Acoustic metamaterial structure based on local resonance mechanism

Abstract

The invention relates to the field of acoustic metamaterials, and discloses an acoustic metamaterial structure based on a local resonance mechanism, the acoustic metamaterial structure comprises a plurality of metamaterial unit cells, each metamaterial unit cell structure comprises a cylindrical steel core, an inner-layer annular rubber connecting piece, an inner-layer annular steel ring, an outer-layer annular rubber connecting piece, an outer-layer annular steel ring and soil, the whole component is designed to be deeply embedded into soil, the embedded depth of the component corresponds to the height of the outer annular steel ring, the stability and harmony of the structure are ensured, the lower portion of the component penetrates into the soil layer and is tightly combined with the soil to form a stable supporting foundation, the upper portion of the component protrudes out of the soil layer, and the component plays a role in the structure; compared with the prior art, the method has a remarkable control and attenuation effect on vibration elastic waves in a region adjacent to a track, a structural band gap is successfully constructed through application of a local resonance theory, adverse effects caused by track traffic vibration are effectively relieved or eliminated, and meanwhile the transmission efficiency of the vibration is remarkably reduced.

Description

Technical Field

[0001] The present invention relates to the field of acoustic metamaterials, and in particular to an acoustic metamaterial structure based on a local resonance mechanism. Background Art

[0002] With the rapid advancement of urbanization, urban population density has increased and traffic pressure has risen significantly. Urban rail transit has become an important part of the modern urban transportation system due to its high efficiency and sustainability. As of January 2024, 55 cities in my country have opened and operated 308 urban rail transit lines, with a total operating mileage of 10,205.6 kilometers. This rapid development has significantly alleviated urban traffic congestion, improved transportation efficiency, and provided residents with convenient, safe and environmentally friendly travel options. However, the increasing compactness of urban rail transit systems has also brought about environmental vibration problems. The vibration caused by rail transit operation is transmitted to the ground and buildings through the structure, which has potential negative effects on the stable operation of precision equipment, the protection of historical buildings, and the daily life and health of residents along the line.

[0003] In order to mitigate these negative effects, the vibration reduction strategies currently adopted can be divided into three categories: reducing vibration at the source, suppressing the vibration propagation path, and implementing passive vibration reduction control on sensitive targets. Vibration source reduction reduces the generation of vibration by using materials with high vibration reduction performance or installing vibration isolators during the design stage. Vibration propagation path reduction blocks or reduces the propagation of vibration waves by setting up vibration isolation barriers, such as installing vibration isolation foundations or vibration isolation trenches. Passive vibration reduction of sensitive sources reduces or eliminates the impact of external vibration by taking measures on the structures or equipment that receive vibration.

[0004] Although traditional vibration isolation measures can reduce vibration propagation to a certain extent, these methods are difficult to achieve accurate and effective control in the face of complex and changing environments and vibration frequencies. Therefore, it is particularly important to research and develop more advanced vibration reduction technologies and strategies.

[0005] Due to its unique bandgap characteristics, metamaterials have shown great application potential in the field of rail vibration reduction. This structure can form a specific bandgap frequency range through periodic arrangement and design, thereby effectively blocking or attenuating the propagation of vibration waves within a specific frequency range. When the vibration waves generated by the operation of a rail train encounter the metamaterial structure, only the vibration waves within the passband frequency range can pass smoothly, while the vibration waves within the bandgap frequency range are significantly suppressed or completely blocked. This characteristic makes the metamaterial structure an ideal vibration reduction structure when the rail line passes through sensitive areas such as residential areas and historical building protection areas. By precisely designing and adjusting the structure and size of the metamaterial, customized vibration reduction can be performed for the specific vibration frequencies generated by rail operation. Combined with the local resonance theory, environmental vibrations can be suppressed and the negative impact on the surrounding environment and residents' lives can be reduced. To this end, the present invention proposes an acoustic metamaterial structure based on the local resonance mechanism. Summary of the invention

[0006] The purpose of the present invention is to provide an acoustic metamaterial structure based on a local resonance mechanism to solve the problems raised in the above background technology.

[0007] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: an acoustic metamaterial structure based on a local resonance mechanism, comprising a plurality of metamaterial unit cells, each of the metamaterial unit cell structures comprising a cylindrical steel core, an inner annular rubber connector, an inner annular steel ring, an outer annular rubber connector, an outer annular steel ring and soil, the lower end of the cylindrical steel core is inserted into the inner annular rubber connector, and the inner annular steel ring is sleeved on the outside of the inner annular rubber connector, the lower end of the inner annular steel ring is inserted into the middle of the outer annular rubber connector, and the outer annular steel ring is wrapped around the outside of the outer annular rubber connector, and the outer annular steel ring is buried in the soil.

[0008] Preferably, the inner annular rubber connector is flush with the top of the inner annular steel ring, and the outer annular rubber connector, the outer annular steel ring and the top of the soil are flush.

[0009] Preferably, 7 / 12 of the height of the cylindrical steel core is inserted into the inner annular rubber connector, and 2 / 7 of the height of the inner annular steel ring is inserted into the outer annular rubber connector.

[0010] Preferably, the cylindrical steel core has a radius of 0.08 m and a height of 0.60 m, and the outer side close to one end is fixed inside the inner annular rubber connector.

[0011] Preferably, the inner radius of the inner annular steel ring is 0.12 m, the outer radius is 0.16 m, the height is 0.35 m, and the lower surface of the inner annular steel ring is fixed inside the outer annular rubber connector.

[0012] Preferably, the outer annular steel ring has an inner radius of 0.20 m, an outer radius of 0.24 m, a height of 0.10 m, and the outer annular steel ring is entirely buried in the soil.

[0013] Preferably, the inner radius of the inner annular rubber connector is 0.08 m, and the outer radius is 0.12 m, and the inner radius of the outer annular rubber connector is 0.16 m, and the outer radius is 0.20 m.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] The structure of the present invention has a significant ability to suppress and attenuate vibration elastic waves near the track, especially in low-frequency vibration suppression. Its materials are easy to obtain, the preparation process is simple, the cost is low, and it has excellent environmental friendliness and is suitable for large-scale applications. The material can effectively alleviate the impact of track operation and natural disasters such as earthquakes on tracks and equipment, extend the service life of equipment, and reduce maintenance costs. It has a wide range of application scenarios, including protection of buildings along the track, vibration reduction of equipment foundations, and optimization of urban environment, showing certain application potential and academic value in the field of rail transit. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the three-dimensional structure of the metamaterial unit cell in the present invention;

[0017] Figure 2 It is an assembly diagram of the metamaterial unit cell in the present invention;

[0018] Figure 3 is a cross-sectional view of a metamaterial unit cell in the present invention;

[0019] Figure 4 This is a schematic diagram of the arrangement of the metamaterial structure provided by the present invention.

[0020] In the figure: 1. cylindrical steel core; 2. inner annular rubber connector; 3. inner annular steel ring; 4. outer annular rubber connector; 5. outer annular steel ring; 6. soil. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Example

[0023] See also Figure 1-Figure 4, the figure shows an acoustic metamaterial structure based on the local resonance mechanism, the acoustic metamaterial includes a plurality of metamaterial unit cells arranged in a square lattice periodicity, each metamaterial unit cell structure includes a cylindrical steel core 1, an inner annular rubber connector 2, an inner annular steel ring 3, an outer annular rubber connector 4, an outer annular steel ring 5 and soil 6, the lower end of the cylindrical steel core 1 is inserted into the inner annular rubber connector 2, and the inner annular steel ring 3 is sleeved on the outside of the inner annular rubber connector 2, the lower end of the inner annular steel ring 3 is inserted into the middle of the outer annular rubber connector 4, and the outer annular steel ring 5 is wrapped around the outer side of the outer annular rubber connector 4, and the outer annular steel ring 5 is buried in the soil 6.

[0024] In this embodiment, the inner annular rubber connector 2 and the inner annular steel ring 3 are flush at both ends, the outer annular rubber connector 4 and the outer annular steel ring 5 are flush at both ends, the overall height of the component is 0.60m, the depth of burial in the soil is 0.10m, the radius of the cylindrical steel core 1 is 0.08m; the inner radius of the inner annular rubber connector 2 is 0.08m, and the outer radius is 0.12m; the inner radius of the inner annular steel ring 3 is 0.12m, and the outer radius is 0.16m; The inner radius of the outer annular rubber connector 4 is 0.16m and the outer radius is 0.20m; the inner radius of the outer annular steel ring 5 is 0.20m and the outer radius is 0.24m. The 7 / 12 height of the cylindrical steel core 1 is inserted into the inner annular rubber connector 2, and the 2 / 7 height of the inner annular steel ring 3 is inserted into the outer annular rubber connector 4. The materials of the designed acoustic metamaterial structure include soil 6, steel, and rubber, wherein the density of the soil 6 is ρ1=1800kg / m 3 , the elastic modulus is E1 = 2 × 10 7 Pa, Poisson's ratio is γ1 = 0.3; density of steel is ρ2 = 7780 kg / m 3 , elastic modulus E2 = 2.106 × 10 11 Pa, Poisson's ratio γ2 = 0.3; rubber density ρ3 = 1300 kg / m 3 , elastic modulus E3 = 1.37 × 10 5 Pa, Poisson's ratio γ3 = 0.463.

[0025] Furthermore, the acoustic metamaterial structure provided by the present invention has a complete band gap for surface waves in the frequency range of 33.24-60.12 Hz, and the band gap width is 26.88 Hz, which can effectively isolate about 45% of the surface wave propagation below 60 Hz, wherein the component as a whole is designed to be deeply embedded in the soil 6, and its embedding depth corresponds to the height of the outer annular steel ring 5, ensuring the stability and harmony of the structure. The lower part of the component penetrates deep into the soil layer and is tightly combined with the soil 6 to form a stable supporting foundation, while the upper part protrudes above the soil layer to perform its function in the structure. The proposed structural design has a significant control and attenuation effect on the vibration elastic waves in the vicinity of the track. Through the application of local resonance theory, a structural band gap is successfully constructed, which effectively alleviates or eliminates the adverse effects of rail transit vibration, while significantly reducing the vibration transmission efficiency.

[0026] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0027] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An acoustic metamaterial structure based on a local resonance mechanism, comprising a plurality of metamaterial unit cells, characterized in that: Each metamaterial unit cell structure comprises a cylindrical steel core (1), an inner annular rubber connector (2), an inner annular steel ring (3), an outer annular rubber connector (4), an outer annular steel ring (5) and soil (6); the lower end of the cylindrical steel core (1) is inserted into the inner annular rubber connector (2), and the inner annular steel ring (3) is sleeved on the outside of the inner annular rubber connector (2); the lower end of the inner annular steel ring (3) is inserted into the middle of the outer annular rubber connector (4), and the outer annular steel ring (5) is wrapped around the outside of the outer annular rubber connector (4); and the outer annular steel ring (5) is buried in the soil (6).

2. The acoustic metamaterial structure based on the local resonance mechanism according to claim 1, characterized in that: The inner annular rubber connector (2) is flush with the top of the inner annular steel ring (3), and the outer annular rubber connector (4), the outer annular steel ring (5) and the top of the soil (6) are flush with each other.

3. The acoustic metamaterial structure based on the local resonance mechanism according to claim 2, characterized in that: 7 / 12 of the height of the cylindrical steel core (1) is inserted into the inner annular rubber connector (2), and 2 / 7 of the height of the inner annular steel ring (3) is inserted into the outer annular rubber connector (4).

4. The acoustic metamaterial structure based on the local resonance mechanism according to claim 3, characterized in that: The cylindrical steel core (1) has a radius of 0.08 m and a height of 0.60 m, and the outer side close to one end (2) is fixed inside the inner ring-shaped rubber connector (2).

5. The acoustic metamaterial structure based on the local resonance mechanism according to claim 4, characterized in that: The inner layer annular steel ring (3) has an inner radius of 0.12 m, an outer radius of 0.16 m, and a height of 0.35 m, and the lower surface of the inner layer annular steel ring (3) is fixed inside the outer layer annular rubber connector (4).

6. The acoustic metamaterial structure based on the local resonance mechanism according to claim 5, characterized in that: The outer annular steel ring (5) has an inner radius of 0.20 m, an outer radius of 0.24 m, a height of 0.10 m, and the outer annular steel ring (5) is entirely buried inside the soil (6).

7. The acoustic metamaterial structure based on the local resonance mechanism according to claim 6, characterized in that: The inner radius of the inner annular rubber connector (2) is 0.08 m, and the outer radius is 0.12 m, and the inner radius of the outer annular rubber connector (4) is 0.16 m, and the outer radius is 0.20 m.

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