Method and device for testing ultrasonic metamaterial complex reflection coefficient using dual hydrophones

Abstract

The application discloses a method for testing ultrasonic metamaterial complex transmission reflection coefficient by using double hydrophones, comprising the following steps: arranging hydrophones and transducers on the left and right sides of the ultrasonic metamaterial; measuring the distance D between the two hydrophones and the thickness d of the ultrasonic metamaterial; after vertically entering water, the two transducers emit ultrasonic waves in succession, and the two hydrophones receive direct signal I1, reflection signal R1, transmission signal T1 and direct signal I2, reflection signal R2 and transmission signal T2; calculating the complex reflection coefficient of phase information by using the direct signal I1, the direct signal I2, the reflection signal R1, the reflection signal R2, the distance D between the two hydrophones and the thickness d of the ultrasonic metamaterial; and calculating the complex transmission coefficient of phase information by using the direct signal I1, the direct signal I2, the transmission signal T1, the transmission signal T2, the distance D between the two hydrophones and the thickness d of the ultrasonic metamaterial. The method can reduce the phase calculation deviation caused by positioning error and obtain the complex transmission reflection coefficient with amplitude and phase information.

Description

Technical Field

[0001] This invention belongs to the field of acoustic parameter testing, and specifically relates to a method and apparatus for testing the retransmission and reflection coefficient of ultrasonic metamaterials using dual hydrophones. Background Technology

[0002] Acoustic metamaterials are a class of artificially periodic materials with extraordinary physical properties, composed of subwavelength structural units. By cleverly designing the structural units of metamaterials, the direction of sound wave propagation can be precisely manipulated, thereby achieving unique functions not possessed by conventional materials. In the research of acoustic metamaterials, testing the complex transmission and reflection coefficients of acoustic metamaterials is one of the important performance characterization methods. For example, Chinese Patent Publication No. CN110609085A discloses a method for measuring the acoustic performance of acoustic metamaterials based on vector hydrophones, including: confirming the directivity of the vector hydrophone and determining its placement position according to the directivity spectrum of the vector hydrophone; measuring and calculating the vector sound intensity at each measurement position without the acoustic metamaterial; measuring and calculating the vector sound intensity at each measurement position with the acoustic metamaterial; calculating the sound intensity reflection coefficient and sound intensity transmission coefficient at each measurement position of the acoustic metamaterial, and the average sound intensity reflection coefficient and average sound intensity transmission coefficient of the entire sample; calculating the sound pressure reflection coefficient and sound pressure transmission coefficient at each measurement position of the acoustic metamaterial, and the average sound pressure reflection coefficient and average sound pressure transmission coefficient of the entire sample. Similarly, Chinese Patent Publication No. CN114965696A discloses a method and system for determining the equivalent acoustic parameters of soft ultrasonic gel materials, which solves the problem of the soft gel metamaterial's reflection signal being too weak to be measured by adding a backing material behind it.

[0003] The transmission and reflection coefficients include amplitude and phase information. While methods for measuring the amplitude of the transmission and reflection coefficients are relatively mature, phase measurement remains a significant challenge. Taking the reflection coefficient as an example, the traditional method for phase measurement is as follows:

[0004]

[0005] in This is the first reflected signal from the sample received by the hydrophone. is the direct wave signal received by the hydrophone, L is the distance between the hydrophone and the sample, and k0 is the ultrasonic wave number in the water.

[0006] Due to factors such as the relatively difficult methods of fixing samples and hydrophones and underwater distance measurement, the measurement error of L is relatively large. Furthermore, when testing samples in batches, it is necessary to change and fix the samples multiple times and measure the distance L between the hydrophone and the sample multiple times. When comparing sample performance, more errors will accumulate, which will seriously affect the phase of the reflection coefficient. The accuracy.

[0007] Therefore, how to reduce the phase test deviation caused by positioning error and thus obtain a relatively accurate retransmission and reflection coefficient of metamaterials is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0008] The purpose of this invention is to provide a method and apparatus for testing the complex transmission and reflection coefficient of ultrasonic metamaterials using dual hydrophones, which can reduce the phase calculation deviation caused by positioning error and obtain the complex transmission and reflection coefficient with amplitude and phase information.

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] A method for testing the complex reflection coefficient of ultrasonic metamaterials using dual hydrophones, the method comprising:

[0011] (1) Hydrophones and transducers are arranged on both the left and right sides of the ultrasonic metamaterial;

[0012] (2) Measure the distance D between the two hydrophones and the thickness d of the ultrasonic metamaterial;

[0013] (3) When the water is vertically submerged, the two transducers emit ultrasonic waves one after another, and the two hydrophones receive the direct signal I1, the reflected signal R1, the transmitted signal T1 and the direct signal I2, the reflected signal R2, the transmitted signal T2 respectively.

[0014] (4) Calculate the complex reflection coefficient of phase information using the direct signal I1, the direct signal I2, the reflected signal R1, the reflected signal R2, the distance D between the two hydrophones, and the thickness d of the metamaterial;

[0015] (5) Calculate the complex transmission coefficient of phase information using the direct signal I1, direct signal I2, transmitted signal T1, transmitted signal T2, the distance D between the two hydrophones, and the thickness d of the metamaterial.

[0016] This invention eliminates the need to measure the distance between the hydrophone and the metamaterial sample; instead, it calculates the phase using the distance between the two hydrophones and the sample thickness. This method eliminates the influence of the sample and hydrophone fixing method and solves the problem of difficult underwater distance testing, thereby reducing phase calculation deviations caused by positioning errors and obtaining a complex transmission and reflection coefficient with amplitude and phase information.

[0017] In step (1), the metamaterial sample used is a symmetric material.

[0018] In step (2), the thickness d of the metamaterial is measured using a vernier caliper or a micrometer, and the distance D between the two hydrophones is measured using a laser.

[0019] In step (3), after all devices are vertically submerged in water, the first transducer first emits ultrasonic waves, the first hydrophone receives the direct signal I1 and the first reflection signal R1 through the ultrasonic metamaterial, and the second hydrophone receives the transmission signal T1 through the ultrasonic metamaterial; after the first transducer is turned off, the second transducer then emits ultrasonic waves, the first hydrophone receives the transmission signal T2 through the ultrasonic metamaterial, and the second hydrophone receives the direct signal I2 and the first reflection signal R2 through the sample.

[0020] In step (4), the complex reflection coefficient R is calculated as follows:

[0021]

[0022]

[0023] Where A R Let AR1, AR2, AI1, and AI2 be the amplitudes of the reflected signals R1, R2, I1, and I2, respectively. The phase of the reflection coefficient, R1, R2, I1, and I2 are the phases of the reflected signals, respectively; D is the distance between the two hydrophones; d is the thickness of the metamaterial sample; and k0 is the ultrasonic wave number in the water.

[0024] In this invention, when calculating the reflection phase of the metamaterial, it is not necessary to measure the distance between the hydrophone and the metamaterial sample. Instead, the distance between the two hydrophones and the sample thickness are used, which can reduce the phase calculation deviation caused by positioning error.

[0025] In step (5), the complex transmission coefficient T is calculated as follows:

[0026]

[0027]

[0028]

[0029] Where A T Let AT1, AT2, AI1, and AI2 be the amplitudes of the transmitted signals T1, T2, I1, and I2, respectively. The phase of the transmission coefficient. , respectively, are the phases of the transmitted signal T1, transmitted signal T2, direct signal I1, and direct signal I2; D is the distance between the two hydrophones, d is the thickness of the metamaterial sample, and k0 is the ultrasonic wave number in water.

[0030] In this invention, when calculating the transmission phase of metamaterials, it is not necessary to measure the distance between the hydrophone and the metamaterial sample. Instead, the distance between the two hydrophones and the sample thickness are used to reduce the phase calculation deviation caused by positioning error.

[0031] The present invention also provides a device for testing the complex transmission and reflection coefficient of ultrasonic metamaterials using dual hydrophones. The device includes signal testing devices disposed on both sides of the ultrasonic metamaterial. Each signal testing device includes a signal generator, a transducer, a hydrophone, a power amplifier, and an oscilloscope. The signal generator emits a specific modulation pulse signal. The transducer converts the electrical signal transmitted by the signal generator into an acoustic signal. The hydrophone detects the acoustic wave propagating in the water tank and converts it back into an electrical signal. After passing through the power amplifier, the oscilloscope collects, records, and outputs the signal.

[0032] The device uses the above method to test the retransmission and reflection coefficient of ultrasonic metamaterials.

[0033] The process involves measuring the distance between the two hydrophones before the signal testing device is submerged in water, and keeping the position of the two hydrophones constant when testing different samples.

[0034] This invention addresses the problem of phase measurement deviation caused by positioning errors in acoustic complex transmission and reflection coefficient testing. It provides a method and apparatus for testing the complex transmission and reflection coefficient of ultrasonic metamaterials using dual hydrophones. This method can eliminate the influence of the sample and hydrophone fixing method and solve the problem of difficult underwater distance testing, thereby obtaining the complex transmission and reflection coefficient with amplitude and phase information. Based on this, acoustic parameters such as equivalent density and equivalent modulus can be measured using the inversion method, providing an important characterization means for acoustic metamaterials. Attached Figure Description

[0035] Figure 1 A schematic diagram of a system for testing the complex transmittance and reflectance coefficient of materials using the dual hydrophone method;

[0036] Figure 2 A flowchart for testing the complex transmittance and reflectance coefficient of materials using the dual hydrophone method;

[0037] Figure 3 The results of the simulated test of the complex reflection coefficient of the steel plate are: a) reflection coefficient amplitude; b) phase.

[0038] Figure 4 The results of the simulated test of the complex transmission coefficient of the steel plate are: a) transmission coefficient amplitude; b) phase. Detailed Implementation

[0039] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings. Here, the embodiments and descriptions of the present invention are used to explain the present invention, but are not intended to limit the present invention.

[0040] The device diagram of the embodiment is as follows Figure 1 As shown, the device includes signal testing devices positioned on both sides of the ultrasonic metamaterial. Each device includes a signal generator, transducers (transducer 1 and transducer 2), hydrophones (hydrophone 1 and hydrophone 2), a power amplifier, and an oscilloscope. The signal generator emits a specific modulated pulse signal. The transducer converts the electrical signal transmitted by the signal generator into an acoustic signal. The hydrophone detects the acoustic wave propagating in the water tank and converts it back into an electrical signal. After passing through the power amplifier, the oscilloscope collects, records, and outputs signal 1 and signal 2.

[0041] The transducer transmits a modulated pulse with a center frequency of 100kHz, carrying frequency information from 40-160kHz. The complex reflection coefficient of a 5mm thick steel plate with a density of 7850kg / m³ was simulated and tested. 3 The speed of sound is 5600 m / s.

[0042] Test flowchart as follows Figure 2 As shown, after all devices are vertically submerged in water, the first transducer (transducer 1) first emits a modulation pulse with a center frequency of 100kHz. The first hydrophone (hydrophone 1) receives the direct signal I1 and the first reflection signal R1 from the sample. The second hydrophone (hydrophone 2) receives the transmission signal T1 from the sample. After the first transducer is turned off, the second transducer (transducer 2) then emits a modulation pulse with a center frequency of 100kHz. The first hydrophone (hydrophone 1) receives the transmission signal T2 from the sample, and the second hydrophone (hydrophone 2) receives the direct signal I2 and the first reflection signal R2 from the sample.

[0043] The amplitude measurement of the reflection coefficient of a material is relatively mature and simple. It is the ratio of the amplitude of the primary reflected signal R1 to the amplitude of the direct signal I1, or the ratio of the amplitude of the primary reflected signal R2 to the amplitude of the direct signal I2. The calculation formula is as follows:

[0044]

[0045] The amplitude spectrum of the reflection coefficient of the steel plate is as follows Figure 3 As shown in a, the simulation test results are almost in perfect agreement with the theoretical derivation results in the range of 40-160kHz.

[0046] Furthermore, the phase reflection coefficient of the material is measured using the dual hydrophone method of this invention, and the calculation formula is as follows:

[0047]

[0048] in , respectively, represent the phases of reflected signal R1, reflected signal R2, direct signal I1, and direct signal I2; D is the distance between the two hydrophones, d is the thickness of the metamaterial sample, and k0 is the ultrasonic wave number in water.

[0049] Simulation verification, under ideal test conditions (i.e., when the distance between the hydrophone and the sample, and the distance between hydrophones), shows that the reflection phase test results using the dual-hydrophone method of this invention and the traditional single-hydrophone method are almost completely consistent in the 40-160kHz frequency band. The simulation test results are as follows: Figure 3 As shown in b in the figure. This result proves the reliability of the dual hydrophone method.

[0050] Similarly, the amplitude and phase of the transmission coefficient of the material are measured using the dual hydrophone method of this invention, and the calculation formula is as follows:

[0051]

[0052]

[0053] Where A T Let AT1, AT2, AI1, and AI2 be the amplitudes of the transmitted signals T1, T2, I1, and I2, respectively. The phase of the transmission coefficient. These represent the phases of the transmitted signal T1, transmitted signal T2, direct signal I1, and direct signal I2, respectively. The test results are as follows: Figure 4 As shown.

[0054] It is worth noting that, under actual testing conditions, the distance between the hydrophone and the sample is difficult to measure accurately and is affected by the way the sample and hydrophone are fixed. This results in a large phase measurement error in the single-hydrophone method during actual testing. Furthermore, when testing batches of samples, it is necessary to change and fix the samples multiple times and measure the distance between the two hydrophones and the sample multiple times, which accumulates more error when comparing sample performance. In contrast, the dual-hydrophone method only requires measuring the distance between the two hydrophones once, and then keeping the positions of the hydrophones unchanged while changing the sample. This method has a small phase measurement error and is reliable.

[0055] The specific embodiments described above illustrate the technical solution and beneficial effects of the present invention in detail. It should be understood that the above description is only the most preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, additions, and equivalent substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for testing the complex transmission and reflection coefficient of ultrasonic metamaterials using dual hydrophones, characterized in that, The method includes: (1) Hydrophones and transducers are arranged on both sides of the ultrasonic metamaterial; (2) Measure the distance D between the two hydrophones and the thickness d of the ultrasonic metamaterial; (3) When the water is vertically submerged, the two transducers emit ultrasonic waves one after another, and the two hydrophones receive the direct signal I1, the reflected signal R1, the transmitted signal T1 and the direct signal I2, the reflected signal R2, the transmitted signal T2 respectively. (4) Calculate the complex reflection coefficient of phase information using the direct signal I1, the direct signal I2, the reflected signal R1, the reflected signal R2, the distance D between the two hydrophones, and the thickness d of the metamaterial; (5) Calculate the complex transmission coefficient of phase information using the direct signal I1, direct signal I2, transmitted signal T1, transmitted signal T2, the distance D between the two hydrophones, and the thickness d of the metamaterial; In step (4), the complex reflection coefficient R is calculated as follows: in The amplitude of the reflection coefficient. , , , These are the amplitudes of the reflected signal R1, reflected signal R2, direct signal I1, and direct signal I2, respectively. The phase of the reflection coefficient, , , , These represent the phases of reflected signals R1, R2, I1, and I2, respectively; D is the distance between the two hydrophones, and d is the thickness of the metamaterial sample. The ultrasonic wave number in water; In step (5), the complex transmission coefficient T is calculated as follows: in The amplitude of the transmission coefficient. , , , These are the amplitudes of the transmitted signal T1, the transmitted signal T2, the direct signal I1, and the direct signal I2, respectively. The phase of the transmission coefficient. , , , , respectively, represent the phases of transmitted signals T1, T2, direct signals I1, and I2; D is the distance between the two dual hydrophones, and d is the thickness of the metamaterial sample. The wavenumber of ultrasonic waves in water.

2. The method for testing the complex reflection coefficient of ultrasonic metamaterials using dual hydrophones according to claim 1, characterized in that, In step (1), the metamaterial sample used is a symmetric material.

3. The method for testing the complex reflection coefficient of ultrasonic metamaterials using dual hydrophones according to claim 1, characterized in that, In step (2), the thickness d of the metamaterial is measured using a vernier caliper or a micrometer, and the distance D between the two hydrophones is measured using a laser.

4. The method for testing the retransmission and reflection coefficient of ultrasonic metamaterials using dual hydrophones according to claim 1, characterized in that, In step (3), after vertical entry into the water, the first transducer emits ultrasonic waves, the first hydrophone receives the direct signal I1 and the first reflection signal R1 from the sample, and the second hydrophone receives the transmission signal T1 from the ultrasonic metamaterial; after the first transducer is turned off, the second transducer emits ultrasonic waves, the first hydrophone receives the transmission signal T2 from the ultrasonic metamaterial, and the second hydrophone receives the direct signal I2 and the first reflection signal R2 from the sample.

5. A device for testing the complex transmission and reflection coefficient of ultrasonic metamaterials using dual hydrophones, characterized in that, The device includes signal testing devices set on both sides of the ultrasonic metamaterial. Each signal testing device includes a signal generator, a transducer, a hydrophone, a power amplifier, and an oscilloscope. The signal generator emits a specific modulated pulse signal. The transducer converts the electrical signal transmitted by the signal generator into an acoustic signal. The hydrophone detects the acoustic wave propagating in the water tank and converts it back into an electrical signal. After passing through the power amplifier, the oscilloscope collects, records, and outputs the signal. The device is used to test the ultrasonic metamaterial retransmission and reflection coefficients R and T using the method described in any one of claims 1-4.

6. The apparatus for testing the complex reflection coefficient of ultrasonic metamaterials using dual hydrophones according to claim 5, characterized in that, Measure the distance between the two hydrophones before immersing the signal testing device in water; keep the position between the two hydrophones unchanged when testing different samples.

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