Sound-absorbing metamaterial unit and device based on coupled resonant structure and broadband impedance modulation body

Abstract

The application discloses a sound-absorbing metamaterial unit and device based on a coupling resonance structure and a broadband impedance modulation body. The sound-absorbing metamaterial unit comprises the coupling resonance structure and the broadband impedance modulation body. A top plate with holes and a surrounding wall and a bottom plate form the coupling resonance structure with a low-frequency resonance effect. Meanwhile, the broadband impedance modulation body in an acoustic waveguide cavity can adjust the characteristic impedance in a wide range. Due to the synergistic effect of the coupling resonance structure and the broadband impedance modulation body, impedance matching can be achieved in a low-frequency broadband range. The sound-absorbing metamaterial unit provided by the application can have good sound-absorbing effect in a low-frequency broadband range, and has the advantages of simple processing and manufacturing, low cost and high reliability. The sound-absorbing metamaterial unit overcomes the defects of a narrow sound-absorbing frequency band, a complex topological configuration and poor reliability of a traditional acoustic metamaterial sound-absorbing structure.

Description

Technical Field

[0001] This invention belongs to the field of new materials and structures for noise control, and in particular relates to a sound-absorbing metamaterial unit and device based on a coupled resonant structure and a broadband impedance modulator. Background Technology

[0002] With social development, noise pollution in production and daily life has become increasingly prominent. Mid-to-high frequency noise has short wavelengths and weak propagation capabilities, making it effectively controllable using traditional sound absorption techniques. However, low-frequency noise has long wavelengths and strong penetrating power, often requiring significant material thickness / mass for control using traditional methods. Achieving efficient low-frequency noise absorption remains a major challenge for both academia and engineering.

[0003] In recent years, the concept and development of acoustic metamaterials have provided new ideas for solving the problem of low-frequency sound absorption. Through the design of artificial microstructures at the subwavelength scale, acoustic metamaterials possess extraordinary physical properties not found in traditional materials / structures (such as negative equivalent mass density, negative equivalent bulk modulus, and double negative values), thus enabling extraordinary manipulation of low-frequency elastic waves and sound waves. Traditional acoustic metamaterial structures for sound absorption mainly include thin-film acoustic metamaterial structures, Helmholtz resonant metamaterial structures, and labyrinth-type channel acoustic metamaterial structures. These acoustic metamaterial structures can overcome the limitations of traditional materials and achieve efficient sound absorption at the subwavelength scale. However, they also have some shortcomings, such as: thin-film acoustic metamaterials are difficult to install (usually requiring an additional fixing frame), the accurate application and maintenance of prestress is difficult, and the thin film is easily damaged and failed by external environmental influences when used in the open; Helmholtz resonant acoustic metamaterial structures have a narrow operating frequency band; and labyrinth-type channel acoustic metamaterial structures have complex configurations, are difficult to process, have high areal density, and increase weight and cost. These shortcomings limit the practical engineering application of traditional acoustic metamaterial sound-absorbing structures, and there is currently no acoustic metamaterial sound-absorbing structure in the background technology that combines the advantages of high reliability, low cost, and good sound absorption performance in the low-frequency broadband range. Summary of the Invention

[0004] This invention provides a sound-absorbing metamaterial unit and device based on a coupled resonant structure and a broadband impedance modulator, which overcomes the shortcomings of existing technologies that cannot simultaneously achieve high reliability, low cost, and good sound absorption performance in the low-frequency broadband range.

[0005] To achieve the above objectives, this invention proposes a sound-absorbing metamaterial unit based on a coupled resonant structure and a broadband impedance modulator, comprising:

[0006] A coupled resonant structure includes a top plate, a surrounding wall, a bottom plate, and an acoustic waveguide cavity formed thereunder; the top plate is a perforated plate or a slotted plate.

[0007] A broadband impedance modulator, located within the acoustic waveguide cavity, includes at least one acoustic module and at least one through section; the acoustic module is installed circumferentially along the wall, and the gap between two acoustic modules or the gap between the acoustic module and the wall constitutes the through section.

[0008] To achieve the above objectives, the present invention also proposes a sound-absorbing metamaterial device based on a coupled resonant structure and a broadband impedance modulator, which is composed of an array of several sound-absorbing metamaterial units as described above.

[0009] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0010] The sound-absorbing metamaterial unit based on a coupled resonant structure and a broadband impedance modulator provided by this invention includes a coupled resonant structure and a broadband impedance modulator. The top plate containing holes (slits) forms a coupled resonant structure with low-frequency resonance effect with the surrounding wall and bottom plate. At the same time, the broadband impedance modulator in the acoustic waveguide cavity can adjust the characteristic impedance over a wide range. Due to the synergistic effect of the coupled resonant structure and the broadband impedance modulator, impedance matching can be achieved in the low-frequency broadband range. (1) The air and acoustic module at the junction of the acoustic module and the through part of the broadband impedance modulator are subjected to intense friction, resulting in sound energy dissipation; (2) Helmholtz resonance effect, sound waves are viscously dissipated at the opening (slit) of the top plate; (3) Inside the acoustic module of the broadband impedance modulator, due to intense friction, sound energy is converted into solid heat energy and dissipated through solid heat conduction. Thus, the sound-absorbing metamaterial unit provided by this invention can achieve efficient sound absorption in the low-frequency broadband range. Furthermore, when multiple sound-absorbing metamaterial units provided by this invention are connected in parallel according to impedance matching conditions, the resulting sound-absorbing metamaterial device based on a coupled resonant structure and a broadband impedance modulator can further broaden the sound absorption frequency band.

[0011] The sound-absorbing metamaterial unit provided by this invention can have good sound absorption effect in the low-frequency broadband range, and is simple to process and manufacture, low in cost and highly reliable, overcoming the shortcomings of traditional acoustic metamaterial sound-absorbing structures such as narrow sound absorption bandwidth, complex topology and poor reliability. Attached Figure Description

[0012] 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.

[0013] Figure 1a Longitudinal cross-sectional view of the sound-absorbing metamaterial unit based on coupled resonant structure and broadband impedance modulator provided by the present invention;

[0014] Figure 1b A three-dimensional perspective view of the sound-absorbing metamaterial unit based on coupled resonant structure and broadband impedance modulator provided by the present invention;

[0015] Figure 2 A schematic diagram showing the passageway formed by the gap between the acoustic module and the enclosure;

[0016] Figure 3 The figures are schematic cross-sectional views of the broadband impedance modulator in contact with the base plate and the top plate, respectively; (a) in the figure shows the broadband impedance modulator in contact with the base plate, and (b) shows the broadband impedance modulator in contact with the top plate.

[0017] Figure 4 This is a cross-sectional view showing the location of the support section and the wrapping section;

[0018] Figure 5 This is a schematic diagram of various structural forms of the roof slab; (c), (d), (e), and (f) in the diagram represent roof slabs with different structural forms, respectively.

[0019] Figure 6 A schematic diagram of the sound-absorbing metamaterial device based on a coupled resonant structure and a broadband impedance modulator provided by the present invention.

[0020] Explanation of reference numerals: 1: Coupled resonant structure; 1-1: Top plate; 1-2: Enclosure; 1-3: Bottom plate; 1-4: Acoustic waveguide cavity; 2: Wideband impedance modulator; 2-1: Acoustic module; 2-2: Through section; 3: Support section; 4: Enclosure section.

[0021] 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

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] This invention proposes a sound-absorbing metamaterial unit based on a coupled resonant structure and a broadband impedance modulator, such as... Figure 1a and Figure 1b As shown, it includes:

[0028] The coupled resonant structure 1 includes a top plate 1-1, a surrounding wall 1-2, a bottom plate 1-3, and an acoustic waveguide cavity 1-4 enclosed by them; the top plate 1-1 is a perforated plate or a slotted plate.

[0029] A broadband impedance modulator 2, located within the acoustic waveguide cavity 1-4, includes at least one acoustic module 2-1 and at least one through-hole 2-2; multiple acoustic modules 2-1 are installed circumferentially along the enclosure wall 1-2, with a gap between two acoustic modules 2-1 (e.g., ...). Figure 1a (as shown) or the gap between acoustic module 2-1 and enclosure 1-2 (as shown) Figure 2 As shown, it constitutes the through section 2-2.

[0030] The acoustic waveguide cavity 1-4 is formed by the top plate 1-1, the surrounding wall 1-2, and the bottom plate 1-3.

[0031] The sound-absorbing metamaterial unit based on the coupled resonant structure and the broadband impedance modulator provided by this invention can adjust the impedance matching over a wide range by adjusting the longitudinal thickness (z-axis direction) of the broadband impedance modulator, the distance between the broadband impedance modulator and the top plate, and the transverse width (x-axis direction) of the through part. By utilizing the synergistic effect of the coupled resonant structure and the broadband impedance modulator, low-frequency broadband high-efficiency sound absorption can be achieved.

[0032] Preferably, the volume of the broadband impedance modulator 2 is smaller than the volume of the acoustic waveguide cavity 1-4. That is, after the broadband impedance modulator 2 is installed in the acoustic waveguide cavity 1-4, there is still some space left inside the acoustic waveguide cavity 1-4. This design allows for flexible adjustment of the impedance matching frequency band to achieve better sound absorption, and also saves on the cost of using the broadband impedance modulator 2.

[0033] Preferably, such as Figure 3 As shown, depending on different operating conditions and sound absorption requirements, the broadband impedance modulator 2 can be in contact with the top plate or the bottom plate. Figure 4 As shown, when the broadband impedance modulator 2 is not in contact with the top plate 1-1 or the bottom plate 1-3, the sound-absorbing metamaterial unit also includes a support part 3, which is set on the enclosure wall 1-2 to support the broadband impedance modulator 2.

[0034] Preferably, the support part 3 is a rigid mesh structure with openings, so as to achieve a good support effect without affecting the function of the broadband impedance modulator 2.

[0035] Preferably, the minimum characteristic dimension of the cross-section of the acoustic waveguide cavity 1-4 (for example, when the cross-section of the acoustic waveguide cavity is rectangular, the minimum characteristic dimension is the minimum value of its side length) is less than one-quarter of the wavelength of the sound wave at the lowest resonant frequency, which facilitates the introduction of sound waves.

[0036] Preferably, the material of the acoustic module 2-1 is one of the following: foam porous material, fiber porous material, lattice porous material, and granular porous material.

[0037] Preferably, the material of the acoustic module 2-1 is one of melamine, polyimide, polyurethane, glass wool, foamed metal, glass fiber, stainless steel fiber, slag wool, and polyester cotton.

[0038] Preferably, the through-section 2-2 is in the direction perpendicular to the bottom plate to the top plate (i.e., the z-axis direction).

[0039] The cross-sectional shape (i.e., the xy plane) of the through section can be a rectangle, triangle, circle, ellipse, or other geometric shapes.

[0040] Preferably, such as Figure 4As shown, according to the requirements of the operating conditions, the sound-absorbing metamaterial unit also includes a wrapping part 4, which wraps the top plate 1-1 from the outside of the coupled resonant structure 1 to prevent or reduce the influence of the external environment (such as dust) on the sound-absorbing metamaterial.

[0041] Preferably, the material of the wrapping part 4 is a fabric with high sound transmission.

[0042] Preferably, the materials of the top plate 1-1, the enclosure 1-2, and the bottom plate 1-3 can be the same or different; the materials can be metal, wood, stone, glass, and plastic, etc.

[0043] The top plate 1-1 may have a single hole (slit) or multiple holes (slits), such as... Figure 5 As shown.

[0044] This invention also proposes a sound-absorbing metamaterial device based on a coupled resonant structure and a broadband impedance modulator, such as... Figure 6 As shown, it is composed of several sound-absorbing metamaterial units arranged in an array as described above.

[0045] In a sound-absorbing metamaterial device, the parameters of each sound-absorbing metamaterial unit can be the same or different.

[0046] Preferably, within the target frequency band, based on impedance matching conditions, several sound-absorbing metamaterial units with different parameters can be combined into a large metaunit, and then the metaunit can be arrayed to form a sound-absorbing metamaterial device, thereby achieving efficient sound absorption over a wider frequency band.

[0047] Example 1

[0048] This embodiment provides a sound-absorbing metamaterial unit based on a coupled resonant structure and a broadband impedance modulator, including:

[0049] The coupled resonant structure includes a top plate, surrounding walls, a bottom plate, and the acoustic waveguide cavity they form; the top plate is a slotted plate (such as...). Figure 5 As shown in (f), the thickness of the top plate is 5mm and the width of the seam is 9mm.

[0050] A broadband impedance modulator, located within the acoustic waveguide cavity and in contact with the top plate, comprises two acoustic modules and a through section (such as...). Figure 3 (as shown in (b)).

[0051] In this embodiment, the sound-absorbing metamaterial unit has a thickness (z-axis dimension) of 55 mm, a width (x-axis dimension) of 100 mm, and a length (y-axis dimension) of 200 mm. The broadband impedance modulator has a thickness (z-axis dimension) of 40 mm, and the cross-sectional shape of the through-section is rectangular, with a width (the gap width between the two acoustic modules) of 7 mm. The acoustic modules are made of polyurethane.

[0052] The sound-absorbing metamaterial unit provided in this embodiment achieves near-perfect sound absorption at 430Hz. In the frequency range of 266 to 894Hz, the minimum sound absorption coefficient is greater than 0.5, and the normalized sound absorption bandwidth (i.e., 2×(894-266) / (894+266)) reaches 1.08, indicating that the sound-absorbing metamaterial unit provided in this embodiment can have a good sound absorption effect in the low-frequency broadband range.

[0053] Example 2

[0054] This embodiment provides a sound-absorbing metamaterial device based on a coupled resonant structure and a broadband impedance modulator. It consists of nine different sound-absorbing metamaterial units (hereinafter referred to as sound-absorbing units) connected in parallel. Each sound-absorbing unit has a cuboid shape, with a thickness (z-axis dimension) of 100 mm, a width (x-axis dimension) of 100 mm, and a length (y-axis dimension) of 300 mm. The nine sound-absorbing units are arranged evenly and closely in a 3×3 configuration in the xy-plane. Following a left-to-right and front-to-back order, each sound-absorbing unit is sequentially named Sound-absorbing Unit 1, Sound-absorbing Unit 2, ..., Sound-absorbing Unit 9. The top plate of each sound-absorbing unit is a perforated plate. From sound-absorbing unit 1 to sound-absorbing unit 9, the perforation rates of the top plates are 19.4%, 5.6%, 19.7%, 1.35%, 19.9%, 1.9%, 19.2%, 19.6%, and 19.3%, respectively; the perforation diameters of the top plates are 0.1mm, 3.6mm, 0.1mm, 4.7mm, 1.9mm, 4.8mm, 0.1mm, 0.2mm, and 1.8mm, respectively. Each broadband impedance modulator contains two high-porosity acoustic modules and a through section, with the through section located in the middle of the broadband impedance modulator. The thickness (z-axis dimension) of the broadband impedance modulator is respectively... The dimensions are: 11mm, 90mm, 8mm, 1mm, 80mm, 36mm, 6mm, 80mm, and 91mm; the cross-sectional shape of the through section is rectangular, with a length (y-direction dimension) of 100mm and a width (x-direction dimension) of 50mm, 10mm, 32mm, 38mm, 5mm, 46mm, 17mm, 8mm, and 5mm respectively; the distances from each broadband impedance modulator to the top plate are: 87mm, 2.6mm, 87mm, 98mm, 18mm, 29mm, 43mm, 16mm, and 6mm respectively; the material of the high-porosity acoustic module is melamine. In the frequency range of 250–1000Hz, the minimum sound absorption coefficient of the sound-absorbing metamaterial device provided in this embodiment is greater than 0.9, and the average sound absorption coefficient is greater than 0.94, indicating that the sound-absorbing metamaterial device provided in this embodiment can have a good sound absorption effect in the low-frequency broadband range.

[0055] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations or substitutions made under the inventive concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A sound absorbing metamaterial unit based on a coupling of a resonant structure and a broadband impedance-modulating body, characterized in that, The sound-absorbing metamaterial unit comprises: a coupling resonance structure comprising a top plate, a surrounding wall, a bottom plate, and an acoustic waveguide cavity formed by the top plate, the surrounding wall, and the bottom plate; the top plate is a perforated plate or a slotted plate, and the minimum feature size of the cross section of the acoustic waveguide cavity is less than one fourth of the wavelength of the acoustic wave at the lowest order resonance frequency; a broadband impedance modulation body located in the acoustic waveguide cavity and comprising at least one acoustic module and at least one through part; the acoustic module is installed along the circumferential direction of the surrounding wall, and the gap between two acoustic modules or the gap between the acoustic module and the surrounding wall constitutes the through part; the impedance matching is adjusted in a wide range by adjusting the longitudinal thickness of the broadband impedance modulation body, the distance between the broadband impedance modulation body and the top plate, and the transverse width of the through part; the material of the acoustic module is one of a foam type porous material, a fiber type porous material, a lattice type porous material, and a particle type porous material; due to severe friction inside the acoustic module, the sound energy is converted into heat energy of the solid and dissipated through solid heat conduction.

2. The sound absorbing metamaterial unit of claim 1, wherein, The volume of the broadband impedance modulation body is smaller than the volume of the acoustic waveguide cavity.

3. The sound absorbing metamaterial unit of claim 1 or 2, wherein, When the broadband impedance modulation body is not in contact with the top plate or the bottom plate, the sound-absorbing metamaterial unit further comprises a supporting part arranged on the surrounding wall and used for supporting the broadband impedance modulation body.

4. The sound absorbing metamaterial unit of claim 3, wherein, The supporting part is an open rigid net structure.

5. The sound absorbing metamaterial unit of claim 1, wherein, The through direction of the through part is a vertical direction from the bottom plate to the top plate.

6. The sound absorbing metamaterial unit of claim 1, wherein, The sound-absorbing metamaterial unit further comprises a wrapping part wrapping the top plate from the outside of the coupling resonance structure.

7. The sound absorbing metamaterial unit of claim 6, wherein, The material of the wrapping part is cloth.

8. A sound absorbing metamaterial device based on a coupling of a resonant structure and a broadband impedance-modulating body, characterized in that, The sound-absorbing metamaterial unit is arranged in an array according to any one of claims 1 to 7.

Images