A corrugated sandwich structure with both mechanical bearing and low broadband sound absorption function

Abstract

The present invention relates to a corrugated sandwich structure with both mechanical bearing and low broadband sound absorption functions, including an upper panel, a lower panel and a corrugated core layer arranged between the upper panel and the lower panel, the upper panel is provided with micropores to form a superstructure surface, the corrugated core layer is periodically arranged between the upper panel and the lower panel, the corrugated core layer is a corrugated structure formed by the continuation of a number of intermediate support plates, the upper and lower ends of each intermediate support plate are connected to the upper panel and the lower panel, and an arc structure is arranged on the lower side of the upper panel. Compared with the prior art, the present invention designs an arc structure similar to a fish belly on the upper panel, and indirectly regulates the thickness of the micropores by changing the position of the micropores, thereby adding a new degree of freedom to the regulation of sound absorption. The invention combines the theory of weak resonance coherent coupling to achieve low broadband sound absorption. The present invention has a simple structure, and only requires one arc structure to achieve low broadband sound absorption, and the arc structure can increase the bending resistance of the structure.

Description

Technical Field

[0001] The present invention relates to the field of sound wave regulation in engineering applications, and in particular to a corrugated sandwich structure with both mechanical bearing and low broadband sound absorption functions. Background Art

[0002] In aerospace, sound absorption performance is related to passenger comfort, equipment safety level and whether the equipment can operate normally; in manufacturing workshops, sound-absorbing materials can be used to protect the health of workers; some special places, such as stadiums, also need sound-absorbing materials to reduce the impact of sound on athletes; sound-absorbing materials in high-speed rail, trains and other transportation vehicles can ensure the safety of drivers. Therefore, excellent sound absorption performance is of great significance to the functional application of lightweight structures. Sound absorption is to reduce the noise in the cabin by absorbing part of the sound waves and reducing reflection.

[0003] Chinese patent CN109763577A discloses a micro-perforated plate sound absorber with rough surface modified micropores, including a perforated panel and a rigid backing, a cavity between the perforated panel and the rigid backing, a rough sound absorbing hole is opened on the perforated panel, the opening direction is perpendicular to the upper panel, and the rough hole shape of the sound absorbing hole opened on the perforated panel is controlled by a function; it has good sound absorption performance in the middle and low frequency bands and a more flexible sound absorption function, while also having the characteristics of light weight. Chinese patent CN113362794A discloses a rough microchannel porous sound absorption structure, including a porous material plate and a rigid backing, a rough sound absorption hole is opened on the material plate, the opening direction is perpendicular to the material plate, and the rough hole shape of the sound absorption hole opened on the porous material plate is controlled by a cosine function; it has good sound absorption performance in the middle and low frequency bands and a more flexible sound absorption function, while also having the characteristics of light weight. However, the sound absorption structures disclosed in the above two patents do not pay much attention to mechanical bearing performance.

[0004] Due to its unique structural characteristics, acoustic metamaterials can effectively control long-wavelength sound waves in a small size and achieve the function of sound absorption. In practical applications, high-absorption wide-band sound absorbers have a large thickness. Although some low-frequency broadband sound absorbers have a small thickness, their structure is relatively complex and the mechanical properties of the structure are ignored.

[0005] Therefore, it is necessary to develop a noise reduction structure that can achieve low-frequency broadband absorption and take into account mechanical properties in practical engineering applications. Summary of the invention

[0006] The object of the present invention is to provide a corrugated sandwich structure having both mechanical bearing and low broadband sound absorption functions.

[0007] The solution provided by the present invention is a multifunctional corrugated sandwich structure. Based on the technical solution of the present invention, broadband sound absorption can be achieved at low frequencies and mechanical bearing performance can be combined, which can provide a solution to the low-frequency noise reduction problem in engineering.

[0008] The purpose of the present invention can be achieved by the following technical solutions:

[0009] The present invention provides a corrugated sandwich structure with both mechanical bearing and low broadband sound absorption functions, comprising an upper panel, a lower panel and a corrugated core layer arranged between the upper panel and the lower panel, wherein micropores are opened on the upper panel to form a superstructure surface, and an arc structure is arranged on the lower side of the upper panel, and a complete arc structure is located between two adjacent middle support plates of the corrugated core layer.

[0010] In one embodiment of the present invention, the corrugated core layer is periodically arranged between the upper panel and the lower panel. The top of the corrugated core layer is fixedly connected to the lower surface of the upper panel, and the bottom of the corrugated core layer is fixedly connected to the upper surface of the lower panel.

[0011] In one embodiment of the present invention, the corrugated core layer is a corrugated structure formed by a plurality of intermediate support plates, and the upper and lower ends of each intermediate support plate are connected to the upper panel and the lower panel.

[0012] In one embodiment of the present invention, the intermediate support plate constituting the corrugated core layer is selected to be a flat plate or an arc-shaped plate with a curved surface.

[0013] In one embodiment of the present invention, all the intermediate support plates constituting the corrugated core layer are an integral structure.

[0014] In one embodiment of the present invention, the upper panel, the lower panel and the corrugated core layer are an integrally formed structure and are made of the same material.

[0015] In one embodiment of the present invention, the microholes provided on the upper panel are through holes, and the diameter, depth (i.e., equivalent to the thickness of the upper panel at the location of the microholes) and number of the microholes provided on the upper panel are related to the sound absorption coefficient, that is, the diameter, depth and number of the microholes provided on the upper panel are adapted to the frequency band of the sound to be absorbed. Since an arc structure is provided on the lower side of the upper panel, and the arc is in the shape of a parabola, the depths of the microholes at different locations on the upper panel are different, and the depth of the microholes can be adjusted by adjusting the position.

[0016] The acoustic impedance of the microvia is calculated as follows:

[0017]

[0018] Among them, d nis the diameter of the microhole on the nth unit cell of the upper panel, t n is the depth of the microhole on the nth unit cell of the upper panel, η is the dynamic viscosity of air, p n is the perforation rate of the upper panel, ω is the angular frequency of sound, ρ0 is the density of air, and the unit cell refers to a unit consisting of two adjacent middle support plates of the corrugated core layer and an upper panel with a complete arc structure located between the two adjacent middle support plates of the corrugated core layer;

[0019] The acoustic impedance of a unit cell is calculated as follows:

[0020]

[0021] Wherein, ρ0 is the air density, c0 is the speed of sound in the air, k is the wave number of the sound wave, D is the ratio of the cavity volume of the unit cell to the area of ​​the arc surface of the arc structure on the lower side of the upper panel in the unit cell, and Z Mn is the acoustic impedance of the micropore;

[0022] The overall acoustic impedance of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption function is calculated as follows:

[0023]

[0024] Among them, Z is the overall acoustic impedance of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption function, Z n is the acoustic impedance of the nth unit cell of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption function, ω n is the width of the nth unit cell of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption functions, A is the overall width of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption functions, the width of the unit cell refers to the farthest distance between the two middle support plates in the unit cell, and the overall width of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption functions refers to the length of the upper panel along the extension direction of the unit cell;

[0025] The sound absorption coefficient of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption function is calculated as follows:

[0026]

[0027] Among them, Z is the overall acoustic impedance of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption functions, ρ0 is the air density, and c0 is the speed of sound in the air.

[0028] The present invention applies a reinforcement learning algorithm and can determine the geometric parameters of the hole according to the required frequency range and absorption performance requirements.

[0029] In one embodiment of the present invention, the thickness of the corrugated sandwich structure is a sub-wavelength thickness, where the thickness referred to herein is the overall thickness including the upper panel, the lower panel and the corrugated core layer.

[0030] In one embodiment of the present invention, specifically, the thickness of the upper panel at both ends of the arc structure is 1 mm, the thickness of the upper panel at the midpoint of the arc structure is 3 mm, the arc is a parabola, the thickness of the corrugated core plate is 1 mm, the thickness of the corrugated core layer is 34.4 mm, and the thickness of the lower panel is 1 mm. That is, the arch height of the arc structure is 3 mm.

[0031] The present invention also provides a design method for a corrugated sandwich structure having both mechanical bearing and low broadband sound absorption functions, for obtaining the corrugated sandwich structure having both mechanical bearing and low broadband sound absorption functions, the design method comprising the following steps:

[0032] S1: Obtain the overall thickness of the corrugated sandwich structure and generate an overall model, wherein the overall model includes an upper panel and its micropores, a lower panel and a corrugated core layer, wherein the arc structure arch height and the diameter, position and number of the micropores of the upper panel are finally determined by calculation in step S2 and continuously modified to meet the requirements;

[0033] S2: The diameter, position and number of the micropores of the upper panel are adapted to the frequency band of the sound to be absorbed, and the reinforcement learning algorithm is applied to calculate the sound absorption coefficient of the overall model at each frequency under various parameters to obtain the working frequency band of the overall model. The sound absorption coefficient of the overall model in the working frequency band is not less than the sound absorption coefficient threshold of the preset value;

[0034] The acoustic impedance of the microvia is calculated as follows:

[0035]

[0036] Among them, d n is the diameter of the microhole on the nth unit cell of the upper panel, t n is the depth of the microhole on the nth unit cell of the upper panel, η is the dynamic viscosity of air, p n is the perforation rate of the nth unit cell of the upper panel, ω is the angular frequency of sound, and ρ0 is the density of air;

[0037] The acoustic impedance of a unit cell is calculated as follows:

[0038]

[0039] Wherein, ρ0 is the air density, c0 is the speed of sound in the air, k is the wave number of the sound wave, D is the ratio of the cavity volume of the unit cell to the area of ​​the arc surface of the arc structure on the lower side of the upper panel in the unit cell, and Z Mn is the acoustic impedance of the micropore;

[0040] The overall acoustic impedance of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption function is calculated as follows:

[0041]

[0042] Among them, Z is the overall acoustic impedance of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption function, Z n is the acoustic impedance of the nth unit cell of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption function, ω n is the width of the nth unit cell of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption functions, A is the overall width of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption functions, the width of the unit cell refers to the farthest distance between the two middle support plates in the unit cell, and the overall width of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption functions refers to the length of the upper panel along the extension direction of the unit cell;

[0043] The sound absorption coefficient of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption function is calculated as follows:

[0044]

[0045] Among them, Z is the overall acoustic impedance of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption functions, ρ0 is the air density, and c0 is the speed of sound in the air;

[0046] S3: Based on the geometric parameters obtained in step S2, a low-frequency, broadband, multifunctional corrugated sandwich structure is manufactured.

[0047] In one embodiment of the present invention, a calculation formula for a unit cell structure is given in step S2, which is intended to explain why the geometric factors of the micropores are related to the sound absorption coefficient. Based on the calculation formula for the unit cell structure, a coupling operation is performed to obtain the sound absorption coefficient of the overall structure. In the present invention, the calculation of the sound absorption coefficient applies the weak resonance coherent coupling theory, and the specific calculation formula is shown above.

[0048] The present invention utilizes a reinforcement learning algorithm in Matlab to generate an overall model and calculate the sound absorption coefficient of the overall model.

[0049] In one embodiment of the present invention, in step S1, satisfying the requirements means achieving the required sound absorption frequency band and sound absorption coefficient, and the calculation principle of the sound absorption coefficient has been given in S2. In step S1, continuously correcting means training of the reinforcement learning algorithm.

[0050] In one embodiment of the present invention, in step S2, the preset sound absorption coefficient threshold is 0.9.

[0051] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0052] (1) The present invention provides a corrugated sandwich structure with both mechanical bearing and low-bandwidth sound absorption functions. Compared with the traditional sandwich structure for noise reduction, the arc structure of the upper panel provides a new degree of freedom for the sound absorption performance of the micro-perforation of the sandwich structure, and the weak resonant coherent coupling effect enables it to achieve low-frequency broadband sound absorption.

[0053] (2) The present invention provides a corrugated sandwich structure with both mechanical bearing and low broadband sound absorption functions. By designing the upper panel into an arc shape similar to a fish belly, the bending resistance of the structure is improved.

[0054] (3) The present invention provides a corrugated sandwich structure having both mechanical bearing and low broadband sound absorption functions. By using the corrugated sandwich structure, the present invention has good compressive resistance and light weight.

[0055] (4) The present invention provides a corrugated sandwich structure with both mechanical bearing and low broadband sound absorption functions. The designed structure is an integrated design, which can be formed into one piece in actual processing. It has a simple structure and is easy to be applied in engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 This is a schematic structural diagram of a corrugated sandwich structure having both mechanical bearing and low broadband sound absorption functions in Example 1 of the present invention;

[0057] Figure 2 This is an experimental sample diagram of a corrugated sandwich structure having both mechanical bearing and low broadband sound absorption functions in Example 1 of the present invention;

[0058] Figure 3 This is a comparison diagram of the theory, simulation and experiment of the sound absorption coefficient of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption function in Example 1 of the present invention;

[0059] Figure 4 It is a comparison diagram of the theory (solid line) and experiment (dashed line) of the relative acoustic impedance of the corrugated sandwich structure having both mechanical bearing and low broadband sound absorption functions in Example 1 of the present invention. DETAILED DESCRIPTION

[0060] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0061] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0062] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0063] In the present invention, unless otherwise clearly defined and limited, the terms "connection", "fixation" and the like should be understood in a broad sense. For example, "fixation" can mean fixed connection, detachable connection, or integration; it can mean direct connection or indirect connection through an intermediate medium, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0064] In the drawings, components with the same structure are indicated by the same numerical labels, and components with similar structures or functions are indicated by similar numerical labels. The size and thickness of each component shown in the drawings are arbitrarily shown, and the present invention does not limit the size and thickness of each component. In order to make the illustration clearer, some parts in the drawings are appropriately exaggerated.

[0065] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0066] Example 1

[0067] A corrugated sandwich structure with both mechanical bearing and low broadband sound absorption function, such as Figure 1 As shown, it includes an upper panel 1, a lower panel 2 and a corrugated core layer 3 arranged between the upper panel and the lower panel, and the upper panel is provided with micropores to form a superstructure surface. Among them, the corrugated core layer is periodically arranged between the upper panel and the lower panel. The top of the corrugated core layer is fixedly connected to the lower surface of the upper panel, and the bottom of the corrugated core layer is fixedly connected to the upper surface of the lower panel. The corrugated core layer is a corrugated structure formed by the continuation of a number of intermediate support plates, and the upper and lower ends of each intermediate support plate are connected to the upper panel and the lower panel. In this embodiment, the intermediate support plates constituting the corrugated core layer are selected as flat plates.

[0068] In this embodiment, an arc structure is provided on the lower side of the upper panel, and a complete arc structure is located between two adjacent middle support plates of the corrugated core layer.

[0069] In this embodiment, the upper panel, the lower panel and the corrugated core layer are an integrally formed structure and are made of the same material.

[0070] In this embodiment, the micro-holes provided on the upper panel are through holes, and the diameter, depth (i.e., equivalent to the thickness of the upper panel at the position where the micro-holes are located) and number of the micro-holes provided on the upper panel are related to the sound absorption coefficient, that is, the diameter, depth and number of the micro-holes provided on the upper panel are adapted to the frequency band of the sound to be absorbed. Since an arc structure is provided on the lower side of the upper panel, and the arc is in a parabolic shape, the depths of the micro-holes at different positions of the upper panel are different, and the depth of the micro-holes can be adjusted by adjusting the position.

[0071] The acoustic impedance of the microvia is calculated as follows:

[0072]

[0073] Among them, d n is the diameter of the microhole on the nth unit cell of the upper panel, t n is the depth of the microhole on the nth unit cell of the upper panel, η is the dynamic viscosity of air, p n is the perforation rate of the nth unit cell of the upper panel, ω is the angular frequency of sound, ρ0 is the density of air, and a unit cell refers to a unit consisting of two middle support plates adjacent to the corrugated core layer and an upper panel with a complete arc structure located between the two middle support plates adjacent to the corrugated core layer. In this embodiment, there are 4 unit cells.

[0074] The acoustic impedance of a unit cell is calculated as follows:

[0075]

[0076] Wherein, ρ0 is the air density, c0 is the speed of sound in the air, k is the wave number of the sound wave, D is the ratio of the cavity volume of the unit cell to the area of ​​the arc surface of the arc structure on the lower side of the upper panel in the unit cell, and Z Mn is the acoustic impedance of the micropore;

[0077] The overall acoustic impedance of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption function is calculated as follows:

[0078]

[0079] Among them, Z is the overall acoustic impedance of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption function, Z n is the acoustic impedance of the nth unit cell of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption function, ω nis the width of the nth unit cell of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption functions, A is the overall width of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption functions, the width of the unit cell refers to the farthest distance between the two middle support plates in the unit cell, and the overall width of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption functions refers to the length of the upper panel along the extension direction of the unit cell;

[0080] The sound absorption coefficient of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption function is calculated as follows:

[0081]

[0082] Among them, Z is the overall acoustic impedance of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption functions, ρ0 is the air density, and c0 is the speed of sound in the air.

[0083] The basic principle is as follows: The micropores and cavities of the corrugated sandwich structure form a micro-perforated plate, which can enhance the sound absorption performance. The weak resonance coherent coupling effect is applied to perform non-local coupling between cavities. Weak resonance means that the sound absorption coefficient of a single cavity is not perfect. After the coupling calculation, the overall model has a broadband quasi-perfect sound absorption, which greatly reduces the thickness of the structure. The arc structure of the upper panel expands the freedom of adjusting the micropores, thereby achieving a wider bandwidth of sound absorption than other structures.

[0084] In this embodiment, the thickness of the corrugated sandwich structure is sub-wavelength thickness, and the thickness of the micropores is millimeter level. The panel and the micropores are integrally formed, and the overall material is the same, so that the overall connection can be stable and reliable, and it is also convenient for processing and manufacturing. In this embodiment, the corrugated sandwich structure is integrally formed by 3D printing, and the material used is photosensitive resin.

[0085] The design method of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption function in this embodiment includes the following steps:

[0086] S1: Obtain the overall thickness of the corrugated sandwich structure and generate an overall model, wherein the overall model includes an upper panel and its micropores, a lower panel and a corrugated core layer, wherein the arc structure arch height and the diameter, position and number of the micropores of the upper panel are finally determined by calculation in step S2 and continuously modified to meet the requirements;

[0087] S2: The diameter, position and number of the micropores of the upper panel are adapted to the frequency band of the sound to be absorbed, and the reinforcement learning algorithm is applied to calculate the sound absorption coefficient of the overall model at each frequency under various parameters to obtain the working frequency band of the overall model. The sound absorption coefficient of the overall model in the working frequency band is not less than the sound absorption coefficient threshold of the preset value;

[0088] The acoustic impedance of the microvia is calculated as follows:

[0089]

[0090] Among them, d n is the diameter of the microhole on the nth unit cell of the upper panel, t n is the depth of the microhole on the nth unit cell of the upper panel, η is the dynamic viscosity of air, p n is the perforation rate of the nth unit cell of the upper panel, ω is the angular frequency of sound, and ρ0 is the density of air;

[0091] The acoustic impedance of a unit cell is calculated as follows:

[0092]

[0093] Wherein, ρ0 is the air density, c0 is the speed of sound in the air, k is the wave number of the sound wave, D is the ratio of the cavity volume of the unit cell to the area of ​​the arc surface of the arc structure on the lower side of the upper panel in the unit cell, and Z Mn is the acoustic impedance of the micropore;

[0094] The overall acoustic impedance of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption function is calculated as follows:

[0095]

[0096] Among them, Z is the overall acoustic impedance of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption function, Z n is the acoustic impedance of the nth unit cell of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption function, ω n is the width of the nth unit cell of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption functions, A is the overall width of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption functions, the width of the unit cell refers to the farthest distance between the two middle support plates in the unit cell, and the overall width of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption functions refers to the length of the upper panel along the extension direction of the unit cell;

[0097] The sound absorption coefficient of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption function is calculated as follows:

[0098]

[0099] Among them, Z is the overall acoustic impedance of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption functions, ρ0 is the air density, and c0 is the speed of sound in the air;

[0100] S3: Based on the geometric parameters obtained in step S2, a low-frequency, broadband, multifunctional corrugated sandwich structure is manufactured.

[0101] The calculation formula of the unit cell structure is given in step S2, which is intended to explain why the geometric factors of the micropores are related to the sound absorption coefficient. Based on the calculation formula of the unit cell structure, a coupling operation is performed to obtain the sound absorption coefficient of the overall structure. In the present invention, the sound absorption coefficient is calculated using the weak resonance coherent coupling theory, and the specific calculation formula is shown above. In this embodiment, a reinforcement learning algorithm is used in Matlab to generate an overall model and calculate the sound absorption coefficient of the overall model. In step S1, meeting the requirements refers to achieving the required sound absorption frequency band and sound absorption coefficient, and the calculation principle of the sound absorption coefficient has been given in S2. In step S1, continuous correction refers to the training of the reinforcement learning algorithm. In step S2, the preset sound absorption coefficient threshold is 0.9.

[0102] In this embodiment, the overall thickness of the structure is 3.64 cm, the thickness of the upper panel at both ends of the arc structure is 1 mm, the thickness of the upper panel at the midpoint of the arc structure is 3 mm, the arc is a parabola, the thickness of the corrugated core plate is 1 mm, the thickness of the corrugated core layer is 34.4 mm, and the thickness of the lower panel is 1 mm, wherein the length and width of the structure are both 9.65 cm. The arch height of the upper panel is 3 mm. The threshold value of the sound absorption coefficient in this embodiment is 0.9. This embodiment can now achieve a sound absorption of an average sound absorption coefficient of 0.93 at 567-758 Hz.

[0103] This application verifies the sound absorption performance of the designed low-frequency broadband multifunctional corrugated sandwich structure through simulation and experiment. Figure 2 As shown in Figure 1, it is an experimental sample manufactured using 3D printing. Figure 3 As shown in the figure, it is a comparison of theory, simulation and experiment. It can be seen from the figure that the structure can achieve a quasi-perfect sound absorption. Figure 4 As shown, it is a theoretical and experimental comparison diagram of the relative acoustic impedance of the structure. The dark color is the acoustic reactance and the light color is the acoustic resistance, which further illustrates the accuracy of the sound absorption effect of the structure and achieves the original design purpose.

[0104] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A corrugated sandwich structure with both mechanical bearing and low broadband sound absorption function, characterized in that: It includes an upper panel, a lower panel and a corrugated core layer arranged between the upper panel and the lower panel. The corrugated core layer is a corrugated structure formed by a plurality of intermediate support plates, and the upper and lower ends of each intermediate support plate are connected to the upper panel and the lower panel; The upper panel is provided with micro-holes to form a meta-structure surface. An arc structure is arranged on the lower side of the upper panel, and a complete arc structure is located between two adjacent middle support plates of the corrugated core layer.

2. The corrugated sandwich structure with both mechanical bearing and low broadband sound absorption function according to claim 1, characterized in that: The corrugated core layer is periodically arranged between the upper panel and the lower panel, the top of the corrugated core layer is fixedly connected to the lower surface of the upper panel, and the bottom of the corrugated core layer is fixedly connected to the upper surface of the lower panel.

3. The corrugated sandwich structure with both mechanical bearing and low broadband sound absorption function according to claim 1, characterized in that: The middle support plate constituting the corrugated core layer is selected to be a flat plate or an arc-shaped plate with a curved surface.

4. The corrugated sandwich structure with both mechanical bearing and low broadband sound absorption function according to claim 1, characterized in that: All the intermediate support plates constituting the corrugated core layer are an integral structure.

5. The corrugated sandwich structure with both mechanical bearing and low broadband sound absorption function according to claim 1, characterized in that: The upper panel, the lower panel and the corrugated core layer are an integrally formed structure and are made of the same material.

6. The corrugated sandwich structure with both mechanical bearing and low broadband sound absorption function according to claim 1, characterized in that: The micro-holes provided on the upper panel are through holes. The diameter, depth and number of the micro-holes provided on the upper panel have the following relationship with the sound absorption coefficient: The acoustic impedance of the micropore is calculated as follows: Among them, d n is the diameter of the microhole on the nth unit cell of the upper panel, t n is the depth of the microhole on the nth unit cell of the upper panel, η is the dynamic viscosity of air, p n is the perforation rate of the nth unit cell of the upper panel, ω is the angular frequency of sound, ρ0 is the density of air, and the unit cell refers to a unit consisting of two adjacent middle support plates of the corrugated core layer and an upper panel with a complete arc structure located between the two adjacent middle support plates of the corrugated core layer; The acoustic impedance of a unit cell is calculated as follows: Wherein, ρ0 is the air density, c0 is the speed of sound in the air, k is the wave number of the sound wave, D is the ratio of the cavity volume of the unit cell to the area of ​​the arc surface of the arc structure on the lower side of the upper panel in the unit cell, and Z Mn is the acoustic impedance of the micropore; The overall acoustic impedance of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption function is calculated as follows: Among them, Z is the overall acoustic impedance of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption function, Z n is the acoustic impedance of the nth unit cell of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption function, ω n is the width of the nth unit cell of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption functions, A is the overall width of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption functions, the width of the unit cell refers to the farthest distance between the two middle support plates in the unit cell, and the overall width of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption functions refers to the length of the upper panel along the extension direction of the unit cell; The sound absorption coefficient of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption function is calculated as follows: Among them, Z is the overall acoustic impedance of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption functions, ρ0 is the air density, and c0 is the speed of sound in the air.

7. The corrugated sandwich structure with both mechanical bearing and low broadband sound absorption function according to claim 1, characterized in that: The thickness of the corrugated sandwich structure is a sub-wavelength thickness, and the thickness of the corrugated sandwich structure is the overall thickness including the upper panel, the lower panel and the corrugated core layer.

8. The corrugated sandwich structure with both mechanical bearing and low broadband sound absorption function according to claim 7, characterized in that: The thickness of the upper panel at both ends of the arc structure is 1mm, the thickness of the upper panel at the midpoint of the arc structure is 3mm, the arc is a parabola, the thickness of the corrugated core board is 1mm, the thickness of the corrugated core layer is 34.4mm, and the thickness of the lower panel is 1mm.

9. The design method of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption function as claimed in claim 1, characterized in that: The design method for obtaining the corrugated sandwich structure having both mechanical bearing and low broadband sound absorption function comprises the following steps: S1: Obtain the overall thickness of the corrugated sandwich structure and generate an overall model, wherein the overall model includes an upper panel and its micropores, a lower panel and a corrugated core layer, wherein the arc structure arch height and the diameter, position and number of the micropores of the upper panel are finally determined by calculation in step S2 and continuously modified to meet the requirements; S2: The diameter, position and number of the micropores of the upper panel are adapted to the frequency band of the sound to be absorbed, and the sound absorption coefficient of the overall model at each frequency under various parameters is calculated to obtain the working frequency band of the overall model. The sound absorption coefficient of the overall model in the working frequency band is not less than the sound absorption coefficient threshold of the preset value; The acoustic impedance of the microhole is calculated as follows: Among them, d n is the diameter of the microhole on the nth unit cell of the upper panel, t n is the depth of the microhole on the nth unit cell of the upper panel, η is the dynamic viscosity of air, p n is the perforation rate of the nth unit cell of the upper panel, ω is the angular frequency of sound, and ρ0 is the density of air; The acoustic impedance of a unit cell is calculated as follows: Wherein, ρ0 is the air density, c0 is the speed of sound in the air, k is the wave number of the sound wave, D is the ratio of the cavity volume of the unit cell to the area of ​​the arc surface of the arc structure on the lower side of the upper panel in the unit cell, and Z Mn is the acoustic impedance of the micropore; The overall acoustic impedance of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption function is calculated as follows: Among them, Z is the overall acoustic impedance of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption function, Z n is the acoustic impedance of the nth unit cell of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption function, ω n is the width of the nth unit cell of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption functions, A is the overall width of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption functions, the width of the unit cell refers to the farthest distance between the two middle support plates in the unit cell, and the overall width of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption functions refers to the length of the upper panel along the extension direction of the unit cell; The sound absorption coefficient of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption function is calculated as follows: Among them, Z is the overall acoustic impedance of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption functions, ρ0 is the air density, and c0 is the speed of sound in the air; S3: Based on the geometric parameters obtained in step S2, a low-frequency, broadband, multifunctional corrugated sandwich structure is manufactured.

10. The design method of the corrugated sandwich structure with both mechanical bearing and low broadband sound absorption function according to claim 9, characterized in that: In step S2, the preset sound absorption coefficient threshold is 0.9.

Images