A method for manufacturing an acoustic metasurface structure for realizing efficient transmission of acoustic waves across a solid barrier layer

Abstract

The application belongs to the technical field of acoustic signal transmission, and particularly relates to a manufacturing method of an acoustic metasurface structure for realizing efficient transmission of sound waves across a solid barrier layer. The method uses a topological optimization mode, takes the transmission efficiency of sound waves in the process of transmission across a solid medium as an optimization target, constantly adjusts the material parameter distribution of a plurality of pixel points in the acoustic metasurface unit cell structure, and constantly iterates, so that the calculated transmittance of sound waves from one side of air through the solid barrier layer and then propagating to the other side of air is close to 100%. According to the parameters of target penetration of a wall, the application can directly inversely optimize and design a unit cell structure meeting the requirements, and accurately and efficiently manufacture the acoustic metasurface structure for realizing efficient transmission of sound waves through the solid barrier layer by using 3D printing.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of acoustic signal transmission, and particularly relates to a manufacturing method of an acoustic metasurface structure for realizing efficient transmission of sound waves across a solid barrier layer. BACKGROUND

[0002] In the industrial production process, although internal damage of a mechanical structure cannot be directly found through visual observation or long-term monitoring, the abnormal sound generated by the damage of the structure can provide conditions for acoustic monitoring, that is, the detection personnel can preliminarily judge whether the equipment is damaged by listening to the sound during the operation of the equipment. However, for some large equipment, especially the equipment with a thick shell, the effect of traditional acoustic detection will be greatly weakened, because there is a large impedance difference between the equipment shell and the air medium on both sides, which leads to a large attenuation of the sound wave and the occurrence of noise when the sound wave propagates through the shell. Therefore, how to realize efficient transmission of sound waves across solid media and how to manufacture an acoustic metasurface structure for realizing efficient transmission of sound waves across a solid barrier layer are problems to be solved. SUMMARY

[0003] The application aims at the deficiencies of the prior art, and provides a manufacturing method of an acoustic metasurface structure for realizing efficient transmission of sound waves across a solid barrier layer, which not only realizes efficient transmission of sound waves across solid media, but also can manufacture the required metasurface structure by the most accurate means.

[0004] In order to achieve the above-mentioned purpose, the application adopts the following technical scheme:

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

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

[0007] Step two, determining the size of the acoustic metasurface unit cell structure to be manufactured according to the λ and the h of step one, limiting the shape of the acoustic metasurface unit cell structure to be a rectangle with a width a and a height b, uniformly dividing the inside of the acoustic metasurface unit cell structure and making the inside of the structure have a plurality of pixel points with a side length s, then the number of pixel points in the width direction m=a / s, and the number of pixel points in the height direction n=b / s;

[0008] Step three, in a topological optimization manner, taking the transmission efficiency of sound waves in the process of transmission across the solid medium as the optimization target, by assigning different material parameters to each pixel point, then calculating the transmission rate of sound waves from one side of air through the solid barrier layer and then propagating to the other side of air under the periodic boundary conditions of a single acoustic metasurface unit cell;

[0009] Step four, repeatedly performing step three through a preset computer program, constantly adjusting the material parameter distribution of several pixel points in the acoustic metasurface unit cell structure, and constantly iterating so that the calculated transmission rate of sound waves from one side of air through the solid barrier layer and then propagating to the other side of air is close to 100%, thereby obtaining the optimal material parameter distribution, i.e. the required acoustic metasurface unit cell structure, and the required acoustic metasurface structure is prepared by 3D printing.

[0010] Further, the step two further comprises: adjusting the side length s of the pixel point and the array number m, n of the unit cell structure in two directions according to different λ, wherein the s, the m and the n are determined by the λ, so as to ensure that the finally obtained acoustic metasurface structure can be scaled with the corresponding wavelength at different frequencies, and high-efficiency transmission of sound waves across the solid barrier layer at different frequencies is realized.

[0011] Further, the step three further comprises: the transmission efficiency is calculated by the complex sound pressure sampled from both sides of the sound field, and the complex sound pressure P i and the complex sound pressure P t are collected in the incident field and the transmission field respectively, and the transmission efficiency is represented as T = |P t | / |P i |, and the configuration of the unit cell structure is constantly adjusted in the process of iterative optimization to realize the transmission efficiency close to 100%.

[0012] Further, the step three further comprises: material parameters of the metasurface unit cell, the solid barrier layer and air are set respectively, and different materials are selected to assign the metasurface unit cell and the solid barrier layer for topological optimization design according to the target requirements.

[0013] Further, the metasurface unit cell selects epoxy resin.

[0014] Further, the solid barrier layer selects epoxy resin or ABS plastic.

[0015] Further, the step three further comprises: a constraint condition of left-right symmetry or internal right-angle structure rounding is set for the metasurface unit cell structure to ensure the continuity of the obtained metasurface unit cell structure. Wherein, the internal right-angle part of the structure is processed by rounding to avoid the influence of stress concentration on the result, and the manufacturing accuracy of the prepared metasurface structure is improved.

[0016] Further, the step four further comprises: the solid material in the material parameter distribution corresponds to the metasurface unit cell structure and the solid barrier layer structure in the topology optimization process are set as elastic bodies, and the interaction between the air sound and the structure is considered, and efficient transmission of the sound wave across the solid barrier layer is realized through vibration of the structure.

[0017] Further, the step two further comprises: setting s=1mm, m=32, and n=16.

[0018] The present application has the following advantages: 1) The present application realizes efficient transmission of the sound wave across the solid barrier layer based on the acoustic metasurface, wherein the experimental model is composed of four layers of medium (air, metasurface, solid barrier layer, and air), which has been simplified into two sides of semi-infinite space medium and two layers of medium with limited thickness in the middle. In order to enhance the transmission of the sound wave across the solid barrier layer, the relationship between the original solid barrier layer and the material properties of the metasurface and the difference in the scale of the two have been fully considered in the initial condition setting, so as to avoid no solution of the optimization caused by incorrect initial condition setting. In addition, the grid division determines the minimum pixel size and the number of array pixels, thereby determining the size of the metasurface unit cell, so that the preparation of the metasurface structure is accurate and correct; 2) The present application solves the problem of how to enhance the transmission of the sound wave across the solid medium in the air through the acoustic metasurface. The acoustic metasurface is designed in a reverse way by using the topology optimization, with the transmission efficiency of the sound wave across the solid barrier layer as the optimization target. The designed acoustic metasurface is placed closely on the surface of the solid barrier layer, so as to realize bidirectional efficient transmission of the sound wave on both sides of the solid layer, with the transmission efficiency close to 100%, which has high practical value and application value. BRIEF DESCRIPTION OF DRAWINGS

[0019] Fig. 1 The flowchart of the present application is provided.

[0020] Fig. 2 The principle diagram of the acoustic metasurface structure design for realizing efficient transmission of the sound wave across the solid barrier layer is provided.

[0021] Fig. 3 The effect diagram of realizing bidirectional efficient transmission of the sound wave on both sides of the solid layer, the effect diagram without the metasurface unit cell, and the vibration mode of the solid structure are provided.

[0022] Fig. 4 The structure diagram of the acoustic metasurface and the efficient transmission effect diagram under different incident sound field conditions are provided.

[0023] Fig. 5The effect diagram of bidirectional efficient transmission of sound waves in the solid layer in the second embodiment of the present application, the effect diagram without the metasurface unit cell, and the vibration mode of the solid structure.

[0024] Fig. 6 The structure schematic diagram of the acoustic metasurface in the second embodiment of the present application and the efficient transmission effect diagram under different incident sound field conditions.

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

[0026] As some terms are used in the description and claims, those skilled in the art should understand that manufacturers can use different names to refer to the same component. The description and claims of the present application do not distinguish components by name difference, but by functional difference. As mentioned throughout the description and claims, "comprising" is an open term, which should be interpreted as "comprising but not limited to". "Approximately" means within an acceptable error range, and 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 application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "horizontal", etc. indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0028] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be understood broadly, for example, it can be fixed connection, or detachable connection, or integral connection; it can be mechanical connection, or electrical connection; it can be direct connection, or indirect connection through intermediate medium, or internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0029] The following will be described in detail Figs. 1-2 The present application will be described in detail, but not as a limitation on the present application.

[0030] As Figs. 1-2As shown, respectively, the flow chart and principle diagram of the acoustic metasurface structure design provided by the application for realizing efficient transmission of sound waves across the solid barrier layer 2, a design and manufacturing method of an acoustic metasurface 3 structure for realizing efficient transmission of sound waves from air 1-1 to air 1-2 across the solid barrier layer 2, the method steps include:

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

[0032] (2) Determine the size of the acoustic metasurface unit cell structure according to the determined sound wave wavelength λ and the thickness h of the solid barrier layer 2, set the shape of the acoustic metasurface unit cell structure to be rectangular, the width is a, the height is b, the acoustic metasurface unit cell structure is uniformly divided into pixel points with a side length of s, then the number of pixel points in the width direction m = a / s, the number of pixel points in the height direction n = b / s, which can be taken as s = 1 mm, m = 32, n = 16;

[0033] (3) Using the topological optimization method, taking the transmission efficiency of the sound wave in the transmission process across the solid medium as the optimization target, different material parameters are given to each pixel point, and then the transmission rate of the sound wave from one side air 1-1 to the other side air 1-2 through the solid barrier layer 2 is calculated under the periodic boundary condition of the single acoustic metasurface unit cell;

[0034] (4) Using a computer program, repeatedly execute step (3), constantly adjust the material parameter distribution of several pixel points in the acoustic metasurface unit cell structure, and constantly iterate, so that the transmission rate of the sound wave from one side air to the other side air through the solid barrier layer is close to 100%, thereby obtaining the best material parameter distribution, that is, the required acoustic metasurface unit cell structure, and the required acoustic metasurface structure is manufactured by 3D printing.

[0035] Obviously, the application inversely designs an acoustic metasurface by taking the transmission efficiency of the sound wave through the wall as the optimization target and combining the genetic algorithm with the topological optimization, the acoustic metasurface is composed of periodically arranged acoustic metasurface unit cells, and the acoustic metasurface unit cell structure is obtained by special design. Placing the designed acoustic metasurface on the surface of the existing solid barrier layer which cannot efficiently transmit sound can realize efficient transmission of sound waves of a specific frequency on both sides of the wall, and the ideal transmission rate is close to 100%.

[0036] The application will be further described in detail below in combination with the accompanying drawings Figs. 3-6 and specific embodiments, but not as a limitation to the application.

[0037] Embodiment One

[0038] In this embodiment one, the efficient transmission of sound wave frequency f = 3000 Hz is set, and the sound wave wavelength λ = 0.114 m is calculated under the sound wave frequency f, the thickness h = 16 mm of the solid barrier layer 2 through which the target passes, and the material of the solid barrier layer 2 is epoxy resin, wherein the width a and the height b of the acoustic metasurface unit structure are respectively taken as a = 32 mm and b = 16 mm, 32 pixel points are divided in the width direction, 16 pixel points are divided in the height direction, a total of 512 pixel points, and the material parameter distribution of the 512 pixel points is optimized by using the topology optimization program.

[0039] In the optimization process of this embodiment one, the lower, left and right boundaries of the acoustic metasurface unit structure are set as solid material epoxy resin parameters, and the left-right symmetry constraint is applied, and the finally optimized first type of acoustic metasurface unit cell structure 3-1 realizes the effect diagram of bidirectional efficient 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 as shown in Fig. 3 It can be seen that the sound wave is transmitted from air 1-1 to air 1-2 or from air 1-2 to air 1-1, and the sound wave is basically completely transmitted, the transmission efficiency is close to 100%, and the transmission effect is significantly enhanced compared with the calculation result without the metasurface, which shows that the designed first type of acoustic metasurface unit cell structure 3-1 can significantly enhance the transmission intensity of the sound wave across the solid barrier layer 2. Further, from the vibration mode of the first type of acoustic metasurface unit cell structure 3-1, it can be seen that the first type of acoustic metasurface unit cell structure 3-1 plays an important role in enhancing the transmission of sound waves.

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

[0041] Embodiment Two

[0042] In the second embodiment, the efficient transmission of the sound wave frequency f = 5043 Hz is set, and the sound wave wavelength λ = 0.068 m is calculated under the sound wave frequency f, the thickness h = 32 mm of the solid barrier layer 2 through which the target passes, and the material of the solid barrier layer 2 is ABS plastic, wherein the width a and the height b of the acoustic metasurface unit structure are respectively a = 32 mm and b = 32 mm, 32 pixel points are divided in the width direction, 32 pixel points are divided in the height direction, and a total of 1024 pixel points are obtained. The material parameter distribution of the 1024 pixel points is optimized by using the topology optimization program.

[0043] In the optimization process of the second embodiment, the lower, left and right boundaries of the acoustic metasurface unit structure are set as the solid material epoxy resin parameters, and the left-right symmetry constraint is applied, and finally the effect diagram of the second type of acoustic metasurface unit structure 3-2 realizing the bidirectional efficient transmission of sound waves on both sides of the solid layer, the effect diagram without the metasurface unit, and the vibration mode of the solid structure are as shown in Fig. 5 As can be seen, the sound wave is transmitted from air 1-1 to air 1-2 or from air 1-2 to air 1-1, and the sound wave is basically completely transmitted, and the transmission efficiency is close to 100%, which is significantly enhanced compared with the calculation result without the metasurface, which shows that the second type of acoustic metasurface unit structure 3-2 can significantly enhance the transmission intensity of the sound wave across the solid barrier layer 2. Further, from the vibration mode of the second type of acoustic metasurface unit structure 3-2, it can be seen that the second type of acoustic metasurface unit structure 3-2 plays an important role in enhancing the transmission of the sound wave.

[0044] Fig. 6 The structure schematic diagram of the acoustic metasurface 3 composed of the periodic arrangement of the second type of acoustic metasurface unit structure 3-2 and the efficient transmission effect diagram under different incident sound field conditions are given, and it can be seen that for different incident sound fields, such as a plane wave sound source under a periodic condition, or a plane wave sound source and a Gaussian beam sound source, the acoustic metasurface 3 can realize the enhanced transmission of the sound wave from air 1-1 to air 1-2, which proves the feasibility of the structure design method of the acoustic metasurface 3 provided by the application for realizing the efficient transmission of the sound wave across the solid barrier layer 2 under the condition of designing the metasurface with different materials of the solid barrier layer 2.

[0045] It can be seen that the application can flexibly adjust the metasurface unit structure and the material according to different target solid barrier layers, and has important application value in the fields of object isolation sound collection, nondestructive testing, military detection, medical detection, fault monitoring and the like.

[0046] Those skilled in the art can make various modifications and variations to the above embodiments based on the disclosure and teachings of this specification. Therefore, the present application should not be limited to the above specific embodiments, and any obvious modifications, replacements or variations made by those skilled in the art based on the present application shall fall within the scope of the present application. 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 on the present application.

Claims

1. A method for fabricating an acoustic metasurface structure that enables efficient transmission of sound waves across a solid barrier layer, characterized in that, Includes the following steps: Step 1: Determine the frequency f of the sound wave to be realized in the air. Calculate the wavelength λ of the sound wave at frequency f based on the propagation speed c of the sound wave in the air and the formula λ = c / f. Also, determine the thickness h of the solid barrier layer to be penetrated and the material properties of the solid barrier layer. Step 2: Determine the size of the acoustic metasurface unit cell structure to be fabricated based on λ and h from Step 1. Simultaneously, define the shape of the acoustic metasurface unit cell structure as 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 multiple 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, with the transmission efficiency of sound waves in the process of propagation across solid media as the optimization target, 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 from one side of the air through the solid barrier layer to the other side of the air. Step 4: Repeat step 3 through a preset computer program to continuously adjust the material parameter distribution of several pixels in the acoustic metasurface unit cell structure. Iterate continuously to make the transmittance of the calculated sound wave from one side of the air through the solid barrier layer to the other side of the air close to 100%, thereby obtaining the optimal material parameter distribution, which is the desired acoustic metasurface unit cell structure. The desired acoustic metasurface structure is then produced by 3D printing.

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

3. The method for fabricating an acoustic metasurface structure for efficient sound wave transmission across a solid barrier layer as described in claim 1, characterized in that, Step three further includes: the transmission efficiency is calculated from the complex sound pressure obtained by sampling from both sides of the sound field, and the complex sound pressure P is collected in the incident field respectively. i and collecting complex sound pressure P in the transmission field t The transmission efficiency is then expressed as T = |P t | / |P i During the iterative optimization process, the configuration of the unit cell structure is continuously adjusted to achieve a transmission efficiency close to 100%.

4. The method for fabricating an acoustic metasurface structure for efficient sound wave transmission across a solid barrier layer as described in claim 1, characterized in that, Step three also includes: setting the material parameters for the metasurface unit cell, the solid barrier layer, and air respectively, and then selecting different materials to equip the metasurface unit cell and the solid barrier layer according to the target requirements before performing topology optimization design.

5. The method for fabricating an acoustic metasurface structure that enables efficient transmission of sound waves across a solid barrier layer as described in claim 4, characterized in that: The metasurface unit cells are made of epoxy resin.

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

7. The method for fabricating an acoustic metasurface structure that enables efficient transmission of sound waves across a solid barrier layer as described in any one of claims 1 to 6, characterized in that, Step three also includes setting constraints on the metasurface unit cell structure for left-right symmetry or rounding of the internal right-angle structure to ensure the continuity of the obtained metasurface unit cell structure.

8. The method for fabricating an acoustic metasurface structure that enables efficient transmission of sound waves across a solid barrier layer as described in any one of claims 1 to 6, characterized in that, Step four further includes: the metasurface unit cell structure and solid barrier layer structure corresponding to the solid material in the material parameter distribution are set as elastic bodies during the topology optimization process, while considering the interaction between airborne sound and the structure, and realizing the efficient transmission of sound waves across the solid barrier layer through the vibration of the structure.

9. The method for fabricating an acoustic metasurface structure that enables efficient transmission of sound waves across a solid barrier layer as described in claim 1, characterized in that: Step two also includes setting s = 1 mm, m = 32, and n = 16.

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