Distributed sound absorption structure and its application

Abstract

The present invention provides a distributed sound absorbing structure and application thereof, wherein the sound absorbing structure comprises: a sound absorbing material, which is suitable for absorbing sound waves; and a plurality of flat plates, which are laid flat on the sound absorbing material in a distributed manner, and are suitable for superimposing the sound absorbing material to form local resonance.

Description

Technical Field

[0001] The present invention relates to the technical field of acoustic noise reduction, and in particular to a distributed sound absorption structure and application thereof. Background Art

[0002] Low-frequency noise is common in daily life, such as noise generated by the operation of mechanical equipment, traffic noise, vibration of construction sites, etc., which has a significant negative impact on the living and working environment. Low-frequency noise has a wide frequency range and a long wavelength, and the difficulty of phase reversal increases accordingly, making low-frequency noise one of the pain points in the field of noise reduction.

[0003] At present, the common solution for noise reduction of low-frequency noise is to design metamaterials or superstructures for low-frequency noise to achieve sound absorption or isolation effects. However, due to the limitations of the application environment and the size of the material, the wide-frequency sound absorption solutions on the market for the frequency range below 400Hz are still imperfect. Summary of the invention

[0004] In view of this, the present invention provides a distributed sound absorption structure and application, which can achieve broadband sound absorption for low-frequency broadband noise.

[0005] As one aspect of the present invention, a distributed sound absorbing structure is provided, which is characterized by comprising: a sound absorbing material suitable for absorbing sound waves; and a plurality of flat plates laid flat on the sound absorbing material in a distributed manner, suitable for stacking the sound absorbing material to form a local resonance system.

[0006] According to an embodiment of the present invention, the sound absorbing material includes any one of foam, fiber, bio-based sound absorbing material, artificial sound absorbing superstructure or sound absorbing metamaterial.

[0007] According to an embodiment of the present invention, the sound absorbing material is an elastic porous material, including any one of glass fiber, polyurethane foam, polyester fiber, and melamine; the material of the flat plate includes any one of polymer material and metal material.

[0008] According to an embodiment of the present invention, the polymer material is selected from any one or more of polycarbonate, polyethylene, polypropylene, polyamide, polyimide, and polyetheretherketone; the metal material is selected from any one or more of aluminum, copper, steel, and iron.

[0009] According to an embodiment of the present invention, a gap is formed between adjacent flat plates; the width of the gap ranges from 0.5 to 100 mm. Preferably, the width of the gap ranges from 2 mm.

[0010] According to the embodiment of the present invention, the thickness of the sound absorbing material is 0.5-100 mm; the thickness of the flat plate is 1-20 mm; the length of the flat plate is 5-1000 mm, and the width is 5-1000 mm.

[0011] As another aspect of the present invention, an application of a sound absorbing structure is invented, comprising: arranging the sound absorbing structure on the surface of a wall or a device component to control noise.

[0012] According to an embodiment of the present invention, the noise is low-frequency broadband noise with a frequency of 100-2000 Hz.

[0013] According to an embodiment of the present invention, the frequency of the noise is 100-1000 Hz.

[0014] Based on the above technical solution, the distributed sound absorbing structure and its application provided by the present invention are formed by laying multiple flat plates on the sound absorbing material in a distributed manner, and combining them to form a local resonance sound absorbing superstructure / metamaterial with a certain thickness. After the sound wave enters the sound absorbing material, the sound energy is dissipated based on the porous structure of the sound absorbing material, and when the sound wave acts on the flat plate, it will cause the vibration of the entire structure. Due to the existence of the damping of the flat plate and the damping of the sound absorbing material, a local resonance is formed to further consume the sound energy, thereby playing a sound absorption role. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a finite element analysis diagram of the sound absorbing structure in an embodiment of the present invention;

[0016] Figure 2 Schematic diagram of the principle of the sound absorbing material in the sound absorbing structure in an embodiment of the present invention;

[0017] Figure 3 is a three-dimensional schematic diagram of a distributed sound absorption structure in an embodiment of the present invention;

[0018] Figure 4 It is a schematic diagram of finite element analysis of the gap of the flat plate on the sound absorbing structure in the embodiment of the present invention;

[0019] Figure 5 is a distribution diagram of sound energy dissipation of each part of the sound absorbing structure in an embodiment of the present invention;

[0020] Figure 6 is a finite element model of the sound absorbing structure in an embodiment of the present invention;

[0021] Figure 7 Schematic diagram of the distribution of the surface plates of the sound absorbing structure in an embodiment of the present invention;

[0022] Figure 8 This is a curve diagram of the sound absorption coefficient obtained by the sound absorption structure inside the reverberation chamber in an embodiment of the present invention.

[0023] [Description of Reference Numerals]

[0024] 1- Flat plate;

[0025] 2-Sound absorbing materials;

[0026] 21 - solid items;

[0027] 22-Fluid term. DETAILED DESCRIPTION

[0028] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0029] Below, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present invention. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of embodiments of the present invention. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of concepts of the present invention.

[0030] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The terms "comprise", "include", etc. used herein indicate the existence of features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0031] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification, and should not be interpreted in an idealized or overly rigid manner.

[0032] When using expressions such as "at least one of A, B, and C, etc.", they should generally be interpreted according to the meaning of the expression commonly understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0033] The test materials and reagents used in the following examples, unless otherwise specified, can be obtained from commercial sources. Specific techniques or conditions not specified in the examples are conventional methods and can be carried out according to the techniques or conditions described in the literature in the field or according to the product instructions.

[0034] In the process of realizing the present invention, it is found that a commonly used method in low-frequency sound absorption technology is to use a micro-perforated plate and a resonant cavity to perform impedance matching sound absorption design.

[0035] Among them, one method is to use COMSOL and a resonant cavity model to process low-frequency noise, which provides a thin-film resonant cavity with adjustable parameters. The absorption frequency and coefficient are adjusted by changing the model size and the thickness of the elastic film to achieve specific absorption of specific frequencies. Specifically, by making resonant cavity models of different specifications and conducting impedance tube tests, combined with theoretical simulations of COMSOL software, until the theoretical data is basically consistent with the experimental data. Then, the influence curve of film thickness and diameter on the sound absorption effect is determined by extended simulation and control variable method, and the absorption effect of specific frequencies is achieved. However, the resonant cavity depth obtained by this method is relatively large, which is not suitable for general application scenarios, and the cylindrical model has space limitations in practical applications, which makes it difficult to adapt to different needs.

[0036] Another method is to install a noise reduction component to reduce low-frequency noise, which can effectively absorb the beat frequency noise generated by the operation of the compressor. The noise reduction component includes a resonant sound absorbing component and a porous sound absorbing layer, wherein the resonant sound absorbing component is open to the front and is hollow, and its front side is connected to the front panel of the casing to form a closed air chamber, and the porous sound absorbing layer is installed on the rear side of the resonant sound absorbing component. This noise reduction component adopts a multi-layer structure of sound absorption + sound insulation + cavity, and has good sound absorption and noise reduction effects. However, this structure is complex and costly, the processing of micropores has high material requirements, and the uniformity is difficult to control, which will lead to poor consistency of sound absorption performance. In addition, when dealing with low-frequency beat frequency noise, it is necessary to increase the weight of the sound insulation layer or the depth of the cavity. This process is difficult to achieve and lacks design for specific frequencies, such as frequencies below 400Hz.

[0037] In view of this, the present invention provides a distributed sound absorption structure and application, specifically, as Figure 1 As shown, as one aspect of the present invention, a distributed sound absorbing structure is provided, comprising: a flat plate 1 and a sound absorbing material 2, wherein the sound absorbing material is suitable for absorbing sound waves; a plurality of flat plates are distributedly laid on the sound absorbing material, suitable for superimposing the sound absorbing material to form local resonance.

[0038] According to an embodiment of the present invention, a plurality of flat plates 1 can be distributed and laid flat on a sound absorbing material to form a sound absorbing structure with a certain thickness. The sound waves enter the porous structure of the sound absorbing material to achieve partial dissipation. At the same time, the sound waves act on the flat plate to cause the vibration of the entire structure, forming a local resonance and further dissipating the sound waves based on the damping of the flat plate and the damping of the material, thereby playing a role in sound absorption. The sound absorbing mechanism is relatively simple and has a high application value in the engineering field.

[0039] According to an embodiment of the present invention, the sound absorbing material 2 includes any one of foam, fiber, bio-based sound absorbing material, artificial sound absorbing superstructure or sound absorbing metamaterial, but is not limited thereto. Other materials that can reduce the reflection of noise and sound waves, thereby reducing the propagation and diffusion of noise can also be selected as needed.

[0040] According to an embodiment of the present invention, the sound absorbing material 2 is an elastic porous material, including any one of glass fiber, polyurethane foam, polyester fiber, and melamine. These materials have good sound absorption performance and durability, and can be widely used in the fields of construction, automobiles, aerospace, etc. to reduce noise and improve the acoustic environment.

[0041] According to an embodiment of the present invention, the material of the plate includes any one of a polymer material and a metal material, wherein the elastic modulus of the polymer material can be selected to be 2×10 5 ~1×10 11 Pa, for example, can be 3×10 6 Pa, 5×10 8 Pa, 8×10 9 Pa, 5×10 10 Pa, etc. Flat plate materials within this range can absorb noise in a wider frequency range.

[0042] According to an embodiment of the present invention, the polymer material is selected from any one or more of polycarbonate, polyethylene, polypropylene, polyamide, polyimide, and polyetheretherketone; the metal material is selected from any one or more of aluminum, copper, steel, and iron.

[0043] Figure 1 4 is a finite element analysis diagram of the sound absorbing structure in an embodiment of the present invention.

[0044] The flat plate material is selected as polycarbonate PC, with a size of 100×100×2mm, and the sound absorbing material is glass fiber, with a size of 100×100×48mm. Through finite element analysis, it is found that when a 1Pa plane wave is vertically incident on the sound absorbing structure, the overall sound energy dissipation distribution is as follows: Figure 1 As shown in the figure, since the plate is thin and the damping of the plate body is small, the total power density of the plane wave on the plate is low. After volume integration, it can be obtained that the sound energy dissipated by the elastic porous material is about 10 -6 W, the sound energy dissipated by the plate is about 10 -9 W.

[0045] Figure 2 Schematic diagram of the principle of the sound absorbing material in the sound absorbing structure in an embodiment of the present invention.

[0046] like Figure 2As shown in the figure, the plate is the main mass part of the whole structure, marked as Mass, and below it is the elastic porous material, which is deconstructed into the solid item 21 and the fluid item 22 of the elastic porous material, wherein the solid item 21 is used to provide stiffness, and the fluid item 22 is used to provide damping. The plate of limited size prevents the local resonance system formed on the elastic porous material of limited thickness. After the sound wave (such as a vertically incident plane wave) enters the elastic porous material, the sound energy is dissipated, and the remaining part of the sound wave will act on the plate to cause the resonance of the whole system, and further consume the sound energy based on the damping of the plate and the elastic porous material, thereby playing a sound absorption role.

[0047] According to an embodiment of the present invention, when a plurality of flat plates are dispersedly attached to the surface of the sound absorbing material, gaps are formed between adjacent flat plates; the width of the gaps ranges from 0.5 to 100 mm, for example, 2 mm, 15 mm, 36 mm, 50 mm, 72 mm, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0048] According to an embodiment of the present invention, preferably, the width of the gap is in the range of 2 mm, and the sound wave enters the elastic porous material through the gap on the side of the flat plate to achieve dissipation of sound energy.

[0049] Figure 3 is a three-dimensional schematic diagram of a distributed sound absorption structure in an embodiment of the present invention; Figure 4 It is a schematic diagram of finite element analysis of the gap of the flat plate on the sound absorbing structure in the embodiment of the present invention.

[0050] like Figure 3 As shown in the figure, when four flat plates are laid flat on the surface of the sound-absorbing material, there will be gaps between the flat plates. The gaps are set to 2 mm. Finite element analysis is performed on the structure, combined with Figure 4 It can be seen that in the energy dissipation power distribution per unit volume, the presence of gaps can bring additional acoustic energy loss.

[0051] Furthermore, by integrating the volume of the flat plate, gap, and porous sound-absorbing material in the sound-absorbing structure, the sound energy dissipation power of each part can be obtained, such as Figure 5 shown.

[0052] Figure 5 Graph showing the sound energy dissipation distribution of each part of the sound absorbing structure in the embodiment of the present invention.

[0053] Depend on Figure 5 It can be seen that sound waves can generate higher sound energy dissipation power in the sound absorbing mechanism provided by the present invention, wherein the porous material plays a major role in dissipating sound energy, and the gaps between the flat plate materials also have a certain effect in dissipating sound energy, which indicates that the structure can have better sound absorption performance.

[0054] According to an embodiment of the present invention, the thickness of the sound absorbing material is 0.5 to 100 mm, for example, 2 mm, 8 mm, 25 mm, 48 mm, 72 mm, 98 mm, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable. It should be noted that the size of the sound absorbing material needs to be larger than the size of the flat plate, and there is no specific restriction.

[0055] According to the embodiment of the present invention, the thickness of the selected flat plate is relatively low, and the thickness of the flat plate is 1-20 mm, for example, it can be 2 mm, 5 mm, 12 mm, 15 mm, 18 mm, etc.; the length of the flat plate is 5-1000 mm, for example, it can be 8 mm, 150 mm, 280 mm, 500 mm, 680 mm, etc.; the width of the flat plate is 5-1000 mm, for example, it can be 10 mm, 350 mm, 480 mm, 650 mm, 810 mm, etc. However, it is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0056] According to an embodiment of the present invention, the above-mentioned sound absorbing structure is relatively simple, and finite element optimization can be used to optimize the thickness and size of the flat plate and the thickness of the sound absorbing material according to the fixed thickness limit required by the sound absorbing structure to achieve the best sound absorption effect in a fixed frequency range.

[0057] Specifically, the thickness of the entire sound-absorbing component and the noise frequency range that needs to be absorbed are first determined according to the application scenario, and the sound-absorbing material that meets the application scenario is selected as the base material. After selecting a thinner flat plate that meets the application scenario, a distributed sound-absorbing structure model is established with the help of finite element simulation or numerical analysis model, such as Figure 6 shown.

[0058] Figure 6 It is the finite element model of the sound absorbing structure in the embodiment of the present invention.

[0059] Then, iterative optimization is performed based on the material parameters of the flat plate and the parameters of the sound-absorbing material to obtain the corresponding flat plate thickness, size and thickness of the sound-absorbing material under the optimal sound absorption coefficient, and then the optimal sound absorption coefficient is inversely calculated to verify the sound absorption coefficient of the sound-absorbing structure.

[0060] It should be noted that the reflection coefficient r of the sound absorbing structure can be calculated based on the transfer function Hi of the incident plane wave, the transfer function Hr of the reflected wave, and the transfer function H12 of the total sound field. The calculation formula is shown in the following formula (1).

[0061]

[0062] The sound absorption coefficient α is then calculated based on the reflection coefficient, and the calculation formula is shown in the following formula (2).

[0063] α=1-|r| 2Formula (2)

[0064] Furthermore, the flat plate material also has sound absorption properties. When setting up the simulation, it is necessary to consider the coupled vibration between the flat plate and the air on both sides. The two sides of the flat plate can be regarded as fluids, and the boundary conditions on both sides of the flat plate can be written as the following equations (3) to (5).

[0065]

[0066]

[0067] F A =(p t ,down-p t ,up)n Formula (5)

[0068] Among them, u tt is the structural acceleration, n is the surface normal direction, p t is the total sound pressure, q d is the acoustic dipole domain sound source, F A is the acoustic load force acting on the structure (force per unit area), ρ c is the density of the fluid on both sides of the plate.

[0069] As another aspect of the present invention, an application of a sound absorbing structure is invented, comprising: arranging the sound absorbing structure on the surface of a wall or a device component to control noise.

[0070] According to an embodiment of the present invention, the noise is low-frequency broadband noise, and the frequency is 100-2000 Hz, for example, 200 Hz, 500 Hz, 800 Hz, 1200 Hz, 1600 Hz, etc. Preferably, the frequency of the noise is 10-1000 Hz, for example, 12 Hz, 80 Hz, 220 Hz, 320 Hz, 700 Hz, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0071] According to an embodiment of the present invention, when it is necessary to improve the sound absorption performance of noise in a wide frequency range of 100 to 1000 Hz in a certain application scenario, the thickness limit can be set to less than 50 mm, the flat plate material is selected as polycarbonate (PC) plastic, and the sound absorbing material is selected as ultra-fine glass fiber. The length and width dimensions of the flat plate are selected to be 100×100 mm, the length and width dimensions of the sound absorbing material are also set to be 100×100 mm, and the initial thickness of the flat plate material is set to 1 mm. Then, according to the sound wave frequency range of 10 to 1000 Hz, the thickness of the flat plate material, the thickness and size of the sound absorbing material are iteratively increased, with the maximization of the sound absorption coefficient within the frequency band as the optimization goal, and the optimal value of the thickness of the flat plate and the sound absorbing material is determined by selecting the range of the thickness of the flat plate and the sound absorbing material.

[0072] The optimization simulation sets the length and width of the plate to 100×100mm, and the length and width of the sound-absorbing material to 600×600mm. Different characteristic frequencies can be obtained in the process of gradually increasing the thickness of the plate. Table 1 shows the corresponding characteristic frequencies in the process of plate thickness superposition optimization. It can be seen from Table 1 that when the thickness of the plate is 2mm, the characteristic frequencies below 100Hz can be covered, so the thickness of the plate is determined to be 2mm and the thickness of the sound-absorbing material is 48mm.

[0073] Table 1

[0074]

[0075] Figure 7 Schematic diagram of the distribution of the surface plates of the sound absorbing structure in an embodiment of the present invention.

[0076] According to the parameters optimized by finite element method, 36 polycarbonate plates with a thickness of 2 mm and a size of 100 × 100 mm were selected, and ultra-fine glass fiber materials with a size of 600 × 600 mm and a thickness of 48 mm were prepared. The plates were bonded to the surface of the sound-absorbing material by gluing, and the following was obtained: Figure 7 The structure shown in the figure. The gluing process can use spray-type solvent glue, spray-type water glue or self-adhesive thin double-sided glue.

[0077] The sample of the sound absorbing structure is placed in a reverberation chamber (for example, a Mecanum reverberation chamber), and the sound absorption coefficient of the sound absorbing structure under irregular incidence conditions is evaluated, and the following is obtained: Figure 8 The curve shown.

[0078] Figure 8 This is a curve diagram of the sound absorption coefficient obtained by the sound absorption structure inside the reverberation chamber in an embodiment of the present invention.

[0079] Depend on Figure 8 It can be seen that the sound absorbing structure provided by the present invention has excellent sound absorbing performance for noise in the frequency range of 100 to 2000 Hz. Preferably, it can cover the frequency range of 100 to 1000 Hz. More preferably, it can achieve low-frequency broadband sound absorbing performance below 400 Hz, and the thickness of the formed metamaterial / metastructure does not exceed 50 mm.

[0080] Based on the above technical solution, the sound-absorbing structure provided by the present invention can cooperate with the flat plate and the sound-absorbing material to form a local resonance system. The structure is relatively simple and has good sound absorption performance for low-frequency broadband noise. Based on limited conditions, the materials and parameters of the flat plate and the sound-absorbing material can be optimized with the help of finite element tool simulation to obtain the optimal parameters corresponding to the frequency to be reduced, so that the performance of the sound-absorbing structure is optimized. In addition, in the specific implementation process, the sound-absorbing structure unit can be modularized, which can reduce costs and facilitate large-scale applications.

[0081] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A distributed sound absorption structure, characterized in that: include: Sound-absorbing materials, suitable for absorbing sound waves; A plurality of flat plates are distributedly laid on the sound absorbing material, and are suitable for stacking the sound absorbing material to form a local resonance system; A gap is formed between adjacent plates; the width of the gap ranges from 0.5 to 100 mm; The sound absorbing material is an elastic porous material, including any one of glass fiber, polyurethane foam, polyester fiber, and melamine; The elastic porous material includes a solid item and a fluid item, the solid item is used to provide stiffness, and the fluid item is used to provide damping; The local resonance system forms a sound absorbing structure by distributing and paving a plurality of flat plates on the sound absorbing material. The sound waves enter the porous structure of the sound absorbing material to achieve partial dissipation. The sound waves act on the flat plates to cause the vibration of the sound absorbing structure, forming a local resonance to dissipate the sound waves.

2. The sound absorbing structure according to claim 1, characterized in that: The material of the plate includes any one of a polymer material and a metal material.

3. The sound absorbing structure according to claim 2, characterized in that: The polymer material is selected from any one or more of polycarbonate, polyethylene, polypropylene, polyamide, polyimide, and polyetheretherketone; The metal material is selected from any one or more of aluminum, copper, steel and iron.

4. The sound absorbing structure according to claim 1, characterized in that: The width of the gap is in the range of 2 mm.

5. The sound absorbing structure according to claim 1, characterized in that: The thickness of the sound absorbing material is 0.5-100 mm; The thickness of the plate is 1 to 20 mm; The length of the flat plate is 5-1000 mm, and the width is 5-1000 mm.

6. Use of the sound absorbing structure according to any one of claims 1 to 5, characterized in that: include: The sound absorbing structure is arranged on the surface of a wall or a device component to control noise.

7. The use according to claim 6, characterized in that: The noise is low-frequency broadband noise with a frequency of 100~2000 Hz.

8. The use according to claim 6, characterized in that: The frequency of the noise is 100~1000 Hz.

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