are frequency domain signal waveforms of ultrasonic signals with frequencies of 2.25MHz, 5MHz, and 10MHz respectively propagating in an acrylic material;

FIG. 5 is a graphical representation of test results for one example of the present invention;

FIG. 6 is a graphical representation of test results for another example of the present invention;

fig. 7 is a schematic structural diagram of an ultrasonic attenuation coefficient measuring apparatus according to an embodiment of the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

The ultrasonic attenuation coefficient measuring method and the ultrasonic attenuation coefficient measuring apparatus according to the embodiments of the present invention will be described below with reference to the drawings.