A sandwich micro-perforated panel sound absorption structure based on triply periodic minimal surface

Abstract

The application provides a sandwich micro-perforated plate sound absorption structure based on triple periodic minimal surface, comprising: a sandwich layer, comprising a plurality of triple periodic minimal surfaces arranged in an array in the XY direction; a plurality of sandwich layers arranged in an array in the Z direction, and a micro-perforated plate arranged between adjacent sandwich layers, wherein the micro-perforated plate is provided with a plurality of micro-holes; the inner cavities of the plurality of triple periodic minimal surfaces are connected in the XY direction and communicated in the Z direction through the micro-holes, thereby forming an inner cavity series connection system; and the outer cavities of the plurality of triple periodic minimal surfaces are connected in the XY direction and communicated in the Z direction through the micro-holes, thereby forming an outer cavity series connection system. The parallel structure of the inner cavity series connection system and the outer cavity series connection system is entangled and circled with each other, thereby effectively increasing the number of sound absorption peaks, so that the sound absorption effect of medium and low frequencies and wide frequencies is achieved. Meanwhile, the space utilization rate is high, and the structure weight is effectively reduced; and the structure volume can be changed according to the use requirement, and the compatibility is very strong.

Description

Technical Field

[0001] This invention relates to the field of sound-absorbing structure technology, and in particular to a sandwich micro-perforated plate sound-absorbing structure based on a triple-period minimal curved surface. Background Technology

[0002] The rapid development of high-speed trains and aerospace technology has increased people's travel speed, but it has also brought serious noise pollution, especially mid- and low-frequency noise, which seriously affects the physical and mental health of passengers and the lifespan of precision instruments. Sound-absorbing structures can reduce noise by absorbing sound waves and reducing reflections. Traditional sound absorption methods include porous materials, resonant sound absorption, and sound-absorbing wedges. Among these, porous materials are difficult to absorb low-frequency sound waves; resonant sound-absorbing structures can achieve low-frequency sound absorption, but the absorption frequency band is too narrow and cannot achieve wide-frequency sound absorption; sound-absorbing wedges are too large, which is not conducive to engineering applications, and none of the above structures / materials can meet the mechanical performance requirements of current structures.

[0003] Sandwich structures possess advantages such as good specific strength and specific stiffness. Compared to traditional sandwich structures, the triple-period minimal curved surface sandwich structure features an open interior and interconnected space. Furthermore, the minimal curved surface is extremely smooth, lacking sharp turns or connection points typical of lattice structures, thus better meeting the needs of practical engineering applications. However, the triple-period minimal curved surface sandwich structure does not possess the aforementioned sound absorption characteristics and cannot achieve sound absorption and noise reduction independently, requiring additional structural design.

[0004] For example, CN112699561A - A triple-period minimal curved surface sound insulation structure filled with oil and its preparation method, involves injecting viscous oil into a triple-period minimal curved surface sandwich structure to achieve sound insulation through solid-liquid coupling; however, this method of injecting viscous oil makes the overall structure extremely heavy, thus limiting the volume / thickness of the sound insulation structure in practical applications, otherwise the material strength may be insufficient to support the weight of the oil, leading to collapse; and extremely high sealing performance is required to prevent oil leakage, thus resulting in high processing and manufacturing costs.

[0005] CN109147749A - A high sound absorption rate connected multi-cavity resonant sound-absorbing covering layer discloses a sound-absorbing structure composed of multiple cavities arranged in a Z-direction array of an air-cavity elastic damping layer. Compared with the aforementioned prior art, it can be stacked multiple times in terms of structural volume / thickness. However, because its cavity structure is only arrayed in one direction, its space utilization rate is very low, and it cannot have the characteristics of internal openness and spatial continuity like a triple-period minimal curved surface sandwich structure.

[0006] In summary, traditional sound-absorbing structures in the prior art have low space utilization of materials, while triple-period minimal curved surface sound-absorbing structures have open space and high space utilization. However, the use of viscous oil results in heavy material weight and limited volume, preventing stacking and increasing manufacturing costs. Summary of the Invention

[0007] The purpose of this invention is to provide a sandwich micro-perforated plate sound absorption structure based on a triple period minimal curved surface, which can make the sandwich sound absorption structure of the triple period minimal curved surface lighter, and the sandwich can be combined and stacked according to actual needs, which is convenient for processing and manufacturing.

[0008] This invention provides a sandwich micro-perforated plate sound-absorbing structure based on triple-periodic minimal curved surfaces, comprising: a sandwich layer including a plurality of triple-periodic minimal curved surfaces arrayed in the XY direction; the plurality of sandwich layers arrayed in the Z direction, and a micro-perforated plate provided between adjacent sandwich layers, the micro-perforated plate having a plurality of micropores; the inner cavities of the plurality of triple-periodic minimal curved surfaces connected in the XY direction and connected in the Z direction through the micropores, forming an inner cavity series system; the outer cavities of the plurality of triple-periodic minimal curved surfaces connected in the XY direction and connected in the Z direction through the micropores, forming an outer cavity series system.

[0009] Furthermore, the inner cavity series system and the outer cavity series system are not connected within the same sandwich layer, forming an inner and outer cavity parallel system.

[0010] Furthermore, it also includes a panel, located outside the outermost sandwich layer, and encloses a triple-period minimal curved surface.

[0011] Furthermore, the panel is disposed outside one of the outermost sandwich layers, and the micro-perforated plate is disposed outside the other opposite outermost sandwich layer.

[0012] Furthermore, the triple periodic minimum surface is obtained by thickening the P-type minimum surface unit cell.

[0013] Furthermore, the mathematical formula for the triple periodic minimum surface is as follows:

[0014]

[0015] In the formula, T is the periodic constant and C is the minimum surface constant.

[0016] Furthermore, the relative acoustic impedance of the nth layer of the microperforated plate:

[0017]

[0018]

[0019] In the formula, t is the thickness of the micro-perforated plate, d is the diameter of the micro-perforation, η is the viscosity coefficient in air, ω is the angular frequency, ψ is the ratio of the perforation area to the plate area, and n Sarea S represents the number of openings on the micro-perforated plate. area Let V be the equivalent area of ​​the micro-perforated plate, V be the cavity volume, T be the periodic constant of the minimum surface, k be the perforated plate constant, ρ0 be the air density, and c0 be the speed of sound propagation.

[0020] Furthermore, the relative acoustic impedance of the sound-absorbing structure:

[0021]

[0022] In the formula:

[0023] and This is the ratio of the equivalent area of ​​the corresponding micro-perforated plates in the inner and outer cavities to the total cross-sectional area;

[0024]

[0025] i = 1, 2

[0026]

[0027]

[0028] Z ti Z represents the equivalent impedance of an n-layer micro-perforated plate structure, where i represents the series connection between the inner and outer cavities, 1 represents the series connection between the inner and outer cavities, 2 represents the series connection between the inner and outer cavities, and Z represents the series connection between the inner and outer cavities. eq2i Z represents the equivalent impedance of the structure composed of the second layer plate and the third to nth layers of micro-perforated plates and cavities, and so on. eq(n-1)i It is the equivalent impedance of the structure composed of the (n-1)th and nth layers of micro-perforated plates and the cavity.

[0029] Furthermore, the sound absorption coefficient of the sound-absorbing structure:

[0030]

[0031] The technical solution of this invention utilizes a series of triple-periodic minimal curved surfaces arrayed in the XYZ directions. The inner cavities of these surfaces are interconnected via micro-perforated plates, forming an inner cavity series system. Similarly, the outer cavities are interconnected via micro-perforated plates, forming an outer cavity series system. These inner and outer cavity series systems form an entangled, interconnected parallel structure, but are not interconnected within the sound-absorbing structure itself. When sound waves pass through the sound-absorbing structure, they circulate through the inner and outer cavity series systems and the minimal curved surfaces in between, achieving sufficient sound absorption through continuous attenuation between the gas and solid media. Furthermore, this design offers high space utilization, effectively reducing structural weight, resulting in a high-performance, lightweight sound-absorbing structure. The structural size can be adjusted to meet specific usage requirements, facilitating manufacturing and providing strong compatibility. Attached Figure Description

[0032] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0034] Figure 2 This is a schematic diagram of a single triple-periodic minimal surface of the present invention;

[0035] Figure 3 This is a schematic diagram of the inner and outer cavities of the minimal curved surface unit cell of the present invention;

[0036] Figure 4 This is a schematic diagram of the micro-perforated plate of the present invention;

[0037] Figure 5 This is a graph showing the sound absorption coefficient of the present invention.

[0038] Figure 6 This is a schematic diagram of the Z-axis array of the triple-periodic minimal surface inner and outer cavities of the present invention;

[0039] Explanation of reference numerals in the attached figures:

[0040] 1-Triple-periodic minimal curved surface, 2-Sandwich layer, 3-Micro-perforated plate, 301-Micropore, 4-Panel, 5-Inner cavity, 6-Outer cavity; Detailed Implementation

[0041] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0043] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. Furthermore, the terms "installed," "connected," and "linked" should be interpreted broadly; for example, they may refer to a fixed connection, a detachable connection, or an integral connection; they may refer to a mechanical connection or an electrical connection; they may refer to a direct connection or an indirect connection through an intermediate medium; and they may refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0044] Example 1

[0045] like Figures 1-4 As shown, the present invention provides a sandwich micro-perforated plate sound-absorbing structure based on triple periodic minimal curved surfaces, comprising: a sandwich layer 2, including a plurality of triple periodic minimal curved surfaces 1 arrayed in the XY direction; a plurality of sandwich layers 2 arrayed in the Z direction, and a micro-perforated plate 3 provided between adjacent sandwich layers 2, the micro-perforated plate 3 having a plurality of micro-holes 301; the inner cavities 5 of the plurality of triple periodic minimal curved surfaces 1 connected in the XY direction and connected in the Z direction through the micro-holes 301, forming an inner cavity series system; the outer cavities 6 of the plurality of triple periodic minimal curved surfaces 1 connected in the XY direction and connected in the Z direction through the micro-holes 301, forming an outer cavity series system.

[0046] Specifically, in this embodiment 1, in the overall structure of the material, several triple-periodic minimal curved surfaces 1 are arrayed in the XY plane to form a sandwich layer 2. Therefore, the number of arrays in the XY direction determines the area of ​​the material. The sandwich layers 2 are also arrayed in the z direction, so the number of arrays in the z direction determines the thickness of the material. According to actual usage requirements, the number of XYZ-direction unit arrays is increased, the thickness of the micro-perforated plate 3 is adjusted, and the number and diameter of the micropores 301 are controlled to control the sound absorption range, and a suitable material volume is designed. Since this application does not contain fillers such as oil, the weight is only relative to the weight of the material itself compared to the prior art. It can be basically infinitely stacked according to usage requirements, greatly increasing the compatibility and applicability of the absorption structure.

[0047] The internal space enclosed by the triple-periodic minimal surface 1 is called the inner cavity 5, and the external space enclosed by it and the micro-perforated plate 3 is called the outer cavity 6. The inner cavity 5 and the outer cavity 6 are separated by the triple-periodic minimal surface 1. To maintain the absorption effect, this embodiment uses the micro-perforated plate 3 to connect the triple-periodic minimal surfaces 1 arrayed in the Z direction, so that all the inner cavities of the triple-periodic minimal surface 1 are connected in series to form a whole inner cavity series system. This inner cavity series system is composed of each basic array unit (minimal surface inner cavity) connected in the XY direction and spaced in the Z direction (through micropores); this outer cavity series system is composed of each basic array unit (minimal surface outer cavity) connected in the XY direction and spaced in the Z direction (through micropores). By utilizing the curved structure of the minimal surface and the inner / outer cavity series system, the material can be guaranteed to have sufficient sound absorption function.

[0048] The internal cavity series system and the external cavity series system form an intertwined and surrounding parallel structure, but they are not interconnected within the sound-absorbing structure. When the sound wave passes through the sound-absorbing structure, it needs to continuously pass through several internal cavities 5, several external cavities 6, and the triple periodic minimal surface 1 between them in the XYZ direction, and achieve the sound absorption effect by continuously attenuating between the gas and solid media.

[0049] The opening diameter of the micro-perforated plate 3 is less than 1mm, and the opening position can be selected according to actual needs.

[0050] Example 2

[0051] This embodiment 2 describes a technical solution to further improve the sound absorption effect.

[0052] like Figures 1-4 and Figure 6 As shown, the inner cavity series system and the outer cavity series system are not connected within the same sandwich layer 2. It also includes a panel 4, located outside the outermost sandwich layer 2, which closes the outer hole of the triple-periodic minimal curved surface 4. A panel is located outside one outermost sandwich layer 2, and a micro-perforated plate 3 is located outside the other opposite outermost sandwich layer 2.

[0053] Specifically, in this sound-absorbing structure, the outermost side of the material is a panel 4, which closes all the holes of the triple periodic minimal curved surface 1 on this side. The other side is a micro-hole 301 plate, which connects the inner cavity series system and the outer cavity series system through the micro-holes 301 on the micro-hole 301 plate, making the entire sound-absorbing structure a whole sound-absorbing cavity.

[0054] Therefore, in this sound-absorbing structure, the internal cavity series system and the external cavity series system are connected in parallel inside the sound-absorbing structure and in series outside the sound-absorbing structure.

[0055] like Figure 5 and Figure 6 As shown, this series-parallel coupled sound absorption system has two absorption peaks corresponding to the inner cavity series system and the outer cavity series system in each sandwich layer. Each additional sandwich layer adds two more absorption peaks (the sound wave attenuates after passing through the previous sandwich layer). By increasing the number of sandwich layers, the number of sound absorption peaks in the system increases. As the number of sound absorption peaks increases, the effective sound absorption frequency widens accordingly, thus achieving a broadband sound absorption effect. According to theoretical calculations, this sound absorption structure is effective for mid-, low-frequency, and broadband sound absorption.

[0056] Example 3

[0057] This embodiment 3 mainly describes the triple periodic minimal surface 1.

[0058] like Figure 2 As shown, the triple periodic minimal surface 1 is obtained by thickening the P-type minimal surface unit cell. The mathematical formula for the triple periodic minimal surface 1 is:

[0059]

[0060] In the formula, T is the periodic constant and C is the minimum surface constant.

[0061] Specifically, the triple-periodic minimal surface 1 used in this sound-absorbing structure is obtained by thickening a P-type minimal surface unit cell. The P-type minimal surface (Schwarz Primitive (P)) is a known minimal surface morphology, and its specific structure will not be described in detail. It has four openings on its four sides and one opening on the top and bottom. The core layer 2 of this sound-absorbing structure is formed by arranging these triple-periodic minimal surfaces 1 in the XY direction, with adjacent triple-periodic minimal surfaces 1 connected to each other through their facing openings. The array in the z-direction is connected through its top and bottom openings via micropores 301, forming a series system within the cavity by connecting all the array units.

[0062] Example 4

[0063] like Figure 5As shown in the figure, this embodiment 4 takes a three-layer array in the z-direction as an example to illustrate the sound absorption effect of this sound absorption structure.

[0064] The relative acoustic impedance of the micro-perforated plate 3:

[0065]

[0066]

[0067] In the formula, t is the thickness of the micro-perforated plate, d is the diameter of the micro-perforation, η is the viscosity coefficient in air, ω is the angular frequency, ψ is the ratio of the perforation area to the plate area, and n Sarea S represents the number of openings on the micro-perforated plate. area Let V be the equivalent area of ​​the micro-perforated plate, V be the cavity volume, T be the periodic constant of the minimum surface, k be the perforated plate constant, ρ0 be the air density, and c0 be the speed of sound propagation.

[0068] Relative acoustic impedance of sound-absorbing structures:

[0069]

[0070] In the formula: and The ratio of the equivalent area of ​​the micro-perforated plate 3 corresponding to the inner cavity 5 and the outer cavity 6 to the total cross-sectional area;

[0071]

[0072] i = 1, 2

[0073]

[0074]

[0075] Z ti Z represents the equivalent impedance of an n-layer micro-perforated plate structure, where i represents the series connection between the inner and outer cavities, 1 represents the series connection between the inner and outer cavities, 2 represents the series connection between the inner and outer cavities, and Z represents the series connection between the inner and outer cavities. eq2i Z represents the equivalent impedance of the structure composed of the second layer plate and the third to nth layers of micro-perforated plates and cavities, and so on. eq(n-1)i It is the equivalent impedance of the structure composed of the (n-1)th and nth layers of micro-perforated plates and the cavity.

[0076] The sound absorption coefficient of the sound-absorbing structure:

[0077]

[0078] The principle of this sound-absorbing structure:

[0079] Each layer of minimal curved surface unit cell divides the cavity between the two micro-perforated plates 3 into two chambers: an inner cavity 5 and an outer cavity 6. The lightweight sandwich micro-perforated sound-absorbing structure with triple-perforated minimal curved surfaces 1 has a total of 2n cavities, where n is the number of basic units in the z-direction array. Through the outermost micro-perforated plate 3, the inner and outer cavities form an inner cavity series system and an outer cavity series system with the micro-perforated plate, respectively. These two series systems are connected in parallel within the sound-absorbing structure, forming a series-parallel coupled sound-absorbing system. By increasing the number of sandwich layers, the number of sound absorption peaks in the system is increased. As the number of sound absorption peaks increases, the effective sound absorption frequency is correspondingly widened, thereby achieving mid- and low-frequency and broadband sound absorption effects.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A sandwich micro-perforated plate sound-absorbing structure based on a triple-period minimal curved surface, characterized in that, include: The sandwich layer comprises several triple-periodic minimal surfaces arrayed in the XY direction; The sandwich layers are arrayed in the Z direction, and a micro-perforated plate is provided between adjacent sandwich layers, the micro-perforated plate being provided with a plurality of micropores; The cavities of several of the triple periodic minimal surfaces are connected in the XY direction and interconnected in the Z direction through the micropores, forming a series cavity system. The outer cavities of several triple periodic minimal surfaces are connected in the XY direction and connected in the Z direction through the micropores to form an outer cavity series system. It also includes a panel, located outside the outermost sandwich layer, which encloses the triple-periodic minimal surface; The panel is disposed outside one of the outermost sandwich layers, and the micro-perforated plate is disposed outside another opposite outermost sandwich layer; The triple periodic minimal surface is obtained by thickening a P-type minimal surface unit cell; The mathematical formula for the triple periodic minimum surface is as follows: ； In the formula, T It is a periodic constant. C It is the minimum surface constant; The relative acoustic impedance of the nth layer of microperforated plate: ； ， ， ； In the formula, t The thickness of the micro-perforated plate. d The diameter of the microperforation. η The viscosity coefficient of air. ω It is the angular frequency. ψ n is the ratio of the perforation area to the plate area. Sarea This refers to the number of holes in the micro-perforated plate. S area The equivalent area of ​​the micro-perforated plate. V The volume of the cavity. T It is the periodic constant of the minimal surface. k Let be the constant of the perforated plate. ρ 0 represents the density of air. c 0 represents the speed of sound propagation; Relative acoustic impedance of sound-absorbing structures: ； In the formula: φ 1 and φ 2 represents the ratio of the equivalent area of ​​the corresponding micro-perforated plates in the inner and outer cavities to the total cross-sectional area; Z ti Z represents the equivalent impedance of an n-layer microperforated plate structure, where i represents the series connection between the inner and outer cavities, 1 represents the series connection between the inner and outer cavities, 2 represents the series connection between the inner and outer cavities, and Z represents the equivalent impedance between the inner and outer cavities. eq2i Z represents the equivalent impedance of the structure composed of the second layer plate and the 3rd to nth layers of micro-perforated plates and cavities, and so on. eq(n-1)i It is the equivalent impedance of the structure composed of the (n-1)th and nth layers of micro-perforated plates and the cavity.

2. The sandwich micro-perforated plate sound-absorbing structure based on a triple-period minimal curved surface according to claim 1, characterized in that, The inner cavity series system and the outer cavity series system are not connected within the same sandwich layer, forming an inner and outer cavity parallel system.

3. The sound-absorbing structure of the sandwich micro-perforated plate based on a triple-period minimal curved surface according to claim 1, characterized in that, The sound absorption coefficient of the sound-absorbing structure: 。

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