Unit cell structure of reconfigurable local resonance valley topology acoustic elastic waveguide, photonic crystal plate and application of photonic crystal plate
By incorporating fluid-solid coupling design into the unit cell structure of a phononic crystal plate and utilizing the selective filling of liquid to break lattice symmetry, path reconfigurability and frequency modulation of low-frequency acoustic elastic waves are achieved. This solves the problems of high frequency and non-reconfigurable structure in existing technologies and is applicable to acoustic sensing and information processing systems.
Patent Information
- Application Number
- CN202511409915.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-29
- Publication Date
- 2026-01-09
AI Technical Summary
Existing valley topological phonon crystals are designed for high frequencies, typically exceeding 1 kHz, and once the structure is manufactured, the geometry or material parameters cannot be changed, making it difficult to achieve control of low-frequency acoustic spatter and flexible adjustment of the propagation path.
By employing a fluid-solid coupling design, liquids of different levels, concentrations, or types are placed in the unit cell structure of the phononic crystal plate to break the lattice symmetry and form a reconfigurable local resonant valley topological acoustic waveguide, thereby realizing path reconfigurability and frequency tuning of low-frequency acoustic elastic waves.
It achieves topological manipulation of low-frequency acoustic elastic waves, enabling selective filling of liquids without altering the basic structure to meet different acoustic characteristic requirements. It realizes low-frequency, path reconfigurable, and frequency-tunable acoustic elastic waves, and is suitable for acoustic sensing and information processing systems in miniaturized scenarios.
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Figure CN121306083A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a unit cell structure of a reconfigurable local resonant valley topological acoustic elastic waveguide, a phononic crystal plate, and their applications, belonging to the field of phononic crystal technology. Background Technology
[0002] Materials or structures with periodically distributed elastic constants and density are called phononic crystals. A phononic crystal is a functional material formed by periodically arranging elastic solids within another solid or fluid medium. When acoustic elastic waves propagate in a phononic crystal, they are blocked from propagating within a certain frequency range (bandgap) due to its internal structure, while they can propagate without loss in other frequency ranges (passband). Therefore, by designing periodic composite materials, phononic crystals can possess unique acoustic elastic wave modulation characteristics, forming phononic bandgap characteristics with complete bandgap features in specific frequency bands.
[0003] Phononic crystals can precisely suppress the propagation of acoustic elastic waves in specific frequency bands through the bandgap effect. By introducing defects into a phononic crystal to disrupt the periodicity of its structure, localized wave states can be formed within its bandgap range, concentrating energy near the defect and causing it to rapidly decay with distance from the defect. Based on this, intelligent waveguide systems with spatial filtering capabilities can be designed. These characteristics make phononic crystal waveguides highly promising for applications in the miniaturization of ultrasonic devices, mechanical vibration isolation, and acoustic stealth, especially their ability to actively control the bandgap frequency range, which provides theoretical support for the development of next-generation programmable acoustic devices.
[0004] Furthermore, valley-topological phononic crystals establish a valley Hall phase by breaking the mirror or inverted symmetry of the lattice, thereby opening the Dirac cone in the band structure. Valley-topological edge states appear at the interface between two structures with opposite valley Hall phases, allowing the propagation of acoustic elastic waves to be unaffected by defects and corners in the transmission path. However, most existing valley-topological phononic crystal designs rely on the Dirac phase transition induced by Bragg scattering, with the corresponding frequency determined by the lattice constant, resulting in high waveguide frequencies, typically exceeding 1 kHz. Therefore, achieving low-frequency topological transmission often requires larger lattice sizes, which does not meet practical application requirements. Simultaneously, once the structure of the phononic crystal in existing research is fabricated, its geometry or material parameters are usually immutable, making it difficult to alter the propagation path and transmission frequency of acoustic elastic waves, significantly limiting the practical application of acoustic elastic wave manipulation.
[0005] The present invention aims to provide a reconfigurable local resonant valley topological acoustic waveguide structure with simple structure, convenient fabrication and excellent low-frequency performance, so as to realize the control of the propagation path and transmission frequency of low-frequency acoustic wave. Summary of the Invention
[0006] To address the problems existing in the prior art, this invention provides a unit cell structure of a reconfigurable local resonant valley topological acoustic elastic waveguide, a phonon crystal plate, and its applications. It adopts a fluid-solid coupling design, combining the low-frequency characteristics of local resonance with the flexibility of fluid dynamic control. Through fluid control, it achieves three effects: low frequency, path reconfigurability, and frequency tunability.
[0007] The present invention achieves the above objectives by adopting the following technical solutions:
[0008] The present invention provides a unit cell structure of a reconfigurable local resonant valley topological acoustic waveguide, comprising a substrate and two cups, wherein each cup is formed by a bottom wall and a circumferential side wall, and the cup is used to hold liquid.
[0009] The substrate is rhomboid in shape, with two through holes. The center line connecting the two through holes is set along one of the diagonals of the rhombus. The lower parts of the two cups are respectively placed in the two through holes, and the lower part of the circumferential sidewall of the cup is connected to the hole wall of the through hole by several connecting beams.
[0010] Specifically, the two cups contain liquids of the same or different levels, concentrations, or types.
[0011] Furthermore, the outer cross-sectional shape and the inner cross-sectional shape of the cup body are circular or regular polygonal.
[0012] Typically, there are three connecting beams.
[0013] The length of the connecting beam extends radially along the cup body.
[0014] The phononic crystal plate provided by the present invention is formed by a periodic arrangement of multiple unit cell structures. The multiple unit cell structures are arranged in an array along the side length direction of the substrate, and the substrates of adjacent unit cell structures are connected as one unit.
[0015] On the one hand, the phonon crystal plate can be used to obtain low-frequency topological edge states, and the application method includes the following steps:
[0016] S1. Calculate the band structure of the unit cell to obtain the low-frequency Dirac cone;
[0017] S2. Change the way the liquid is filled in the unit cell structure cup to break the spatial symmetry and form a unit cell structure with opposite valley topological phase. Combine the unit cell structures into a phonon crystal plate and calculate its band structure. A topological edge state is formed at the junction of opposite valley topological phases.
[0018] On the other hand, the phonon crystal plate can be used to control the propagation path of the acoustic wave. The application method includes the following steps: liquid filling of the unit cell structure on both sides of the specified transmission path according to different filling methods.
[0019] The transmission path includes straight, L-shaped, Z-shaped, or bifurcated types, and the different filling methods include different liquid levels, types, or concentrations.
[0020] Furthermore, the phonon crystal plate can be used to control the transmission frequency of acoustic splice waves, and the application method includes the following steps:
[0021] The frequency of acoustic wave transmission can be controlled by changing the way the liquid is filled in the unit cell structure on both sides of a specified transmission path.
[0022] The beneficial effects of the present invention include, but are not limited to:
[0023] The present invention provides a reconfigurable local resonant valley topology acoustic elastic waveguide unit cell structure, phononic crystal plate and its application. Through the principle of local resonance and fluid-solid coupling design, the topology of low-frequency acoustic elastic waves is realized. Without changing the basic structure, liquid can be selectively filled in the resonant cavity to meet different acoustic characteristic requirements. It realizes the low frequency, path reconfigurability and frequency control of acoustic elastic waves, and solves the problems of limited low-frequency transmission and non-reconfigurable structure of traditional valley topology phononic crystals.
[0024] On the one hand, the structure based on local resonance of a cup-shaped resonant cavity provided by this invention can form Dirac cones in the low-frequency range (<1kHz). By making the liquid volumes in the two resonant cavities of the unit cell structure different, the lattice symmetry can be broken, realizing valley topological edge states. Specifically, the periodically arranged phonon crystal plate composed of the cup-shaped resonant cavity and the connecting beam introduces low-frequency Dirac degeneracy through local resonance, breaking the low-frequency limitation of traditional Bragg-type topological structures that depend on lattice size. When the liquid selectively fills different resonant cavities, the lattice symmetry is destroyed, forming an interface with opposite topological phases, allowing topologically protected edge states to propagate along the interface.
[0025] On the other hand, this invention adjusts the spatial distribution of liquid filling by selectively filling different resonant cavities with liquid, and flexibly reconstructs waveguide paths such as straight, L-shaped, Z-shaped and bifurcated types, so as to realize the efficient transmission of acoustic elastic waves along different paths. This dynamic path control capability enables low-loss transmission of elastic waves along complex paths.
[0026] Furthermore, the present invention can also change the effective mass of the resonant cavity by adjusting the liquid parameters (such as liquid level or concentration) in the resonant cavity, continuously control the transmission frequency of the acoustic wave, so that the frequency band of the topological edge state can be continuously adjusted, and the tuning effect is not affected by the shape of the waveguide path.
[0027] This invention combines the low-frequency characteristics of local resonance with the flexibility of fluid dynamic control, providing a programmable acoustic wave manipulation platform for intelligent acoustic sensing, adaptive acoustic waveguides and information processing systems, especially suitable for the precision manipulation requirements of low-frequency acoustic waves in miniaturized scenarios. Attached Figure Description
[0028] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:
[0029] Figure 1 This is a schematic diagram of a unit cell structure, where (a) is an axonometric sectional view and (b) is a top view. The gray and blue areas represent solids and liquids, respectively.
[0030] Figure 2 This is a top view of the periodic structure of a phonon crystal plate.
[0031] Figure 3 In the diagrams (a), (b), and (c), respectively, are model diagrams and band structure diagrams of type A, type B, and type C unit cells. The chromaticity bars represent the polarization of the vibrational displacement in the z-direction.
[0032] Figure 4 Let (a) be the topological boundary states of a supercell composed of B-type unit cells and C-type unit cells, where (a) is the finite element model of the supercell, (b) is the band structure of the supercell, and (c) is the eigenmode of the supercell; in (b), the horizontal axis is the reduced wave vector and the vertical axis is the dimensionless frequency.
[0033] Figure 5 The propagation characteristics of the acoustic wave along different topological propagation paths are shown in (a)-(e), where (f)-(j) are the finite element models of different propagation paths, (f)-(j) are the numerical simulation propagation spectra, and (k)-(o) are the displacement field distribution of the phonon crystal plate at 465Hz.
[0034] Figure 6 The diagrams show the transmission characteristics of acoustic elastic waves along linear and Z-shaped topological paths in phononic crystal plates filled with water at different levels. (a) shows the relationship between the topological edge state frequency and the water level h, (b) shows the transmission spectrum of the linear waveguide, (c) shows the transmission spectrum of the Z-shaped waveguide, (d)-(f) show the displacement field distribution of the linear waveguide, and (g)-(i) show the displacement field distribution of the Z-shaped waveguide.
[0035] Figure 7 The transmission characteristics of acoustic elastic waves along linear and zigzag topological paths in phononic crystal plates containing MgSO4 solutions of different concentrations are shown. (a) represents the relationship between the topological edge state frequency and the MgSO4 solution concentration, (b) represents the transmission spectrum of the linear waveguide, (c) represents the transmission spectrum of the zigzag waveguide, (d)-(f) represent the displacement field distribution of the linear waveguide, and (g)-(i) represent the displacement field distribution of the zigzag waveguide.
[0036] In the figure, 1 is the substrate; 11 is the through hole; 2 is the cup body; 21 is the bottom wall; 22 is the circumferential side wall; 3 is the liquid; and 4 is the connecting beam. Detailed Implementation
[0037] To clearly illustrate the technical features of this solution, the invention will be described in detail below through specific implementation methods and in conjunction with the accompanying drawings.
[0038] It should be noted that many specific details are set forth in the following description to provide a thorough understanding of the invention; however, the invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the invention is not limited to the specific embodiments disclosed below.
[0039] Example 1:
[0040] like Figure 1 As shown, the unit cell structure provided in this embodiment includes a substrate 1 and two cups 2. The cups 2 are enclosed by a bottom wall 21 and a circumferential side wall 22 to form a cup cavity, which is used to hold liquid 3.
[0041] Specifically, the circumferential sidewall 22 of the cup body 2 is perpendicular to the bottom wall 21 and the substrate 1. The substrate 1 is rhomboid in shape, and two through holes 11 are formed on the substrate 1. The center line of the two through holes 11 is arranged along one of the diagonals of the rhombus. The two cup bodies 2 are respectively placed in the two through holes 11, and the lower part of the circumferential sidewall 22 of the cup body 2 is connected to the hole wall of the through hole through several thin connecting beams 4. Figure 1 The blue area represents the liquid 3 contained within, while the gray area represents the solid structure, including the substrate 1, the cup body 2, and the connecting beam 4.
[0042] In this embodiment, the dimensions of the unit cell structure are as follows:
[0043] The side length of the substrate is a = 100 mm, the diameter of the through hole is R = 24.5 mm, the inner diameter of the cup is r1 = 19 mm, the outer diameter of the cup is r2 = 21 mm, the horizontal width of the connecting beam is b = 3 mm, the bottom wall thickness of the cup is t = 2 mm, the thickness of the substrate and connecting beam is d = 4 mm, the height of the cup is c = 50 mm (excluding the bottom wall), and h1 and h2 are the liquid levels in the left and right cups, respectively.
[0044] In this embodiment, the solid structure is made of epoxy resin (density ρ). s =1130kg / m 3 (Poisson's ratio v = 0.42, Young's modulus E = 2.65 GPa). It should be noted that this invention does not limit the type of solid structure or liquid; the appropriate type can be selected based on the actual situation.
[0045] Example 2:
[0046] like Figure 2As shown, the phononic crystal plate is formed by arranging multiple unit cell structures in an array along the side length direction of the substrate, i.e., along the two basis vector directions a1 and a2, with adjacent unit cell structures connected as a single unit. The phononic crystal plate provided in this embodiment can be formed by 3D printing or other processing methods.
[0047] Example 3:
[0048] In this embodiment, the low-frequency topological edge states are obtained by calculating the band structure of the unit cell and the phononic crystal plate, as follows:
[0049] S1. Using finite element simulation, a Floquet-Bloch periodic boundary condition is applied to a unit cell structure, and a sweep is performed along the first irreducible Brillouin zone in the reciprocal space to calculate the band structure characteristics and obtain the low-frequency Dirac cone.
[0050] S2. Change the filling method of the liquid in the cup resonator of the unit cell structure, such as the position, level or type of liquid, to break the spatial symmetry and form a unit cell structure with opposite valley topological phase. Combine the unit cell structures into a phonon crystal plate and calculate its band structure. There are topological edge states at the junction of opposite valley topological phases.
[0051] Specifically, in this embodiment, three types of unit cell structures were constructed: type A unit cell, type B unit cell, and type C unit cell.
[0052] Each cup cavity within the unit cell structure constitutes a resonant cavity.
[0053] In the A-type unit cell, the water level in both resonant cavities is 25 mm.
[0054] In the B-type unit cell, the left resonant cavity is empty of water, while the right resonant cavity is filled with water at a level of 50 mm.
[0055] In the C-type unit cell, the left resonant cavity is filled with water at a level of 50 mm, while the right resonant cavity is not filled with water.
[0056] like Figure 3 The diagram shows three unit cell structures and their band structures. For type A unit cells, since the liquid levels in the two resonant cavities are the same, their resonant frequencies are the same, and the spatial symmetry of the lattice remains intact. Therefore, the eigenfrequency degeneracy occurs at the high symmetry point K (425Hz), forming a Dirac cone in the band structure. Figure 3 As shown in (a). For type B and type C unit cells, due to the destruction of the mirror symmetry of the lattice, the degeneracy of the K point disappears, the Dirac cone opens, thus forming a band gap of 423-513 Hz in the band structure, as shown in (a). Figure 3 As described in (b) and (c).
[0057] Next, a supercell composed of B-type and C-type unit cells is used to verify the existence of topological edge modes within the local resonant bandgap frequency range. For example... Figure 4 As shown in (a), the finite element model of the phononic crystal plate has five B-type unit cells and five C-type unit cells arranged periodically on both sides of the middle interface, and the topological phases of the unit cells on both sides of the interface are different.
[0058] like Figure 4 As shown in (b), the band structure of this supercell reveals a passband connected by a solid red line within the band gap range (423-513 Hz) formed after the lattice symmetry is broken. The z-direction eigenmodes at any point A (e.g., 473 Hz) on this passband are as follows... Figure 4 As shown in (c), the modal diagram reveals that the characteristic modes of the supercell are symmetrical with respect to the interface. The vibrational displacements in the z-direction are concentrated near the supercell interface and decay rapidly away from the interface (subsequent displacement fields all represent the vibrational displacement fields in the z-direction). The results indicate that this passband represents the valley topology edge mode. Simultaneously, the maximum vibrational displacement occurs in the resonant cavity near the interface, which is due to local resonance.
[0059] Example 4:
[0060] In this embodiment, a phonon crystal plate is used to control the propagation path of acoustic splicing waves. The application method includes the following steps: filling the unit cell structures on both sides of a specified transmission path with liquid according to different filling methods; the transmission path includes linear, L-shaped, Z-shaped, or bifurcated types, etc., and the different filling methods include different liquid levels, types, or concentrations. For example, different waveguide paths can be designed on the phonon crystal plate by changing the position of the cup filled with liquid.
[0061] Specifically, in the unit cell structure to the left of the transmission direction indicated by the arrow in the specified transmission path (linear, L-shaped, Z-shaped), the cup located at the lower left corner of the unit cell structure is left unfilled, while the cup located at the upper right corner is filled with liquid. In the unit cell structure to the right of the specified transmission path arrow, the cup located at the lower left corner of the unit cell structure is filled with liquid, while all cups located at the upper right corner are filled with liquid. In the formed phonon crystal plate, each cup can form a repeating hexagonal structure.
[0062] For example, Figure 5 In diagrams (a)-(e), the resonant cavities at different locations on both sides of the interface of the phononic crystal plate are filled with water, while the remaining resonant cavities are empty. Different filling methods on both sides of the interface create specific transmission paths, resulting in linear, L-shaped, Z-shaped, and bifurcated transmission paths. The bifurcated path includes both cases where the wave propagation direction changes and cases where the wave propagation direction remains unchanged. The excitation position (black star) and the receiving position (red and green stars) are marked at the beginning and end of the transmission path, respectively.
[0063] like Figure 5 As shown in (f)-(j), by analyzing the propagation characteristics of the acoustic jet wave along different propagation paths, it can be found that strong resonance peaks appear in the white region of the propagation spectrum for different paths, while the propagation rate of the acoustic jet wave decreases rapidly in the gray region. The frequency range of the white region is similar to... Figure 4 The frequency matching of the topological edge states in the supercell band structure of (b) is good, indicating that the acoustic elastic waves in the frequency range of the topological edge states can propagate along different topological paths.
[0064] The displacement field distribution of an acoustic ballistic wave propagating along different topological paths at 465Hz is as follows: Figure 5 As shown in (k)-(o), it can be seen that the vibrations are well concentrated near the designed transmission path. Observing the displacement distribution, it can be seen that the interface between the vibration and the wave propagation path is also symmetrical. Therefore, this embodiment proves that the designed reconfigurable valley topology phonon crystal can control the topological propagation path of the acoustic elastic wave by selectively adding water to different resonant cavities to design different topological interface paths.
[0065] Example 5:
[0066] In this embodiment, the phonon crystal plate is used to control the propagation frequency of the acoustic elastic wave. The application method includes the following steps:
[0067] The frequency of acoustic wave transmission can be controlled by changing the liquid level, concentration, or type of liquid in the unit cell structure on both sides of a specified transmission path.
[0068] For example, the liquid level or concentration in the cups to the left and right of the direction of transmission indicated by the arrow in the specified transmission path (straight line, Z-shaped) can be changed.
[0069] First, we introduce the case of controlling the topological edge state frequency by adjusting the water level in the resonant cavity. Specifically, for linear and Z-shaped paths, we keep the empty resonant cavity unchanged and set the water level in the resonant cavity to 32mm, 38mm, and 44mm, respectively, to study the change of the topological edge state frequency with the water level.
[0070] like Figure 6 As shown in Figure (a), the dispersion bands of the topological edge states in the supercell band structure change when water is added at different levels. It can be seen that the frequency of the dispersion bands gradually decreases as the water level h increases.
[0071] like Figure 6 Figures (b) and (c) show the transmission spectra of the acoustic elastic wave propagating along linear and zigzag topological paths when water is added at different levels. It can be seen that as the water level h increases, the frequency of the resonance peaks in the transmission spectrum gradually decreases, and the range of resonance frequencies is similar to... Figure 6The frequency range of the dispersion bands of the supercell topological edge modes remains consistent in (a).
[0072] like Figure 6 As shown in (d)-(f) and (g)-(i), the displacement fields of the linear and zigzag topological transmission paths at different water levels are obtained. It can be seen that the vibrations are well concentrated on the linear and zigzag paths, and the vibration modes are symmetrical along the transmission interface, consistent with the supercell eigenmodes. This indicates that as the water level h increases, the frequency of the topological edge modes decreases, thus achieving frequency modulation of the acoustic elastic wave transmission.
[0073] Next, MgSO4 solution was used as the solution added into the resonant cavity, and the frequency of the topological edge states was controlled by changing the concentration of MgSO4 solution in the resonant cavity.
[0074] Specifically, for both linear and Z-shaped paths, the empty resonant cavity was kept constant, and the concentration ratio of MgSO4 solution in a 50mm cup was set to 8%, 16%, and 24%, respectively, to study the change of topological edge state frequencies with the concentration of added liquid.
[0075] like Figure 7 As shown in Figure (a), the changes in the dispersion bands of the topological edge states in the supercell band structure are observed when different concentrations of MgSO4 solution are added. It can be seen that the frequency of the dispersion bands gradually decreases with increasing MgSO4 solution concentration.
[0076] like Figure 7 Figures 7(b) and 7(c) show the transmission spectra of the acoustic elastic waves propagating along linear and zigzag topological paths when different concentrations of MgSO4 solution are added. It can be seen that as the concentration of MgSO4 solution increases, the frequency of the resonance peaks in the transmission spectrum decreases, and the resonance frequency range is similar to... Figure 7 The frequency range of the dispersion bands at the edge modes of the supercell topology in (a) is consistent.
[0077] like Figure 7 Figures (d)-(f) and (g)-(i) show the displacement fields of the linear and zigzag topological transmission paths, respectively. It can be seen that the vibrations are well concentrated on the linear and zigzag paths, and the vibration modes are symmetrical along the transmission interface, consistent with the supercell eigenmodes. This indicates that the frequency of the topological edge modes decreases with increasing MgSO4 solution concentration, thus achieving frequency modulation of the acoustic elastic wave transmission.
[0078] In the description of this invention, it should be understood that the terms "center", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.
[0079] In this invention, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," "link," and "fix" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium. For those skilled in the art,
[0080] The specific meaning of the above terms in this invention can be understood according to the specific circumstances.
[0081] Any aspects of this invention not described in detail are well-known to those skilled in the art.
Claims
1. A unit cell structure for a reconfigurable locally resonant valley topological acoustoelastic waveguide, characterized in that, It includes a base plate and two cups, each cup being formed by a bottom wall and circumferential side walls, and the cups being used to hold liquids; The substrate is rhomboid in shape, with two through holes. The center line connecting the two through holes is set along one of the diagonals of the rhombus. The lower parts of the two cups are respectively placed in the two through holes, and the lower part of the circumferential sidewall of the cup is connected to the hole wall of the through hole by several connecting beams.
2. The unit cell structure according to claim 1, characterized in that, The two cups contain liquids of the same or different levels, concentrations, or types.
3. The unit cell structure according to claim 1, characterized in that, The outer cross-sectional shape and the inner cross-sectional shape of the cup are circular or regular polygonal.
4. The unit cell structure according to claim 1, characterized in that, The number of connecting beams is 3.
5. The unit cell structure according to claim 1, characterized in that, The length of the connecting beam extends radially along the cup body.
6. A phonon crystal plate, characterized in that, It is formed by the periodic arrangement of multiple unit cell structures, which are arranged in an array along the side length of the substrate, and the substrates of adjacent unit cell structures are connected as one unit.
7. The application of the phonon crystal plate as described in claim 6, characterized in that, The application of phononic crystal plates to obtain low-frequency topological edge states includes the following steps: S1. Calculate the band structure of the unit cell to obtain the low-frequency Dirac cone; S2. Change the way the liquid is filled in the unit cell structure cup to break the spatial symmetry and form a unit cell structure with opposite valley topological phase. Combine the unit cell structures into a phonon crystal plate and calculate its band structure. A topological edge state is formed at the junction of opposite valley topological phases.
8. The application of the phonon crystal plate as described in claim 6, characterized in that, The application of phonon crystal plates to control the propagation path of acoustic elastic waves includes the following steps: liquid filling of the unit cell structures on both sides of the specified transmission path according to different filling methods; The transmission path includes straight, L-shaped, Z-shaped, or bifurcated types, and the different filling methods include different liquid levels, types, or concentrations.
9. The application of the phonon crystal plate as described in claim 8, characterized in that, The application of phonon crystal plates to control the transmission frequency of acoustic elastic waves includes the following steps: The frequency of acoustic wave transmission can be controlled by changing the way the liquid is filled in the unit cell structure on both sides of a specified transmission path.