A semi-opened piano type low-wide frequency high-efficient underwater sound absorption structure

Abstract

The application discloses a semi-opened piano type low-wide-frequency high-efficiency underwater sound absorption structure, and belongs to the technical field of mechanical vibration and noise control. In order to solve the problems that the traditional underwater sound absorption structure cannot realize low-wide-frequency high-efficiency absorption of sound waves and has relatively poor sound absorption performance in a complex marine environment, the sound absorption structure comprises a plurality of sound absorption single cell units, the plurality of sound absorption single cell units are sequentially and equidistantly arranged along the length extension direction of the sound absorption structure, the sound absorption single cell unit comprises a bottom plate, N longitudinal steel plates and N-1 sound absorption assemblies, N is a positive integer, the N longitudinal steel plates are sequentially and equidistantly arranged on the upper surface of the bottom plate along the length extension direction of the bottom plate, the bottom of each longitudinal steel plate is fixedly connected with the upper surface of the bottom plate, a sound absorption assembly arrangement area is formed between the adjacent two longitudinal steel plates, each sound absorption assembly is arranged in a sound absorption assembly arrangement area in correspondence, and each sound absorption assembly is fixedly connected with the adjacent longitudinal steel plate. The application is used for the sound absorption structure in an underwater working device.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of mechanical vibration and noise control, and particularly relates to a semi-opened piano type low-wide frequency high-efficiency underwater sound absorption structure. BACKGROUND

[0002] With the continuous development of underwater science and technology in China, underwater sound absorption structures have been widely concerned. Compared with sound absorption structures in air medium, underwater sound absorption structures will be affected by a series of complex marine environments. At present, the main problem of underwater sound absorption materials is poor sound absorption performance in low frequency and wide frequency range. The traditional underwater sound absorption structure filled with rubber mainly converts sound energy into heat energy or other forms of energy through the internal friction mechanism and interface energy dissipation mechanism of rubber material. However, the limited thickness of underwater sound absorption structure cannot realize low-wide frequency high-efficiency absorption of sound waves. Moreover, due to the complex marine environment, the sound absorption performance of the traditional underwater sound absorption structure filled with rubber will be poor. Starting from the actual application demand of underwater sound absorption, higher requirements are put forward for the sound absorption performance of underwater sound absorption structure. First, the acoustic impedance of underwater sound absorption structure needs to be matched with the characteristic impedance of water, so that the incident sound wave energy can be efficiently entered into the underwater sound absorption structure to realize the first step of sound absorption process. Second, the underwater sound absorption structure needs to have an effective sound absorption mechanism inside, so that the entering sound wave energy can be effectively absorbed to reduce the sound reflection at the interface of the underwater sound absorption structure. In addition, the underwater sound absorption material also needs to have properties such as pressure resistance, corrosion resistance and low temperature resistance. Therefore, it is very practical to develop a semi-opened piano type low-wide frequency high-efficiency underwater sound absorption structure based on the above requirements. SUMMARY

[0003] The present application is to solve the problem that the traditional underwater sound absorption structure cannot realize low-wide frequency high-efficiency absorption of sound waves and has relatively poor sound absorption performance in complex marine environment, and further provides a semi-opened piano type low-wide frequency high-efficiency underwater sound absorption structure.

[0004] A semi-opened piano type low-wide frequency high-efficiency underwater sound absorption structure, the sound absorption structure comprises a plurality of sound absorption single cell units, the plurality of sound absorption single cell units are sequentially and equidistantly arranged along the length extension direction of the sound absorption structure, and the adjacent two sound absorption single cell units are fixedly connected.

[0005] The sound absorption single cell unit comprises a bottom plate, N longitudinal steel plates and N-1 sound absorption assemblies, N is a positive integer, the N longitudinal steel plates are sequentially and equidistantly arranged on the upper surface of the bottom plate along the length extension direction of the bottom plate, and the bottom of each longitudinal steel plate is fixedly connected with the upper surface of the bottom plate, the adjacent two longitudinal steel plates form a sound absorption assembly placement area, each sound absorption assembly is correspondingly arranged in one sound absorption assembly placement area, and each sound absorption assembly is fixedly connected with the adjacent longitudinal steel plate.

[0006] The sound absorption assembly comprises a first damping layer and a second damping block, the first damping layer is arranged at the top opening of the sound absorption assembly placement area, and the two sides of the first damping layer are fixedly connected with the adjacent longitudinal steel plates respectively, the second damping block is arranged below the first damping layer, and the two sides of the second damping block are fixedly connected with the adjacent longitudinal steel plates respectively;

[0007] The first damping layer comprises two first damping blocks, the two first damping blocks are oppositely arranged along the center line of the width direction of the sound absorption assembly placement area, and a micro gap is arranged between the two first damping blocks, and each first damping block is fixedly connected with the adjacent longitudinal steel plate;

[0008] Further, a water cavity is arranged between the first damping layer and the second damping block, and the top of the water cavity is in communication with the bottom of the micro gap;

[0009] Further, an air cavity is arranged between the second damping block and the bottom plate;

[0010] Further, the material of the first damping block is rubber, and the material of the second damping block is the same as that of the first damping block;

[0011] Further, the height of the water cavity is the same as the height of the air cavity;

[0012] Further, when the N-1 sound absorption assemblies are arranged, the thicknesses of the N-1 first damping layers are sequentially and equidistantly increased, the thicknesses of the N-1 second damping blocks are sequentially and equidistantly decreased, and the increasing distance between the adjacent two first damping layers is equal to the decreasing distance between the adjacent two second damping blocks;

[0013] Further, the slitting rate of the micro gap is 5%;

[0014] Further, the decreasing distance between the adjacent two second damping blocks is equal to the height of the second damping block multiplied by 1 / (N-1).

[0015] The beneficial effects of the present application relative to the prior art are:

[0016] The application fills multiple layers of rubber, air cavities and naturally filled water cavities between steel plates to form a semi-opened piano type underwater sound absorption structure with low broadband high efficiency underwater sound absorption characteristics. The application adopts damping blocks made of rubber material, and makes the damping blocks tightly connected with the steel plates. Due to the vibration discordance between the steel plates and the rubber, the shear strain of the rubber near the steel plates is increased, so that the sound wave energy is dissipated. The application introduces water cavities in communication with the outside water to make the incident sound wave energy efficiently enter the underwater sound absorption structure to realize the first link of the sound absorption process. The air cavities are filled to make the bottom boundary condition of the rubber free, improve the deformation ability of the rubber, and thus improve the sound absorption performance. Compared with the traditional underwater sound absorption structure filled with rubber, the application has excellent low frequency sound absorption performance, a wider frequency range, and stronger adaptability to complex underwater working conditions, and has wide application and promotion;

[0017] The application adopts a semi-opened structure, part of the internal structure of the application is in communication with the outside water area, so that the incident sound wave energy can enter the opened area of the underwater sound absorption structure to realize multi-stage consumption of the incident sound wave energy.

[0018] Compared with the traditional underwater sound absorption structure filled with rubber, the application can obtain a larger underwater sound absorption frequency range while keeping the overall size and thickness small. Based on the sound absorption coefficient 0.8, the starting sound absorption frequency of the application is as low as 1 / 7.5 of the starting sound absorption frequency of the traditional rubber filled underwater sound absorption structure, and the application has outstanding low frequency underwater sound absorption performance.

[0019] The sound absorption coefficient of the application at the starting sound absorption frequency is 4 times the sound absorption coefficient of the traditional rubber filled underwater sound absorption structure, and the application realizes high efficiency absorption of low frequency underwater incident sound waves. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is an axial side view of the sound absorption structure described in the application;

[0021] Figure 2 It is a front view of a sound absorption unit structure in the sound absorption structure described in the application;

[0022] Figure 3 It is a front view of a sound absorption unit structure in the sound absorption structure described in the application

[0023] Figure 4 It is a side view of the sound absorption unit structure described in the application;

[0024] Figure 5 It is a top view of the sound absorption unit structure described in the application;

[0025] Figure 6 It is a front view of the sound absorption unit structure described in the application;

[0026] Figure 7 Figure 2 is a comparison chart of the sound absorption coefficient curves of the underwater sound absorption structure of the traditional filled damping material and the underwater sound absorption structure described in the present application;

[0027] Figure 1 is a bottom plate, 2 is a longitudinal steel plate, 3 is a first damping layer, 4 is a micro gap, 5 is a water cavity, 6 is a second damping block, and 7 is an air cavity. DETAILED DESCRIPTION

[0028] Specific implementation one: in combination Figures 1 to 7 In this embodiment, a semi-open piano type low wide frequency high efficiency underwater sound absorption structure is provided, which includes a plurality of sound absorption single cell units, the plurality of sound absorption single cell units are sequentially and equidistantly arranged along the length extension direction of the sound absorption structure, and the adjacent two sound absorption single cell units are fixedly connected, the sound absorption single cell unit includes a bottom plate 1, N longitudinal steel plates 2 and N-1 sound absorption assemblies, N is a positive integer, the N longitudinal steel plates 2 are sequentially and equidistantly arranged on the upper surface of the bottom plate 1 along the length extension direction of the bottom plate 1, and the bottom of each longitudinal steel plate 2 is fixedly connected with the upper surface of the bottom plate 1, the sound absorption assembly arrangement area is formed between the adjacent two longitudinal steel plates 2, each sound absorption assembly is arranged in one sound absorption assembly arrangement area, and each sound absorption assembly is fixedly connected with the adjacent longitudinal steel plate 2;

[0029] The sound absorption assembly includes a first damping layer 3 and a second damping block 6, the first damping layer 3 is arranged at the top opening of the sound absorption assembly arrangement area, and the two sides of the first damping layer 3 are fixedly connected with the adjacent longitudinal steel plate 2 respectively, the second damping block 6 is arranged below the first damping layer 3, and the two sides of the second damping block 6 are fixedly connected with the adjacent longitudinal steel plate 2 respectively;

[0030] The first damping layer 3 includes two first damping blocks, the two first damping blocks are oppositely arranged along the center line of the sound absorption assembly arrangement area in the width direction, and a micro gap 4 is arranged between the two first damping blocks, and each first damping block is fixedly connected with the adjacent longitudinal steel plate 2.

[0031] The purpose of the semi-open piano type low wide frequency high efficiency underwater sound absorption structure provided in this embodiment is to absorb the detection wave of the active sonar and suppress the echo and vibration sound response, so as to realize the stealth of the underwater mobile equipment, which is generally fixed on the outer surface of the underwater mobile equipment, in order to ensure the sound absorption performance of the sound absorption structure described in the present application, the plurality of sound absorption single cell structures in the sound absorption structure described in the present application are arranged in a periodic array in the length direction and are infinitely extended in the width direction.

[0032] Specific implementation two: in combination Figures 1 to 7The difference between the embodiment and the first specific embodiment is that the water cavity 5 is arranged between the first damping layer 3 and the second damping block 6, and the top of the water cavity 5 is arranged in communication with the bottom of the micro slit 4. The other components and connection modes are the same as those in the first specific embodiment.

[0033] The sound absorption structure in the embodiment adopts a semi-open structure, and part of the internal structure of the sound absorption structure is in communication with the external water area, so that the incident sound wave energy can enter the open area in the underwater sound absorption structure, and multi-stage consumption of the incident sound wave energy is realized. The micro slit 4 is a channel for the water cavity 5 to communicate with the outside.

[0034] Specific embodiment three: combination Figures 1 to 7 The difference between the embodiment and the second specific embodiment is that the air cavity 7 is arranged between the second damping block 6 and the bottom plate 1. The other components and connection modes are the same as those in the second specific embodiment.

[0035] In the embodiment, the rubber bottom boundary condition is changed to be free by filling the air cavity, the deformation ability of the rubber is improved, and thus the sound absorption performance is improved.

[0036] Specific embodiment four: combination Figures 1 to 7 The difference between the embodiment and the third specific embodiment is that the material of the first damping block is rubber, and the material of the second damping block 6 is the same as that of the first damping block. The other components and connection modes are the same as those in the third specific embodiment.

[0037] In the embodiment, the same material of the first damping block and the second damping block 6 is arranged, which can ensure the uniformity of the vibration of the damping block of the sound absorption structure in use, and avoid the incoordination of the vibration between the steel plate and the rubber in the two damping layers.

[0038] Specific embodiment five: combination Figures 1 to 7 The difference between the embodiment and the fourth specific embodiment is that the height of the water cavity 5 is the same as that of the air cavity 7. The other components and connection modes are the same as those in the fourth specific embodiment.

[0039] Specific embodiment six: combination Figures 1 to 7 The difference between the embodiment and the fifth specific embodiment is that when the N-1 sound absorption assemblies are arranged, the thicknesses of the N-1 first damping layers 3 are sequentially and equidistantly increased, the thicknesses of the N-1 second damping blocks 6 are sequentially and equidistantly decreased, and the increasing distance between the adjacent two first damping layers 3 is equal to the decreasing distance between the adjacent two second damping blocks 6. The other components and connection modes are the same as those in the fifth specific embodiment.

[0040] In this embodiment, the damping layer in each unit cell presents a stepped arrangement by changing the thickness of the first damping layer 3 and the second damping layer 6. The stepped arrangement has the advantage that different thicknesses of the damping layer have good sound absorption effect in different frequency intervals, but each effective sound absorption frequency interval is narrow and the sound absorption effect in other frequency intervals is poor. By arranging the damping layer in steps and connecting the damping layers with different thicknesses in parallel, the problem of narrow sound absorption frequency interval of a single thickness of the damping layer can be solved without significantly reducing the sound absorption coefficient amplitude, achieving wideband and high-efficiency sound absorption.

[0041] Specific embodiment seven: in combination Figures 1 to 7 This embodiment is different from specific embodiment six in that the slitting rate of the micro slit 4 is 5%. The other components and connection modes are the same as those of specific embodiment six.

[0042] In this embodiment, the slitting rate refers to the width of a single slit / the distance between adjacent longitudinal plates, or the total peak width / the total length of the structure. For example, if the distance between adjacent longitudinal plates is 20 mm, the width of the micro slit 4 is 1 mm.

[0043] Specific embodiment eight: in combination Figures 1 to 7 This embodiment is different from specific embodiment seven in that the decreasing distance between the two adjacent second damping blocks 6 is equal to the height of the second damping block 6 multiplied by 1 / N-1. The other components and connection modes are the same as those of specific embodiment seven.

[0044] In this embodiment, the overall thickness of the structure is 60 mm, which is equal to the bottom plate 5 mm plus the cavity 5 mm plus the lower damping layer 5 mm plus the water cavity 5 mm plus the upper damping layer 40 mm. For example, in a single sound absorption unit cell structure, there are seven sound absorption components, and the height of each decreasing part is 5 mm.

[0045] The present application has been disclosed in the above-mentioned preferred embodiments, however, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to the above-mentioned disclosed structure and technical content without departing from the scope of the technical solution of the present application, and equivalent embodiments with equivalent changes can be obtained. However, any simple modification, equivalent change and modification made to the above-mentioned embodiments according to the technical essence of the present application are still within the scope of the technical solution of the present application.

[0046] Working principle

[0047] In use, the components are assembled together according to the connection relationship described in Embodiment 1 to Embodiment 6. In use, the device is located underwater, and the incident plane wave hits the upper surface of the sound absorption structure described in the application. The first damping layer 3 and the micro slit 4 are in parallel relationship, a part of the plane wave enters the water cavity through the micro slit 4, and the other part of the plane wave is effectively dissipated through the first damping layer 3. The undissipated plane wave is transmitted into the water cavity 5. Here, the dissipation mechanism of the first damping layer 3 to the plane wave is that due to the obvious impedance mismatch between the damping layer and the parallel steel plate, the vibration between the two is often not coordinated under the action of sound excitation. Therefore, when the damping layer and the parallel steel plate are well combined, the shear friction force inside each damping material of the damping layer close to the parallel steel plate is significantly enhanced, so that more sound energy can be dissipated. The plane wave entering the water cavity 5 continues to be incident to the second damping layer and is effectively dissipated. Here, the dissipation mechanism of the damping layer to the plane wave is consistent with the dissipation mechanism of the first row of damping layers to the plane wave described above. The back cavity air cavity 7 exists below the second damping layer, and the air cavity can make the bottom boundary condition of the damping layer free, improve the deformation ability of the damping layer, and thus improve the sound absorption performance. However, the lower surface of the bottom steel plate in the application is fixedly connected with the infinite matrix, so the wave speed here can be regarded as 0, and the sound absorption coefficient is A=1-R, R is the reflection coefficient.

Claims

1. A semi-open, piano-shaped, low-bandwidth, high-efficiency underwater sound-absorbing structure, characterized in that: The sound absorption structure comprises a plurality of sound absorption cellular units, which are sequentially and equidistantly arranged along the length extension direction of the sound absorption structure, and two adjacent sound absorption cellular units are fixedly connected; The sound absorption cellular unit comprises a bottom plate (1), N longitudinal steel plates (2) and N-1 sound absorption assemblies, N is a positive integer, the N longitudinal steel plates (2) are sequentially and equidistantly arranged on the upper surface of the bottom plate (1) along the length extension direction of the bottom plate (1), and the bottom of each longitudinal steel plate (2) is fixedly connected with the upper surface of the bottom plate (1), the sound absorption assembly arrangement area is formed between two adjacent longitudinal steel plates (2), each sound absorption assembly is arranged in one sound absorption assembly arrangement area, and each sound absorption assembly is fixedly connected with the adjacent longitudinal steel plate (2); The sound absorption assembly comprises a first damping layer (3) and a second damping block (6), the first damping layer (3) is arranged at the top opening of the sound absorption assembly arrangement area, and the two sides of the first damping layer (3) are fixedly connected with the adjacent longitudinal steel plate (2), the second damping block (6) is arranged below the first damping layer (3), and the two sides of the second damping block (6) are fixedly connected with the adjacent longitudinal steel plate (2); The first damping layer (3) comprises two first damping blocks, the two first damping blocks are oppositely arranged along the center line of the sound absorption assembly arrangement area in the width direction, and a micro gap (4) is arranged between the two first damping blocks, and each first damping block is fixedly connected with the adjacent longitudinal steel plate (2); The water cavity (5) is arranged between the first damping layer (3) and the second damping block (6), and the top of the water cavity (5) is in communication with the bottom of the micro gap (4).

2. A semi-opened lyre-shaped low-wide frequency high-efficient underwater sound absorption structure according to claim 1, characterized in that: The air cavity (7) is arranged between the second damping block (6) and the bottom plate (1).

3. A semi-opened lyre-shaped low-wide frequency high-efficient underwater sound absorption structure according to claim 2, characterized in that: The material of the first damping block is rubber, and the material of the second damping block (6) is the same as that of the first damping block.

4. A semi-opened lyre-shaped low-wide frequency high-efficient underwater sound absorption structure according to claim 3, characterized in that: The height of the water cavity (5) is the same as that of the air cavity (7).

5. A semi-opened lyre-shaped low-wide frequency high-efficient underwater sound absorption structure according to claim 4, characterized in that: When the N-1 sound absorption assemblies are arranged, the thicknesses of the N-1 first damping layers (3) are sequentially and equidistantly increased, the thicknesses of the N-1 second damping blocks (6) are sequentially and equidistantly decreased, and the increasing distance between two adjacent first damping layers (3) is equal to the decreasing distance between two adjacent second damping blocks (6).

6. A semi-opened lyre-shaped low-wide frequency high-efficient underwater sound absorption structure according to claim 5, characterized in that: The slitting rate of the micro gap (4) is 5%.

7. A semi-opened lyre-shaped low-wide frequency high-efficient underwater sound absorption structure according to claim 6, characterized in that: The decreasing distance between two adjacent second damping blocks (6) is equal to the height of the second damping block (6) multiplied by 1 / (N-1).

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