A lightweight acoustic metamaterial cell and its low-frequency broadband sound absorption superstructure device

Abstract

The application discloses a kind of lightweight acoustic metamaterial cell and its low-frequency broadband sound absorption superstructure device, and the supermaterial cell includes siphon resonance module and impedance adaptive module;Siphon resonance module includes bottom wall, enclosure wall, first tuning part and siphon inlet;The bottom end of enclosure wall is connected with bottom wall, and first tuning part is arranged at one side of the top end of enclosure wall, and the other side of the top end is siphon inlet, and bottom wall, enclosure wall, first tuning part form cavity in communication with siphon inlet;Impedance adaptive module includes first high porosity sound absorption medium and impedance adaptive cavity;First high porosity sound absorption medium is arranged in the side of cavity corresponding to siphon inlet, and the width of first high porosity sound absorption medium is greater than the width of siphon inlet, and the other side of cavity is impedance adaptive cavity.The application is applied to the field of noise reduction materials, can realize good low-frequency, broadband, high-efficiency sound absorption performance, also has more flexible, more flexible, more flexible, more flexible, more flexible, more flexible, more flexible, more flexible, more flexible, more flexible, more flexible, more flexible, more flexible, more flexible, more flexibility, more flexibility, more flexibility, more flexibility, more flexibility, more flexibility, more flexibility, and more flexibility, more flexibility, more flexibility, more flexibility, more flexibility, more flexibility, more flexible, more flexible, more flexible, more flexible, more flexible, more flexible, and more flexibility, more flexibility, more flexibility, more flexibility, more flexibility, more flexibility.

Description

Technical Field

[0001] This invention relates to the field of new noise reduction materials technology, specifically a lightweight acoustic metamaterial cell and its low-frequency broadband sound-absorbing superstructure device, which can be applied to high-tech equipment such as aircraft, rail trains, large ships, intelligent vehicles, new power transmission and transformation systems, and silent air conditioners, or to functional buildings such as wind tunnels, highways, bridges / tunnels, waiting halls / halls, conference venues, recording / broadcasting studios, and anechoic chambers. Background Technology

[0002] With social development, noise pollution in production and daily life has become increasingly prominent, and has become an important factor affecting the sound and vibration quality of equipment and the quality of people's lives. In terms of noise control, materials or structures with sound absorption and noise reduction functions are generally divided into two main categories according to different sound absorption principles: porous sound-absorbing materials and resonant sound-absorbing structures.

[0003] In engineering practice, mid- and high-frequency noise (above 1000Hz) has short wavelengths and relatively weak propagation capabilities, making traditional sound absorption techniques (porous sound absorption) effective. However, these techniques have some limitations: they define five macroscopic parameters of the material: porosity, flow resistance, tortuosity, viscous characteristic length, and thermal characteristic length. These parameters typically require altering the equivalent bulk modulus and density of the porous material to influence its overall sound absorption performance. Considering the actual manufacturing process, the adjustment range of these five macroscopic parameters for acoustic performance is very limited within the feasible fabrication range, making wide-bandwidth, large-amplitude adjustment difficult. Furthermore, the optimal absorption frequency of traditional sound absorption techniques primarily depends on the overall thickness of the material. For every doubling of the thickness, the optimal absorption frequency shifts one octave lower, making it difficult to achieve efficient sound absorption in the low-frequency range.

[0004] Low-frequency noise (below 1000Hz) is difficult to control using traditional techniques due to its long wavelength and strong propagation ability, often requiring significant material thickness and weight costs. To address this challenge, existing technologies typically employ resonant sound-absorbing structures (such as thin-film resonant sound-absorbing structures, labyrinth-type resonant sound-absorbing structures, and micro-perforated plate resonant sound-absorbing structures). However, these technologies also have limitations: for example, with thin-film resonant sound-absorbing structures, current research indicates that without a back cavity, the maximum absorption coefficient is generally no more than 0.5. The absorption coefficient can be improved through coherent absorption of multi-layer thin-film structures or hybrid resonance between the thin-film structure and the cavity, achieving efficient absorption of sound waves at low frequencies. Furthermore, the use of thin-film resonant sound-absorbing structures often requires prestressing the film, and the precise application of this prestress significantly increases the difficulty and cost of implementation. Additionally, the film is susceptible to external damage, resulting in poor reliability and stability, which limits its engineering applications. For micro-perforated plate-type resonant sound-absorbing structures, improving low-frequency sound absorption performance requires a significant increase in the thickness of the back cavity. Furthermore, since the absorption peak is mainly near the resonant frequency, achieving broadband and efficient absorption is difficult. For labyrinth-type resonant sound-absorbing structures, a labyrinthine channel can be formed by bending / folding to extend the sound wave propagation path, achieving low-frequency and efficient sound absorption while reducing the overall thickness. However, labyrinth-channel structures are complex in configuration and difficult to manufacture, typically requiring 3D printing additive manufacturing, and their high surface density increases weight and cost. To achieve broadband sound absorption, resonant sound-absorbing structures usually use resonant coupling to connect a sufficient number of resonant sound-absorbing structures with different absorption frequencies in parallel, effectively broadening the sound absorption bandwidth. However, as the sound absorption bandwidth widens, the sound absorption coefficient decreases, making it difficult to achieve broadband and efficient low-frequency sound absorption. In summary, existing resonant sound-absorbing structures struggle to achieve a perfect balance of lightweight, low-frequency, and broadband sound absorption. Summary of the Invention

[0005] To address the shortcomings of the existing technologies, this invention provides a lightweight acoustic metamaterial cell and its low-frequency broadband sound-absorbing superstructure device, overcoming the problem that existing sound-absorbing materials and structures are unable to efficiently absorb low-frequency broadband sound waves due to limitations in structural space size / weight, processing and manufacturing technology, and cost in engineering applications.

[0006] To achieve the above objectives, the present invention provides a lightweight acoustic metamaterial cell, including a siphon resonance module and an impedance adjustment module; The impedance adjustment module includes a first high-porosity sound-absorbing medium and an impedance adjustment cavity. The siphon resonance module includes a bottom wall, a surrounding wall, a primary tuning section, and a siphon inlet; The bottom end of the enclosure is connected to the bottom wall, the primary tuning part and the siphon inlet are located at the top end of the enclosure, and the bottom wall, the enclosure, and the primary tuning part form a cavity that communicates with the siphon inlet; The primary tuning section is either a plate-like structure without perforations or a plate-like structure with perforations. If the primary tuning section is a plate-like structure without perforations: the primary tuning section is located on one side of the top of the enclosure wall, and the other side of the top of the enclosure wall is the siphon inlet; the first high porosity sound-absorbing medium is located in the cavity on one side corresponding to the siphon inlet and is in close contact with the enclosure wall, and the width of the first high porosity sound-absorbing medium is greater than the width of the siphon inlet, and the other side of the cavity is the impedance adjustment cavity; If the primary tuning section is a perforated plate structure: the primary tuning section completely covers the top of the enclosure wall, the perforation on the primary tuning section is the siphon inlet, the first high porosity sound-absorbing medium is disposed on one side of the cavity and is in close contact with the enclosure wall, and the other side of the cavity is the impedance-adjusting cavity.

[0007] In one embodiment, a cavity modulation module is also included; The cavity wave modulation module includes a cavity wave modulation execution unit and a cavity wave modulation control unit. There is a gap between the bottom end of the first high porosity sound-absorbing medium and the bottom wall. The cavity wave modulation execution unit is located at the position corresponding to the gap in the cavity, and the side of the cavity wave modulation execution unit is tangent to the surrounding wall. The cavity wave modulation actuator has a stroke within the interval that moves along the tangential direction of the inner surface of the enclosure wall, and the cavity wave modulation manipulation unit is connected to the cavity wave modulation actuator to drive the cavity wave modulation actuator to move.

[0008] In one embodiment, the impedance adjustment module further includes a second high-porosity sound-absorbing medium, which is disposed within the cavity and in close contact with the surrounding wall. The interval is located between the bottom end of the first high-porosity sound-absorbing medium and the top end of the second high-porosity sound-absorbing medium.

[0009] In one embodiment, the cavity wave modulation actuator is a plate-like structure with a non-flat and rough surface.

[0010] In one embodiment, the cavity modulation module further includes a support portion connected to the upper and / or lower part of the cavity modulation actuator.

[0011] In one embodiment, a secondary tuning unit is further included, which is disposed within the cavity and located on one side or the other side of the cavity wave modulation execution unit.

[0012] In one embodiment, the secondary tuning section includes a tuning plate and tuning cavities disposed on the tuning plate, the side of the tuning plate being tangent to the surrounding wall.

[0013] In one embodiment, a porous sound-absorbing thin layer is further included, which is disposed in the cavity, with the side portion of the porous sound-absorbing thin layer tangent to the surrounding wall and located below the secondary tuning section.

[0014] In one embodiment, the primary tuning section has a flat plate structure.

[0015] In one embodiment, the primary tuning section includes two or more flat plates; The flat plates are stacked and overlapped in sequence to form a retractable stepped structure, so as to achieve flexible adjustment of the size of the siphon inlet.

[0016] In one embodiment, if the primary tuning section is a plate-shaped structure with perforations, the area of ​​a single perforation on the primary tuning section is S, the number of perforations is N, N is greater than 2, and the intersection area of ​​the bottom of the primary tuning section and the cavity is K, 0.10 ≤ (N×S) / K≤ 0.35.

[0017] To achieve the above objectives, the present invention also provides a low-frequency broadband sound-absorbing superstructure device, characterized in that it comprises two or more of the above-mentioned lightweight acoustic metamaterial cells.

[0018] Compared with existing technologies, the lightweight acoustic metamaterial cell and its low-frequency broadband sound-absorbing superstructure device provided by this invention can achieve good low-frequency, broadband and efficient sound absorption performance while being lightweight and simple. It also has advantages such as more flexible and wider range of control capabilities, stronger matching and applicability, and overcomes the shortcomings of traditional resonant sound-absorbing structures such as narrow sound absorption bandwidth, complex topology and poor reliability. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the first embodiment of the lightweight acoustic metamaterial cell in Example 1, wherein (a) is a schematic diagram of a plate-like structure with a non-perforated cavity as the primary tuning part, and (b) is a schematic diagram of a plate-like structure with a perforated cavity as the primary tuning part. Figure 2 This is a schematic diagram of the second embodiment of the lightweight acoustic metamaterial cell in Example 1, wherein (a) is a schematic diagram of a plate-like structure with a non-perforated cavity as the primary tuning part, and (b) is a schematic diagram of a plate-like structure with a perforated cavity as the primary tuning part. Figure 3 This is a schematic diagram of the third embodiment of the lightweight acoustic metamaterial cell in Example 1, wherein (a) is a schematic diagram of a plate-like structure with a non-perforated cavity as the primary tuning part, and (b) is a schematic diagram of a plate-like structure with a perforated cavity as the primary tuning part. Figure 4 This is a schematic diagram of the fourth embodiment of the lightweight acoustic metamaterial cell in Example 1, wherein (a) is a schematic diagram of a plate-like structure with a non-perforated cavity as the primary tuning part, and (b) is a schematic diagram of a plate-like structure with a perforated cavity as the primary tuning part. Figure 5 The diagram shows the cross-sectional shape of the first high-porosity sound-absorbing medium in Example 1, where (a) is a rectangular cross-section, (b) is a triangular cross-section, and (c) is a trapezoidal cross-section. Figure 6 This is a schematic diagram of an embodiment where the primary tuning section is retractable in Example 1; Figure 7 This is a schematic diagram of the implementation of the lightweight acoustic metamaterial cell when the first-level tuning part is stretchable in Example 1, wherein (a) is a schematic diagram of the top end of the first high porosity sound-absorbing medium contacting the first-level tuning part, and (b) is a schematic diagram of the top end of the first high porosity sound-absorbing medium having a gap with the first-level tuning part. Figure 8 This is a schematic diagram of the first embodiment of the lightweight acoustic metamaterial cell in Example 2, wherein (a) is a schematic diagram when the primary tuning part is a flat plate, and (b) is a schematic diagram when the primary tuning part is a telescopic plate. Figure 9 This is a schematic diagram of the second embodiment of the lightweight acoustic metamaterial cell in Example 2, wherein (a) is a schematic diagram when the second operating part is a double cantilever beam, (b) is a schematic diagram when the second operating part is a ring, and (c) is a schematic diagram when the second operating part is a single cantilever beam. Figure 10 This is a schematic diagram of the third embodiment of the lightweight acoustic metamaterial cell in Example 2, wherein (a) is a schematic diagram of the support part located above the cavity wave modulation execution part, and (b) is a schematic diagram of the support part located above and below the cavity wave modulation execution part; Figure 11 This is a three-dimensional configuration diagram of the lightweight acoustic metamaterial cell in Example 2; Figure 12This is a schematic diagram of the fourth embodiment of the lightweight acoustic metamaterial cell in Example 2, wherein (a) is a schematic diagram when the primary tuning part is a flat plate, (b) is a schematic diagram when the primary tuning part is a telescopic plate and has only a first operating part, and (c) is a schematic diagram when the primary tuning part is a telescopic plate and has a first operating part and a second operating part. Figure 13 This is a schematic diagram of the first embodiment of the lightweight acoustic metamaterial cell in Example 3, wherein (a) is a schematic diagram when the cavity wave modulation actuator is a sawtooth non-flat rough shape, and (b) is a schematic diagram when the cavity wave modulation actuator is an irregular non-flat rough shape. Figure 14 This is a schematic diagram of the second implementation of the lightweight acoustic metamaterial cell in Example 3; Figure 15 This is a schematic diagram of the first embodiment of the low-frequency broadband sound-absorbing superstructure device in Example 4; Figure 16 This is a schematic diagram of the second embodiment of the low-frequency broadband sound-absorbing superstructure device in Example 4; Figure 17 This is a schematic diagram of the third implementation of the low-frequency broadband sound-absorbing superstructure device in Example 4; Figure 18 This is a schematic diagram of the fourth implementation of the low-frequency broadband sound-absorbing superstructure device in Example 4.

[0021] Reference numerals: 1-bottom wall, 2-enclosure wall, 3-first-stage tuning section, 4-siphon inlet, 5-impedance adjustment module, 51-first high-porosity sound-absorbing medium, 52-impedance adjustment cavity, 53-second high-porosity sound-absorbing medium, 6-cavity wave modulation module, 61-cavity wave modulation execution section, 62-cavity wave modulation control section, 63-support section, 62a-first control section, 62b-second control section, 7-second-stage tuning section, 71-tuning plate, 72-tuning cavity, 8-porous sound-absorbing thin layer, 9a-guide groove, 9b-adjusting slider, 10-lightweight acoustic metamaterial cell, 11-low-frequency broadband sound-absorbing superstructure device.

[0022] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0024] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0025] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0026] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection, an electrical connection, a physical connection, or a wireless communication connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two elements or the interaction between two elements, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0027] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0028] Example 1 like Figure 1-7 The image shows a lightweight acoustic metamaterial cell disclosed in this embodiment, which mainly includes a siphon resonance module and an impedance adjustment module 5.

[0029] Specifically, the impedance adjustment module 5 includes a first high-porosity sound-absorbing medium 51 and an impedance adjustment cavity 52. ​​The first high-porosity sound-absorbing medium 51 can be made of organic fiber porous material, inorganic fiber porous material, foam porous material, or metal porous material, such as melamine or metal foam. The siphon resonance module includes a bottom wall 1, a surrounding wall 2, a primary tuning section 3, and a siphon inlet 4. The bottom wall 1 can be a flat plate structure or a curved plate structure, and the surrounding wall 2 is a hollow cylindrical structure with openings at both ends, such as a cylinder, square cylinder, conical cylinder, or other irregularly shaped cylinder. The bottom wall 1 and the surrounding wall 2 can be formed by threaded connection, riveting, welding, or adhesive connection, or they can be integrally formed by casting or additive manufacturing. The primary tuning section 3 and the siphon inlet 4 are located at the top of the surrounding wall 2, and the bottom wall 1, the surrounding wall 2, and the primary tuning section 3 form a cavity communicating with the siphon inlet 4.

[0030] The primary tuning section 3 is either a plate-like structure without perforations or a plate-like structure with perforations. refer to Figure 1 (a) Figure 2 (a) Figure 3 (a) Figure 4 (a) If the primary tuning section 3 is a non-perforated plate structure: the primary tuning section 3 is located on one side of the top of the enclosure wall 2, and the other side of the top of the enclosure wall 2 is the siphon inlet 4. The first high porosity sound absorbing medium 51 is located in the cavity on one side corresponding to the siphon inlet 4 and is in close contact with the enclosure wall 2, and the width of the first high porosity sound absorbing medium 51 is greater than the width of the siphon inlet 4, that is, the part of the primary tuning section 3 near the siphon inlet 4 and all the siphon inlets 4 are located directly above the first high porosity sound absorbing medium 51; the other side of the cavity is the impedance adjustment cavity 52.

[0031] refer to Figure 1 (b) Figure 2 (b) Figure 3 (b) Figure 4 (b) The primary tuning section 3 is a plate-like structure with perforations: the primary tuning section 3 completely covers the top of the enclosure 2, and the perforations on the primary tuning section 3 are the siphon inlet 4. The first high-porosity sound-absorbing medium 51 is disposed on one side of the cavity and is in close contact with the enclosure 2. The other side of the cavity is the impedance-adjusting cavity 52. ​​The diameter of a single perforation on the primary tuning section 3 can be 2mm-20mm, preferably 4mm-8mm, and its area is S. The number of perforations is N, where N is greater than 2. If the intersection area between the bottom of the primary tuning section 3 and the cavity is K, then 0.10 ≤ (N×S) / K≤0.35.

[0032] It should be noted that the direct function of the holes in the first-stage tuning section 3 in this embodiment is not for sound absorption. The sound absorption principle in this embodiment is not achieved by the friction or resonance of the holes. The function of the holes in the first-stage tuning section is to reduce weight and reduce processing difficulty and cost. On the other hand, it can also improve the stability of the structure and prevent dust from affecting the sound absorption performance. At the same time, it helps the overall structure to take into account the mid-to-high frequency performance.

[0033] In practical implementation, regardless of whether the primary tuning section 3 is a non-perforated plate structure or a perforated plate structure, the top end of the first high-porosity sound-absorbing medium 51 can either be in close contact with the bottom surface of the primary tuning section 3 and the bottom surface of the siphon inlet 4, or it can have a certain distance between it and the bottom surface of the primary tuning section 3 and the bottom surface of the siphon inlet 4, with the distance value being greater than 1 mm; the bottom end of the first high-porosity sound-absorbing medium 51 can either be in close contact with the bottom wall 1, or it can have a certain distance between it and the bottom wall 1, with the distance value being greater than 1 mm. (Reference) Figure 1 This is an embodiment in which the top and bottom ends of the first high-porosity sound-absorbing medium 51 contact the bottom surface and bottom wall 1 of the primary tuning unit 3, respectively. Figure 1 (a) The primary tuning section 3 is a plate-like structure without perforations. Figure 1 (b) The primary tuning section 3 is a plate-like structure with perforated holes; Reference Figure 2 This means that there is a gap between the top end of the first high-porosity sound-absorbing medium 51 and the bottom surface of the first-stage tuning part 3, and the bottom end of the first high-porosity sound-absorbing medium 51 is in contact with the bottom wall 1. Figure 2 (a) The primary tuning section 3 is a plate-like structure without perforations. Figure 2 (b) The primary tuning section 3 is a plate-like structure with perforated holes; Reference Figure 3 This means that the top of the first high-porosity sound-absorbing medium 51 is in contact with the bottom surface of the first-stage tuning part 3, and there is a gap between the bottom end of the first high-porosity sound-absorbing medium 51 and the bottom wall 1. Figure 3 (a) The primary tuning section 3 is a plate-like structure without perforations. Figure 3 (b) The primary tuning section 3 is a plate-like structure with perforated holes; Reference Figure 4 This means that there is a gap between the top of the first high-porosity sound-absorbing medium 51 and the bottom surface of the first-stage tuning part 3, and a gap between the bottom end of the first high-porosity sound-absorbing medium 51 and the bottom wall 1, wherein... Figure 4 (a) The primary tuning section 3 is a plate-like structure without perforations. Figure 4 (b) The primary tuning section 3 is a plate-like structure with perforations.

[0034] In this embodiment, the bottom wall 1 and the surrounding wall 2 of the siphon resonance module are made of hard boundary plate material, which can be metal (stainless steel, aluminum alloy, galvanized steel), ABS plastic, hard fiber, composite laminate, gypsum, synthetic resin or tempered glass; the primary tuning part 3 can be made of galvanized steel, hard fiber, ABS plastic or tempered glass.

[0035] refer to Figure 5 In this embodiment, the cross-sectional shape of the first high-porosity sound-absorbing medium can be a rectangular structure, a trapezoidal structure, a triangular structure, or other irregular structures.

[0036] In this embodiment, the primary tuning section 3 can be a flat plate structure, i.e. Figure 1-4 As shown.

[0037] In a preferred embodiment, the primary tuning unit 3 includes two or more flat plates. (See reference...) Figure 6-7 In this embodiment, the plates are stacked in sequence to form a retractable stepped structure, so as to achieve flexible adjustment of the size of the siphon inlet 4. The upper surface of the bottom plate can be provided with a guide groove 9a, the lower surface of the top plate can be provided with an adjusting slider 9b, and the upper surface of the remaining middle plates can be provided with a guide groove 9a and the lower surface can be provided with an adjusting slider 9b. In each adjacent plate, the guide groove 9a of the lower plate cooperates with the adjusting slider 9b of the upper plate, and the plates can be adjusted to each other by sliding, thereby achieving flexible adjustment of the siphon inlet 44.

[0038] The working principle and technical effect of the lightweight acoustic metamaterial cell in this embodiment are as follows: First, the bottom wall 1, the surrounding wall 2, and the primary tuning section 3 form a cavity that communicates with the siphon inlet 4. The cavity, together with the bottom wall 1, the surrounding wall 2, the primary tuning section 3, and the siphon inlet 4, forms a siphon resonance module. On the one hand, when sound waves enter the cavity through the siphon inlet 4, they excite the low-frequency coupling resonance of the siphon resonance module, accelerating the movement of sound wave particles into the cavity, increasing its coupling strength with the impedance adjustment module, and generating a siphon resonance effect, so that the structure produces a highly efficient resonance absorption peak in the low-frequency range. On the other hand, by stacking the flat plates in the primary tuning section 3 in sequence, a stretchable stepped structure is formed, which enables flexible adjustment of the size of the siphon inlet 4. This facilitates precise and flexible adjustment of the low-frequency coupling resonance frequency of the siphon resonance module, thus broadening its adaptability. Secondly, by introducing the impedance adjustment module 5 into the cavity, on the one hand, the characteristic impedance of the cavity can be adjusted over a wide range, and wideband adjustment matching with the characteristic impedance of the siphon resonance module can be achieved; on the other hand, the high porosity sound-absorbing medium of the impedance adjustment module 5 itself can form a secondary coupling resonance with the impedance adjustment cavity 52, thereby enhancing the sound absorption performance; at the same time, the siphon resonance effect will accelerate the friction between the sound wave particles and the high porosity sound-absorbing medium in the impedance adjustment module 5, so that the sound wave energy is consumed as heat energy.

[0039] Example 2 like Figure 8-12 The image shows a lightweight acoustic metamaterial cell disclosed in this embodiment. This embodiment adds a cavity wave modulation module 6 based on embodiment 1.

[0040] refer to Figure 8 In this embodiment, there is a gap between the bottom end of the first high-porosity sound-absorbing medium 51 and the bottom wall. The cavity wave modulation module 6 includes a cavity wave modulation execution unit 61 and a cavity wave modulation control unit 62. The cavity wave modulation execution unit 61 is disposed in the cavity under the impedance adjustment module at a corresponding interval position, and the side of the cavity wave modulation execution unit 61 is tangent to the surrounding wall. The cavity wave modulation execution unit 61 has a stroke that moves along the tangent direction of the inner surface of the surrounding wall within the cavity. The cavity wave modulation control unit 62 is connected to the cavity wave modulation execution unit 61 to drive the cavity wave modulation execution unit 61 to move.

[0041] The cavity wave modulation actuator 61 is a plate-like structure with a rough, non-flat surface, and its surface profile control function can be a sine function or a Bezier function. The material used to manufacture the cavity wave modulation actuator 61 can be ABS plastic, carbon fiber composite material, acrylic, aluminum alloy, stainless steel, or wood.

[0042] In practical implementation, a groove can be provided on the inner wall of the enclosure, and a protrusion embedded in the groove can be provided on the side wall of the cavity wave modulation execution unit 61 to guide the sliding process of the cavity wave modulation execution unit 61. (Reference) Figure 9 The cavity wave modulation control unit 62 includes a first operating part 62a, which can be cylindrical, beam-shaped, or rod-shaped. One end of the first operating part 62a is connected to the cavity wave modulation execution unit 61, and the other end can pass through the bottom wall or enclosure wall and be located outside the cavity, so as to facilitate manual operation of the cavity wave modulation execution unit 61 to slide within the cavity. Preferably, the cavity wave modulation control unit 62 also includes a second operating part 62b, which is connected below the first operating part 62a. The second operating part 62b can be configured as a double cantilever beam, a single cantilever beam, a ring, or other configurations that facilitate operation.

[0043] The first operating part 62a of the cavity wave modulation control unit 62 may be made of steel, aluminum alloy, ABS plastic, tempered glass, carbon fiber composite material, or wood; the second operating part 62b of the cavity wave modulation control unit 62 may be made of ABS plastic, rubber, aluminum alloy, or stainless steel.

[0044] Of course, the cavity wave modulation control unit 62 is not limited to the manual implementation of the first operation unit 62a and the second operation unit 62b. It can also be an automatic mode driven by electricity, for example, the cavity wave modulation control unit 62 is composed of a motor and a screw. The motor is located below the bottom wall and is connected to the screw drive. The screw runs vertically through the cavity and rotates in the same direction as the bottom wall and the tuning part. The cavity wave modulation execution unit 61 is threadedly connected to the screw. By driving the screw to rotate by the motor, the cavity wave modulation execution unit 61 can be driven to slide vertically linearly within the cavity.

[0045] As a preferred embodiment, refer to Figure 10-11 The cavity wave modulation module 6 also includes a support portion 63 for supporting the cavity wave modulation execution unit 61. The support portion 63 is connected to the upper and / or lower part of the cavity wave modulation execution unit 61. The side of the support portion 63 is tangential to and slides within the surrounding wall, meaning the support portion 63 slides within the cavity along with the cavity wave modulation execution unit 61. Alternatively, the side of the support portion 63 may not contact the surrounding wall, allowing the support portion 63 to move within the cavity along with the cavity wave modulation execution unit 61.

[0046] As a preferred embodiment, refer to Figure 12 In this embodiment, the impedance adjustment module further includes a second high-porosity sound-absorbing medium 53. The second high-porosity sound-absorbing medium 53 is disposed within the cavity and in close contact with the surrounding wall. Specifically, the material of the second high-porosity sound-absorbing medium 53 is the same as that of the first high-porosity sound-absorbing medium 51, and the material of the second high-porosity sound-absorbing medium 53 can be located on one or more sides of the cavity. The gap is located between the bottom end of the first high-porosity sound-absorbing medium 51 and the top end of the second high-porosity sound-absorbing medium 53, that is, the cavity wave modulation execution unit 61 has a stroke that moves along the tangential direction of the inner surface of the surrounding wall at the position between the first high-porosity sound-absorbing medium 51 and the second high-porosity sound-absorbing medium 53.

[0047] The working principle and technical effects of the lightweight acoustic metamaterial cell in this embodiment are as follows: Based on the effects of Embodiment 1, the introduction of the cavity wave modulation module 6 in this embodiment can, on the one hand, flexibly adjust the cavity volume without replacing parts, realize secondary adjustment of the siphon resonance frequency, and increase its applicability; at the same time, the cavity wave modulation module 6 can also generate new coupled resonance, increase the number of resonant sound absorption peaks, and improve the speed and efficiency of impedance adaptation matching; on the other hand, by introducing non-flat roughness on the surface of the cavity wave modulation execution part 61 of the cavity wave modulation module 6, the disturbance vortex of the sound wave in the cavity can be increased, the direction of sound wave propagation and the frequency of reflection can be increased, the sound wave propagation loss path in the cavity can be extended, and the attenuation of sound energy can be further enhanced, thereby improving the overall sound absorption performance.

[0048] Example 3 like Figure 13 The image shows a lightweight acoustic metamaterial cell disclosed in this embodiment. This embodiment adds a secondary tuning section 7 to the embodiment 1. The secondary tuning section 7 is located in the cavity and is located on one side or the other side of the cavity wave modulation execution section.

[0049] Specifically, the secondary tuning section 7 includes a tuning plate 71 and tuning cavities 72 disposed on the tuning plate 71, with the side portion of the tuning plate 71 tangent to the surrounding wall. The tuning cavities 72 may be microslits, micropores, or a combination of both.

[0050] Preferably, refer to Figure 14 The lightweight acoustic metamaterial cell also includes a porous sound-absorbing thin layer 8, which is disposed within the cavity. The side of the porous sound-absorbing thin layer 8 is tangent to the surrounding wall and located below the secondary tuning section 7 at a distance of 1-3 mm. The porous sound-absorbing thin layer 8 can be made of polyurethane or glass wool.

[0051] As can be seen from the above embodiments 1-3, the lightweight acoustic metamaterial cell provided by the present invention, through ingenious conception and design, utilizes the siphon resonance effect of the siphon resonance module, the secondary coupling resonance between the high-porosity sound-absorbing medium of the impedance-adjusting module and the impedance-adjusting cavity, the friction effect between accelerated sound particles and the high-porosity sound-absorbing medium, the broadband adaptive matching effect of the characteristic impedance of the impedance-adjusting module and the siphon resonance module, the coupling peak enhancement effect of the cavity wave modulation module, and the energy dissipation effect of intracavity disturbance waves, to achieve efficient absorption of low-frequency broadband sound waves. The present invention achieves excellent low-frequency, broadband, and efficient sound absorption performance in a lightweight and relatively small space, and also has advantages such as simple structure, ease of processing, flexible adjustment, and low manufacturing and usage costs.

[0052] Example 4 like Figure 15-18The diagram shows a low-frequency broadband sound-absorbing metastructure device 11 disclosed in this embodiment, comprising two or more lightweight acoustic metamaterial cells 10 as described in Embodiment 1 and / or Embodiment 2 and / or Embodiment 3. The lattice size of each lightweight acoustic metamaterial cell, the total thickness of the siphon resonant module, the distance from the primary tuning section to the surrounding wall (the opening size of the siphon inlet), the width of the high-porosity sound-absorbing medium, the distance from the high-porosity sound-absorbing medium to the bottom surface of the siphon inlet, the amplitude and phase angle of the surface profile control function of the cavity wave modulation execution section, the distance from the cavity wave modulation execution section to the bottom wall, the thickness of the tuning plate in the secondary tuning section, and the size and number of tuning holes are predetermined and can be the same or different. Figure 15 The image shows a low-frequency broadband sound-absorbing superstructure device 11 composed of two identical lightweight acoustic metamaterial cells 10, as shown in Example 1. Figure 16 The image shows a low-frequency broadband sound-absorbing superstructure device 11 composed of three different lightweight acoustic metamaterial cells 10, as shown in Example 1. Figure 17 The image shows a low-frequency broadband sound-absorbing superstructure device 11 composed of three different lightweight acoustic metamaterial cells 10, as shown in Example 2. Figure 18 The diagram shows a low-frequency broadband sound-absorbing superstructure device 11 composed of three different lightweight acoustic metamaterial cells 10 in Example 2 and two different lightweight acoustic metamaterial cells 10 in Example 3.

[0053] Example 5 Based on Example 4, this embodiment, as a preferred embodiment, can, according to the broadband coordination target, assemble several lightweight acoustic metamaterial cells with different parameters into a large superunit, and then array this superunit to form the low-frequency broadband sound-absorbing superstructure device. The low-frequency broadband sound-absorbing superstructure device disclosed in this embodiment includes three lightweight acoustic metamaterial cells, each with a lattice size (length * width) of 66.6mm * 66.6mm. The total thickness of the siphon resonance module is 100mm. The bottom wall, surrounding wall, and primary tuning section are all made of aluminum alloy with a wall thickness of 1.0mm. Each cell contains a cavity wave modulation module. The distances of the three cavity wave modulation execution sections to the bottom wall are 5.3mm, 1.0mm, and 1.0mm, respectively. The high-porosity sound-absorbing medium is made of melamine material with a porosity of 0.96. The distance from the high-porosity sound-absorbing medium in each of the three cells to the bottom surface of the corresponding siphon inlet is 6mm. The structure achieves an average sound absorption coefficient of 0.972 and a minimum sound absorption coefficient of 0.833 in the 355Hz-10000Hz range, realizing low-frequency, broadband, and efficient sound absorption.

[0054] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A lightweight acoustic metamaterial cell, characterized in that, Includes a siphon resonance module and an impedance adjustment module; The impedance adjustment module includes a first high-porosity sound-absorbing medium and an impedance adjustment cavity. The siphon resonance module includes a bottom wall, a surrounding wall, a primary tuning section, and a siphon inlet; The bottom end of the enclosure is connected to the bottom wall, the primary tuning part and the siphon inlet are located at the top end of the enclosure, and the bottom wall, the enclosure, and the primary tuning part form a cavity that communicates with the siphon inlet; The primary tuning section is either a plate-like structure without perforations or a plate-like structure with perforations. If the primary tuning section is a plate-like structure without perforations: the primary tuning section is located on one side of the top of the enclosure wall, and the other side of the top of the enclosure wall is the siphon inlet; the first high porosity sound-absorbing medium is located in the cavity on one side corresponding to the siphon inlet and is in close contact with the enclosure wall, and the width of the first high porosity sound-absorbing medium is greater than the width of the siphon inlet, and the other side of the cavity is the impedance adjustment cavity; If the primary tuning section is a perforated plate structure: the primary tuning section completely covers the top of the enclosure wall, the perforation on the primary tuning section is the siphon inlet, the first high porosity sound-absorbing medium is disposed on one side of the cavity and is in close contact with the enclosure wall, and the other side of the cavity is the impedance-adjusting cavity.

2. The lightweight acoustic metamaterial cell according to claim 1, characterized in that, It also includes a cavity modulation module; The cavity wave modulation module includes a cavity wave modulation execution unit and a cavity wave modulation control unit. There is a gap between the bottom end of the first high porosity sound-absorbing medium and the bottom wall. The cavity wave modulation execution unit is located at the position corresponding to the gap in the cavity, and the side of the cavity wave modulation execution unit is tangent to the surrounding wall. The cavity wave modulation actuator has a stroke within the interval that moves along the tangential direction of the inner surface of the enclosure wall, and the cavity wave modulation manipulation unit is connected to the cavity wave modulation actuator to drive the cavity wave modulation actuator to move.

3. The lightweight acoustic metamaterial cell according to claim 2, characterized in that, The impedance adjustment module also includes a second high-porosity sound-absorbing medium, which is disposed in the cavity and in close contact with the surrounding wall. The interval is located between the bottom end of the first high-porosity sound-absorbing medium and the top end of the second high-porosity sound-absorbing medium.

4. The lightweight acoustic metamaterial cell according to claim 2, characterized in that, The cavity wave modulation actuator is a plate-like structure with a non-flat and rough surface.

5. The lightweight acoustic metamaterial cell according to claim 2, 3, or 4, characterized in that, The cavity wave modulation module further includes a support portion, which is connected to the upper and / or lower part of the cavity wave modulation execution portion.

6. The lightweight acoustic metamaterial cell according to claim 2, 3, or 4, characterized in that, It also includes a secondary tuning unit, which is disposed in the cavity and located on one side or the other side of the cavity wave modulation execution unit.

7. The lightweight acoustic metamaterial cell according to claim 6, characterized in that, The secondary tuning section includes a tuning plate and tuning cavities disposed on the tuning plate, the side of the tuning plate being tangent to the enclosure wall.

8. The lightweight acoustic metamaterial cell according to claim 6, characterized in that, It also includes a porous sound-absorbing thin layer, which is disposed in the cavity, and the side of the porous sound-absorbing thin layer is tangent to the surrounding wall and located below the secondary tuning section.

9. The lightweight acoustic metamaterial cell according to claim 1, 2, 3, or 4, characterized in that, The primary tuning section has a flat plate structure.

10. The lightweight acoustic metamaterial cell according to claim 1, 2, 3, or 4, characterized in that, The primary tuning section includes two or more flat plates; The flat plates are stacked and overlapped in sequence to form a retractable stepped structure, so as to achieve flexible adjustment of the size of the siphon inlet.

11. The lightweight acoustic metamaterial cell according to claim 1, 2, 3, or 4, characterized in that, If the primary tuning section is a flat plate structure with perforations, the area of ​​a single perforation on the primary tuning section is S, the number of perforations is N, N is greater than 2, and the area of ​​the intersection between the bottom of the primary tuning section and the cavity is K, 0.10≤(N×S) / K≤0.

35.

12. A low-frequency broadband sound-absorbing superstructure device, characterized in that, It includes two or more lightweight acoustic metamaterial cells as described in any one of claims 1 to 10.

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