Annular acoustic lens based on a five-mode material

Abstract

The application provides a kind of annular acoustic lens based on five-mode material, and the whole acoustic lens is composed of multilayer array of five-mode material units, and the acoustic lens center is filled with silicone oil.The traditional acoustic lens made of natural materials has problems such as single directivity and destruction of the original sound field, the application breaks the limitation of traditional materials, adopts five-mode material in acoustic metamaterial, based on band theory and transformation acoustics theory, studies the coupling effect of five-mode material structure and material parameters on equivalent properties, so that the equivalent density and bulk modulus of each layer of five-mode material unit are anisotropic distribution, and an annular acoustic lens based on five-mode material is designed.Using the technical scheme of the application, sound waves pass through the acoustic lens, realize the convergence of sound waves in the lens, and do not affect the external sound field, and have certain application value and practical engineering significance for sound wave detection with stealth function.

Description

Technical Field

[0001] This invention relates to the field of acoustic detection technology in engineering applications, and more particularly to a ring acoustic lens based on a five-mode material. Background Technology

[0002] Marine exploration technologies encompass a wide range of fields, including acoustics, optics, electromagnetics, heat flux, gravity and magnetics, and radioactivity detection. Compared to visible light and electromagnetic waves, sound waves attenuate more slowly and travel farther in seawater; therefore, acoustic detection is one of the most commonly used methods for acquiring marine information. Acoustic lenses can converge or diverge sound waves, facilitating subsequent detection and processing. Research on acoustic lenses is a hot topic in acoustics, materials science, and marine science, and is also a key factor limiting the accuracy and sensitivity of acoustic detection.

[0003] Due to the properties of materials in nature, traditional acoustic lenses suffer from problems such as energy dissipation, unidirectionality, and disruption of the original sound field. Acoustic lenses based on metamaterials can overcome some of the shortcomings of traditional lenses.

[0004] Acoustic metamaterials are a novel type of artificial material and a current research hotspot both domestically and internationally. Five-mode materials, as a type of acoustic metamaterial, are also a key research area. Designing a ring-shaped acoustic lens based on five-mode materials has significant theoretical and practical value. Summary of the Invention

[0005] To address the technical problems of traditional acoustic lenses, such as energy dissipation, unidirectionality, and disruption of the original sound field, this invention provides a ring-shaped acoustic lens based on a five-mode material. This invention primarily utilizes a ring-shaped acoustic lens based on a five-mode material, which can achieve sound wave focusing within the lens without affecting its external sound field.

[0006] The technical means employed in this invention are as follows:

[0007] A ring-shaped acoustic lens based on a five-mode material includes a layered structure formed by discretization and a silicone oil matrix embedded in the center of the acoustic lens. The layered structure is composed of multiple layers of a five-mode material unit array. The acoustic lens achieves impedance matching with water underwater.

[0008] Furthermore, the layered structure is a multi-layered annular metal layer formed by an array of several five-mode material units. The multiple metal layers are arranged concentrically from the center of the lens outwards, and each metal layer includes multiple five-mode material units arranged in a ring and closely connected to each other.

[0009] Furthermore, each of the metal layers has the same width, and the metal layers are composed of alternating layers of metal material.

[0010] Furthermore, the five-mode material unit has a symmetrical structure and is made of a metallic material that matches the water resistance.

[0011] Furthermore, the solid structure of the five-mode material unit is a completely symmetrical rectangular structure, formed by connecting equal arm lengths; several five-mode material units are arranged in a periodic array to form a honeycomb structure.

[0012] Among them, the solid structure of the five-mode material unit has a diamond-shaped intermediate arm in the middle. Each end of the intermediate arm is connected to a V-shaped arm. The two V-shaped arms have the same structure and are symmetrical. The V-shaped arm includes two symmetrical bent arms with equal arm lengths. The bent arms include a first arm and a second arm set at an angle. The first arm has the same structure as the intermediate arm. One end of the first arm of the two bent arms of each V-shaped arm is connected to the end of the intermediate arm at the same time. The other end of each first arm is connected to the second arm. The second arm is used to connect with the second arm of the adjacent five-mode material unit.

[0013] A hexagon is formed between two adjacent five-module material units in the horizontal direction, and a hexagon is formed after the V-shaped arms of two directly opposite five-module material units in the vertical direction are connected.

[0014] The two bent arms on the same V-shaped arm are set at an angle. By changing the angle between the two bent arms, the equivalent bulk modulus and equivalent density of the five-mode material unit can be adjusted, thereby achieving the purpose of adjusting the equivalent velocity.

[0015] Furthermore, the arm lengths of the solid structures of five-mode material units in the same layer are equal, while the arm lengths of the solid structures of five-mode material units in different layers are different.

[0016] Furthermore, the equivalent density and bulk modulus of the five-modulus material unit are anisotropically distributed, and the distribution of the equivalent density and bulk modulus is as follows:

[0017]

[0018] Where J represents the Jacobian matrix, J T Let J be the transpose of J. -1 Let J be the inverse matrix; ρ be the equivalent density of the five-mode material element, ρ b K is the density of the medium water; K is the bulk modulus of the five-modulus material unit. b Let r be the bulk modulus of the medium water; r be the radius of the virtual space; and R be the radius of the physical space.

[0019] The velocity matching the water impedance is determined based on the required equivalent density and bulk modulus. The velocity calculation formula is as follows:

[0020]

[0021] ρV r =ρ水 V 水 ;

[0022] Among them, V r and V ⊥ Let ρ be the velocity in the x and y directions. 水 V is the density of water. 水 The velocity of the water is determined by the formula; the required theoretical value is then applied to the simulation parameters, and the structural parameters of the five-module unit are adjusted to achieve a velocity that matches the theoretical value.

[0023] Furthermore, the annular radius of the metal layer is 0.55-1m; the layer width of the metal layer is 0.05m; and the number of metal layers is 9.

[0024] Furthermore, the metal layer is made of aluminum and is integrally formed using slow wire cutting technology.

[0025] Furthermore, during fabrication, the lens is integrally formed using slow wire cutting technology. Specifically, the metal layer structure is cut out on an aluminum base plate with matching acoustic impedance using slow wire cutting. After cutting, the center of the lens is sealed and filled with silicone oil to complete the lens fabrication.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] 1. The ring-shaped acoustic lens based on five-mode material provided by the present invention is achieved by alternating layers of homogeneous material. By adjusting the density and bulk modulus of each layer, sound waves can be converged inside the lens over a wide frequency range without affecting the external sound field.

[0028] 2. The ring-shaped acoustic lens based on five-mode material provided by the present invention, compared with the planar acoustic lens, which does not have a stealth function and is unidirectional, can achieve omnidirectional manipulation of sound waves without affecting the external sound field, thereby achieving the stealth effect.

[0029] 3. The ring acoustic lens based on five-mode material provided by this invention is suitable for underwater acoustic detection technology and can achieve stealth detection function in a wide frequency range.

[0030] Based on the above reasons, this invention can be widely applied in fields such as underwater acoustic detection. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the 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 based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of a ring acoustic lens structure based on a five-mode material according to the present invention.

[0033] Figure 2 This is a schematic diagram of the structure of a single five-mode material unit of the present invention.

[0034] Figure 3 This is a partial structural diagram of the connection of multiple five-mode material units in this invention.

[0035] Figure 4 This is a sound field diagram of the acoustic lens of the present invention in a background field of water.

[0036] Figure 5 This is a schematic diagram of the wavelength in this invention. Detailed Implementation

[0037] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. 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.

[0039] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0040] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0041] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms 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, and therefore should not be construed as a limitation on the scope of protection of this invention. The directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0042] For ease of description, spatial relative terms such as "above," "over," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation besides the orientation of the device as described in the figures. For example, if the device in the figures is inverted, a device described as "above" or "above" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0043] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0044] The 21st century is the century of the ocean, and the ocean is a key area for development and research. Acoustic detection is one of the most common methods for acquiring ocean information, and acoustic lenses can effectively focus sound waves to quickly obtain ocean information. However, omnidirectional, low-loss, broadband, and stealthy acoustic lenses have not yet emerged. Traditional acoustic lenses, such as planar lenses, allow sound waves to propagate in only one direction and lack stealth capabilities. Existing ring-shaped acoustic lenses mainly focus sound waves on one side of the lens; lenses that converge sound waves at the center have not yet appeared. Therefore, research on omnidirectional, low-loss, broadband, and stealthy acoustic lenses based on five-mode materials is a development trend and an inevitable requirement.

[0045] This invention provides a ring-shaped acoustic lens based on a five-mode material, belonging to the field of underwater acoustic detection, and applicable to various underwater sound wave detection needs. This invention not only enables the manipulation of sound waves without affecting the external sound field, achieving stealth detection capabilities, and can be applied to the field of underwater stealth acoustic detection. Specifically, the application of a five-mode metamaterial in acoustic metamaterials breaks through the limitations of traditional material properties in nature. Combining band theory and transformation acoustics theory, an omnidirectional, broadband, low-loss, stealth acoustic lens is designed, which has certain application value for acoustic detection with stealth capabilities.

[0046] like Figure 1 As shown, this invention discloses a ring-shaped acoustic lens based on a five-mode material. The overall acoustic lens is composed of multiple layers of a five-mode material unit array, with the center of the acoustic lens filled with silicone oil. Traditional acoustic lenses made from natural materials suffer from problems such as unidirectionality and disruption of the original sound field. This invention breaks through the limitations of traditional materials.

[0047] The working principle of this invention is based on a five-mode material from acoustic metamaterials. Using band theory and transformation acoustics, it studies the coupling effect of the five-mode material's structure and material parameters on its equivalent properties, resulting in anisotropic distribution of the equivalent density and bulk modulus of each five-mode material unit. A ring-shaped acoustic lens based on this five-mode material is designed to manipulate sound waves without affecting the external sound field. Using this invention, sound waves pass through the acoustic lens, achieving internal focusing without impacting the external sound field. This has significant application value and practical engineering significance for sound wave detection with stealth capabilities.

[0048] The acoustic lens comprises multiple rings and a central material, namely, multiple ring-shaped metal layers and a silicone oil matrix embedded in the center of the acoustic lens (the central filling material of the ring-shaped acoustic lens is silicone oil). The multiple ring-shaped metal layers are formed by an array of five-mode material units, which have a symmetrical structure and are made of a metal material matched to water impedance. The multiple ring-shaped metal layers are arranged concentrically, with the five-mode material units in each layer closely connected. From the inside out, the width of each ring-shaped metal layer is the same. That is, the ring-shaped metal layer consists of multiple concentric circles, and the layer width does not change from the inside out.

[0049] Specifically, each five-mode material unit in the metal layer has a symmetrical structure. Furthermore, the equivalent density and bulk modulus of each five-mode material unit layer exhibit anisotropic distribution. The distribution of the equivalent density and bulk modulus of each five-mode material unit layer is as follows:

[0050]

[0051] Where J represents the Jacobian matrix, J T Let J be the transpose of J. -1 Let J be the inverse matrix; ρ be the equivalent density of the five-mode material element, ρ b K is the density of the medium water; K is the bulk modulus of the five-modulus material unit. b Let r be the bulk modulus of the medium water; r be the radius of the virtual space; and R be the radius of the physical space.

[0052] The velocity matching the water impedance is determined based on the required equivalent density and bulk modulus. The velocity calculation formula is as follows:

[0053]

[0054] ρV r =ρ 水 V 水 ;

[0055] Among them, V r and V ⊥ Let ρ be the velocity in the x and y directions. 水 V is the density of water. 水 The velocity of the water is determined by the formula; the required theoretical value is then applied to the simulation parameters, and the structural parameters of the five-module unit are adjusted to achieve a velocity that matches the theoretical value.

[0056] like Figure 2 and Figure 3As shown, the solid structure of the five-mode material unit is a rectangular structure, formed by connecting equal arm lengths, and is a symmetrical structure. Specifically, several five-modulus material units are arranged in a periodic array to form a honeycomb structure. Each five-modulus material unit has a rhomboid intermediate arm in its solid structure, with a V-shaped arm connecting to each end. The two V-shaped arms are identical and symmetrical, each comprising two symmetrical, equally long bent arms. Each bent arm includes a first arm and a second arm angled together. The first arm has the same structure as the intermediate arm. One end of the first arm of each V-shaped arm's two bent arms is connected to the end of the intermediate arm, and the other end of each first arm is connected to the second arm. The second arm connects to the second arm of an adjacent five-modulus material unit. Laterally adjacent five-modulus material units form a hexagon, and vertically, the V-shaped arms of two opposing five-modulus material units connect to form a hexagon. The two bent arms on the same V-shaped arm are angled together. By changing the angle between the two bent arms, the equivalent bulk modulus and equivalent density of the five-modulus material unit are adjusted, thereby regulating the equivalent velocity.

[0057] The arm lengths of the solid structures of the five-mode material units within the same layer are equal, but the arm lengths of the solid structures within each (different) layer of the five-mode material units are not the same. The arm lengths of different layers can be adjusted. When the different five-mode material units are arranged in layers, the sound waves converge inside the lens when passing through it, and the external sound field is unaffected. The acoustic lens consists of nine layers. The basic five-mode material units in different layers are different, while the units within the same layer are identical. The units in different layers have different sizes and velocities, achieving the purpose of matching acoustic impedance. In other words, the sizes and velocities of the five-mode material units within the same layer are the same, while the sizes and velocities of the five-mode material units in different layers are different, achieving the purpose of matching acoustic impedance.

[0058] The metal layer is made of aluminum. The annular radius of the metal layer is 0.55-1m, the layer width is 0.05m, and the number of layers is 9. The acoustic lens is integrally formed using slow wire cutting technology.

[0059] The present invention provides a ring-shaped acoustic lens based on a five-mode material that can achieve impedance matching underwater. For example... Figure 4 The image shown is a sound field diagram of the acoustic lens of the present invention in a background field of water. Figure 5 This is a schematic diagram of wavelength.

[0060] This invention employs a discretization approach, dividing the lens into a layered structure. By adjusting the equivalent density and bulk modulus of the five-mode material units in each layer, sound waves can be manipulated over a wide frequency range. Utilizing transformation acoustics and band structure theory, this invention alters the propagation path of sound waves, converging them at the center of the lens without affecting the external sound field, thus achieving stealth detection capabilities. This invention employs slow wire EDM technology, simplifying the manufacturing process.

[0061] Example 1

[0062] like Figure 1 As shown, the present invention provides a ring acoustic lens based on a five-mode material, comprising a metal layer and a centrally filled silicone oil.

[0063] The metal layer is formed by alternating layers of aluminum, with equal widths from the center of the lens outwards. The width of each layer is the difference in radius between the inner and outer circles of the layers. The radius of the metal layer ring is 0.55-1m.

[0064] Specifically, during fabrication, the lens can be integrally formed using wire cutting technology. On an aluminum substrate with matching acoustic impedance, the structure of the metal layer is cut out by wire cutting. After cutting, the center of the lens is sealed and filled with silicone oil to complete the lens fabrication.

[0065] The process of simulating the design of an acoustic lens based on a five-mode material, using this scheme, is as follows:

[0066] Based on the transformation acoustic theory, the required properties of the annular acoustic lens are obtained. By discretization, it is decomposed into a layered structure, and the required properties of each layer are obtained. A five-mode material unit that meets the needs of each layer is designed.

[0067] This scheme simulates the design of the required annular acoustic lens. Using COMSOL Multiphysics to set the required material parameters, a simulation of acoustic-structure interaction is performed. The simulation results show that sound waves can be transmitted well through the lens and have a good converging effect at the lens center.

[0068] 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 ring-shaped acoustic lens based on a five-mode material, characterized in that, It includes a layered structure formed by discretization and a silicone oil matrix embedded in the center of an acoustic lens, which achieves impedance matching with water underwater; The layered structure is a multi-layered annular metal layer formed by an array of five-mode material units. The multi-layered annular metal layer is formed by an array of five-mode material units. The five-mode material units are symmetrical and made of metal material that matches the water impedance. The multi-layered metal layers are arranged concentrically from the center of the lens outward. Each metal layer includes multiple five-mode material units arranged in a ring and closely connected to each other. The arm lengths of the solid structures of the same layer of five-mode material units are equal, but the arm lengths of the solid structures of each layer of five-mode material units are not the same. The arm lengths of different layers can be adjusted. After the different five-mode material units are arranged in layers, the sound waves converge inside the lens when they pass through the lens, and the external sound field is not affected. The acoustic lens is divided into 9 layers. The basic five-mode material units between different layers are different, while the units in the same layer are the same. The units in different layers have different sizes and velocities, so as to achieve the purpose of matching acoustic impedance. That is, the five-mode material units in the same layer have the same size and velocity, while the five-mode material units in different layers have different sizes and velocities, so as to achieve the purpose of matching acoustic impedance.

2. The annular acoustic lens based on five-mode material according to claim 1, characterized in that, Each of the metal layers has the same width, and the metal layers are composed of alternating layers of metal material.

3. The annular acoustic lens based on a five-mode material according to claim 1 or 2, characterized in that, The solid structure of the five-mode material unit is a completely symmetrical rectangular structure, formed by connecting equal arm lengths; several five-mode material units are arranged in a periodic array to form a honeycomb structure. Among them, the solid structure of the five-mode material unit has a diamond-shaped intermediate arm in the middle. Each end of the intermediate arm is connected to a V-shaped arm. The two V-shaped arms have the same structure and are symmetrical. The V-shaped arm includes two symmetrical bent arms with equal arm lengths. The bent arms include a first arm and a second arm set at an angle. The first arm has the same structure as the intermediate arm. One end of the first arm of the two bent arms of each V-shaped arm is connected to the end of the intermediate arm at the same time. The other end of each first arm is connected to the second arm. The second arm is used to connect with the second arm of the adjacent five-mode material unit. A hexagon is formed between two adjacent five-module material units in the horizontal direction, and a hexagon is formed after the V-shaped arms of two directly opposite five-module material units in the vertical direction are connected. The two bent arms on the same V-shaped arm are set at an angle. By changing the angle between the two bent arms, the equivalent bulk modulus and equivalent density of the five-mode material unit can be adjusted, thereby achieving the purpose of adjusting the equivalent speed.

4. The annular acoustic lens based on five-mode material according to claim 3, characterized in that, The solid structure arm lengths of five-mode material units in the same layer are equal, while the solid structure arm lengths of five-mode material units in different layers are different; the size and velocity of five-mode material units in the same layer are the same, while the size and velocity of five-mode material units in different layers are different, so as to achieve the purpose of matching acoustic impedance.

5. The annular acoustic lens based on a five-mode material according to claim 1, 2, or 4, characterized in that, The equivalent density and bulk modulus of the five-modulus material unit are anisotropically distributed, and the distribution of the equivalent density and bulk modulus is as follows: ； in, Represents the Jacobian matrix. for The transpose of the matrix, for The inverse matrix; The equivalent density of the five-module material unit, The density of the medium, water; The bulk modulus of the five-element material unit. The bulk modulus of the medium, water; This represents the radius of the virtual space. This represents the radius of the physical space. The velocity matching the water impedance is determined based on the calculated equivalent density and bulk modulus. The velocity calculation formula is as follows: ； ； in, and for x and y velocity in direction, The density of water, The velocity of the water is determined by the formula; the required theoretical value is then applied to the simulation parameters, and the structural parameters of the five-module unit are adjusted to achieve a velocity that matches the theoretical value.

6. The annular acoustic lens based on a five-mode material according to claim 1 or 2, characterized in that, The radius of the annular layer of the metal layer is 0.55-1m; the width of the metal layer is 0.05m; and the number of metal layers is 9.

7. The annular acoustic lens based on a five-mode material according to claim 1 or 2, characterized in that, The metal layer is made of aluminum and is integrally formed using slow wire cutting technology.

8. The annular acoustic lens based on five-mode material according to claim 1, characterized in that, During fabrication, the lens is integrally formed using slow wire cutting technology. Specifically, the metal layer structure is cut out on an aluminum base plate with matching acoustic impedance. After cutting, the center of the lens is sealed and filled with silicone oil to complete the lens fabrication.

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