A nonlinear compact metamaterial structure to enhance acoustic sensing and acoustic source localization

Abstract

The application discloses a nonlinear compact metamaterial structure for enhancing sound sensing and sound source positioning, and relates to the technical field of sound sensing enhancement. The application discloses a nonlinear compact metamaterial structure for enhancing sound sensing and sound source positioning, and relates to the technical field of sound sensing enhancement. The application discloses a nonlinear compact metamaterial structure for enhancing sound sensing and sound source positioning, and relates to the technical field of sound sensing enhancement. The application discloses a nonlinear compact metamaterial structure for enhancing sound sensing and sound source positioning, and relates to the technical field of sound sensing enhancement. The application discloses a nonlinear compact metamaterial structure for enhancing sound sensing and sound source positioning, and relates to the technical field of sound sensing enhancement. The application discloses a nonlinear compact metamaterial structure for enhancing sound sensing and sound source positioning, and relates to the technical field of sound sensing enhancement. The application discloses a nonlinear compact metamaterial structure for enhancing sound sensing and sound source positioning, and relates to the technical field of sound sensing enhancement. The application discloses a nonlinear compact metamaterial structure for enhancing sound sensing and sound source positioning, and relates to the technical field of sound sensing enhancement. The application discloses a nonlinear compact metamaterial structure for enhancing sound sensing and sound source positioning, and relates to the technical field of sound sensing enhancement. The application discloses a sound sensing and sound source positioning device.

Description

A nonlinear compact metamaterial structure to enhance sound sensing and sound source localization Technical Field

[0001] This invention relates to the field of acoustic sensing enhancement technology, and in particular to a nonlinear compact metamaterial structure for enhancing acoustic sensing and sound source localization. Background Technology

[0002] Acoustic sensing structures and sound source localization structures play a crucial role in military and aerospace telemetry and control, industrial measurement, underwater acoustic communication, structural health monitoring, gas pipeline leak detection, and earthquake prediction. However, in actual production processes, the desired useful signals are often very weak and easily interfered with by complex background noise. For example, harmonic signals caused by friction, impact, or material structural damage are very weak and may be drowned out by strong background noise. Therefore, eliminating background noise interference, enhancing the transmission of useful signals, improving acoustic sensing, and strengthening sound source localization are currently the main research and development directions for acoustic sensing structures and sound source localization structures.

[0003] Acoustic metamaterials are artificial composite materials with double negative parameters. By altering the structure of acoustic metamaterials, the propagation of sound waves can be controlled, achieving special acoustic properties such as acoustic waveguides, sound insulation and noise reduction, acoustic enhancement, acoustic focusing, acoustic cloaking, and acoustic prisms. These special acoustic properties provide a technological foundation for the development of acoustic enhancement and sound source localization technologies based on acoustic metamaterials. For example, gradient metamaterials can achieve broadband sound wave isolation through spatially varying cell structures; gradient refractive index structures made of rectangular steel plates can enhance sound wave sensing through strong compression wave effects, thus overcoming the detection limits of traditional sound wave sensors; and using metamaterials with high refractive index media to create coiled structures can reduce the size of the metamaterial structure and achieve sound energy focusing. In coiled structures, sound waves are forced to propagate within the channel system, greatly increasing the total propagation time, thereby producing the effects of low sound velocity and high refractive index.

[0004] However, the overall size of current acoustic metamaterial structures is relatively large. The dimensional parameters of the components in the structural design are fixed. The air gap depth in the acoustic metamaterial structure only shows a linear change. Therefore, sometimes a mismatch between the wave vector and mode field between the metamaterial waveguide and the background medium (air) occurs.

[0005] In view of this, how to provide an acoustic metamaterial structure that is compact, appropriately sized, and can avoid wave vector and mode field mismatch between the metamaterial waveguide and the background medium is a technical problem that urgently needs to be solved by those in the field. Summary of the Invention

[0006] The purpose of this invention is to provide a nonlinear compact metamaterial structure that enhances sound sensing and sound source localization, thereby addressing the problems existing in the prior art.

[0007] To achieve the above objectives, the present invention provides the following solution: The present invention provides a nonlinear compact metamaterial structure for enhancing sound sensing and sound source localization, comprising: acoustic gratings, wherein there are multiple acoustic gratings arranged vertically, the multiple acoustic gratings are spaced apart along a predetermined direction, an air gap is formed between adjacent acoustic gratings, the width of the multiple air gaps increases along the predetermined direction, and the depth of the multiple air gaps increases nonlinearly along the predetermined direction;

[0008] The component has multiple acoustic gratings whose upper ends are located on the same horizontal plane. The upper surface of the component has an arc-shaped surface, which is adapted to the depth of the multiple air gaps, and the lower end of the acoustic grating is fixedly connected to the arc-shaped surface.

[0009] The thin plate, there are multiple thin plates, the multiple thin plates are located in multiple air gaps and are evenly spaced in the vertical direction, the multiple thin plates located in the same air gap are cross-arranged and fixedly connected to the adjacent sound grating plate, and the length of the multiple thin plates increases in a set direction.

[0010] Furthermore, the multiple acoustic gratings have the same width and their thickness increases along a set direction.

[0011] Furthermore, the width W of the plurality of acoustic gratings is 150 mm, and the thickness increases along a set direction according to the rule t. n = t1 + (n-1) × S1, where t1 = 3.95 mm, t n The thickness of the nth acoustic grating plate is S1 = 0.035 mm.

[0012] Furthermore, the number of acoustic gratings is 34.

[0013] Furthermore, the widths of the plurality of air gaps increase in a predetermined direction according to a pattern that satisfies g. m = g1 + (m-1) × S2, where g1 = 8.5mm, g m S2 is the width of the m-th air gap, where S2 = 0.05 mm.

[0014] Furthermore, the 34 acoustic grating plates form 33 air gaps. A coordinate system is established with the set direction as the X-axis, the vertically downward direction as the Y-axis, and the upper end of the first acoustic grating plate away from the set direction as the origin. The depth of the first 16 air gaps increases along the set direction according to the following pattern h. e = 0.0981 × X1 + 30, where X1 is the x-coordinate value of the side of the e-th air gap closest to the origin, and h e Let be the depth of the e-th air gap; the depth of the subsequent 17 air gaps increases along a predetermined direction according to the following rule. Where X2 is the x-coordinate value of the side of the f-th air gap closest to the origin, h f Let f be the depth of the f-th air gap.

[0015] Furthermore, the width D of the plurality of thin plates is 150 mm, the thickness r is 3 mm, and the length increasing along the set direction satisfies b. i = b1 + (i-1) × S3, where b1 = 5.5 mm, b i S3 is the length of the thin plate in the i-th air gap, S3 = 0.05 mm, and the distance between two adjacent thin plates is c = 7.5 mm.

[0016] Furthermore, the adjacent thin plates are respectively fixedly connected to different acoustic grating plates, and the thin plates are perpendicular to the acoustic grating plates.

[0017] Furthermore, the acoustic grating plate, thin plate, and components are integrally formed by photosensitive resin 3D printing, with a density ρ = 1130 kg / m³. 3 The elastic modulus E = 2.65 × 10 3 Mp a Shear modulus G = 2.22 × 10 3 MPa.

[0018] The present invention discloses the following technical effects:

[0019] This application employs an acoustic metamaterial structure composed of acoustic gratings, thin plates, and components. The acoustic gratings serve as a gradient structure, while the thin plates form a spatially coiled structure. The thickness of the acoustic gratings and the length of the thin plates both increase along a predetermined direction. Air gaps are formed between the acoustic gratings, with the width of these air gaps increasing non-linearly along the predetermined direction, and the depth increasing non-linearly. Intersecting thin plates create a meandering air channel. When sound waves enter the metamaterial structure, the total propagation distance and time from the upper entrance of the air gap to the bottom increase, resulting in a high relative refractive index. Sound waves can propagate with a large wave vector within the metamaterial, allowing wave energy to be concentrated and amplified spatially, while simultaneously reducing the operating frequency. This enables sound source localization and provides better acoustic sensing enhancement. Compared to traditional structural components, this application exhibits a regular variation, making the structure more compact and smaller overall. The non-linear variation in air gap depth effectively avoids wave vector and mode field mismatch between the metamaterial waveguide and the background medium. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 is a schematic diagram of the structure of the present invention;

[0022] Figure 2 is a front view of the present invention;

[0023] Figure 3 is a schematic diagram of the air gap of the present invention;

[0024] Figure 4 shows the pressure frequency response diagram;

[0025] Figure 5 shows the sound field pressure distribution.

[0026] Figure 6 is a schematic diagram of the directional response simulation;

[0027] Figure 7 shows the normalized sound pressure level diagram of the directional response;

[0028] Among them, 1. acoustic grating; 2. air gap; 3. thin plate. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only 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.

[0030] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] Referring to Figures 1-3, the present invention provides a nonlinear compact metamaterial structure for enhancing sound sensing and sound source localization, comprising: a plurality of acoustic grating plates 1, wherein multiple acoustic grating plates 1 are arranged vertically, the plurality of acoustic grating plates 1 are spaced apart along a predetermined direction, and air gaps 2 are formed between adjacent acoustic grating plates 1, the width of the plurality of air gaps 2 increases along the predetermined direction, and the depth of the plurality of air gaps 2 increases nonlinearly along the predetermined direction; a component, wherein the upper ends of the plurality of acoustic grating plates 1 are located on the same horizontal plane, the upper surface of the component has an arc-shaped surface, the arc-shaped surface is adapted to the depth of the plurality of air gaps 2, and the lower ends of the acoustic grating plates 1 are fixedly connected to the arc-shaped surface; and a plurality of thin plates 3, wherein the plurality of thin plates 3 are located within the plurality of air gaps 2 and are evenly spaced along the vertical direction, the plurality of thin plates 3 located within the same air gap 2 are intersected and fixedly connected to adjacent acoustic grating plates 1, and the length of the plurality of thin plates 3 increases along the predetermined direction.

[0032] In this embodiment, the multiple acoustic grating plates 1 have the same width, and their thickness increases along a predetermined direction. The width W of the multiple acoustic grating plates 1 is 150 mm, and the thickness increases along the predetermined direction according to the rule t. n = t1 + (n-1) × S1, where t1 = 3.95 mm, t n S1 is the thickness of the nth acoustic grating plate 1, where S1 = 0.035 mm.

[0033] In this embodiment, 34 acoustic grating plates 1 form 33 air gaps 2. A coordinate system is established with the set direction as the X-axis, the vertically downward direction as the Y-axis, and the upper end of the first acoustic grating plate 1 away from the set direction as the origin (point P in Figure 2 is the origin). The depth of the first 16 air gaps 2 increases along the set direction according to the rule h. e = 0.0981 × X1 + 30, where X1 is the x-coordinate value of the side of the e-th air gap 2 closest to the origin, h e The depth of the e-th air gap 2; the depth of the subsequent 17 air gaps 2 increases along a predetermined direction according to the following rule. Where X2 is the x-coordinate value of the side of the f-th air gap 2 closest to the origin, h f Let f be the depth of the f-th air gap 2. The width D = 150 mm and thickness r = 3 mm of the multiple thin plates 3, with their lengths increasing along a predetermined direction according to the rule b. i = b1 + (i-1) × S3, where b1 = 5.5 mm, b i S3 is the length of the thin plate 3 in the i-th air gap 2, where S3 = 0.05 mm and the distance between two adjacent thin plates 3 is c = 7.5 mm.

[0034] In this embodiment, adjacent thin plates 3 are fixedly connected to different acoustic grating plates 1, and the thin plates 3 are perpendicular to the acoustic grating plates 1. The acoustic grating plates 1, thin plates 3, and components are integrally formed by photosensitive resin 3D printing, with a density ρ = 1130 kg / m³. 3 The elastic modulus E = 2.65 × 10 3 Mp a Shear modulus G = 2.22 × 10 3 MPa.

[0035] Figure 4 shows the pressure-frequency response diagram of the acoustic metamaterial structure. This diagram considers the effects of thermoviscosity. The response diagram displays the frequency and pressure ratio at the bottom of the 27th air gap 2 (357.135 mm from the first acoustic grating plate 1 (thickness t1 = 3.95 mm)), the bottom of the 28th air gap 2 (371.855 mm from the first acoustic grating plate 1 (thickness t1 = 3.95 mm)), and the bottom of the 29th air gap 2 (386.66 mm from the first acoustic grating plate 1 (thickness t1 = 3.95 mm)). The frequency and pressure ratios at the bottom of the 30th air gap 2 (401.55mm from the first acoustic grating plate 1 (thickness t1 = 3.95mm), the bottom of the 31st air gap 2 (416.525mm from the first acoustic grating plate 1 (thickness t1 = 3.95mm), the bottom of the 32nd air gap 2 (431.585mm from the first acoustic grating plate 1 (thickness t1 = 3.95mm), and the bottom of the 33rd air gap 2 (446.73mm from the first acoustic grating plate 1 (thickness t1 = 3.95mm)).

[0036] The pressure ratio refers to the ratio of the sound pressure amplitude of a sound wave propagating in a metamaterial structure to the sound pressure amplitude of the sound wave propagating in the air domain without the metamaterial. The maximum pressure ratio of this structure is measured at k = 64.16 at the bottom of the 33rd air gap 2, 446.73 mm from the first acoustic grating plate 1 (thickness t1 = 3.95 mm), with a maximum pressure ratio frequency of 420 Hz. This demonstrates that the structure exhibits excellent acoustic enhancement in each air gap 2, without any mismatch in wave vector and mode field between the material waveguide and the background medium (air), and the operating frequency is also reduced.

[0037] Figure 5 shows the sound field pressure distribution of the acoustic metamaterial structure. This distribution is also considered in light of the thermoviscosity effect. When sound waves enter the metamaterial structure, the total propagation distance and time from the upper entrance of air gap 2 to the bottom increase, resulting in a high relative refractive index. This allows sound waves to propagate with a larger wave vector within the metamaterial, concentrating and amplifying the wave energy in space. The sound field pressure distribution at which the structure achieves the maximum pressure ratio is observed, specifically at the bottom k of the 33rd air gap 2, 446.73 mm from the first acoustic grating plate 1 (thickness t1 = 3.95 mm), where the maximum pressure ratio is achieved—that is, the pressure field distribution at a sound wave frequency of 420 Hz. It can be seen that this structure has excellent acoustic capture performance, capable of separating and capturing sound waves of different frequencies, and achieving excellent acoustic enhancement.

[0038] Figure 6 is a simulation diagram of the directional response of the acoustic metamaterial structure. It illustrates how to achieve the change of angle in the simulation from the perspective of the metamaterial structure as a whole. In the simulation, the sound source is fixed and the rotation center of the structure is the bottom point k of the 33rd air gap 2.

[0039] Figure 7 shows the normalized sound pressure level (SPL) plot of the directional response of the acoustic metamaterial structure. The normalized SPL plot also considers the influence of thermoviscosity, and the sound pressure enhancement effect is normalized, meaning the SPL enhancement effect at each angle is compared to the SPL enhancement effect at 0 angle. In the 3D simulation, the sound source is fixed, and the structure rotates 5° each time, with the rotation center at point k, the bottom of the 33rd gap. As shown in the figure, the structure still maintains a relatively good directional response and can be used for sound source localization.

[0040] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0041] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A nonlinear compact metamaterial structure for enhancing sound sensing and sound source localization, characterized in that, include: A plurality of acoustic gratings (1) are arranged vertically, and the plurality of acoustic gratings (1) are arranged at intervals along a set direction. An air gap (2) is formed between adjacent acoustic gratings (1). The width of the plurality of air gaps (2) increases along the set direction, and the depth of the plurality of air gaps (2) increases non-linearly along the set direction. A component has the upper ends of the plurality of acoustic gratings (1) located on the same horizontal plane. The upper surface of the component has an arc-shaped surface. The arc-shaped surface is adapted to the depth of the plurality of air gaps (2), and the lower end of the acoustic gratings (1) is fixedly connected to the arc-shaped surface. A thin plate (3) is arranged in a plurality of thin plates (3). The plurality of thin plates (3) are located in the plurality of air gaps (2) and are evenly spaced along the vertical direction. The plurality of thin plates (3) located in the same air gap (2) are arranged crosswise and fixedly connected to the adjacent acoustic gratings (1). The length of the plurality of thin plates (3) increases along the set direction.

2. The nonlinear compact metamaterial structure for enhancing sound sensing and sound source localization according to claim 1, characterized in that, The multiple acoustic gratings (1) have the same width and their thickness increases along the set direction.

3. The nonlinear compact metamaterial structure for enhancing sound sensing and sound source localization according to claim 2, characterized in that, The width of the plurality of acoustic gratings (1) =150mm, and the thickness increases along the set direction according to the following rule: ,in =3.95mm, For the first The thickness of the acoustic grating plate (1) =0.035mm。 4. The nonlinear compact metamaterial structure for enhancing sound sensing and sound source localization according to claim 3, characterized in that, The number of acoustic gratings (1) is 34.

5. The nonlinear compact metamaterial structure for enhancing sound sensing and sound source localization according to claim 4, characterized in that, The widths of the multiple air gaps (2) increase along the predetermined direction according to the following rule. ,in =8.5mm, For the first The width of the spacing between the air gaps (2), =0.05mm。 6. The nonlinear compact metamaterial structure for enhancing sound sensing and sound source localization according to claim 4, characterized in that, The 34 acoustic grating plates (1) form 33 air gaps (2). A coordinate system is established with the set direction as the X-axis, the vertical downward direction as the Y-axis, and the upper end of the first acoustic grating plate (1) away from the set direction as the origin. The depth of the first 16 air gaps (2) increases along the set direction according to the following rule. ,in For the first The x-coordinate value of the side of each air gap (2) closest to the origin. For the first The depth of each air gap (2); the depth of the latter 17 air gaps (2) increases along the set direction according to the following rule. ,in For the first The x-coordinate value corresponding to the side of the air gap (2) closest to the origin. For the first The depth of the air gap (2) mentioned above.

7. The nonlinear compact metamaterial structure for enhancing sound sensing and sound source localization according to claim 6, characterized in that, The width of the plurality of thin plates (3) =150mm, thickness =3mm, and the length increasing pattern along the set direction satisfies the following: ,in =5.5mm, For the first The length of the thin plate (3) in the air gap (2), =0.05mm, the distance between two adjacent thin plates (3) =7.5mm。 8. The nonlinear compact metamaterial structure for enhancing sound sensing and sound source localization according to claim 7, characterized in that, The thin plates (3) that are adjacent to each other are fixedly connected to different acoustic grating plates (1), and the thin plates (3) are perpendicular to the acoustic grating plates (1).

9. A nonlinear compact metamaterial structure for enhancing sound sensing and sound source localization according to any one of claims 1-8, characterized in that, The acoustic grating plate (1), the thin plate (3), and the components are integrally formed by photosensitive resin 3D printing, and their density is... elastic modulus shear modulus 。

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