Manufacturing method of acoustic metasurface structure for realizing sound wave cross-solid barrier layer and efficient transmission

Abstract

The invention belongs to the technical field of acoustic signal transmission, and particularly relates to a manufacturing method of an acoustic metasurface structure for realizing sound wave cross-solid barrier layer and high-efficiency transmission, which adopts a topological optimization mode and takes the transmission efficiency of sound waves in a cross-solid medium transmission process as an optimization target. And continuously adjusting the material parameter distribution of a plurality of pixel points in the acoustic metasurface unit cell structure, and continuously iterating, so that the transmittance of the calculated sound wave propagating from the air on one side to the air on the other side through the solid barrier layer is close to 100%. According to the method, the unit cell structure meeting the requirement can be obtained through direct reverse optimization design according to the parameters of the target penetrating wall, and the acoustic metasurface structure enabling sound waves to efficiently penetrate through the solid barrier layer is accurately and efficiently manufactured in a 3D printing mode.

Description

Technical Field

[0001] The present invention belongs to the technical field of acoustic signal transmission, and specifically relates to a method for manufacturing an acoustic metasurface structure that can realize efficient transmission of sound waves across a solid barrier layer. Background Art

[0002] In the industrial production process, although the internal damage of mechanical structures often cannot be directly discovered or monitored over a long period of time through visual observation, the abnormal noises caused by the damage to these structures can provide conditions for acoustic monitoring, that is, the inspectors can preliminarily judge whether the equipment is damaged by listening to the sound of the equipment in operation. However, for some large equipment, especially those with thicker shells, the effect of traditional acoustic detection will be greatly weakened. This is because there is a huge impedance difference between the equipment shell and the air medium on both sides, which causes the intensity of the sound waves to be greatly attenuated when propagating through the shell and accompanied by noise. Therefore, how to achieve efficient transmission of sound waves across solid media and how to achieve the production of acoustic metasurface structures that can efficiently transmit sound waves across solid barrier layers is an urgent problem to be solved. Summary of the invention

[0003] The purpose of the present invention is to address the deficiencies in the prior art and to provide a method for manufacturing an acoustic metasurface structure that can achieve efficient transmission of sound waves across a solid barrier layer, which not only achieves efficient transmission of sound waves across solid media, but also can produce the required metasurface structure by the most precise means.

[0004] In order to achieve the above object, the present invention adopts the following technical solution:

[0005] A method for manufacturing an acoustic metasurface structure that realizes efficient transmission of sound waves across a solid barrier layer comprises the following steps:

[0006] Step 1: determine the frequency f of the sound wave in the air to be achieved, calculate the wavelength λ of the sound wave at the frequency f according to the propagation speed c of the sound wave in the air and the formula λ=c / f, and determine the thickness h of the solid barrier layer to be passed through and the material properties of the solid barrier layer;

[0007] Step 2: Determine the size of the acoustic metasurface unit cell structure to be manufactured according to the λ and the h in step 1, and limit the shape of the acoustic metasurface unit cell structure to a rectangle with a width of a and a height of b, divide the interior of the acoustic metasurface unit cell structure evenly and make the interior of the structure have a plurality of pixels with a side length of s, then the number of pixels in the width direction is m=a / s, and the number of pixels in the height direction is n=b / s;

[0008] Step 3: Using topology optimization, taking the transmission efficiency of sound waves in the process of transmitting across solid media as the optimization target, assigning different material parameters to each pixel point, and then calculating the transmittance of a single acoustic metasurface unit cell under periodic boundary conditions when the sound wave propagates from the air on one side through the solid barrier layer to the air on the other side;

[0009] Step 4: Repeat step 3 through a preset computer program, continuously adjust the material parameter distribution of several pixel points in the acoustic metasurface unit cell structure, and continuously iterate so that the calculated transmittance of the sound wave from the air on one side through the solid barrier layer to the air on the other side is close to 100%, thereby obtaining the optimal material parameter distribution, that is, the required acoustic metasurface unit cell structure, and manufacturing the required acoustic metasurface structure by means of 3D printing.

[0010] Furthermore, the step two also includes: adjusting the side length s of the pixel point and the array numbers m and n in two directions of the unit cell structure according to the different λ, wherein the s, the m and the n are all determined by the λ, so as to ensure that the acoustic metasurface structure finally obtained at different frequencies can be scaled proportionally with the corresponding wavelength, so as to achieve efficient transmission of sound waves at different frequencies across the solid barrier layer.

[0011] Furthermore, the step three also includes: the transmission efficiency is calculated by the complex sound pressure sampled on both sides of the sound field, and the complex sound pressure P is collected in the incident field respectively. i and the complex sound pressure P collected in the transmission field t , then the transmission efficiency is expressed as T = |P t | / |P i |, the configuration of the unit cell structure is continuously adjusted during the iterative optimization process to achieve a transmission efficiency close to 100%.

[0012] Furthermore, the step three also includes: respectively setting material parameters of the metasurface unit cell, the solid barrier layer and the air, selecting different materials to impart to the metasurface unit cell and the solid barrier layer according to target requirements, and then performing topological optimization design.

[0013] Furthermore, the metasurface unit cell is made of epoxy resin.

[0014] Furthermore, the solid barrier layer is made of epoxy resin or ABS plastic.

[0015] Furthermore, the step three also includes: setting left-right symmetry or rounding constraints on the metasurface unit cell structure to ensure the continuity of the obtained metasurface unit cell structure. In the optimization process, rounding the right-angled parts of the structure can avoid the influence of stress concentration on the results and improve the manufacturing accuracy of the metasurface structure to be prepared.

[0016] Furthermore, the step four also includes: the metasurface unit cell structure and the solid barrier layer structure corresponding to the solid material in the material parameter distribution are set as elastic bodies during the topology optimization process, and the interaction between air sound and the structure is considered at the same time, so as to realize efficient transmission of sound waves across the solid barrier layer through the vibration of the structure.

[0017] Furthermore, the step 2 also includes setting s=1 mm, m=32, and n=16.

[0018] The beneficial effects of the present invention are as follows: 1) The present invention realizes efficient transmission of sound waves across a solid barrier layer based on an acoustic metasurface, wherein the experimental model consists of four layers of media (air, metasurface, solid barrier layer, air), which have been simplified to semi-infinite space media on both sides and two layers of finite thickness media in the middle. In order to enhance the transmission of sound waves across the solid barrier layer, the relationship between the original solid barrier layer and the metasurface material properties, as well as the scale difference between the two, have been fully considered in the initial condition setting to avoid optimization failure due to incorrect initial condition setting. In addition, the minimum pixel size and array pixel size are first determined in the grid division. The number of points is determined, thereby determining the size of the metasurface unit cell, so that the preparation of the metasurface structure is accurate and correct; 2) The present invention solves the problem of how to enhance the transmission of sound waves in the air across solid media through an acoustic metasurface, and takes the transmission efficiency of sound waves across a solid barrier layer as the optimization goal. An acoustic metasurface is reversely designed by topological optimization. The acoustic metasurface is composed of a periodically arranged acoustic metasurface unit cell array. The designed acoustic metasurface is placed closely on the surface of the solid barrier layer, which can achieve efficient bidirectional transmission of sound waves on both sides of the solid layer, and the transmission efficiency is close to 100%, which has extremely high practical value and application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a production flow chart of the present invention.

[0020] Figure 2 A schematic diagram of the principle of the acoustic metasurface structure design provided by the present invention for achieving efficient transmission of sound waves across a solid barrier layer.

[0021] Figure 3 These are the effect diagrams of achieving efficient bidirectional transmission of sound waves on both sides of a solid layer in Example 1 of the present invention, the effect diagram without a metasurface unit cell, and the vibration modes of the solid structure.

[0022] Figure 4 It is a schematic diagram of the structure of the acoustic metasurface in Example 1 of the present invention and a diagram of the efficient transmission effect under different incident sound field conditions.

[0023] Figure 5These are the effect diagrams of achieving efficient bidirectional transmission of sound waves on both sides of a solid layer in the second embodiment of the present invention, the effect diagram without a metasurface unit cell, and the vibration modes of the solid structure.

[0024] Figure 6 It is a schematic diagram of the structure of the acoustic metasurface in Example 2 of the present invention and a diagram of the efficient transmission effect under different incident sound field conditions.

[0025] Among them: 1-1, air; 1-2, air; 2, solid barrier layer; 3, acoustic metasurface; 3-1, first type acoustic metasurface unit cell structure; 3-2, second type acoustic metasurface unit cell structure. DETAILED DESCRIPTION

[0026] If certain words are used in the specification and claims to refer to specific components, those skilled in the art should understand that manufacturers may use different terms to refer to the same component. This specification and claims do not use differences in names as a way to distinguish components, but use differences in the functions of components as the criteria for distinction. As mentioned throughout the specification and claims, "including" is an open term and should be interpreted as "including but not limited to". "Approximately" means that within an acceptable error range, those skilled in the art can solve technical problems within a certain error range and basically achieve technical effects.

[0027] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by the terms "up", "down", "front", "back", "left", "right", "horizontal", etc. are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0028] In the invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to specific circumstances.

[0029] The following is combined with Figures 1-2 The present invention is described in detail, but is not intended to be limited to the present invention.

[0030] like Figures 1-2As shown, they are respectively a flow chart and a principle diagram of the acoustic metasurface structure design for realizing efficient transmission of sound waves across a solid barrier layer 2 provided by the present invention, and a design and production method for an acoustic metasurface 3 structure for realizing efficient transmission of sound waves from air 1-1 to air 1-2 across a solid barrier layer 2, the method steps comprising:

[0031] (1) Determine the frequency f of the sound wave in the air 1-1 or the air 1-2 to be realized, and calculate the wavelength λ of the sound wave at the sound wave frequency f according to λ=c / f, where c is the propagation speed of the sound wave in the air 1-1 or the air 1-2, which can be c=343m / s, and determine the thickness h of the solid barrier layer 2 that the target passes through, as well as its material properties;

[0032] (2) The size of the acoustic metasurface unit cell structure is determined according to the determined acoustic wave wavelength λ and the thickness h of the solid barrier layer 2. The outer shape of the unit cell structure of the metasurface is set to be a rectangle with a width a and a height b. The interior of the acoustic metasurface unit cell structure is evenly divided into pixels with a side length of s. The number of pixels in the width direction is m=a / s, and the number of pixels in the height direction is n=b / s. It can be taken that s=1 mm, m=32, and n=16;

[0033] (3) Using topology optimization, the transmission efficiency of sound waves in the process of transmitting across solid media is optimized. Different material parameters are assigned to each pixel point, and then the transmittance of a single acoustic metasurface unit cell under periodic boundary conditions is calculated when the sound wave propagates from the air 1-1 on one side through the solid barrier layer 2 to the air 1-2 on the other side.

[0034] (4) Using a computer program, repeat step (3) to continuously adjust the material parameter distribution of a number of pixel points in the acoustic metasurface unit cell structure, and continuously iterate so that the calculated transmittance of the sound wave from the air on one side through the solid barrier layer to the air on the other side is close to 100%, thereby obtaining the optimal material parameter distribution, which is the desired acoustic metasurface unit cell structure, and manufacturing the desired acoustic metasurface structure by means of 3D printing.

[0035] Obviously, the present invention takes the transmission efficiency of sound waves through walls as the optimization goal, and uses a genetic algorithm combined with topology optimization to reversely design an acoustic metasurface, which is composed of periodically arranged acoustic metasurface cells, and the acoustic metasurface cell structure is obtained by special design. Placing the designed acoustic metasurface on the surface of an existing solid barrier layer that cannot efficiently transmit sound can achieve efficient transmission of sound waves of a specific frequency on both sides of the wall, and the ideal transmittance is close to 100%.

[0036] The following is combined with Figure 3-6 The present invention is further described in detail with reference to the following specific embodiments, but is not intended to limit the present invention.

[0037] Embodiment 1

[0038] In the first embodiment, the sound wave frequency f of efficient transmission is set to 3000 Hz, and the sound wave wavelength λ is calculated to be 0.114 m at the sound wave frequency f. The thickness of the solid barrier layer 2 passed by the target is h=16 mm. The material of the solid barrier layer 2 is epoxy resin. The width a and height b of the acoustic metasurface unit structure are respectively a=32 mm and b=16 mm. The width direction is divided into 32 pixels and the height direction is divided into 16 pixels, for a total of 512 pixels. The topology optimization program is used to optimize the material parameter distribution of these 512 pixels.

[0039] In the optimization process of the first embodiment, the three boundaries of the acoustic metasurface unit structure, namely, the bottom, left, and right boundaries, are set as solid material epoxy resin parameters, and the left-right symmetry constraint of the structure is imposed. The effect diagram of the first type of acoustic metasurface unit cell structure 3-1 finally optimized to achieve efficient bidirectional transmission of sound waves on both sides of the solid layer, the effect diagram without the metasurface unit cell, and the vibration mode of the solid structure are shown in FIG. Figure 3 As shown, it can be seen that no matter the sound wave is transmitted from air 1-1 to air 1-2 or from air 1-2 to air 1-1, the sound wave is basically completely transmitted, and the transmission efficiency is close to 100%. Compared with the calculation results without the metasurface condition, the transmission effect has been significantly enhanced, indicating that the designed first-type acoustic metasurface unit cell structure 3-1 can significantly enhance the transmission intensity of the sound wave when it is transmitted across the solid shielding layer 2. Furthermore, from the vibration mode of the first-type acoustic metasurface unit cell structure 3-1, it can be seen that the first-type acoustic metasurface unit cell structure 3-1 plays an important role in enhancing the transmission of sound waves.

[0040] Figure 4 A structural schematic diagram of an acoustic metasurface 3 composed of a periodic arrangement of a first-type acoustic metasurface unit cell structure 3-1 and a diagram of the efficient transmission effect under different incident sound field conditions are given. It can be seen that for different incident sound fields, such as a plane wave sound source under periodic conditions, or a plane wave sound source, or a Gaussian beam sound source, the acoustic metasurface 3 can achieve enhanced transmission of sound waves from air 1-1 to air 1-2, proving the feasibility of the structural design method of the acoustic metasurface 3 provided by the present invention for achieving efficient transmission of sound waves across a solid barrier layer.

[0041] Embodiment 2

[0042] In the second embodiment, the sound wave frequency f=5043 Hz for efficient transmission is set, and the sound wave wavelength λ=0.068 m at the sound wave frequency f is calculated. The thickness of the solid barrier layer 2 passed by the target is h=32 mm, and the material of the solid barrier layer 2 is ABS plastic. The width a and height b of the acoustic metasurface unit structure are respectively a=32 mm and b=32 mm. The width direction is divided into 32 pixels, and the height direction is divided into 32 pixels, with a total of 1024 pixels. The topology optimization program is used to optimize the material parameter distribution of these 1024 pixels.

[0043] In the optimization process of the second embodiment, the three boundaries of the acoustic metasurface unit structure at the bottom, left and right are set as the solid material epoxy resin parameters, and the left-right symmetric constraints of the structure are imposed. Finally, the second type of acoustic metasurface unit cell structure 3-2 is optimized to achieve the effect diagram of efficient bidirectional transmission of sound waves on both sides of the solid layer, the effect diagram without the metasurface unit cell, and the vibration mode of the solid structure are as follows: Figure 5 As shown, it can be seen that no matter the sound wave is transmitted from air 1-1 to air 1-2 or from air 1-2 to air 1-1, the sound wave is basically completely transmitted, and the transmission efficiency is close to 100%. Compared with the calculation results without the metasurface condition, the transmission effect has been significantly enhanced, indicating that the designed second type of acoustic metasurface unit cell structure 3-2 can significantly enhance the transmission intensity of the sound wave when it is transmitted across the solid shielding layer 2. Furthermore, from the vibration mode of the second type of acoustic metasurface unit cell structure 3-2, it can be seen that the second type of acoustic metasurface unit cell structure 3-2 plays an important role in enhancing the transmission of sound waves.

[0044] Figure 6 A structural schematic diagram of an acoustic metasurface 3 composed of a periodic arrangement of a second-type acoustic metasurface unit cell structure 3-2 and a diagram of efficient transmission effects under different incident sound field conditions are given. It can be seen that for different incident sound fields, such as a plane wave sound source under periodic conditions, or a plane wave sound source, or a Gaussian beam sound source, the acoustic metasurface 3 can achieve enhanced transmission of sound waves from air 1-1 to air 1-2, proving the feasibility of the structural design method of the acoustic metasurface 3 provided by the present invention for achieving efficient transmission of sound waves across a solid barrier layer 2 under the condition of designing a metasurface made of a material different from the solid barrier layer 2.

[0045] It can be seen that the present invention can flexibly adjust the metasurface unit cell structure and materials according to the different target solid barrier layers, and has important application value in the fields of sound reception through objects, non-destructive testing, military detection, medical testing, fault monitoring, etc.

[0046] According to the disclosure and teaching of the above description, those skilled in the art to which the present invention belongs can also change and modify the above embodiment. Therefore, the present invention is not limited to the above specific embodiment, and any obvious improvement, replacement or modification made by those skilled in the art on the basis of the present invention belongs to the protection scope of the present invention. In addition, although some specific terms are used in this specification, these terms are only for the convenience of description and do not constitute any limitation to the present invention.

Claims

1. A method for manufacturing an acoustic metasurface structure that realizes efficient transmission of sound waves across a solid barrier layer, characterized in that: The following steps are involved: Step 1: determine the frequency f of the sound wave in the air to be achieved, calculate the wavelength λ of the sound wave at the frequency f according to the propagation speed c of the sound wave in the air and the formula λ=c / f, and determine the thickness h of the solid barrier layer to be passed through and the material properties of the solid barrier layer; Step 2: Determine the size of the acoustic metasurface unit cell structure to be manufactured according to the λ and the h in step 1, and limit the shape of the acoustic metasurface unit cell structure to a rectangle with a width of a and a height of b, divide the interior of the acoustic metasurface unit cell structure evenly and make the interior of the structure have a plurality of pixels with a side length of s, then the number of pixels in the width direction is m=a / s, and the number of pixels in the height direction is n=b / s; Step 3: Using topology optimization, taking the transmission efficiency of sound waves in the process of transmitting across solid media as the optimization target, assigning different material parameters to each pixel point, and then calculating the transmittance of a single acoustic metasurface unit cell under periodic boundary conditions when the sound wave propagates from the air on one side through the solid barrier layer to the air on the other side; Step 4: Repeat step 3 through a preset computer program, continuously adjust the material parameter distribution of several pixel points in the acoustic metasurface unit cell structure, and continuously iterate so that the calculated transmittance of the sound wave from the air on one side through the solid barrier layer to the air on the other side is close to 100%, thereby obtaining the optimal material parameter distribution, that is, the required acoustic metasurface unit cell structure, and manufacturing the required acoustic metasurface structure by means of 3D printing.

2. The method for manufacturing an acoustic metasurface structure for realizing efficient transmission of sound waves across a solid barrier layer as claimed in claim 1, characterized in that: The step 2 also includes: adjusting the side length s of the pixel point and the array numbers m and n in two directions of the unit cell structure according to the different λ, wherein the s, the m and the n are all determined by the λ to ensure that the acoustic metasurface structure finally obtained at different frequencies can be scaled proportionally with the corresponding wavelength, thereby achieving efficient transmission of sound waves at different frequencies across the solid barrier layer.

3. The method for manufacturing an acoustic metasurface structure for realizing efficient transmission of sound waves across a solid barrier layer according to claim 1, characterized in that: The step three also includes: the transmission efficiency is calculated by the complex sound pressure sampled on both sides of the sound field, and the complex sound pressure P is collected in the incident field respectively. i and the complex sound pressure P collected in the transmission field t , then the transmission efficiency is expressed as T = |P t | / |P i |, the configuration of the unit cell structure is continuously adjusted during the iterative optimization process to achieve a transmission efficiency close to 100%.

4. The method for manufacturing an acoustic metasurface structure for realizing efficient transmission of sound waves across a solid barrier layer according to claim 1, characterized in that: The step three also includes: respectively setting the material parameters of the metasurface unit cell, the solid barrier layer and the air, selecting different materials to be given to the metasurface unit cell and the solid barrier layer according to the target requirements, and then performing topological optimization design.

5. The method for manufacturing an acoustic metasurface structure for realizing efficient transmission of sound waves across a solid barrier layer as claimed in claim 4, characterized in that: The super surface unit cell is made of epoxy resin.

6. The method for manufacturing an acoustic metasurface structure for realizing efficient transmission of sound waves across a solid barrier layer according to claim 4, characterized in that: The solid barrier layer is made of epoxy resin or ABS plastic.

7. The method for manufacturing an acoustic metasurface structure for realizing efficient transmission of sound waves across a solid barrier layer according to any one of claims 1 to 6, characterized in that: The step three also includes: setting left-right symmetry or rounding constraints on the metasurface unit cell structure to ensure the continuity of the obtained metasurface unit cell structure.

8. The method for manufacturing an acoustic metasurface structure for realizing efficient transmission of sound waves across a solid barrier layer according to any one of claims 1 to 6, characterized in that: The step four also includes: the metasurface unit cell structure and the solid barrier layer structure corresponding to the solid material in the material parameter distribution are set as elastic bodies during the topology optimization process, and the interaction between air sound and the structure is considered at the same time, so as to realize the efficient transmission of sound waves across the solid barrier layer through the vibration of the structure.

9. The method for manufacturing an acoustic metasurface structure for realizing efficient transmission of sound waves across a solid barrier layer according to claim 1, characterized in that: The step 2 also includes setting s=1 mm, m=32, and n=16.

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