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Low-sound-velocity metamaterial layer and medium-low-frequency efficient sound-absorbing metamaterial composite structure made of same

A composite structure and metamaterial technology, which is applied in the field of metamaterial composite structures with high-efficiency sound absorption at medium and low frequencies, can solve problems such as engineering application constraints and large overall thickness of the structure, and achieve improved low-frequency sound absorption coefficient, small overall thickness, and improved mid-range Effect of Low Frequency Sound Absorption Coefficient

Pending Publication Date: 2019-11-19
CHINA RAILWAY DESIGN GRP CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In order to form a broadband sound absorption effect, it is necessary to alternately arrange multiple layers of micro-perforated plates and air layers, resulting in an excessively large overall thickness of the structure, which greatly restricts engineering applications.

Method used

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  • Low-sound-velocity metamaterial layer and medium-low-frequency efficient sound-absorbing metamaterial composite structure made of same
  • Low-sound-velocity metamaterial layer and medium-low-frequency efficient sound-absorbing metamaterial composite structure made of same
  • Low-sound-velocity metamaterial layer and medium-low-frequency efficient sound-absorbing metamaterial composite structure made of same

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0055] A sheet of metamaterial having a thickness of 20 mm comprising a perforated sheet of 1 mm thickness disposed in the middle thereof, the perforated sheet being made of a hard resin. The distance between adjacent perforations on the perforated sheet is 20 mm, the perforation radius is 1 mm, and the maximum effective control frequency is 1150 Hz. Substituting the combination of the above formulas, the normal sound velocity of the metamaterial sheet in the range of 20-1150Hz is 78-89m / s, of which the normal sound velocity at 200Hz is 88.8m / s, and the normal sound velocity at 500Hz is 87.4m / s, the normal sound velocity at 1000Hz is 81.2m / s.

Embodiment 2

[0057] A metamaterial composite structure with high-efficiency sound absorption at medium and low frequencies, the porous sound-absorbing material layer has a flow resistance of 20000Pa·s / m 2 It is made of some kind of polyurethane sound-absorbing material with a thickness of 20mm; the low sound velocity metamaterial layer is composed of a layer of metamaterial sheet; the thickness of the metamaterial sheet is 20mm, including a perforated sheet with a thickness of 1mm, and the perforated sheet is made of hard Made of resin, the perforation spacing is 20mm, and the perforation radius is 1mm; the hard reflective material is a flat concrete wall.

[0058] Figure 4 It is the effect sound absorption curve of the second embodiment. It can be known by calculation that within the range of 100-2000 Hz, the normal sound velocity of the metamaterial sheet is 60-89 m / s. Figure 4 It shows that when there is an air cavity between the porous sound-absorbing material and the hard reflecti...

Embodiment 3

[0060] A metamaterial composite structure with high-efficiency sound absorption at medium and low frequencies. The porous sound-absorbing material layer is composed of a certain flow resistance rate of 40000Pa·s / m 2 It is made of porous sound-absorbing material with a thickness of 10mm. There is a 100mm air cavity between the porous sound-absorbing material layer and the hard reflective material. The peak value of sound absorption is around 800Hz. Under the premise of reducing the amount of acoustic materials, the peak of sound absorption is moved to 400Hz. After design, the original plan is replaced by a metamaterial composite structure with high-efficiency sound absorption at low and medium frequencies. The low-sonic metamaterial layer is composed of 5 layers of metamaterial sheets. The thickness of the metamaterial sheet is 20mm, and the perforated sheet of the metamaterial sheet is made of aluminum alloy. The thickness of the perforated sheet is 1 mm, the perforation radiu...

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Abstract

The invention discloses a medium-low-frequency efficient sound-absorbing metamaterial composite structure. The composite structure comprises a porous sound-absorbing material layer, a low-sound-velocity metamaterial layer and a hard reflecting material which are sequentially and continuously arranged from outside to inside, wherein the low-sound-velocity metamaterial layer is formed by overlappingmetamaterial sheets with the same thickness; each metamaterial sheet is a sheet material which can be regarded as a uniform fluid in a sound field; an extension direction of each metamaterial sheet is parallel to the inner surface of a porous sound-absorbing material; the normal sound velocity of each metamaterial sheet is smaller than the sound velocity of air; each metamaterial sheet is composed of air with a certain thickness and a perforated sheet embedded in the air; and the normal sound velocity of each metamaterial sheet is related to parameters such as the thickness, the small hole area and the like of the perforated sheet. According to the composite structure, a medium-low-frequency sound-absorbing coefficient is obviously improved by using a relatively small cavity size; and themedium-low-frequency noises in railways, factories and buildings can be greatly reduced.

Description

technical field [0001] The invention relates to a sound-absorbing structure, in particular to a low-sonic-velocity metamaterial layer and a metamaterial composite structure with high-efficiency sound-absorbing mid-low frequency made of it. Background technique [0002] Low-frequency sound absorption control is one of the common problems in the field of noise control. Porous sound-absorbing materials widely used in engineering have good absorption effect on medium and high-frequency sound waves, but poor absorption effect on low-frequency sound waves. In order to make up for the low-frequency defects of porous sound-absorbing materials, the most common method is to add a cavity between the porous sound-absorbing material and the rigid reflective wall (plate). When the cavity depth is an odd multiple of 1 / 4 of the wavelength of the sound wave, the incident sound wave and the reflected sound wave form an interference effect at the sound-absorbing material, and the sound absorp...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G10K11/168
CPCG10K11/168
Inventor 胡文林刘冀钊何宾王少林
Owner CHINA RAILWAY DESIGN GRP CO LTD
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