Cross-medium sound transmission enhanced sound lens

Abstract

The invention belongs to the field of acoustic devices, and particularly relates to a cross-medium sound transmission enhancement acoustic lens. Comprising a circular cover plate, a cylindrical supporting frame and a positioning ring, a plurality of unit holes are formed in the circular cover plate, and the circular cover plate is fixedly arranged at the end of the supporting frame; and the positioning ring is fixed on the inner wall of the supporting frame. According to the invention, through the parallel arrangement of the plurality of unit holes, the sound lens realizes the cross-medium sound penetration enhancement design; the transmission amplitude of the underwater acoustic lens at multiple frequencies is increased by more than two times, and the transmission gain exceeds 6dB; the working stability of the acoustic lens is further improved; the acoustic lens designed by the invention is simple in structure, a complicated design method is not needed, large-scale manufacturing and application are facilitated, and the cover plate is of an ultrathin structure, so that the requirements of compact structure and light weight can be met; according to the invention, the simple structure can realize cross-medium sound penetration enhancement, can realize cross-medium transmission of sound waves, and has wide application prospects in the fields of underwater detection, cross-medium communication and the like.

Description

Technical Field

[0001] The present invention belongs to the field of acoustic devices, and particularly relates to a cross-medium sound transmission enhanced acoustic lens. Background Art

[0002] As a new type of artificial structure, acoustic metamaterials have characteristics that transcend the behavior of natural materials, such as negative mass density, negative bulk modulus, and extreme Poisson's ratio, etc., bringing new degrees of freedom and great possibilities for controlling sound waves. As an important category of acoustic metamaterials, acoustic superlenses are widely used devices for manipulating sound waves and have the ability to increase the intensity of spatial sound energy. The ratio of the acoustic impedance at the water-air interface is as high as 3600, and only 0.5% of the sound energy can be transmitted, which makes most acoustic superlenses can only work in a uniform background medium and cannot meet the increasing demands of water-air communication applications.

[0003] Although some acoustic metamaterials can enhance the sound penetration ability at the water-air interface. For example, immersing 3D-printed hydrophobic nylon material in water can capture an air layer underwater and resonate with the upper water layer, achieving a transmission enhancement of more than 20 dB at 4 kHz. In order to increase its operating frequency, a bionic lotus metamaterial surface was proposed based on a similar principle, improving the sound transmission in the middle frequency range. However, the hydrophobic treatment of solid materials undoubtedly increases the complexity of the structure, which is not conducive to large-scale popularization and use. Due to the principle based on bubble resonance, their operating frequency band is narrow. At the same time, since most of the materials used are soft materials with poor strength, it is difficult to meet the application requirements.

[0004] In view of the above technical requirements, resonance can enable efficient energy transmission between two mismatched media and has been widely used in fields such as acoustics. Immersed coupled resonance bubbles underwater are an effective method to improve sound transmission at the water-air interface, and its basic principle can be described by a mass-spring resonance model. The resonance exhibited by bubbles in water is called Minnaert resonance. Considering the bubble and the upper water layer as a mass-spring resonance system, the maximum transmission frequency can be obtained as the intrinsic resonance frequency of the bubble.

[0005] Existing bubble metamaterials require hydrophobic treatment of solid materials, greatly increasing the processing difficulty and manufacturing cost, which is not conducive to large-scale manufacturing and application.

[0006] Therefore, a simple and feasible design method is needed for the design of bubble structures. Summary of the Invention

[0007] The purpose of the present invention is to overcome the deficiencies of the existing acoustic superlenses with high processing difficulty and high manufacturing cost, and provide a cross-medium sound transmission enhanced acoustic lens for realizing enhanced cross-medium sound penetration.

[0008] To achieve the above object, the present invention adopts the following technical solution: A cross-media sound transmission enhanced acoustic lens, comprising a circular cover plate, a cylindrical support frame and a positioning ring. A plurality of unit holes are provided on the circular cover plate and are fixedly arranged at the end of the support frame; the positioning ring is fixed on the inner wall of the support frame.

[0009] Further, the above-mentioned plurality of unit holes are periodically distributed.

[0010] Further, on the above-mentioned circular cover plate, a unit hole is provided at the center, and two circles of unit holes are arranged equidistantly and concentrically from the inside to the outside, and the diameter sizes of the unit holes gradually decrease.

[0011] Further, the shape of the above-mentioned unit holes is circular.

[0012] Further, the thickness of the above-mentioned circular cover plate is 8 - 12 mm.

[0013] Further, the material of the above-mentioned circular cover plate 1 is a photosensitive resin polymer, and its mass density, Young's modulus and Poisson's ratio are ρ r = 1320 kg / m 3 、E r = 2.2×10 9 Pa and υ r = 0.375.

[0014] Compared with the prior art, the present invention has the following beneficial technical effects:

[0015] 1. Through the structure of a plurality of unit holes arranged in parallel, the present invention simply realizes cross-media sound transmission enhancement for the entire acoustic lens; the designed acoustic lens structure of the present invention is simple, does not require complex design methods, is convenient for large-scale manufacturing and application, and the circular cover plate itself is an ultra-thin structure with a thickness of only about 10 mm, meeting the requirements of structural compactness and light weight; the processing of the unit holes is simple and the manufacturing cost is low.

[0016] 2. Through integrated design, the waveguide is designed as a cylindrical shape, that is, a cylindrical support frame, which is closely connected to the circular cover plate provided with a plurality of unit holes, improving the working stability of the entire acoustic lens; the present invention generates coupled resonance bubbles through a plurality of unit holes, and the generation method is simple, which can enable sound waves to pass through the water-air interface, enabling the acoustic lens to achieve cross-media sound penetration enhancement design. The underwater acoustic lens has a transmission amplitude increase of more than 2 times and a transmission gain of more than 6 dB at multiple frequencies.

[0017] 3. The simple structure of the present invention can achieve cross-media sound penetration enhancement, can realize cross-media transmission of sound waves, and has broad application prospects in the fields of underwater detection and cross-media communication, etc. Description of the Drawings

[0018] Figure 1 Schematic diagram of a cross - medium acoustic transmission - enhancing acoustic lens;

[0019] Figure 2 is Figure 1 the A - A sectional view of;

[0020] Figure 3 Diagram of the simulation calculation results of the transmittance;

[0021] Figure 4 Diagram of the experimental device layout;

[0022] Figure 5 Diagram of the experimental test results of the cross - medium acoustic transmission - enhancing acoustic lens;

[0023] Among them, the reference signs are as follows:

[0024] 1 - circular cover plate, 2 - support frame, 3 - positioning ring, 4 - unit hole. Detailed implementation manners

[0025] Next, in combination with the embodiments and drawings of the present invention, the technical solutions of the present invention will be described in detail.

[0026] Embodiment:

[0027] Referring to Figure 1 and Figure 2 , a cross - medium acoustic transmission - enhancing acoustic lens provided by the present invention includes a circular cover plate 1, a cylindrical support frame 2 and a positioning ring 3. A plurality of unit holes 4 are provided on the circular cover plate 1 and are fixedly arranged at the end of the support frame 2; the positioning ring 3 is fixed on the inner wall of the support frame 2 to form a cylindrical acoustic lens structure. The thickness of the circular cover plate 1 is 10 mm.

[0028] By using the well - known topology optimization method, continuously iteratively optimizing the size of the unit holes 4 on the cover plate 1 to obtain the optimal size, cross - medium acoustic transmission enhancement can be achieved.

[0029] In this embodiment, the shapes of the unit holes 4 are all circular. The plurality of unit holes 4 are distributed periodically. On the circular cover plate 1, a unit hole 4 with a diameter of 10 mm is provided at the center, and two concentric circles of unit holes 4 are arranged equidistantly from the inside to the outside. The diameter sizes of the unit holes 4 in the inner circle and the outer circle are the optimal size parameters obtained by topology optimization.

[0030] In an embodiment, the circular cover plate 1 is a flat plate having a plurality of unit holes 4. By constructing a divided water area with a gradient area to form spring-mass resonance systems of different degrees, the circular cover plate 1 designed by us can effectively improve the cross-media sound transmission ability. This structure can not only meet the requirements of transmission gain, but also has a very simple form and has potential engineering application value. Since the resonance frequency of the system is related to the mass, a single unit hole 4 acts as a mass block and resonates with the air above to generate a resonance frequency, and several unit holes 4 with gradient areas can generate multiple resonance frequencies, thus generating multiple maximum transmission frequencies. For the convenience of testing and verification, in the commercial multi-physics field coupling finite element analysis software COMSOL, the acoustic-solid coupling module is used, and the circular cover plate 1 is designed with a rigid wall. The rigid wall material is selected as a photosensitive resin polymer, and its mass density, Young's modulus and Poisson's ratio are ρ r = 1320 kg / m 3 , E r = 2.2×10 9 Pa and υ r = 0.375. The selected sound propagation media are air and water. The sound speed and density of air are c0 = 343 m / s and ρ0 = 1.29 kg / m 3 ; the sound speed and density of water are c0 = 1500 m / s and ρ0 = 1000 kg / m 3 . The results calculated by the simulation numerical model are as shown in Figure 2 . Peaks with a transmittance exceeding 0.05 continuously appear within 20 - 50 kHz, among which there are many and dense peaks within 30 - 50 kHz, and the transmittance at multiple frequencies exceeds 0.3. The simulation results verify the feasibility of the present invention. By constructing a divided water area with a gradient area to form spring-mass resonance systems of different degrees, the cross-media sound transmission ability is improved.

[0031] Next, the performance of the above cross-media sound transmission enhanced acoustic lens is tested to verify that it can achieve enhanced sound penetration at the water-air interface and realize the function of enhanced sound penetration.

[0032] Using a photosensitive resin material, the cross-media sound transmission enhanced acoustic lens provided by the present invention is manufactured by a photocuring 3D printing technology. In the structure, the thickness of the circular cover plate 1 is 10 mm, and the diameter of the support frame 2 is 100 mm. The experimental device is as shown in Figure 4As shown, the experimental sample - the cross - medium acoustic transmission enhanced acoustic lens of the present invention is fixed on the waveguide and placed together in a 50 cm × 50 cm × 50 cm plexiglass water tank. The transducer on the right side of the water tank acts as a sound source, and the hydrophone is placed on the left side of the acoustic lens to receive the acoustic wave signal passing through the double - layer water - air interface. The specific experimental procedure is as follows: A harmonic signal of 2000 - 20000 Hz is generated by a signal generator, with a duration of 1 s for each frequency. After being amplified by a power amplifier, it is used to generate an acoustic wave excitation by the transducer. The sound signal is collected by the hydrophone, and the collected information is fed back to the computer. The computer performs a Fourier transform on the collected time - domain signal to convert it into a frequency - domain signal, and extracts the sound pressure amplitude at different frequencies.

[0033] The test results are as Figure 5 shown. Compared with the control group without the underwater acoustic lens, the transmission amplitude increases between 33 kHz and 34 kHz, and increases by about 2 times at 36.5 kHz and 38.75 kHz.

[0034] The above content should not be used to limit the protection scope of the present invention. Any modification made on the basis of the technical solution according to the technical idea proposed by the present invention falls within the protection scope of the present invention.

Claims

1. A trans-medium sound-transmitting enhanced acoustic lens, characterized in that: It comprises a circular cover plate (1), a cylindrical support frame (2) and a positioning ring (3); the circular cover plate (1) is provided with a plurality of unit holes (4) and is fixedly arranged at the end of the support frame (2); the positioning ring (3) is fixed on the inner wall of the support frame (2).

2. The cross-medium sound transmission enhanced acoustic lens according to claim 1, characterized in that: The plurality of unit holes (4) are distributed periodically.

3. The cross-medium sound transmission enhanced acoustic lens according to claim 2, characterized in that: The circular cover plate (1) is provided with a unit hole (4) at the center, and two circles of unit holes (4) are provided from the inside to the outside at equal intervals and co-center, and the diameters of the unit holes (4) decrease in sequence.

4. The cross-medium sound transmission enhanced acoustic lens according to claim 2 or 3, characterized in that: The unit holes (4) are all circular in shape.

5. The cross-medium sound transmission enhanced acoustic lens according to claim 4, characterized in that: The thickness of the circular cover plate (1) is 8-12 mm.

6. The cross-medium sound transmission enhanced acoustic lens according to claim 5, characterized in that: The material of the circular cover plate (1) is a photosensitive resin polymer, and its mass density, Young's modulus and Poisson's ratio are respectively ρ r =1320kg / m 3 、E r =2.2×10 9 Pa and υ r =0.375.

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