CN111179895A

CN111179895A - Lightweight honeycomb type low-frequency sound insulation metamaterial structure

Info

Publication number: CN111179895A
Application number: CN201911344654.5A
Authority: CN
Inventors: 肖学楷; 上官文斌; 谢新星
Original assignee: South China University of Technology SCUT; Ningbo Tuopu Group Co Ltd
Current assignee: South China University of Technology SCUT; Ningbo Tuopu Group Co Ltd
Priority date: 2019-12-24
Filing date: 2019-12-24
Publication date: 2020-05-19

Abstract

The invention relates to the field of metamaterial sound insulation, and discloses a lightweight honeycomb type low-frequency sound insulation metamaterial structure which comprises an upper layer of framework, a lower layer of framework, an elastic film between the two layers of framework, a mass block attached to the film and a homogeneous thin plate covering the outer side of the framework. The frame is composed of a plurality of regularly arranged hexagonal honeycomb units, and the positions of the honeycomb units of the upper layer of frame and the lower layer of frame are in one-to-one correspondence. The mass blocks are attached to the elastic film of each honeycomb unit, can be all the same or different and are combined and arranged according to a certain rule, and the shapes of the mass blocks comprise a circular ring shape, a cylindrical shape and a circular truncated cone shape. The honeycomb type acoustic metamaterial is superior to the traditional sound insulation material, has excellent sound insulation performance in a low-frequency section, can effectively control the overall quality of a structure by selecting a light frame material, achieves the purpose of light low-frequency sound insulation, and has a very wide application prospect in the fields of automobiles, buildings and the like.

Description

Lightweight honeycomb type low-frequency sound insulation metamaterial structure

Technical Field

The invention relates to the field of sound insulation of acoustic metamaterials, in particular to a lightweight honeycomb type low-frequency sound insulation metamaterial structure.

Background

In many places in life, serious noise problems exist, and noise is more and more serious in the traffic fields of automobiles, subways, aviation and the like and the life fields of architectural decoration and the like. The sound insulation walls on two sides of the expressway and the subway rail, the sound insulation material of the KTV box, the front wall of the automobile, the carpet sound insulation pad and the like can attenuate the transmission of noise to a certain extent, but can not effectively isolate the noise of a low frequency band. The problem of solving low-frequency noise is always a very difficult challenge, the low-frequency noise has long wavelength and strong penetrating power, the traditional material usually achieves the sound insulation effect by increasing the thickness and the quality of the traditional material, and the benefit is very little. The appearance of the acoustic metamaterial provides a new idea for solving the problem of low frequency.

The concept of the acoustic metamaterial is proposed by analogy to the electromagnetic metamaterial, the acoustic metamaterial is a sub-wavelength artificial periodic structure or material, and the acoustic metamaterial has negative equivalent mass density and negative elastic modulus under certain conditions through special design of the structure, and has good acoustic performance due to special physical properties. Based on the principle of local resonance, the acoustic metamaterial can achieve the effect of controlling large wavelength in a small size, the limitation that the traditional homogeneous material follows the mass law is broken through, and light weight and noise reduction are achieved.

In recent years, research on acoustic metamaterials at home and abroad has made good progress, and the proposal of various different types of metamaterials and different unit structures provides a plurality of open ideas for solving various noise problems. According to the structural classification, the acoustic metamaterial comprises a thin plate type, a thin film type and a Helmholtz resonant cavity type, wherein the thin film type acoustic metamaterial has a good application prospect due to simple structure, convenience in manufacturing and low cost.

Disclosure of Invention

The invention aims to provide a lightweight honeycomb type low-frequency sound insulation metamaterial structure, which can effectively solve the problem of low-frequency noise, meet the requirement of lightweight, change the sound insulation frequency range and the sound insulation peak value by adjusting the structural parameters of the metamaterial structure, and meet the requirement of lightweight low-frequency sound insulation.

The invention changes the sound insulation frequency range and the sound insulation peak value by adjusting the material parameters or the dimension parameters of the frame, the film or the mass block.

The invention is realized by adopting the following technical scheme:

a lightweight honeycomb type low-frequency sound insulation metamaterial structure comprises a homogeneous thin plate and a honeycomb metamaterial layer; the upper surface and the lower surface of the honeycomb metamaterial layer are covered with homogeneous thin plates; the honeycomb metamaterial layer comprises an upper frame, a lower frame, an elastic film between the two frames, and a mass block attached to the elastic film; the upper frame and the lower frame are composed of a plurality of hexagonal honeycomb units which are regularly arranged, each honeycomb unit in the upper frame corresponds to each honeycomb unit in the lower frame in position one by one, the mass blocks are attached to the elastic film of each honeycomb unit, the homogeneous thin plate covers the outer side of the frame, and the honeycomb metamaterial layer is wrapped in the middle; the homogeneous sheet is a metamaterial upper homogeneous sheet layer and a metamaterial lower homogeneous sheet layer.

Further, the radius of the bottom surface of the mass block is 3mm-10 mm; the mass of the mass block is 0.1 g-2.5 g.

Further, the upper frame and the lower frame are selected from ABS resin, EVA or PVC material; the thickness of each layer of the frame structure is 1-3 mm; the upper frame is provided with an upper frame protruding structure, and the lower frame is provided with a lower frame groove structure, so that the assembly of two layers of frames and the effective isolation between units are ensured.

Further, the elastic film is selected from an elastic silicon rubber film, a polyethylene film or a polyimide film; the thickness of the elastic film is 0.1-1 mm.

Furthermore, the mass blocks are all the same or different and are combined and arranged according to a certain rule, and the shapes of the mass blocks comprise a circular ring shape, a cylindrical shape and a circular truncated cone shape; the mass block is selected from ABS resin, EVA, aluminum sheets or iron sheets; the height of the mass block is 1-3 mm; the mass block is adhered to the center of each hexagonal honeycomb unit by glue.

Further, the homogeneous sheet is selected from EVA, formed felt or glass fiber board; the thickness of the homogeneous thin plate is not more than 2 mm.

Further, the mass block comprises a large mass block, a small mass block and a circular ring-shaped mass block; the sound insulation frequency bandwidth is widened through different arrangements of different mass blocks; the large mass block is a round or cylindrical mass block with a larger bottom area; the small mass block is a round or cylindrical mass block with a small bottom area.

Furthermore, the mass blocks in the same shape are arranged in each row, and the mass blocks in different shapes are arranged between adjacent rows, namely, the large mass block, the small mass block and the circular mass block are alternately arranged in each row.

Furthermore, the whole metamaterial layer is divided into a plurality of equal-part areas, mass blocks with the same shape are arranged in each area, and the arrangement modes of the mass blocks with different shapes are arranged in adjacent areas; the zone consists of 7-10 smallest honeycomb metamaterial unit cells.

Furthermore, each region is provided with additional mass blocks with the same shape, adjacent regions are provided with mass blocks with different shapes in an arrangement mode, and a defect unit is arranged in the middle of each region; the zone consists of 7-10 smallest honeycomb metamaterial unit cells.

Further, the mass block is adhered to the elastic film by glue, and should be located at the center of each hexagonal honeycomb unit.

Further, the homogeneous sheet can be selected from EVA, formed felt or glass fiber board. The thickness of the thin plate is not more than 2 mm.

The frame is composed of hexagonal units which are regularly arranged, and the upper hexagonal unit, the lower hexagonal unit, the elastic film clamped in the middle and the attached mass block form a honeycomb metamaterial sound insulation unit.

Compared with the prior art, the invention has the beneficial effects that:

1. the light-weight honeycomb type low-frequency sound insulation metamaterial structure provided by the invention adopts a hexagonal honeycomb structure to form a basic unit, and the structure has excellent geometric mechanical properties and high structural strength.

2. The lightweight honeycomb type low-frequency sound insulation metamaterial structure provided by the invention is made of light materials such as ABS resin, so that the overall mass of the structure can be effectively reduced, and the effect of light low-frequency sound insulation is achieved.

3. The lightweight honeycomb type low-frequency sound insulation metamaterial structure can generate an obvious sound insulation peak value at a low-frequency band of 100-1000 Hz, is obviously superior to the performance of the traditional sound insulation material at the low-frequency band, and can ensure that the sound insulation quantity and the sound insulation bandwidth meet the design requirements by adjusting the structural parameters and the arrangement of the mass blocks.

Drawings

FIG. 1 is a schematic structural diagram of a lightweight honeycomb type low-frequency sound insulation metamaterial according to an embodiment of the invention;

FIG. 2 is an exploded view of a lightweight honeycomb type low-frequency sound insulation metamaterial structure according to an embodiment of the invention;

FIG. 3 is a schematic structural view of the honeycomb metamaterial layer shown in FIG. 2;

FIG. 4 is a schematic view of a hexagonal honeycomb cell structure of the honeycomb metamaterial layer shown in FIG. 3;

FIG. 5 is a partial enlarged view of the upper and lower frame assembly surfaces of the honeycomb metamaterial layer shown in FIG. 3;

FIG. 6 is a schematic view of one arrangement of intermediate cellular metamaterial layers;

FIG. 7 is a schematic view of one arrangement of intermediate cellular metamaterial layers;

FIG. 8 is a schematic view of one arrangement of intermediate cellular metamaterial layers;

FIG. 9 is a comparison graph of mass acoustic transmission loss curves for different base areas of a metamaterial in accordance with an embodiment of the present invention;

FIG. 10 is a graph comparing mass bulk acoustic transmission loss curves for different masses of a metamaterial in accordance with an embodiment of the present invention;

FIG. 11 is a graph comparing the acoustic transmission loss curves of a metamaterial and homogeneous equal-weight EVA of an embodiment of the invention.

Reference is made to the accompanying drawings in which:

1-metamaterial upper homogeneous sheet layer, 2-metamaterial lower homogeneous sheet layer, 3-honeycomb metamaterial layer, 30-honeycomb metamaterial unit, 31-upper frame, 32-lower frame, 33-elastic film, 34-mass block, 4-convex structure of upper frame, 5-concave structure of lower frame, 6-large mass block, 7-small mass block and 8-circular mass block.

Detailed Description

For a better understanding of the present invention, embodiments thereof are described in further detail below with reference to the accompanying drawings.

Fig. 1 shows a schematic structural diagram of a lightweight honeycomb type low-frequency sound-insulating metamaterial according to an embodiment of the invention, and fig. 2 shows an explosion diagram of the lightweight honeycomb type low-frequency sound-insulating metamaterial according to the embodiment, which includes an upper homogeneous sheet layer 1 and a lower homogeneous sheet layer 2 which are covered on a metamaterial, and a honeycomb metamaterial layer 3 which is wrapped in the middle. Fig. 3 shows a schematic structural view of the middle cellular metamaterial layer 3, which includes two layers of frames (upper frame 31 and lower frame 32), an elastic membrane 33 between the two layers of frames, and an additional mass 34 on one side of the membrane, all of the masses being of the same size.

The frame is composed of a plurality of regularly arranged hexagonal honeycomb units, the positions of each honeycomb unit of the upper layer of frame and the lower layer of frame correspond to each other one by one, and the mass blocks are attached to the elastic film of each honeycomb unit. The upper honeycomb hexagonal upper frame 31, the lower honeycomb hexagonal lower frame 32, the elastic membrane 33 clamped in the middle and the attached mass block 34 form a honeycomb metamaterial sound insulation unit, as shown in fig. 4. Such a hexagonal honeycomb cell is the core structure of the whole metamaterial.

The upper and

lower frames

31 and 32 of this embodiment are made of ABS resin, and each layer is 3mm thick, so the overall structure can be controlled to be very light and thin, and meet certain strength requirements, and are convenient to use in various different situations. The elastic film 33 is made of polyethylene film with the thickness of 0.1mm, the polyethylene film is firmly adhered to the frames on the two sides by using 3M glue, the polyethylene film is low in price and easy to process, the odor requirement can be met, the odor is an important assessment index in the automotive interior sound insulation product, and the extra risk of the product can be reduced by using the polyethylene film. The mass 34 is also made of ABS resin, and for best sound insulation, all the masses of this embodiment should be placed in the center of each honeycomb unit and glued to the membrane. EVA materials are selected for the upper and lower

homogeneous sheets

1 and 2 on the outer side of the frame of the embodiment, and the thicknesses of the sheets are both 1 mm. The outline of the whole metamaterial of the embodiment is square, and the length and the width are 506 x 506 mm.

Fig. 5 is a partially enlarged view of an assembly surface of upper and lower frames, the upper frame having a protrusion structure 4 of the upper frame and the lower frame having a groove structure 5 of the lower frame, by which it is ensured that the upper and lower positions of each honeycomb unit correspond to each other and no positional deviation occurs, and which also allows the entire film to be effectively divided into individual units, minimizing the interference effect between the units.

Widen several different arrangement forms of sound insulation frequency bandwidth:

fig. 6 shows an arrangement schematic diagram of the middle honeycomb metamaterial layer 3, the area in the dotted line contains three different mass blocks, namely, a round (cylindrical) mass block 6 with a large bottom area, a round (cylindrical) mass block 7 with a small bottom area, a circular ring-shaped mass block 8, the mass blocks in each row are the same, but the mass blocks in the rows are different from those in the rows, and are sequentially and alternately arranged according to the rule, so that the sound insulation frequency band width of the honeycomb metamaterial is widened, sound insulation peaks can be formed in different frequency bands due to different masses or additional mass blocks with different bottom areas, and the circular ring-shaped mass blocks can form two sound insulation peaks.

Fig. 7 is another schematic layout diagram of the middle honeycomb metamaterial layer 3, the honeycomb metamaterial is divided into a plurality of regions, mass blocks with the same specification are arranged in each region, the specifications of the mass blocks in different regions are different, three different mass blocks are contained in fig. 7 and are alternately arranged according to the rule, and the purpose is to desirably widen the sound insulation frequency bandwidth of the honeycomb metamaterial.

Fig. 8 shows another schematic layout of the middle honeycomb metamaterial layer 3, which is divided into several regions, each region is provided with a mass block with the same specification, the specifications of the mass blocks of different regions are different, but a defective unit is arranged in the middle of each region. The defect states of the acoustic metamaterial extend from the defect states of the phononic crystal. The destruction of the ideal periodic structure is called a defect, and can be classified into a point defect, a line defect, and a plane defect in terms of dimensions, and when a defect state exists, an elastic wave within a band gap can be localized at the defect or propagated in the direction of the defect, and thus can be used to control the propagation of the elastic wave. The honeycomb metamaterial defect structure constructed by the embodiment can generate two new sound insulation peaks on two sides of the original sound insulation peak, the original sound insulation peak is changed into a wave trough, and the sound insulation frequency band width is widened on the whole.

The acoustic transmission loss curve of the sample piece is tested by using an impedance tube, the outer contour of the sample piece is designed to be circular, the diameter of the sample piece is 100mm, the sample piece totally comprises 7 honeycomb units, and 7 mass blocks are selected from all identical cylindrical types, like the arrangement form of the figure 3. The impedance tube test is carried out by adopting a four-sensor method, when sound waves vertically enter the surface of the metamaterial, reverse local resonance occurs between the film and the mass block in the corresponding frequency band, sound wave energy is prevented from being transmitted to the other side in a reflection mode, and a sound insulation peak value can occur at the frequency. Fig. 9 shows a sound transmission loss curve of the middle honeycomb metamaterial layer 3 tested alone, wherein a curve 1 is a sound insulation curve of a test piece of the mass block a, a sound insulation peak value appears at 288Hz, the sound insulation amount is 31.3dB, the sound insulation bandwidth larger than 20dB is about 256Hz, and data show that the honeycomb-type metamaterial has a prominent low-frequency sound insulation effect.

The sound insulation frequency range and the sound insulation amplitude can be adjusted by modifying the geometric parameters of the metamaterial. As shown in fig. 9, which is a comparison graph of sound insulation of mass blocks with different bottom areas of the metamaterial according to the embodiment of the present invention, under the condition of keeping the mass unchanged, the bottom area of the mass block in contact with the thin film is changed, the radius of the bottom surface of the mass block is changed from 3mm to 5mm, the sound insulation peak value moves to high frequency along with the increase of the bottom area, and is changed from 288Hz to 392Hz, and the sound insulation amount is increased to 32.5 Hz. As shown in fig. 10, which is a comparison graph of the transmission loss curves of the masses tested separately for the middle honeycomb metamaterial layer 3, the masses of B, A, C are 0.12g, 0.18g and 0.22g respectively, the sound insulation peak value moves to the low frequency with the increase of the masses, respectively 480Hz, 288Hz and 248Hz, the sound insulation amount increases, respectively 29.2Hz, 31.3Hz and 36.5Hz, and the low frequency sound insulation effect of the honeycomb type metamaterial is prominent.

As shown in fig. 11, the test curve of the sound transmission loss of the whole honeycomb type acoustic metamaterial is shown, homogeneous EVA with the same mass is selected for comparison, and the curve results show that the sound insulation performance of the honeycomb metamaterial at the low frequency range of 50-500Hz is obviously superior to that of the homogeneous EVA, the honeycomb metamaterial has a wider sound insulation frequency bandwidth, and the low-frequency sound insulation effect is outstanding.

Compared with homogeneous sound insulation materials with the same weight, the lightweight honeycomb type low-frequency sound insulation metamaterial structure has a good sound insulation effect at low frequency, breaks through the limitation of the quality law of the traditional sound insulation materials, meets the requirements of lightweight low-frequency sound insulation on the premise of not increasing the thickness and the quality, is excellent in geometric characteristics, and can be applied to a plurality of sound insulation occasions.

The above-described embodiments are only preferred embodiments of the present invention, and are not intended to limit the present invention in any way, and other variations and modifications may be made without departing from the spirit of the invention as set forth in the claims.

Claims

1. The utility model provides a lightweight honeycomb type low frequency sound insulation metamaterial structure which characterized in that: comprises a homogeneous thin plate and a honeycomb metamaterial layer (3); the upper surface and the lower surface of the honeycomb metamaterial layer (3) are covered with homogeneous thin plates; the honeycomb metamaterial layer (3) comprises an upper frame (31), a lower frame (32), an elastic film (33) between the two frames, and a mass block (34) attached to the elastic film; the upper frame (31) and the lower frame (32) are composed of a plurality of hexagonal honeycomb units which are regularly arranged, each honeycomb unit in the upper frame (31) corresponds to each honeycomb unit in the lower frame (32) in position one by one, the mass blocks (34) are attached to an elastic film of each honeycomb unit, the homogeneous thin plate covers the outer side of the frame, and a honeycomb metamaterial layer is wrapped in the middle; the homogeneous sheet is a metamaterial upper homogeneous sheet layer (1) and a metamaterial lower homogeneous sheet layer (2).

2. The lightweight honeycomb type low-frequency sound insulation metamaterial structure according to claim 1, wherein: (ii) a The radius of the bottom surface of the mass block (34) is 3mm-10 mm; the mass of the mass block (34) is 0.1 g-2.5 g.

3. The lightweight honeycomb type low-frequency sound insulation metamaterial structure according to claim 1, wherein: the upper frame (31) and the lower frame (32) are selected from ABS resin, EVA or PVC material; the thickness of each layer of the frame structure is 1-3 mm; the upper frame (31) is provided with an upper frame convex structure (4), and the lower frame (32) is provided with a lower frame concave structure (5), so that the assembly of two layers of frames and the effective isolation between units are ensured.

4. The lightweight honeycomb type low-frequency sound insulation metamaterial structure according to claim 1, wherein: the elastic film is selected from an elastic silicon rubber film, a polyethylene film or a polyimide film; the thickness of the elastic film is 0.1-1 mm.

5. The lightweight honeycomb type low-frequency sound insulation metamaterial structure according to claim 1, wherein: the mass blocks are all the same or different and are combined and arranged according to a certain rule, and the shapes of the mass blocks comprise a circular ring shape, a cylindrical shape and a circular truncated cone shape; the mass block is selected from ABS resin, EVA, aluminum sheets or iron sheets; the height of the mass block is 1-3 mm; the mass block is adhered to the center of each hexagonal honeycomb unit by glue.

6. The lightweight honeycomb type low-frequency sound insulation metamaterial structure according to claim 1, wherein: the homogeneous sheet is selected from EVA, molding felt or glass fiber board; the thickness of the homogeneous thin plate is not more than 2 mm.

7. The lightweight honeycomb type low-frequency sound insulation metamaterial structure according to claim 1, wherein: the mass block (34) comprises a large mass block (6), a small mass block (7) and a circular mass block (8); the sound insulation frequency bandwidth is widened through different arrangements of different mass blocks; the large mass block (6) is a round or cylindrical mass block with a large bottom area; the small mass block is a round or cylindrical mass block with a small bottom area.

8. The lightweight honeycomb type low-frequency sound insulation metamaterial structure according to claim 7, wherein: the mass blocks (34) with the same shape in each row are adopted, and the arrangement mode of the mass blocks (34) with different shapes between adjacent rows is adopted, namely the mode that the large mass block (6), the small mass block (7) and the circular mass block (8) are alternately arranged in each row.

9. The lightweight honeycomb type low-frequency sound insulation metamaterial structure according to claim 7, wherein: dividing the whole metamaterial layer into a plurality of equal-part areas, wherein mass blocks (34) with the same shape are arranged in each area, and the arrangement modes of the mass blocks (34) with different shapes are arranged in adjacent areas; the zone is composed of 7-10 smallest honeycomb metamaterial units (30) units.

10. The lightweight honeycomb type low-frequency sound insulation metamaterial structure according to claim 7, wherein: the additional mass blocks (34) with the same shape are arranged in each area, the mass blocks (34) with different shapes are arranged in the adjacent areas, and a defect unit exists in the middle of each area; the zone is composed of 7-10 smallest honeycomb metamaterial units (30) units.