阅读说明：本技术 超表面声学材料 (Super surface acoustic material ) 是由 李连春 蒋伟康 吴海军 于 2021-02-19 设计创作，主要内容包括：一种超表面声学材料,由水平横向布置的若干单体结构组成,每个单体结构包括四个相对交错设置的Helmholtz共鸣器腔体以及位于共鸣器腔体之间的迷宫形卷曲折叠槽；Helmholtz共鸣器腔体两两相对,各个腔体的颈口交错且正对迷宫形卷曲折叠槽的分隔板,通过调整颈口至迷宫形卷曲折叠槽的分隔板的距离,实现全2π相位控制。本发明结合了迷宫形卷曲折叠声学超表面材料和Helmholtz共鸣器型声学超表面的共振匹配模式,不仅可以精简的调整一个参数实现超表面对声波的各种操纵功能,而且理论上易于改变为任意厚度以满足实际应用中对特定厚度的超表面的需求。(A super-surface acoustic material is composed of a plurality of single structures which are horizontally and transversely arranged, wherein each single structure comprises four Helmholtz resonator cavities which are oppositely staggered and a labyrinth-shaped curling folding groove which is positioned between the resonator cavities; the Helmholtz resonator cavities are opposite to each other in pairs, the neck openings of the cavities are staggered and are just opposite to the partition plates of the labyrinth-shaped curling folding grooves, and the full 2 pi phase control is realized by adjusting the distance from the neck openings to the partition plates of the labyrinth-shaped curling folding grooves. The invention combines the resonance matching mode of the labyrinth-shaped curled and folded acoustic super-surface material and the Helmholtz resonator type acoustic super-surface, not only can simply adjust one parameter to realize various control functions of the super-surface on sound waves, but also can be easily changed into any thickness in theory to meet the requirement of the super-surface with specific thickness in practical application.)

1. A super-surface acoustic material is characterized by comprising a plurality of monomer structures which are horizontally and transversely arranged, wherein each monomer structure comprises four Helmholtz resonator cavities which are oppositely staggered and a labyrinth-shaped curling folding groove which is positioned between the resonator cavities;

the relative staggered arrangement means that: the Helmholtz resonator cavities are opposite to each other in pairs, the neck openings of the cavities are staggered and are just opposite to the partition plates of the labyrinth-shaped curling folding grooves, and the full 2 pi phase control is realized by adjusting the distance from the neck openings to the partition plates of the labyrinth-shaped curling folding grooves.

2. A super-surface acoustic material as claimed in claim 1, wherein the acoustic impedance of the Helmholtz resonator cavity and the labyrinth-shaped crimped groove material of the acoustic super-surface is more than 100 times the acoustic impedance of the background medium.

3. The super-surface acoustic material as set forth in claim 1, wherein said labyrinth-shaped crimp folding slot is a five-segment structure based on four Helmholtz resonator cavities arranged in opposition.

4. The super-surface acoustic material according to claim 1, wherein the thickness of the Helmholtz resonator cavity and the wall surface of the labyrinth-shaped crimp folding groove is more than 1 mm.

5. The super-surface acoustic material according to claim 1, wherein when the operating frequency of the super-surface acoustic material is above 3000Hz, the thickness of the material is greater than or equal to 1/4 of the operating wavelength, so that the viscous loss is ensured to be negligible to the device performance;

when the working frequency of the super-surface acoustic material is below 500Hz, the thickness of the material is less than or equal to 1/2 of the working wavelength, and high-order mode components of sound waves in the labyrinth-shaped curling folding groove are ensured to be in a deep cut-off state.

Technical Field

The invention relates to the technology in the field of acoustic materials, in particular to a super-surface acoustic material with adjustable thickness, which has strong portability of thickness adjustment parameters; the structure with different thickness can realize various acoustic wave manipulation functions under the same frequency.

Background

The metamaterial is formed by combining materials according to a specific mode through artificial design, and the application of the metamaterial to an acoustic super surface realizes special regulation and control on transmitted sound waves, such as: anomalous transmission, negative refraction, plane wave focusing, etc. Meanwhile, the surface thickness is only 1/10 orders of magnitude of the wavelength of the working frequency, and the small size is achieved to control the large wavelength. However, currently, all designed acoustic super-surfaces can only have a fixed design thickness at a specific frequency for each structure, and if the specific thickness of the application scene is required to be adapted, redesign and heavy parameter optimization are required; this essentially limits the development of ultra-surfaces of any thickness to the manipulation of acoustic waves.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides the super-surface acoustic material, which is based on the combination of a space rolling super-surface structure and a Helmholtz resonator and achieves the control of the super-surface with any thickness on sound waves.

The invention is realized by the following technical scheme:

the super-surface acoustic material is composed of a plurality of single structures which are horizontally and transversely arranged, and each single structure comprises four Helmholtz resonator cavities which are oppositely staggered and a labyrinth-shaped curling folding groove which is positioned between the resonator cavities.

The model parameters of each monomer are customized according to the realized sound wave manipulation function.

The acoustic impedance of the Helmholtz resonator cavity and the labyrinth-shaped curled folding groove material of the acoustic super surface is more than 100 times of that of a background medium, and the material can be physically used as a rigid wall surface.

The relative staggered arrangement means that: the Helmholtz resonator cavities are opposite to each other in pairs, and the neck openings of the cavities are staggered and are opposite to the partition plates of the labyrinth-shaped curling folding grooves.

The labyrinth-shaped curling folding groove is of a five-section structure based on four Helmholtz resonator cavities which are oppositely arranged.

In order to reduce the adverse effect of viscous loss on the performance of the device, the thicknesses of the cavity of the Helmholtz resonator and the wall surface of the labyrinth-shaped curling folding groove are more than 1 mm.

When the operating frequency of the super-surface acoustic material is more than 3000Hz, the thickness of the material is greater than or equal to 1/4 of the operating wavelength, and the viscous loss is ensured to be negligible to the performance of the device.

When the working frequency of the super-surface acoustic material is below 500Hz, the thickness of the material is less than or equal to 1/2 of the working wavelength, and high-order mode components of sound waves in the labyrinth-shaped curling folding groove are ensured to be in a deep cut-off state.

Technical effects

The invention integrally solves the defect that the thickness of the conventional acoustic super-surface is invariable, and the acoustic super-surface designed under a specific working condition has more than two thicknesses without repeated parameter optimization and complex design.

Compared with the prior art, the invention combines the resonance matching mode of the labyrinth-shaped curled and folded acoustic super surface material and the Helmholtz resonator type acoustic super surface, can simply adjust one parameter to realize various control functions of the super surface on sound waves, and can be easily changed into any thickness in theory to meet the requirement of the super surface with specific thickness in practical application.

Drawings

FIGS. 1(a) and 1(b) are schematic structural views of the present invention;

FIG. 2 is a dimensional representation of one embodiment of the present invention;

FIG. 3 is a cloud plot of the numerical simulated acoustic focusing sound pressure at incident of the combined 1000Hz planar acoustic wave of the embodiment of FIG. 1;

FIG. 4 is a cloud image of the numerical simulated acoustic focusing sound pressure upon incidence of the 1000Hz point source sound wave of the embodiment of FIG. 1;

FIG. 5 is a cloud graph of the numerical simulation extraordinary transmission sound pressure at the incident of the combined 1000Hz plane sound wave of the embodiment of FIG. 1;

FIG. 6 is a cloud graph of the acoustic intensity of a numerically simulated Bessel beam at the incidence of a combined 1000Hz planar acoustic wave of the embodiment of FIG. 1;

in the figure: the resonator comprises a Helmholtz resonator cavity 1, a neck opening 2, a labyrinth-shaped curling and folding groove 3 and a partition plate 4.

Detailed Description

As shown in fig. 1(a), the present embodiment relates to a super-surface acoustic material with any thickness, which is composed of several horizontally and transversely arranged single structures, as shown in fig. 1(b), the single structure includes: four Helmholtz resonator cavities 1 which are arranged in a relatively staggered manner and a labyrinth-shaped curling folding groove 3 which is positioned in the middle and has a 5-section structure, wherein: the incident sound wave is incident from one end of the labyrinth-shaped crimp folding groove 3 and is transmitted from the other end.

The relative staggered arrangement means that: the Helmholtz resonator cavities 1 are opposite in pairs, the neck openings 2 of the cavities are staggered and are just opposite to the partition plates 4 of the labyrinth-shaped curling folding grooves, and the full 2 pi phase control is realized by adjusting the distance from the neck openings to the partition plates of the labyrinth-shaped curling folding grooves.

As shown in fig. 2, the thickness w, the width s, the length w3 of the Helmholtz resonator cavity, the width h3, the length w2 of the neck 2, the width h2, the width w1 of the labyrinth-shaped crimp folding groove, the width h1 of the crimp, the thickness t of the compartment and the length L preferably satisfy the following conditions:

the length of an inlet compartment and an outlet compartment of the labyrinth-shaped curling and folding groove 3 is L/2;

②w2＝0.03w、w3＝0.225w、h2＝0.1w、t＝0.02w、L＝0.35w。

the thickness w of the monomer structure is an independent parameter and can be adjusted at will according to needs and working frequency.

When 1000Hz is selected as the working frequency, w is selected as 1/4(w is 0.0858m) of the working wavelength, and the monomer with different phase delays is obtained by changing the value of the independent parameter h 1: h1 is 0.25w, 0.27w, 0.33w, 0.36w, 0.38w, 0.40h, 0.21h, 0.22h, 0.23h, 0.24h monomer respectively corresponding to phase retardation pi/10, 2 pi/10, 3 pi/10, 4 pi/10, 5 pi/10, 6 pi/10, 7 pi/10, 8 pi/10, 9 pi/10, pi. At the moment, monomers with different phase delays are arranged in the direction vertical to the wave front, and the phase delay of each monomer is selected according to the incident wave condition and the super surface realization function. Therefore, when the incident sound wave reaches the acoustic phase control array, the final transmission sound wave can be changed through the specific control of the phase control array on the sound wave, and the required transmission sound wave is generated. For example: the transmitted sound wave acoustic focusing when the plane sound wave is incident, as shown in fig. 3, the transmitted sound wave acoustic focusing when the spherical sound wave is incident, as shown in fig. 4, the transmitted sound wave is extraordinary transmitted when the plane sound wave is incident, as shown in fig. 5, and the transmitted sound wave forms a bessel beam when the plane sound wave is incident, as shown in fig. 6.

When the operating frequency is selected to be below 1000Hz, the thickness w is 1/4 of the wavelength. If other thicknesses are used, the requirements are satisfied, the w3 Xh 3 value before and after modification is kept unchanged, and the total length of the labyrinth-shaped crimp folding groove before and after modification is kept unchanged.

As shown in FIG. 3, 1000Hz incident sound waves enter the super-surface device from below, a transmission sound focus is formed above the device, and a cloud image is shown as a sound intensity cloud image. The device is composed of 20 designed super-surface single devices which are transversely arranged. The phase control size of each monomer is calculated by the type of incident sound wave and the focusing position of transmitted sound through the generalized snell's theorem. Since the phase delay functions of the monomers are adjusted by the parameter h1, the monomers h1 for realizing the functions of fig. 3 are respectively 0.242h, 0.244h, 0.2485h, 0.2605h, 0.312h, 0.358h, 0.3885h, 0.2115h, 0.2335h and 0.2415h, and are distributed in the middle to the rightmost 10 monomers, and the 10 monomers on the left side are mirror-symmetrical to the right side. Simulation effect shows that the sound intensity of a plane wave sound source penetrating through a super-surface focusing position is 9 times higher than that of a non-focusing position.

As shown in FIG. 4, a 1000Hz point source incident sound wave enters the super-surface device from the lower part, a transmission sound focus is formed above the device, and a display cloud picture is a sound pressure cloud picture. The device is composed of 80 designed super-surface single devices which are transversely arranged. The phase control size of each monomer is calculated by the position of an incident point source and the position of a transmitted sound focus through the generalized snell's theorem. Corresponding h1 is 0.242h, 0.2455h, 0.255h, 0.311h, 0.367h, 0.429h, 0.234h, 0.2605h, 0.372h, 0.222h, 0.2565h, 0.382h, 0.235h, 0.331h, 0.213h, 0.2595h, 0.4065h, 0.2465h, 0.3835h, 0.2415h, 0.3735h, 0.2395h, 0.37h, 0.239h, 0.371h, 0.24h, 0.376h, 0.242h, 0.3845h, 0.246h, 0.399h, 0.2515h, 0.4285h, 0.2665h, 0.2125h, 0.1615h, 0.2245h, 0.3475h, 0.235h and 0.369h respectively, and 40 monomers on the left side are mirror images of the right side. Simulation effect shows that the sound pressure of the point sound source penetrating through the super-surface focusing position is 3 times higher than that of the non-focusing position.

As shown in fig. 5, an incident plane wave of 1000Hz is incident on the super-surface device from below, and two beams of obliquely transmitted sound beams are formed above the device, and the display cloud is a sound pressure cloud. The h1 corresponding to each monomer on the right side 10 is 0.25h, 0.27h, 0.33h, 0.36h, 0.38h, 0.40h, 0.21h, 0.22h, 0.23h and 0.24h respectively, and the 10 monomers on the left side are in mirror symmetry with the right side. The simulation effect shows that the plane wave sound source generates abnormal refraction through the super surface, and the abnormal refraction on the two sides is 45 degrees and 135 degrees respectively.

As shown in fig. 6, an incident plane wave of 1000Hz is incident to the super-surface device from the left, and a long-focused bessel beam is formed on the right of the device, and the display cloud is an acoustic intensity cloud. The lower 40 monomers correspond to h1 and are respectively 0.242h, 0.243h, 0.2445h, 0.2465h, 0.429h, 0.234h, 0.2605h, 0.372h, 0.222h, 0.2565h, 0.382h, 0.235h, 0.331h, 0.213h, 0.2595h, 0.4065h, 0.2465h, 0.3835h, 0.2415h, 0.3735h, 0.2395h, 0.37h, 0.239h, 0.371h, 0.24h, 0.376h, 0.242h, 0.3845h, 0.246h, 0.399h, 0.2515h, 0.4285h, 0.2665h, 0.2125h, 0.1615h, 0.2245h, 0.3475h, 0.235h and 0.369h, and the upper 40 monomers are mirror images of the right side. Simulation effect shows that the sound intensity of the focusing position of the long focusing Bessel sound beam is 6dB higher than that of the non-focusing position.

The foregoing embodiments may be modified in many different ways by those skilled in the art without departing from the spirit and scope of the invention, which is defined by the appended claims and all changes that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.