Three-dimensional acoustic vibration Moire metasurface constructed by using non-local anisotropy principle

Abstract

The invention belongs to the technical field of acoustic vibration metamaterials and fluctuation regulation and control, and particularly relates to a three-dimensional acoustic vibration Moire metasurface constructed by utilizing a non-local anisotropy principle, which is of a three-dimensional structure formed by stacking a plurality of three-dimensional units along x, y and z directions, all the three-dimensional units of each plane in the three-dimensional structure can be twisted by a set angle around the central axis perpendicular to the plane, and the three-dimensional structure not only has the capability of free torsion regulation, but also can adjust the interlayer coupling relation under different torsion angles. The system can accurately control the propagation direction and mode of sound waves in a wider three-dimensional space, meanwhile, the three-dimensional units are stacked to form a non-local state, transmission of sound energy between the units is achieved, and the sound energy of any unit can be transmitted to any other unit.

Description

Technical Field

[0001] The present invention belongs to the technical field of acoustic vibration metamaterials and wave regulation, and specifically relates to a three-dimensional acoustic vibration moiré metasurface constructed using the principle of non-local anisotropy. Background Art

[0002] Wave vibration control is a key direction in modern engineering and physics research. Especially driven by metamaterials and metasurface technologies, precise control of vibration and wave behavior has become possible. Traditional vibration systems usually rely on periodic structures or resonant units to adjust the propagation characteristics of waves, but such systems are often limited by structural scale, local resonance effects, and wavelength-related control ranges, making it difficult to achieve multi-dimensional, tunable vibration and wave control.

[0003] Due to its unique quasi-periodic control characteristics, moiré metasurfaces have shown important research value in the fields of vibration, wave and energy transfer. By applying different relative twist angles to the double-layer periodic structure, the moiré metasurface can induce novel wave propagation modes, such as magic angle flat bands, asymmetric localization, unidirectional channelization, etc. These characteristics greatly expand the application of metamaterials in vibration isolation, precision wave control and energy management. However, the current research on double-layer moiré metasurfaces is still mainly focused on two-dimensional structures, and the potential advantages of three-dimensional systems have not been fully utilized. In the research of three-dimensional vibration and wave metamaterials, non-local effects and extreme anisotropy are two key factors. Non-local effects refer to the fact that wave propagation is not only affected by local structures, but also by the coupling of long-distance structures. This characteristic is particularly significant in high-order metamaterials. On the other hand, anisotropy makes the system exhibit significantly different wave behaviors in different directions, thereby forming low-loss unidirectional channelization characteristics in specific directions, while localization can be achieved in other directions, but the research on these two factors has not yet been realized in three-dimensional systems. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention proposes a solution for realizing a three-dimensional acoustic-vibration moiré metasurface based on the principle of non-local extreme anisotropy.

[0005] The technical solution adopted by the present invention to solve the technical problem is as follows: A three-dimensional acoustic-vibration moiré metasurface constructed using the principle of non-local anisotropy is a three-dimensional structure formed by stacking a number of three-dimensional units along the x, y, and z directions. All the three-dimensional units in each plane of the three-dimensional structure can be twisted to a set angle around a central axis perpendicular to the plane.

[0006] The spacing between the planes of the three-dimensional structure can be changed.

[0007] The three-dimensional unit comprises a central resonant cavity, six end faces of the central resonant cavity are respectively provided with coupling pipes, ends of the coupling pipes are provided with coupling cavities, and the coupling pipes and coupling cavities on the symmetrical end faces of the central resonant cavity are the same.

[0008] At least one parameter of the coupling pipe lengths, coupling cavity volumes and corresponding end surface areas of the central resonant cavity on the three groups of symmetrical end surfaces of the central resonant cavity is kept different.

[0009] The coupling pipe and the coupling cavity are hollow structures, and the diameter of the coupling pipe is 1 mm to 4 mm.

[0010] A three-dimensional acoustic-vibration moiré metasurface constructed using the principle of non-local extreme anisotropy also includes a point sound source placed at the center of the three-dimensional structure.

[0011] The coupling pipe and the coupling cavity are made of light solid material.

[0012] The beneficial effects of the present invention are as follows: 1. The three-dimensional unit structure of the present application is stacked in multiple directions to form a three-dimensional structure. The three-dimensional structure not only has the ability of free torsion regulation, but also can adjust the interlayer coupling relationship at different torsion angles, so that the system can accurately control the propagation direction and mode of sound waves in a wider three-dimensional space. Compared with traditional metamaterial systems, the present invention breaks the limitations of a single structure and a fixed distance between layers, realizes the ability of continuously adjustable sound field regulation, and provides a new physical mechanism for sound wave channelization, unidirectional propagation, hyperbolic dispersion regulation, and localized wave modes.

[0013] 2. The three-dimensional structure of the present application can be a cube, a cuboid or a pyramid, and the metasurface can be applied to different array modes. By optimizing the unit arrangement and coupling parameters, the present invention can flexibly adapt to different application requirements and show excellent application potential in the fields of metasurface acoustics, ultrasonic imaging, acoustic stealth, and high-precision beam control.

[0014] 3. The three-dimensional unit stacking of the present application forms a non-local state, realizing the transfer of sound energy between units, so that the sound energy of any unit can be transferred to any other unit. This non-local characteristic means that the sound energy between different units no longer depends on the direct proximity relationship, and the propagation of sound waves is affected by the global system structure; this characteristic makes the propagation of sound waves on the metasurface more flexible, and can achieve more precise sound field control.

[0015] 4. This application takes into account the anisotropy principle and, through ingenious design, makes the acoustic impedance of the three-dimensional unit in three directions differ greatly, and the sound waves propagate along the direction perpendicular to the hyperbolic dispersion lines, thus realizing hyperbolic propagation.

[0016] 5. The metasurface of the present application has good robustness and stability, and damage to individual three-dimensional units will not significantly weaken the control effect of the overall sound wave.

[0017] 6. The three-dimensional metasurface of the present application has a relatively light overall mass and a small area, and can achieve efficient control of sound waves while maintaining the necessary strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of the structure of a three-dimensional acoustic vibration moiré supersurface of the present invention; Figure 2 A front view of the three-dimensional acoustic-vibration moiré supersurface of the present invention; Figure 3 A top view of the three-dimensional acoustic-vibration moiré supersurface of the present invention; Figure 4 It is an acoustic vibration pressure field diagram of the three-dimensional acoustic vibration moiré supersurface of the present invention under the excitation of a point sound source; Wherein, (a) is the acoustic vibration pressure field diagram of the zx plane of the three-dimensional acoustic vibration moiré supersurface of the present invention; (b) is an acoustic vibration pressure field diagram of the xy plane of the three-dimensional acoustic vibration moiré supersurface of the present invention; (c) is an acoustic vibration pressure field diagram of the yz plane of the three-dimensional acoustic vibration moiré supersurface of the present invention; Figure 5 is a dispersion curve diagram of a single stereo unit of the three-dimensional acoustic vibration moiré metasurface of the present invention; Description of reference numerals: 1. Stereo unit; 2. Central resonant cavity; 3. Coupling pipe; 301. Z-direction coupling pipe; 302. X-direction coupling pipe; 303. Y-direction coupling pipe; 4. Coupling cavity; 401. Z-direction coupling cavity; 402. Y-direction coupling cavity; 403. X-direction coupling cavity. DETAILED DESCRIPTION

[0019] The specific implementation modes of the present invention are described in detail below with reference to the accompanying drawings.

[0020] See also Figure 1-3 A three-dimensional acoustic-vibration moiré metasurface constructed using the principle of non-local anisotropy is a three-dimensional structure formed by stacking a number of three-dimensional units 1 along the x, y, and z directions. All the three-dimensional units 1 in each plane of the three-dimensional structure can be twisted around a central axis perpendicular to the plane at a set angle. The three-dimensional structure can be flexibly assembled into a cube, a rectangular parallelepiped, or a pyramidal structure according to needs. Different forms of three-dimensional structures can be divided into multiple planes that can be twisted with each other according to different directions, and the spacing between the planes of the three-dimensional structure can be changed. Partitions can be added between the planes or all the three-dimensional units 1 in one of the planes can be raised to a set height.

[0021] The three-dimensional acoustic vibration moiré metasurface system of the present application is based on the "magic mode" torsion structure. The three-dimensional structure can be divided into several planes according to the x direction, y direction, z direction or inclined plane direction. Each plane can be twisted around the central axis perpendicular to the plane at a certain angle, thereby effectively expanding the adjustment freedom of the system and realizing flexible adjustment of the sound wave propagation path, phase and amplitude; at the same time, the present application considers the non-local idea, and forms a three-dimensional structure by stacking several three-dimensional units 1 along the x, y and z directions to form a non-local metasurface, realizing the transmission of sound energy between units, so that the sound energy of any three-dimensional unit can be transmitted to any other three-dimensional unit, and the sound energy can be efficiently transmitted in the entire system, rather than being limited to a certain local area, thereby realizing a non-local state. This non-local characteristic means that the sound energy between different units no longer depends on the direct proximity relationship, and the propagation of sound waves is affected by the global system structure; this characteristic makes the propagation of sound waves on the metasurface more flexible, and more precise sound field control can be achieved; and the spacing between the planes of the present application can be changed, thereby changing the coupling strength, greatly reducing energy loss, and enhancing the unidirectional and localized acoustic vibration isolation effect of the system.

[0022] The three-dimensional unit 1 includes a central resonant cavity 2, and coupling pipes 3 are respectively provided on the six end faces of the central resonant cavity 2. A coupling cavity 4 is provided at the end of the coupling pipe 3. The coupling pipes 3 and the coupling cavity 4 on the symmetrical end faces of the central resonant cavity 2 are the same. The coupling pipes 3 and the coupling cavity 4 are hollow structures. The diameter of the coupling pipe 3 is 1-4 mm, and the coupling pipes 3 and the coupling cavity 4 are made of lightweight solid materials.

[0023] The lengths of the coupling pipes 3 on the three groups of symmetrical end faces of the central resonant cavity 2, the volumes of the coupling cavities 4 and the corresponding end face areas of the central resonant cavity 2 keep at least one parameter different. This setting is to ensure that the acoustic impedances of the central resonant cavity 2 in the x, y and z directions are different, thereby showing anisotropy. The lengths of the coupling pipes, the volumes of the coupling cavities and the corresponding plane areas of the central resonant cavity all have a certain influence on the parameters of the acoustic impedance. Therefore, at least one of the above three parameters needs to be kept different during the setting.

[0024] This application takes into account the anisotropy principle and, through the clever design of the size of the three-dimensional unit, makes the acoustic impedance in three directions have a large difference, thus successfully achieving extreme anisotropy. In the isotropic metasurface, the dispersion curve of the wave is circular, and the sound wave diffuses in all directions, and the wave propagation is unrestricted. Figure 5 As shown, the dispersion curve of our metasurface is hyperbolic, which means that the sound wave propagates along the vertical direction of the hyperbola, that is, hyperbolic propagation is achieved, which is a manifestation of the extreme anisotropy effect.

[0025] The three-dimensional acoustic vibration moiré metasurface constructed using the principle of non-local anisotropy also includes a point sound source, which is placed at the center of the three-dimensional structure. The point sound source is used for acoustic vibration excitation of the metasurface, so that the sound energy can be efficiently coupled and directly transmitted to the metasurface unit array to maximize the efficiency of sound wave injection and ensure that the energy is evenly distributed to the surrounding units. This is the most important "sound source coupling area".

[0026] Example 1

[0027] In this embodiment, the three-dimensional acoustic vibration moiré metasurface is firmly mounted on the frame, which is a 5×5×5 array structure formed by stacking a number of three-dimensional units 1 along the x, y, and z directions. The lattice step length of each three-dimensional unit 1 is 40 mm. The three-dimensional unit 1 includes a z-direction coupling pipe 301, a z-direction coupling cavity 401, a y-direction coupling cavity 402, an x-direction coupling cavity 403, a central resonant cavity 2, an x-direction coupling pipe 302, and a y-direction coupling pipe 303. The symmetrical end faces of the central resonant cavity 2 along the x, y, and z directions are respectively provided with an x-direction coupling pipe 302, a y-direction coupling pipe 303, and a z-direction coupling pipe 301. The ends of the x-direction coupling pipe 302, the y-direction coupling pipe 303, and the z-direction coupling pipe 301 are respectively provided with an x-direction coupling cavity 403, a y-direction coupling cavity 402, and a z-direction coupling cavity 401.

[0028] Considering the anisotropy principle, in this embodiment, the central resonant cavity 2 is a rectangular parallelepiped structure, the z-direction coupling cavity 401 corresponds to the plane with the largest planar area of ​​the central resonant cavity 2, the area of ​​the plane corresponding to the x-direction coupling cavity 403 is second, and the area of ​​the plane corresponding to the y-direction coupling cavity 402 is the smallest. Therefore, in the design, the cavity volume of the z-direction coupling cavity 401 is the largest, and the cavity areas of the y-direction coupling cavity 402 and the x-direction coupling cavity 403 are the same; the length of the x-direction coupling pipe 302> the length of the z-direction coupling pipe 301> the length of the y-direction coupling pipe 303, at this time, the cavity volume of the z-direction coupling cavity 401 is larger than the y-direction coupling cavity 402 and the x-direction coupling cavity 403, which causes the acoustic impedance in the z direction to be smaller than that in the x and y directions; at the same time, the central resonant cavity 2 is a rectangular parallelepiped shape, and the size difference between its short side and long side makes the acoustic impedance in the x and y directions also different, so the acoustic impedance of a single three-dimensional unit is relatively different, thereby successfully realizing extreme anisotropy.

[0029] The specific dimensions of the central resonant cavity 2 are 18 mm long × 15 mm wide × 6 mm high; the z-direction coupling cavity 401 is 12 mm long, 10 mm high, and the z-direction coupling pipe 301 is a cylindrical channel with a radius of 2 mm and a height of 7 mm; the x-direction coupling cavity 403 and the y-direction coupling cavity 402 are 9 mm long, 5 mm high, the length of the x-direction coupling pipe 302 is 7.5 mm, and the length of the y-direction coupling pipe 303 is 6 mm, and the pipe radius of both is 2 mm; each stereo unit 1 is printed using R4600 resin material additive manufacturing technology (3D), and the wall thickness of the printed parts is 1 mm, which can reduce the overall weight while ensuring the acoustic vibration performance and structural accuracy. If it is necessary to adapt to lower frequency applications, the unit size can be enlarged as a whole; if higher frequencies are required, the unit size can be reduced while maintaining the precise proportion between the various components of the structure.

[0030] In order to ensure that the entire structure can obtain the optimal sound source coupling effect, the present invention places a point sound source at the connection of the central resonant cavity in the center of the three-dimensional structure. The sound source model is 13A05-8Ω, so that the sound waves can be efficiently coupled and transmitted to each three-dimensional unit of the metasurface three-dimensional structure. At the array scale of 5×5×5, by combining the point sound source with the three-dimensional metasurface structure and utilizing the coupling characteristics of the pipe and the cavity in the three-dimensional direction, the system achieves efficient regulation and uniform distribution of sound waves. This design scheme can not only flexibly adjust the sound field distribution, but also exhibits excellent stability and adaptability, and is suitable for multiple fields such as sound wave detection, beamforming, and ultrasonic imaging.

[0031] In this embodiment, the materials, dimensions, and torsion angles of each layer of each unit and its coupling pipe and coupling cavity can be adjusted proportionally within a certain range. In terms of size design and frequency adaptability, this embodiment selects a lattice step length of 40 mm, and can proportionally enlarge or reduce the unit size according to demand to adapt to different operating frequency requirements. In terms of manufacturing and assembly process, the present invention uses 3D printing technology to ensure structural accuracy and acoustic vibration characteristics, and at the same time designs alignment and positioning structures on the unit edge and connection surface to simplify the assembly process and improve system stability.

[0032] The metasurface in this embodiment is verified by fixing a point sound source at the center of the metasurface and arranging multiple point sensors around it to measure the sound field, which verifies the invention's ability to precisely control sound waves in multiple dimensions and its robustness to external noise and reflected wave interference in complex environments. At the same time, the metasurface can maintain excellent acoustic vibration control performance in multiple frequency bands, ensuring its wide applicability in practical applications.

[0033] like Figure 4As shown, the acoustic vibration pressure field analysis of the metasurface of the present application is performed, and the middle three layers of the metasurface of the present application are twisted 23° along the z-axis direction for acoustic vibration pressure field analysis. The analysis results show that by adjusting the twisting angle, a unidirectional hyperbolic wave propagation generated in space occurs in the zx plane of the metasurface, a highly concentrated low-loss channelized propagation occurs in the xy plane, and a localized wave phenomenon occurs in the yz plane. A metasurface has three kinds of manipulated waves in three different spatial planes, which shows that the metasurface has precisely intervened in the propagation of waves in high dimensions, achieving the purpose of efficient regulation and uniform distribution. By comparing the size of the system and the length of the spatial wave propagation path, it can be found that: relative to the affected spatial range, the size of the metasurface is very small and the efficiency is very high, which is conducive to a wide range of applications.

[0034] Through the planar torsion adjustment of the 5×5×5 moiré metasurface, the present invention can flexibly realize a variety of acoustic vibration modes, including channelized propagation, unidirectional hyperbolic wave propagation, and localized wave modes, providing richer and more diverse acoustic vibration control capabilities. This innovative control method effectively solves the adjustment limitations caused by the fixed interlayer distance in traditional metamaterial systems, and enables the system to have higher tunability and acoustic vibration energy management capabilities.

[0035] like Figure 5 As shown in the figure, the isofrequency curve analysis of the structure of a single three-dimensional unit was performed using COMSOL Multiphysics software. The analysis results show that the different resonance cavity volumes, central cavity shapes and pipe connection lengths in the x, y and z directions together lead to differences in the resonance modes in the three directions, resulting in differences in acoustic impedance in different directions, resulting in anisotropy. This anisotropy leads to Figure 5 Hyperbolic dispersion curves are shown in Figure 1, where the dispersion lines change from the middle to the edge. These hyperbolas indicate that the group velocity of the sound waves no longer spreads out in all directions, but is affected by anisotropy and propagates in the direction perpendicular to the hyperbolas. The frequency range shown also shows that the propagation of waves in the metasurface exhibits deep subwavelength characteristics.

[0036] In this embodiment, by designing and precisely controlling the size, length and structural parameters of the coupling pipe and the coupling cavity in the x, y and z directions, the system exhibits differentiated acoustic impedance in different directions, thereby exhibiting hyperbolic dispersion characteristics (i.e., extreme anisotropy) in each dimensional plane. With this characteristic, the propagation path and mode of the sound wave can be flexibly controlled by adjusting the torsion angle of each layer or the distribution between units.

[0037] In this embodiment, a 5×5×5 layer moiré system stacking strategy is adopted. This scheme successfully realizes a variety of wave behaviors, including channelized propagation, unidirectional hyperbolic propagation, and localized wave modes, demonstrating excellent regulation capabilities and broad application potential.

[0038] Based on the principle of non-local anisotropy, this application proposes a design scheme for realizing a three-dimensional acoustic vibration moiré metasurface. The three-dimensional acoustic vibration moiré metasurface of the present invention realizes ultra-low loss unidirectional channelization and localized acoustic vibration control while ensuring the ability to control multi-dimensional acoustic vibration propagation, greatly improving the efficiency of energy transfer and vibration control. Based on the principle of non-local anisotropy, the system reasonably designs the torsion angle so that all dimensions can be transformed into a "magic angle" with flat band characteristics, thereby breaking the traditional system's dependence on a single torsion angle and expanding the freedom of acoustic vibration control.

[0039] This application adopts a non-local design concept. Through the connection of multiple three-dimensional units, that is, the cross connection between the pipe and the cavity, energy can be freely transmitted in the entire system, further improving the control efficiency and flexibility of sound wave propagation. Through this innovative design, the present invention has excellent beam control capabilities without significantly increasing the overall mass and volume. Due to the existence of hyperbolic acoustic dispersion characteristics, the system exhibits extreme anisotropy in multiple directions, achieving efficient and controllable propagation modulation of sound waves in a wide frequency band.

[0040] At the same time, the anisotropy principle, the shape of the central resonant cavity, the volume of the coupling cavity and the length of the coupling pipe are taken into consideration, so that the system exhibits unique directional selectivity in different directions, resulting in a large difference in acoustic impedance in the three directions, thus successfully achieving extreme anisotropy.

[0041] The present invention has the advantages of flexible structural design, strong controllability, and strong scalability. At the same time, by optimizing the interlayer coupling mechanism and adjusting the parameters of the coupling tube, the energy transmission and acoustic vibration control process of the system can be made more stable, energy loss can be reduced, and the unidirectional and localized acoustic vibration isolation effect of the system can be enhanced. The innovativeness of this technology gives it broad application prospects in the fields of high-precision vibration control, energy transfer, subwavelength wave manipulation, and high-sensitivity sensing, and provides a new solution for the further development of wave and vibration control technology.

[0042] The above examples are only used to illustrate the feasibility and practical operation of the present invention, and are not intended to limit the present invention. Within the scope of knowledge possessed by those skilled in the art, corresponding adjustments and optimizations can also be made without departing from the core concept of the present invention. Through the above design and adjustable method, the present invention successfully realizes a three-dimensional metasurface structure with characteristics such as extreme anisotropic dispersion, flexible torsion regulation, and multi-frequency acoustic vibration adaptation. It can be widely used in multiple fields such as acoustic imaging, acoustic stealth, and ultrasonic sensing, providing an innovative solution for the research and application of acoustic vibration metasurfaces.

Claims

1. A three-dimensional acoustic vibration moiré metasurface constructed using the principle of non-local anisotropy, characterized in that: It is a three-dimensional structure formed by stacking a number of three-dimensional units along the three directions of x, y and z. All the three-dimensional units in each plane of the three-dimensional structure can be twisted at a set angle around a central axis perpendicular to the plane.

2. The three-dimensional acoustic vibro-moiré metasurface constructed using the non-local anisotropy principle according to claim 1, characterized in that: The spacing between the planes of the three-dimensional structure can be changed.

3. The three-dimensional acoustic vibro-moiré metasurface constructed using the non-local anisotropy principle according to claim 1, characterized in that: The three-dimensional unit comprises a central resonant cavity, six end faces of the central resonant cavity are respectively provided with coupling pipes, ends of the coupling pipes are provided with coupling cavities, and the coupling pipes and coupling cavities on the symmetrical end faces of the central resonant cavity are the same.

4. The three-dimensional acoustic vibro-moiré metasurface constructed using the non-local anisotropy principle according to claim 3, characterized in that: At least one parameter of the coupling pipe lengths, coupling cavity volumes and corresponding end surface areas of the central resonant cavity on the three groups of symmetrical end surfaces of the central resonant cavity is kept different.

5. The three-dimensional acoustic vibro-moiré metasurface constructed using the non-local anisotropy principle according to claim 3, characterized in that: The coupling pipe and the coupling cavity are hollow structures, and the diameter of the coupling pipe is 1mm-4mm.

6. The three-dimensional acoustic vibro-moiré metasurface constructed using the non-local anisotropy principle according to claim 1, characterized in that: A point sound source is also included, which is placed at the center of the three-dimensional structure.

7. The three-dimensional acoustic vibro-moiré metasurface constructed using the non-local anisotropy principle according to claim 3, characterized in that: The coupling pipe and the coupling cavity are made of light solid material.

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