A phononic crystal vibration damping wall and method

Abstract

This invention discloses a phonon crystal vibration-damping wall and method, belonging to the technical field of vibration-damping walls. It includes a wall with phonon crystal units arranged in an array along the height of the wall. Each phonon crystal unit comprises multiple phonon crystal cells, which are spaced apart along the length of the wall. Both ends of each phonon crystal cell extend beyond the outer side of the wall and are horizontally arranged along the width of the wall, with a minimum spacing of 20 mm between adjacent phonon crystal cells. This method effectively controls mid-to-low frequency broadband noise, effectively reducing low-frequency vibration and noise caused by pipes, equipment, etc., and solving the problem of ineffective vibration reduction of mid-to-low frequency noise.

Description

Technical Field

[0001] This invention relates to the field of vibration damping wall technology, and more particularly to a phonon crystal vibration damping wall and method. Background Technology

[0002] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art.

[0003] Noise is mainly low-frequency noise generated by mechanical vibration. Compared with high-frequency noise, low-frequency noise has a longer wavelength and attenuates very slowly in the air, making it easy to pass through obstacles. Therefore, in current engineering applications, common materials and structures can play a good role in isolating and absorbing high-frequency noise, but the isolation effect on low-frequency noise is not very obvious. Therefore, it is often necessary to adopt a combination of methods to control low-frequency noise, which not only greatly increases the technical cost, but also consumes a lot of time and effort.

[0004] For the isolation and absorption of low-frequency noise, due to the inherent physical properties of traditional materials and the numerous limitations in practical engineering applications, artificial composite materials with special physical properties have become the focus of attention and have experienced rapid development in recent years.

[0005] Acoustic metamaterials, as opposed to electromagnetic metamaterials, are most typically characterized by subwavelength dimensions and anomalous dynamic equivalent parameters, such as negative equivalent density and negative bulk modulus, and highly anisotropic density. When sound waves propagate in such structures, they are modulated by the structure, thus affecting the propagation of the sound waves. This enables unique acoustic properties such as acoustic cloaks, acoustic imaging, negative refraction and reflection of sound waves, unidirectional transmission of sound waves, and acoustic focusing.

[0006] Currently, the application of acoustic metamaterials is mainly in the high-frequency range above 1000Hz. Effective control of noise in the mid-to-low frequency range cannot be achieved, especially noise control in the low-frequency range, which is still very difficult.

[0007] Furthermore, existing technologies rarely apply acoustic metamaterials to wall designs, focusing primarily on vibration reduction; moreover, they mainly target vibration reduction at mid-to-high frequencies. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the purpose of this invention is to provide a phonon crystal vibration-damping wall and method, which can effectively reduce wall vibration and noise problems caused by vibrations from pipes, equipment, etc.

[0009] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0010] A phononic crystal vibration damping wall includes a wall, wherein phononic crystal units are disposed within the wall and arranged in an array along the height direction of the wall; each phononic crystal unit includes multiple phononic crystal cells, which are spaced apart along the length direction of the wall.

[0011] The two ends of the phononic crystal unit cell both pass through the outer side of the wall and are horizontally arranged along the width direction of the wall.

[0012] Furthermore, the phononic crystal unit cell includes a central axis, a rubber ring, and a preload screw;

[0013] A limiting device is fitted in the middle of the central shaft, and the limiting device has limiting grooves on both sides along the length of the central shaft; the rubber ring is fitted on the central shaft and is located inside the limiting groove; additional mass units are fitted at both ends of the central shaft, and pre-tightening washers are provided on both sides of the additional mass units, and the pre-tightening screw passes through the pre-tightening washers and is fixed to the end of the central shaft.

[0014] Preferably, the limiting device is made of concrete, and the cross-section of the limiting device along the circumferential direction is quadrilateral or hexagonal.

[0015] Preferably, the additional mass unit is a ring structure made of metal.

[0016] Furthermore, the wall has an H-shaped structure.

[0017] Furthermore, the distance from the outer diameter of the rubber ring to the edge of the limiting device is at least 10 mm.

[0018] This invention also provides a method for preparing a phonon crystal vibration damping wall, which, based on the aforementioned phonon crystal vibration damping wall, includes the following steps:

[0019] The shape of the phononic crystal unit cell is determined based on the compactness of the spatial structure.

[0020] Determine the size of the phononic crystal unit cell based on the target vibration reduction frequency;

[0021] Based on the size and shape of the phononic crystal unit cell, determine the structural parameters of the phononic crystal unit cell and manufacture it;

[0022] Multiple phononic crystal unit cells are installed in the wall to form a phononic crystal vibration damping wall.

[0023] Furthermore, determining the size of the phononic crystal unit cell based on the target vibration reduction frequency includes:

[0024] Based on Bloch's theorem, the band structure of a phononic crystal unit cell is obtained;

[0025] Based on the band structure of the phononic crystal unit cell, the internal dimensions of the phononic crystal unit cell are assumed, and the band structure of the phononic crystal unit cell is obtained by physical field coupling analysis finite element software, thereby obtaining the corresponding band gap generation location and band gap width.

[0026] Using physical field coupling analysis finite element software, the internal geometric dimensions and material parameters of the phononic crystal unit cell are adjusted so that the target vibration reduction frequency is enveloped by the band gap.

[0027] Furthermore, a gap is provided between the edge of the wall and the phonon crystal unit cell, and the gap is filled with concrete, the thickness of which is at least 100 mm.

[0028] Furthermore, the phononic crystal unit cell is a hexagonal phononic crystal unit cell.

[0029] One or more technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:

[0030] 1. The technical solution provided by this invention can effectively reduce the low-frequency vibration and noise problems of walls caused by the vibration of pipes, equipment, etc. Compared with blank walls, the vibration of the phonon crystal damping wall can achieve an attenuation of more than 4dB in the plane and an attenuation of more than 15dB out of the plane near the target frequency. Attached Figure Description

[0031] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0032] Figure 1 This is a schematic diagram of the structure of a phononic crystal unit cell provided in an embodiment of the present invention;

[0033] Figure 2 This is a schematic diagram of the structure of a quadrilateral phononic crystal unit cell provided in an embodiment of the present invention;

[0034] Figure 3 This is a schematic diagram of the structure of a hexagonal phononic crystal unit cell provided in an embodiment of the present invention;

[0035] Figure 4 This is a schematic diagram of the phonon crystal vibration damping wall provided in an embodiment of the present invention;

[0036] Figure 5 This is a cross-sectional schematic diagram of the phonon crystal vibration damping wall provided in an embodiment of the present invention;

[0037] Figure 6 This is a schematic diagram of the device connection for the vibration transmission characteristics of a phononic crystal finite periodic structure provided in an embodiment of the present invention;

[0038] In the diagram: 1. Limiting device; 2. Preload washer; 3. Preload screw; 4. Rubber ring; 5. Central shaft; 6. Additional mass unit.

[0039] The distances or dimensions between parts have been exaggerated to show their positions; the diagram is for illustrative purposes only. Detailed Implementation

[0040] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0041] Example 1

[0042] As described in the background section, existing wall systems cannot address the low-frequency vibrations and noise caused by vibrations from pipes, equipment, etc. In order to solve the above-mentioned technical problems, this invention proposes a phonon crystal vibration-damping wall system.

[0043] Combination Figures 1-5 This embodiment describes a phonon crystal vibration damping wall, which includes a wall with an H-shaped structure, such as... Figure 4 , Figure 5 As shown, the wall is equipped with 7 phonon crystal units, which are arranged in an array along the height of the wall and located in the horizontal part of the H-shaped structure. Each phonon crystal unit includes 6 phonon crystal cells, which are distributed at intervals along the length of the wall. The two ends of each phonon crystal cell pass through the outside of the wall and are arranged horizontally along the width of the wall.

[0044] In this embodiment, the space between the phononic crystal unit cell and the wall is not filled with a single metamaterial, which ensures the stability of the wall structure while achieving low-frequency vibration reduction.

[0045] Furthermore, such as Figure 1 As shown, the phononic crystal unit cell includes a central axis, a rubber ring, and a preload screw; a limiting device is fitted in the middle of the central axis, and limiting grooves are opened on both sides of the limiting device along the length of the central axis; the rubber ring is fitted on the central axis and is located inside the limiting groove; additional mass units are fitted at both ends of the central axis, and preload washers are fitted on both sides of the additional mass units, and the preload screw passes through the preload washers and is fixed to the end of the central axis.

[0046] The limiting device is made of concrete, and its circumferential cross-section is quadrilateral or hexagonal. Quadrilateral phononic crystal unit cells have a simple structure, are easy to manufacture, and have a low cost. However, due to their geometric relationship, they are not as spatially compact as hexagonal phononic crystal unit cells, and stress concentration is prone to occur at corners, thus affecting the load-bearing capacity of the structure. Therefore, in this embodiment, the limiting device has a hexagonal cross-section.

[0047] To make the rubber more easily deformable, a limiting device made of concrete restricts the circumferential movement of the rubber ring, while the axial grooves facilitate the axial deformation of the rubber, thereby controlling the direction of deformation of the rubber ring and thus controlling the direction of vibration.

[0048] The additional mass unit is used to control the frequency of vibration, and the central axis is used to connect two additional mass units and limit their positions. The additional mass units are limited by preload washers and preload screws to ensure the structural stability of the phononic crystal unit cell.

[0049] In this embodiment, the additional mass unit is a ring structure made of metal; the distance between the rubber rings of two adjacent phononic crystals is at least 10mm, that is, the minimum thickness of the limiting device is 10mm, so that the concrete between the unit cells can be connected and have a certain load-bearing capacity.

[0050] The wall is 800mm long, 800mm wide, and 200mm thick. The height of the hexagonal cross-section of the limiting device is 120mm. The outer diameter of the rubber ring is 94mm, the thickness of the rubber ring is 30mm, and the diameter of the central axis is 68mm.

[0051] The phononic crystal unit cell structure has a band gap from 180Hz to 200Hz, with a width of 20Hz, which includes vibrations at the desired 190Hz frequency point.

[0052] Example 2

[0053] This embodiment discloses a method for preparing a phonon crystal vibration damping wall, based on the phonon crystal vibration damping wall described in Embodiment 1, including the following steps:

[0054] S1. Determine the shape of the phononic crystal unit cell based on the compactness of the spatial structure.

[0055] For example, the shape of the phononic crystal unit cell here is the cross-sectional shape of the limiting device. The quadrilateral unit cell structure is simple, easy to manufacture and has a low cost, but due to its own geometric relationship, its spatial compactness is not as good as that of the hexagonal unit cell, and stress concentration is prone to occur at the corners, thus affecting the load-bearing capacity of the structure; therefore, in this embodiment, the shape of the phononic crystal unit cell is hexagonal.

[0056] S2. Determine the size of the phononic crystal unit cell based on the target vibration reduction frequency; determine the structural parameters of the phononic crystal unit cell based on its size and shape, and then manufacture it.

[0057] Specifically, it includes:

[0058] S201. Based on Bloch's theorem, obtain the band structure of a phononic crystal unit cell.

[0059] S202. Based on the band structure of the phononic crystal unit cell, assume the internal dimensions of the phononic crystal unit cell, and use physical field coupling analysis finite element software to calculate the band structure of the phononic crystal unit cell, thereby obtaining the corresponding band gap generation location and band gap width.

[0060] S203. Using physical field coupling analysis finite element software, adjust the internal geometric dimensions and material parameters of the phononic crystal unit cell so that the target vibration reduction frequency is enveloped by the band gap.

[0061] S204. Fabricate phononic crystal units according to the internal geometric dimensions and material parameters of the phononic crystal unit cell.

[0062] For example, as a periodic structure, the elastic wave equation of a phononic crystal also obeys Bloch's theorem. Therefore, based on Bloch's theorem, the band gap of a phononic crystal can be calculated using the planar expansion method.

[0063] Specifically, by expanding the periodic elastic parameters and wave functions in the reciprocal lattice space and substituting them into the wave equation, and taking a finite number of plane waves, the wave equation is expanded into a generalized eigenvalue equation relating the eigenfrequency w and the Bloch wave vector k. By traversing the reciprocal lattice space and taking values ​​for k, all the eigenfrequency of the phononic crystal, i.e., the band structure, can be obtained.

[0064] By empirically assuming the internal dimensions of the phononic crystal and using physical field coupling analysis finite element software to calculate the band structure of the phononic crystal unit cell, the location and width of the band gap (i.e. the frequency range where vibration reduction is more effective) are obtained.

[0065] In finite element software for physical field coupling analysis, by repeatedly adjusting the internal geometric dimensions and material parameters of the phononic crystal to make the target vibration reduction frequency enveloped by the band gap, and outputting the corresponding geometric dimensions and material parameters, the key frequency can be controlled.

[0066] For example, the finite element software for physical field coupling analysis is Comsol Multiphysics, a large-scale advanced numerical simulation software. In Comsol Multiphysics, a computational model of a unit cell is established, and free tetrahedral elements are used for mesh generation. The shape functions are determined according to the general finite element method steps, the stiffness matrix and mass matrix within the unit cell are established, and Bloch periodic boundary conditions are applied at the boundaries.

[0067] In Comsol Multiphysics software, by selecting the Eigenvalue solver and specifying a value for k, a set of structural eigenfrequency can be obtained. As mentioned earlier, when the wave vector k traverses the reduced Brillouin zone boundary along the Γ-XM-Γ direction, a complete dispersion relation between the wave vector and the eigenfrequency can be obtained, i.e., the band structure diagram.

[0068] In this embodiment, the final dimensions of the phononic crystal unit cell structure are as follows: the height of the hexagonal cross-section of the limiting device is 120 mm, the outer diameter of the rubber ring is 94 mm, the thickness of the rubber ring is 30 mm, and the diameter of the central axis is 68 mm. The phononic crystal unit cell structure has a bandgap from 180 Hz to 200 Hz, a width of 20 Hz, and includes the vibration at the required 190 Hz frequency point.

[0069] S3. Install multiple phononic crystal unit cells inside the wall to form a phononic crystal vibration damping wall.

[0070] In this embodiment, the wall is 800mm long and 800mm wide, and 200mm thick.

[0071] To maximize the vibration damping performance of the phonon crystal structure, it is designed as a partition wall structure during installation, such as... Figure 4 and Figure 5 As shown. To ensure the wall's load-bearing capacity, at least 100mm of excess concrete should be reserved at the top, bottom, left, and right edges of the wall. To save installation space, phonon crystal unit cells are installed inside the wall, forming an embedded wall.

[0072] Next, combined Figure 6 In order to quantitatively evaluate the wave propagation suppression capability and sound radiation suppression capability of phononic crystal vibration damping wall, the phononic crystal finite periodic structure is used to perform end-face excitation and center excitation on the phononic crystal vibration damping wall. End-face excitation, also known as end-face vibration pickup, is used to calculate the frequency response function, while center excitation wall method is used to calculate the test vibration response.

[0073] Final implementation results: In-plane test results showed a 4 dB reduction in vibration relative to a blank wall at 190 Hz; out-of-plane vibration suppression capability showed a reduction of approximately 15 dB in vibration relative to a blank wall at 190 Hz.

[0074] The list of equipment and parameters used in the experiment are detailed in Tables 1 to 3:

[0075]

[0076] Table 2 Technical parameters of the vibrator

[0077]

[0078] Table 3 Accelerometer Technical Parameters

[0079]

[0080] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A phononic crystal vibration damping wall, characterized by, The system includes a wall, which is provided with phononic crystal units arranged in an array along the height direction of the wall; each phononic crystal unit includes multiple phononic crystal cells, which are spaced apart along the length direction of the wall. The two ends of the phononic crystal unit cell both pass through the outer side of the wall and are horizontally arranged along the width direction of the wall; The phononic crystal unit cell includes a central axis, a rubber ring, and a preload screw; A limiting device is fitted in the middle of the central shaft, and the limiting device has limiting grooves on both sides along the length of the central shaft; the rubber ring is fitted on the central shaft and is located inside the limiting groove; additional mass units are fitted at both ends of the central shaft, and pre-tightening washers are provided on both sides of the additional mass units, and the pre-tightening screw passes through the pre-tightening washers and is fixed to the end of the central shaft.

2. The phononic crystal vibration damping wall of claim 1, wherein, The limiting device is made of concrete, and the cross-section of the limiting device along the circumference is quadrilateral or hexagonal.

3. The phononic crystal vibration damping wall of claim 1, wherein, The additional mass unit is a ring structure made of metal.

4. The phononic crystal vibration damping wall of claim 1, wherein, The wall has an H-shaped structure.

5. The phonon crystal vibration damping wall as described in claim 1, characterized in that, The distance from the outer diameter of the rubber ring to the edge of the limiting device is at least 10 mm.

6. A method for preparing a phonon crystal vibration damping wall, characterized in that, The phonon crystal vibration damping wall according to any one of claims 1-5 includes the following steps: The shape of the phononic crystal unit cell is determined based on the compactness of the spatial structure. Determine the size of the phononic crystal unit cell based on the target vibration reduction frequency; Based on the size and shape of the phononic crystal unit cell, determine the structural parameters of the phononic crystal unit cell and manufacture it; Multiple phononic crystal unit cells are installed in the wall to form a phononic crystal vibration damping wall.

7. The phononic crystal vibration damping wall production method according to claim 6, wherein Determining the size of the phononic crystal unit cell based on the target vibration reduction frequency includes: Based on Bloch's theorem, the band structure of a phononic crystal unit cell is obtained; Based on the band structure of the phononic crystal unit cell, the internal dimensions of the phononic crystal unit cell are assumed, and the band structure of the phononic crystal unit cell is obtained by physical field coupling analysis finite element software, thereby obtaining the corresponding band gap generation location and band gap width. Using physical field coupling analysis finite element software, the internal geometric dimensions and material parameters of the phononic crystal unit cell are adjusted so that the target vibration reduction frequency is enveloped by the band gap.

8. The phononic crystal vibration damping wall production method according to claim 6, wherein A gap is provided between the edge of the wall and the phonon crystal unit cell, and the gap is filled with concrete with a thickness of at least 100 mm.

9. The phononic crystal vibration damping wall production method according to claim 6, wherein The phononic crystal unit cell is a hexagonal phononic crystal unit cell.

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