阅读说明：本技术 一种具有双螺旋卷曲空间的吸声超材料及其制备方法 (Sound absorption metamaterial with double-helix curling space and preparation method thereof ) 是由 宋波 范军翔 史玉升 于 2020-06-30 设计创作，主要内容包括：本发明属于声学超材料相关技术领域,其公开了一种具有双螺旋卷曲空间的吸声超材料及其制备方法,所述吸声超材料包括多个吸声超材料单元,多个所述吸声超材料单元组成阵列；其中,所述吸声超材料单元包括自上而下设置的微穿孔板、双螺旋卷曲结构及背板,所述双螺旋卷曲结构包括隔板,所述隔板按照双螺旋形式设置,且形成了双螺旋卷曲空间；所述双螺旋卷曲空间包括螺旋状的第一声通道及第二声通道；所述微穿孔板开设有两个微孔,两个所述微孔分别与所述第一声通道及所述第二声通道相连通。本发明有效扩宽了吸声频率范围,达到更为理想的吸声效果。(The invention belongs to the technical field of acoustic metamaterial correlation, and discloses a sound absorption metamaterial with a double-spiral curled space and a preparation method thereof, wherein the sound absorption metamaterial comprises a plurality of sound absorption metamaterial units, and an array is formed by the plurality of sound absorption metamaterial units; the sound absorption metamaterial unit comprises a micro-perforated plate, a double-spiral curled structure and a back plate which are arranged from top to bottom, wherein the double-spiral curled structure comprises a partition plate which is arranged in a double-spiral mode and forms a double-spiral curled space; the double spiral curling space comprises a spiral first sound channel and a spiral second sound channel; two micropores are formed in the micro-perforated plate and are respectively communicated with the first sound channel and the second sound channel. The invention effectively widens the sound absorption frequency range and achieves more ideal sound absorption effect.)

1. A sound absorption metamaterial with double helix curling space is characterized in that:

the sound absorption metamaterial comprises a plurality of sound absorption metamaterial units, and an array is formed by the plurality of sound absorption metamaterial units;

the sound absorption metamaterial unit comprises a micro-perforated plate, a double-spiral curled structure and a back plate which are arranged from top to bottom, wherein the double-spiral curled structure comprises a partition plate which is arranged in a double-spiral mode and forms a double-spiral curled space; the double spiral curling space comprises a spiral first sound channel and a spiral second sound channel; two micropores are formed in the micro-perforated plate and are respectively communicated with the first sound channel and the second sound channel.

2. The sound absorbing metamaterial having a double spiral crimp space as claimed in claim 1, wherein: the shape of the first sound channel is the same as that of the second sound channel, and the tortuosity n of the first sound channel and the second sound channel is larger than or equal to 3.

3. The sound absorbing metamaterial having a double spiral crimp space as claimed in claim 1, wherein: the sound absorption metamaterial unit is square, the side length a of the sound absorption metamaterial unit is 20 mm-200 mm, and the thickness t of the sound absorption metamaterial unit is 0.2 mm-2 mm.

4. The sound absorbing metamaterial having a double spiral crimp space as in claim 3, wherein: the diameters of two micropores are respectively d₁And d₂And the value ranges are all 0.2 mm-5 mm.

5. The sound absorbing metamaterial having a double spiral crimp space as in claim 4, wherein: the widths of the first sound channel and the second sound channel are w respectively₁And w₂And the value ranges are all 2 mm-30 mm, and simultaneously the following relation d is satisfied₁≤w₁，d₂≤w₂，([n/2]+1)×(w1+w2)+(2×[n/2]+3) x b ═ a, where [ n/2-]Represents an integer part of n/2; n is the tortuosity of the first acoustic channel.

6. The sound absorbing metamaterial having a double spiral crimp space as claimed in any one of claims 1 to 5, wherein: the depth of the first sound channel is the same as that of the second sound channel, the minimum value of the depth D of the first sound channel is greater than or equal to 2mm, and the maximum value of the depth D of the first sound channel is less than or equal to 1/100 of the working wavelength.

7. The sound absorbing metamaterial having a double spiral crimp space as claimed in any one of claims 1 to 5, wherein: the thickness b of the separator ranges from 0.5mm to 3 mm.

8. The sound absorbing metamaterial having a double spiral crimp space as claimed in any one of claims 1 to 5, wherein: the thickness of the back plate is 1 mm-5 mm.

9. A method for preparing the sound absorption metamaterial having the double spiral crimp space as claimed in any one of claims 1 to 8.

Technical Field

The invention belongs to the technical field of acoustic metamaterials, and particularly relates to a sound absorption metamaterial with a double-spiral curling space and a preparation method thereof.

Background

The problem of low-frequency noise is widely existed in daily life, the low-frequency noise has long propagation distance and strong sound transmission capability, the brain central function of a human body is reduced after the low-frequency noise is exposed in a low-frequency noise environment for a long time, physical discomfort such as dizziness, fatigue and the like is easy to generate, and diseases of a nervous system, a spine and a gastrointestinal tract are also caused, so that the control of the low-frequency noise is a key point and a difficulty point in the modern noise reduction process. In natural materials, the acoustic wave is blocked following the mass law, which is expressed in particular as:

TL＝20lg(f)+20lg(M)-42

wherein TL is the sound insulation quantity dB; f is the acoustic frequency, Hz; m is the areal density of the sound insulator, kg/M². Therefore, the sound insulation quantity is influenced by the sound wave frequency and the surface density of the sound insulator, the higher the sound wave frequency is, the easier the sound wave frequency is to be blocked, and the lower the sound wave frequency is, the stronger the penetrating power is. In order to obtain the same sound insulation amount as that of a high-frequency sound wave for a low-frequency sound wave, a sound insulator is required to have a better surface density, and in the case of the same material, the sound insulator has a larger thickness. For example, for an areal density of 200kg/m²The sound insulation of (2) is 84dB when the sound wave frequency is 10000Hz, and is only 44Hz when the sound wave frequency is reduced to 100 Hz. To obtain the same sound insulation amount as 10000Hz sound wave, the surface density of the sound insulator needs to be increased to 19953kg/m²The thickness is increased by nearly 100 times! Is clearly impractical in practical applications. Therefore, it is a subject to be studied intensively how to reasonably control the noise level and propose a simple and efficient control method to suppress the noise.

The metamaterial is a material with an artificial periodic structure, has extraordinary physical properties which cannot be realized by natural materials, such as negative Poisson's ratio, negative refraction, sound wave focusing, stealth, absorption and the like, and has a very wide application prospect. The micro-perforated plate silencer is a novel sound absorption material made of a micro-perforated plate sound structure, and consists of a thin plate with regularly arranged micropores and a cavity behind the thin plate, and when the micro-perforated plate silencer is applied to absorption of low-frequency sound waves, the size of the cavity behind the back reaches the magnitude of meters, so that the micro-perforated plate silencer is difficult to apply to practice. In order to solve the problem, a scholars creatively curls up the background cavity to achieve the purpose of reducing the size, and obtains a more ideal effect, the size can be reduced to 1/100 of the wavelength of the sound wave, the acoustic metamaterial can achieve nearly 100% of sound absorption effect under specific frequency, but the frequency range is narrow, the half-peak width (the absorption peak bandwidth with the sound absorption coefficient of 50%) is usually between 20-100 Hz, and the application in the wider frequency range is difficult to meet.

Disclosure of Invention

Aiming at the defects or the improvement requirements of the prior art, the invention provides a sound absorption metamaterial with a double-spiral crimp space and a preparation method thereof, wherein the sound absorption metamaterial is provided with a double-spiral crimp structure, the double-spiral crimp structure is provided with the double-spiral crimp space, the double-spiral crimp space comprises two spiral sound channels, two micropores of a micro-perforated plate are respectively communicated with the two sound channels, each micropore corresponds to an absorption peak with the corresponding sound channel, when sound waves are emitted to the sound metamaterial from one side of the micro-perforated plate, the two sound channels are mutually influenced, the sound absorption frequency range can be effectively widened by matching with preset size parameters, and a more ideal sound absorption effect is achieved.

In order to achieve the above object, according to one aspect of the present invention, there is provided a sound absorption metamaterial having a double spiral crimp space, the sound absorption metamaterial comprising a plurality of sound absorption metamaterial units, a plurality of the sound absorption metamaterial units forming an array;

the sound absorption metamaterial unit comprises a micro-perforated plate, a double-spiral curled structure and a back plate which are arranged from top to bottom, wherein the double-spiral curled structure comprises a partition plate which is arranged in a double-spiral mode and forms a double-spiral curled space; the double spiral curling space comprises a spiral first sound channel and a spiral second sound channel; two micropores are formed in the micro-perforated plate and are respectively communicated with the first sound channel and the second sound channel.

Further, the shape of the first acoustic channel is the same as that of the second acoustic channel, and the tortuosity n of the first acoustic channel and the second acoustic channel is greater than or equal to 3.

Furthermore, the sound absorption metamaterial unit is square, the side length a of the sound absorption metamaterial unit is 20 mm-200 mm, and the thickness t of the sound absorption metamaterial unit is 0.2 mm-2 mm.

Further, the method can be used for preparing a novel materialTwo of the micropores have a diameter d₁And d₂And the value ranges are all 0.2 mm-5 mm.

Further, the widths of the first acoustic channel and the second acoustic channel are w respectively₁And w₂And the value ranges are all 2 mm-30 mm, and simultaneously the following relation d is satisfied₁≤w₁，d₂≤w₂，([n/2]+1)×(w1+w2)+(2×[n/2]+3) x b ═ a, where [ n/2-]Represents an integer part of n/2; n is the tortuosity of the first acoustic channel.

Further, the depth of the first acoustic channel is the same as the depth of the second acoustic channel, the minimum value of the depth D of the first acoustic channel should be greater than or equal to 2mm, and the maximum value should be less than or equal to 1/100 of the working wavelength.

Furthermore, the thickness b of the separator ranges from 0.5mm to 3 mm.

Furthermore, the thickness of the back plate is 1 mm-5 mm.

According to another aspect of the invention, a preparation method of the sound absorption metamaterial with the double spiral curling space is provided.

Generally, compared with the prior art, the sound absorption metamaterial with the double-spiral curling space and the preparation method thereof provided by the invention have the following beneficial effects:

1. the double-helix curling space comprises two spiral sound channels, two micropores of the micro-perforated plate are respectively communicated with the two sound channels, each micropore corresponds to an absorption peak with the corresponding sound channel, when sound waves irradiate to the acoustic metamaterial from one side of the micro-perforated plate, the two sound channels are mutually influenced, the sound absorption frequency range can be effectively widened by matching with preset size parameters, and a more ideal sound absorption effect is achieved.

2. The sound absorption metamaterial couples the two curling space sound channels with different orientations, different sound absorption effects can be obtained when various size parameters of the sound absorption metamaterial are changed, the widths of different sound channels are not limited to be equal, and the sound absorption effect far superior to that of a single spiral curling space metamaterial can be achieved through matching of different sizes.

3. Under the same size limitation, the traditional single-spiral curled space micro-perforated plate sound absorption metamaterial only has one sound channel and can only obtain a single resonance absorption peak, and the double-spiral curled space can enable the sound channels with different sound absorption effects to be coupled in a smaller space to obtain two resonance absorption peaks, so that the sound absorption frequency range of the metamaterial is widened.

4. The sizes of the sound absorption meta-material are set in a proper range, so that the sound resistance of the sound absorption meta-material is equal to that of air, and the sound reactance is 0, and the optimal sound absorption effect is obtained.

Drawings

FIG. 1 is a schematic structural diagram of a sound-absorbing metamaterial provided by the present invention and having a double spiral crimp space;

fig. 2 (a), (b), and (c) are schematic diagrams of the sound absorption metamaterial having the double spiral crimp space in fig. 1 along different angles, respectively;

fig. 2 (d) is a cross-sectional view of the sound-absorbing metamaterial having a double spiral crimp space of fig. 1;

in fig. 3, (a), (b), (c) are respectively schematic position arrangements of different micropores of the sound absorption metamaterial with double spiral curling space in fig. 1;

fig. 4(a) and (b) are graphs showing the variation of sound absorption coefficient with frequency of the sound absorption metamaterial having the double spiral crimp space in fig. 1, respectively.

The same reference numbers will be used throughout the drawings to refer to the same or like elements or structures, wherein: 1-a micro-perforated plate, 2-a double-spiral coiled structure, 3-a back plate, 4-micropores, 5-a first sound channel, 6-a clapboard and 7-a second sound channel.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

Referring to fig. 1 and 2, the sound absorption metamaterial with a double spiral crimp space provided by the present invention is directed to the problems of low sound absorption efficiency and too narrow sound absorption frequency of the conventional sound absorption material in a low frequency range, and the sound absorption metamaterial couples two micro perforated plates with different sound absorption frequency ranges and a sound absorber in the crimp space in a double spiral manner, so that a better sound absorption effect and a wider sound absorption frequency range can be obtained compared with the common array combination manner, a perfect sound absorption effect close to 100% can be realized in a certain frequency range, and meanwhile, compared with the conventional single spiral crimp space sound absorption metamaterial, the sound absorption metamaterial has a smaller size for obtaining the same sound absorption frequency, and is easier to meet practical applications.

In the embodiment, in a double-helix oriented curled space sound absorption metamaterial unit, two micropores respectively correspond to a curled space sound channel; when sound waves are emitted to the sound absorption metamaterial from one side of the micro-perforated plate 1, the thickness of a flow boundary layer and a thermal boundary layer is not negligible compared with the pore diameter of the micropores, so that a large error occurs in theoretical calculation of pressure acoustics inside the micropores, analysis should be performed by using a thermal viscous acoustics theory, meanwhile, the pore diameter of the micropores is negligible compared with the wavelength of the sound waves, the sound waves are considered to be plane waves when being emitted to the sound absorption metamaterial, and the acoustic impedance of the micropores can be obtained by using the basic theory of the thermal viscous acoustics. The sound wave generates extra acoustic resistance when passing by the micro-perforated plate 1, the micro-pore sound wave generates extra acoustic reactance when radiating outwards, and the acoustic impedance of the micro-perforated plate can be obtained through correction, so that the micro-perforated plate can be considered to provide an acoustic resistance and an acoustic mass, and the acoustic resistance can be equal to the characteristic impedance of air through elaborately setting the size parameters of the micro-perforated plate; the sound channel of the curled space can be equivalent to a sound quality, the acoustic impedance of the sound channel can be obtained by using an impedance transfer formula, and then the acoustic impedance of a real sound absorption metamaterial unit can be obtained, under the boundary condition of a sound hard field, the acoustic impedance of the sound absorption metamaterial is only related to the shape and size parameters of the sound metamaterial, and the sound ultrasonic coupling with the sound quality of the micro-perforated plate can be counteracted through fine size adjustment; the back plate can effectively prevent the leakage of sound waves. Finally, the acoustic metamaterial with acoustic resistance equal to air characteristic impedance and acoustic reactance of 0 in a certain frequency range is obtained, and therefore the resonance sound absorption effect close to 100% can be achieved. Because each micropore and the sound channel have a specific resonance sound absorption frequency, the double-helix curled space sound channels can be mutually coupled by accurately designing the size parameters of the micropores, and the effect of widening the sound absorption frequency range is realized.

The sound absorption metamaterial comprises a plurality of sound absorption metamaterial units, wherein the sound absorption metamaterial units form an array, and the size parameters of each unit can be different from each other. The sound absorption metamaterial unit comprises a micro-perforated plate 1, a double-spiral curling structure 2 and a back plate 3, wherein the micro-perforated plate 1, the double-spiral curling structure 2 and the back plate 3 are arranged from top to bottom, the double-spiral curling structure 2 comprises a partition plate 6, the partition plate 6 is arranged in a double-spiral mode, a double-spiral curling space is formed, the double-spiral curling space comprises a spiral first sound channel 5 and a second sound channel 7, and the first sound channel 5 is the same as the second sound channel 7 in shape.

In this embodiment, the tortuosity (i.e., the bending frequency of the acoustic channel) n of the first acoustic channel 5 and the second acoustic channel 7 is 6, which can be adjusted according to actual needs, and the value of n is equal to or greater than 3, and n is a positive integer; the widths of the first sound channel 5 and the second sound channel 7 are w respectively₁、w₂The value range is 2-30 mm, and the following relation is satisfied: d₁≤w₁，d₂≤w₂，([n/2]+1)×(w1+w2)+(2×[n/2]+3) x b ═ a, where [ n/2-]Represents an integer part of n/2; the depth of the acoustic channel is D, the minimum value is not less than 2mm, and the maximum value is not more than 1/100 of the working wavelength; the thickness b of the partition plate 6 ranges from 0.5mm to 3 mm.

Two micropores 4 are formed on the micro-perforated plate 1, and the two micropores 4 are respectively communicated with the first sound channel 5 and the second sound channel 7. Referring to fig. 3, there are three corresponding manners of the micro-holes 4 and the sound channel, and different sound absorption effects can be obtained by different corresponding manners.

The micro-perforated plate 1 is squareThe side length is a, the value range is 20-200 mm, the thickness is t, and the value range is 0.2-2 mm; the diameters of two micropores 4 are respectively d₁And d₂The value range is 0.2-5 mm; backplate 3 is the solid sheet metal of square, can play the effect that prevents the sound wave and spill over, and its thickness is h, and the value range is 1 ~ 5 mm.

The impedance of the material selected by the sound absorption metamaterial is greatly different from that of air, the surface of the material can be regarded as a hard boundary, different parts can be made of the same material or different materials, when sound waves enter the surface of the material, total reflection can occur, and the sound absorption effect is completely caused by the structure.

The sound absorption metamaterial with the double helix curling space is prepared by adopting an additive manufacturing technology.

The present invention will be further described with reference to specific examples.