An adjustable multifunctional meta-acoustic grating structure

Abstract

This invention discloses an adjustable multifunctional metacluster structure, comprising several groups of equally spaced unit structures and a reflector plate arranged on one side of each unit structure. Each unit structure includes three C-shaped tube sub-unit structures, and the opening position of each sub-unit can be adjusted by rotation. This invention can adjust the sub-unit structures according to actual needs to achieve different wavefront modulation functions. It can realize functions such as anomalous reflection, perfect beam splitting, and multi-channel energy distribution with arbitrary ratios at the operating frequency, overcoming the technical bottleneck of existing acoustic metamaterials being limited to a single function once printed. This multifunctional metacluster structure is flexible and adjustable, enabling various wavefront modulation functions, and has high practical value.

Description

Technical Field

[0001] This invention relates to the field of acoustic metamaterials, and in particular to an adjustable multifunctional metastructure acoustic grating. Background Technology

[0002] The emergence of acoustic metamaterials has enabled more precise and diverse manipulation of sound waves, such as sound focusing, sound absorption, sound holography, and asymmetric transmission. The technology of directional manipulation of sound waves using phase-gradient metasurfaces based on the generalized Snell's law is becoming increasingly mature. However, phase-gradient metasurfaces suffer from low power efficiency, primarily focusing on directional filtering of sound wave energy, which limits their application range, functionality, and practicality. Summary of the Invention

[0003] To overcome the shortcomings of existing acoustic metamaterials, such as low power efficiency and limited functionality, this invention provides an adjustable, multifunctional metacluster structure capable of diverse manipulation of sound waves at a given frequency, including anomalous reflection, perfect beam splitting, and multi-channel arbitrary energy distribution. This structure not only exhibits low energy loss but also possesses precise and flexible characteristics, meeting practical needs.

[0004] Technical solution: To solve the above technical problems, this application provides an adjustable multifunctional metamorphic acoustic grating structure, including a reflector and a plurality of unit structures arranged sequentially on one side of the reflector, wherein adjacent unit structures maintain an equal distance, and each unit structure maintains an equal distance from the reflector.

[0005] Preferably, each unit structure consists of three C-shaped tube subunits, one of which is located at the top and the other two at the bottom.

[0006] Preferably, the upper C-shaped tube has an outer radius of 1.30 cm, a wall thickness of 0.20 cm, and an opening angle of 43.90°; the two lower C-shaped tubes have the same dimensions, with an outer radius of 0.57 cm, a wall thickness of 0.20 cm, and an opening angle of 43.06°.

[0007] Preferably, all C-shaped tubes within the unit structure can rotate around the axis.

[0008] Preferably, in the cross-sectional direction of the unit structure, the distance between the upper C-shaped tube axis and the distance between the two lower C-shaped tube axes are the same, and the distance between the two lower C-shaped tubes and the reflector is the same.

[0009] Preferably, the distance between the upper C-shaped tube and the two lower C-shaped tubes is 0.79cm, the distance between the two lower C-shaped tubes is 0.42cm, and the distance between the two lower C-shaped tubes and the reflector is 0.52cm.

[0010] Preferably, the wall acoustic impedance of the raw materials of the unit structure and the reflector is much greater than that of the background medium, at least 100 times the acoustic impedance of the background medium.

[0011] Preferably, the material of the sound-absorbing structural unit is metal or organic plastic.

[0012] The above-described solution of the present invention has the following beneficial effects:

[0013] 1. The metamorphic acoustic grating structure provided by this invention, due to the opening in the neck of the subunit and the asymmetric geometric distribution, induces coupled polarization responses through the interaction between sound waves and the unit structure. By rationally adjusting the rotation angle of the C-tube subunit, acoustic energy can be effectively directionally reflected to a specified diffraction order, while suppressing energy from passing through other diffraction orders. Simultaneously, this tunable unit structure ensures the diversity of asymmetric scattering, allowing for adjustment of the energy efficiency of each diffraction order as needed, thereby achieving various functional wavefront modulations.

[0014] 2. The present invention has a simple structure, is easy to manufacture, and has a low production cost. It also has the ability to adjust the internal components according to actual needs to achieve different acoustic wave control functions, overcoming the technical bottleneck that existing acoustic metamaterials are limited to a single function once printed, and has high practical value. Attached Figure Description

[0015] Figure 1 This is a front view of the overall structure of the present invention;

[0016] Figure 2 This is a structural diagram of a single structural unit;

[0017] Figure 3 A schematic diagram of the diffraction of the acoustic grating structure;

[0018] Figure 4 (a) is a schematic diagram of the unit structure for abnormal reflection function;

[0019] Figure 4 (b) is the diffraction efficiency diagram of the anomalous reflection function;

[0020] Figure 4 (c) is the incident sound field diagram of the abnormal reflection function;

[0021] Figure 4 (d) is the reflected sound field diagram of the abnormal reflection function;

[0022] Figure 5 (a) is a schematic diagram of the unit structure with perfect beam splitting function;

[0023] Figure 5 (b) is the diffraction efficiency diagram of perfect beam splitting function;

[0024] Figure 5 (c) is the incident sound field diagram with perfect beam splitting function;

[0025] Figure 5 (d) is the reflected sound field diagram with perfect beam splitting function;

[0026] Figure 6 (a) is a schematic diagram of the unit structure for multi-channel arbitrary ratio energy distribution function;

[0027] Figure 6 (b) is the diffraction efficiency diagram of the multi-channel arbitrary ratio energy distribution function;

[0028] Figure 6 (c) Incident sound field diagram for multi-channel arbitrary ratio energy distribution function;

[0029] Figure 6 (d) is the reflected sound field diagram of the multi-channel arbitrary ratio energy distribution function. Detailed Implementation

[0030] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0031] It should be noted that the terms "set" and "connect" should be interpreted broadly. For example, they can refer to direct setting, installation, or connection, or indirect setting or connection through centered components or structures. Furthermore, the orientations or positional relationships indicated by terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" in this invention are based on the orientations or positional relationships shown in the accompanying drawings or in conventional placement or usage states. They are used solely for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the structures, features, devices, or elements referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the invention.

[0032] When designing the above structural parameters, the parameters can be adjusted according to the actual environmental requirements. In this embodiment, a working frequency of 6860Hz is used as an example to illustrate the technical solution of this application.

[0033] like Figure 1As shown in the figure, this application discloses a multifunctional metamorphic acoustic grating structure, including a plurality of sequentially arranged unit structures and a reflector plate arranged on one side of the unit structures. The distance between two adjacent unit structures is equal, and the distance between each unit structure and the reflector plate is equal.

[0034] In this embodiment, refer to Figure 2 The period (distance between adjacent unit structures) of the metastructure acoustic grating is a = 5.77 cm. Each unit structure consists of 3 C-shaped tube sub-units, one located at the top and the other two at the bottom. The outer radius of the upper C-shaped tube is r1 = 1.30 cm, the tube wall thickness is t1 = 0.20 cm, and the opening angle is α1 = 43.90°.

[0035] Reference Figure 2 The two lower C-tubes are identical in size, with an outer radius of r2 = 0.57 cm, a wall thickness of t2 = t1 = 0.20 cm, and an opening angle of α2 = 43.06°. These C-tubes can rotate around their center. The upper C-tube is designated β1, and the two lower C-tubes are designated β2 and β3. β1, β2, and β3 are set according to the required wavefront control function. The distance between the upper C-tube and the two lower C-tubes is d1 = 0.79 cm, the distance between the two lower C-tubes is d2 = 0.42 cm, and the distance between the two lower C-tubes and the reflector is d3 = 0.52 cm.

[0036] Reference Figure 1 The meta-sound grating has 41 structural units, which are prepared by 3D printing. The acoustic impedance of the raw materials of the unit structure and the reflector is much greater than that of the background medium, at least 100 times that of the background medium. The raw materials can be copper or organic plastic.

[0037] In this embodiment, the simulation analysis operates at a frequency of f = 6860 Hz, the incident wave type is set to a Gaussian plane wave, and the sound pressure amplitude distribution satisfies... A plane wave is incident from a direction perpendicular to the surface of the acoustic grating, with the incident end 110cm from the left side of the structure. The sound pressure response of the structure is analyzed.

[0038] For a normally incident plane wave, the diffraction equation of the acoustic grating is k0sinθ. n ·a=n·2π, n=0,±1,±2… where a is the structural period. λ is the wave number in free space, λ is the wavelength of the incident wave, and θ is the wave number in free space. n It is the nth order diffraction angle (the angle between the normal perpendicular to the grating and the direction of the incident sound wave), where n is the diffraction order. The above formula can also be written as: asinθ n=nλ, n = 0, ±1, ±2… Since the incident sound wave frequency is 6860Hz, the wavelength is 5cm. The period of the superstructure acoustic grating is a = 5.77cm. According to the acoustic grating diffraction equation, the diffracted wave only occurs when n = 0, ±1, and the corresponding three diffraction angles are θ. +1 =60°, θ0=0° and θ -1 = -60°, such as Figure 3 As shown.

[0039] Adjust the C-tube rotation angles so that β1 = 38.1°, β2 = 41.9°, and β3 = 299.0°. Figure 4 As shown in (a). At this time, the metamorphic acoustic grating has an anomalous reflection function. Through finite element simulation, it can be seen that at the operating frequency f = 6860Hz, the efficiency of the -1st order diffraction order is as high as 99% or more, while the 0th and +1st order diffraction orders are completely suppressed, and the diffraction efficiency is almost 0, as shown in (a). Figure 4 As shown in (b). Figure 4 As shown in (c) and 4(d), the incident sound wave is perpendicularly incident on the surface of the meta-sound grating and then reflected by the meta-sound grating to the -1st order diffraction direction, while scattering in other directions can be ignored.

[0040] Adjust the C-tube rotation angles so that β1 = 168.2°, β2 = 9.5°, and β3 = 50.7°. Figure 5 As shown in (a). At this point, the meta-cage has perfect beam-splitting capability. Through finite element simulation, the diffraction efficiencies of each order are demonstrated. Figure 5 (b) shows that at the operating frequency f = 6860 Hz, the diffraction efficiency of both the +1st and -1st orders is 50%, which accurately achieves the perfect beam splitting function. Figure 5 (c) and 5(d) more intuitively demonstrate the effect of perfect beam splitting, where the meta-sound grating distributes the sound waves evenly into two beams with almost no 0th-order diffraction waves.

[0041] By adjusting the C-tube rotation angle, the meta-grating can also achieve multi-channel energy distribution with arbitrary ratios. Taking a +1, 0, and -1 order diffraction efficiency ratio of 2:0:8 as an example, adjusting the rotation angles β1 = 146.5°, β2 = 37.2°, and β3 = 16.6° will... Figure 6 As shown in (a), the diffraction efficiencies of each order are demonstrated through finite element simulation. Figure 6 (b) shows that at the operating frequency f = 6860 Hz, the +1st order diffraction efficiency is 20% and the -1st order diffraction efficiency is 80%, which accurately realizes the energy distribution function of multiple channels in any proportion. Figure 6 (c) and 6(d) more intuitively demonstrate the effect of energy distribution in arbitrary proportions across multiple channels.

[0042] Furthermore, adjusting β1, β2, and β3 allows for flexible implementation of multi-channel energy distribution functions with other ratios. For example, Table 1 shows simulation results for several different energy ratios. Therefore, this meta-cage exhibits flexibility, and the average absolute error of the diffraction efficiency for all wavefront modulation functions is within 0.01, demonstrating excellent accuracy.

[0043]

[0044] Table 1

[0045] In summary, this invention discloses a multifunctional meta-acoustic grating structure. Its tunable sub-unit structure can excite asymmetric sound wave scattering, effectively controlling sound wave propagation. It can achieve functions such as anomalous reflection, perfect beam splitting, and multi-channel energy distribution with arbitrary ratios at the operating frequency. Its flexible structure and rich functionality make it highly practical.

[0046] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. An adjustable multifunctional metasonic barrier structure, characterized in that, It comprises a reflecting plate and several unit structures arranged in sequence on one side of the reflecting plate, the distance between two adjacent unit structures is equal, and the distance between each unit structure and the reflecting plate is equal; each unit structure is composed of three C-shaped tube subunits, one of which is located above and the other two are located below.

2. The adjustable multifunctional metasurface acoustic grating structure according to claim 1, wherein the outer radius of the C-shaped tube located above is 1.30 cm, the tube wall thickness is 0.20 cm, and the opening angle is 43.90°; the two C-shaped tubes located below are of the same size, the outer radius is 0.57 cm, the tube wall thickness is 0.20 cm, and the opening angle is 43.06°.

3. The adjustable multifunctional metasurface acoustic grating structure according to claim 1, wherein the C-shaped tubes in the unit structure can rotate around the axis.

4. The adjustable multifunctional metasurface acoustic grating structure according to claim 1, wherein in the cross-sectional direction of the unit structure, the distance between the axis of the C-shaped tube located above and the axes of the two C-shaped tubes located below is uniform, and the distance between the two C-shaped tubes located below and the reflecting plate is uniform.

5. The adjustable multifunctional metasurface acoustic grating structure according to claim 4, wherein the distance between the C-shaped tube located above and the two C-shaped tubes located below is 0.79 cm, the distance between the two C-shaped tubes located below is 0.42 cm, and the distance between the two C-shaped tubes located below and the reflecting plate is 0.52 cm.

6. The adjustable multifunctional metasurface acoustic grating structure according to claim 1, wherein the wall acoustic impedance of the raw material of the unit structure and the reflecting plate is much larger than that of the background medium, at least 100 times that of the background medium.

7. The adjustable multifunctional metasurface acoustic grating structure according to claim 6, wherein the material of the unit structure is metal or organic plastic. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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