Micro-nano gradient fiber and film acoustic metamaterial composite structure
By combining micro-nano gradient fibers with thin-film acoustic metamaterials, the problem of low-frequency and high-frequency noise absorption is solved by utilizing the combination of gradient fiber layers and thin-film acoustic metamaterial layers. This achieves a wide-band sound absorption and insulation effect, and the structure is lightweight and efficient.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANGHAI UNIV OF ENG SCI
- Filing Date
- 2023-12-07
- Publication Date
- 2026-06-26
AI Technical Summary
In existing technologies, micro- and nano-gradient fibers have good sound absorption effects in the mid-to-high frequency range, but their absorption effect on low-frequency sounds is poor. Meanwhile, the sound absorption band gap of thin-film acoustic metamaterials is limited, making it impossible to achieve effective sound insulation for wide-band and high-frequency sounds.
By employing a composite structure of micro-nano gradient fibers and thin-film acoustic metamaterials, and by setting metal blocks and gradient-distributed micro-nano fiber layers in the thin-film acoustic metamaterial layer, the absorption of low-frequency and high-frequency noise can be achieved by combining the properties of both.
It improves sound absorption and insulation, expands the sound absorption and insulation frequency band, achieves good sound absorption and insulation performance in the low, medium and high frequency range, and maintains a lightweight structure.
Smart Images
Figure CN118560121B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of sound-absorbing materials, and in particular to a composite structure of micro / nano gradient fibers and thin-film acoustic metamaterials. Background Technology
[0002] Nonwoven materials are made from high-molecular polymers, forming an aggregate of randomly arranged fibers. These materials are not produced through traditional knitting or weaving processes; instead, the fibers are bonded together using mechanical, chemical, or other methods to form a network structure. These materials are characterized by high porosity, small fiber diameter, and lightweight texture, and excel in sound absorption due to their superior acoustic properties.
[0003] Micro- and nano-gradient fibers are a special type of nonwoven material. They combine micron- and nano-sized fibers through electrospinning to form a structure with a gradient distribution. This structure not only provides excellent sound absorption and insulation in the high-frequency range but also significantly broadens the material's sound absorption frequency domain, increasing its absorption capacity for mid- and low-frequency sound waves. Acoustic metamaterials are a class of artificial composite materials with extraordinary physical properties. These properties are primarily manifested in their ability to suppress the propagation of low-frequency elastic waves within a certain frequency range (called the "bandgap") and possess extraordinary physical properties not found in natural materials, such as negative equivalent mass density and negative equivalent elastic modulus. Utilizing the low-frequency bandgap characteristics and extraordinary physical properties of acoustic metamaterials, it is possible to achieve functions such as superior low-frequency sound absorption, sound insulation, vibration reduction, vibration isolation, and sound target intensity control.
[0004] The design of thin-film acoustic metamaterials typically involves arranging mass blocks on a thin-film unit. Under the tension of the thin-film unit and the influence of mass blocks of different sizes, a band gap is formed in the low-frequency range.
[0005] Gradient fibers exhibit good sound absorption in the mid-to-high frequencies, but their absorption of low-frequency sounds is poor. Furthermore, thin-film acoustic metamaterials have limited sound absorption band gaps, making it impossible to achieve sound insulation across a wide frequency range and at high frequencies. Summary of the Invention
[0006] In order to solve the problems existing in the prior art, improve the sound absorption and sound insulation effect and expand the sound absorption and sound insulation frequency band, the present invention provides a composite structure of micro-nano gradient fibers and thin film acoustic metamaterials.
[0007] Therefore, the present invention adopts the following technical solution:
[0008] A composite structure of micro / nano gradient fibers and thin-film acoustic metamaterials includes several layers of micro / nano gradient fibers and several layers of thin-film acoustic metamaterials, wherein:
[0009] The micro-nano gradient fiber layer is composed of micro-nano fibers with a gradient distribution of average pore size and porosity, and is used to absorb high-frequency noise.
[0010] The thin-film acoustic metamaterial layer has a three-layer structure, including two outer layers and an intermediate layer disposed between the two outer layers. The two outer layers are micro / nano gradient fiber layers with uniformly spaced through-holes. The intermediate layer is a thin film. A metal block is bonded to the center of the thin film within the through-holes of the three-layer structure. Low-frequency noise is absorbed by the vibration of the metal block on the thin film. The through-holes and the metal block are square or circular in shape. There are one or more uniformly spaced through-holes.
[0011] The micro / nanofiber layer comprises a microfiber layer and a nanofiber layer. The microfiber layer is a polypropylene fiber layer, a polyester fiber layer, or a polyethylene fiber layer, and the nanofiber layer is a polyacrylonitrile fiber layer or a polyvinyl alcohol fiber layer. The film is a polyimide film, a polyvinyl chloride film, or a polyethylene film.
[0012] The porosity of the micro / nano gradient fiber layer ranges from 80% to 95%; the average pore size of the microfiber layer is 2-10 μm, and the average pore size of the nanofiber layer is 5-10 nm.
[0013] Compared with the prior art, the present invention has the following beneficial effects:
[0014] 1. The composite structure of this invention fully utilizes the sound absorption and insulation properties of both micro / nano-gradient micro / nanofibers and thin-film acoustic metamaterials. The micro / nano-gradient micro / nanofiber layer has a gradient porous structure that can absorb sound energy; while the thin-film acoustic metamaterial has special acoustic properties that can achieve sound absorption and insulation effects such as negative refraction. By combining the two, the sound absorption and insulation effect is improved and the sound absorption and insulation frequency band is extended.
[0015] 2. The composite structure of this invention is lightweight and highly efficient. Micro-nano gradient micro-nanofibers themselves have low density and are lightweight, while thin-film acoustic metamaterials can also achieve thin and light structures. Therefore, the composite structure of this invention can maintain high sound absorption and sound insulation performance while keeping the weight relatively small. Attached Figure Description
[0016] Figure 1 This is a schematic diagram of a composite structure according to one aspect of the present invention;
[0017] Figure 2 This is a top view schematic diagram of the intermediate layer of the thin-film acoustic metamaterial in this invention;
[0018] Figure 3 This is a schematic diagram of the composite structure of the present invention in the experiment;
[0019] Figure 4 This is a graph showing the changes in sound transmission loss caused by the present invention and two comparative materials at different frequencies;
[0020] Figure 5 This is a graph showing the sound absorption coefficient variation of the present invention and two comparative materials at different frequencies;
[0021] In the picture:
[0022] 1. Micro / nano gradient fiber materials; 2. Thin films; 3. Metal blocks; 4. Thin film acoustic metamaterial unit cells; 5. Micro / nano gradient fibers composed of polyacrylonitrile and polypropylene; 6. PI thin films; 7. Small lead blocks. Detailed Implementation
[0023] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.
[0024] See Figures 1-2 The micro / nano gradient fiber and thin film acoustic metamaterial composite structure of the present invention includes: n layers of micro / nano gradient fiber and m layers of thin film acoustic metamaterial, where m and n are integers ≥1.
[0025] in:
[0026] The micro-nano gradient fiber layer is composed of micro-nano fibers with a gradient distribution of average pore size and porosity, and is used to absorb high-frequency noise.
[0027] Each of the aforementioned thin-film acoustic metamaterial layers has a three-layer structure, including two outer layers and an intermediate layer disposed between the two outer layers. The two outer layers are micro / nano gradient fiber layers with uniformly spaced through-holes. The intermediate layer is a thin film, and a metal block is bonded to the center of the thin film located within the through-holes to absorb low-frequency noise. The composite structure consisting of each through-hole, the thin film within it, and the metal block bonded to the thin film is called a thin-film acoustic metamaterial unit cell.
[0028] In the aforementioned gradient micro / nanofibers layer, the microfiber layer is a polypropylene fiber layer, a polyester fiber layer, or a polyethylene fiber layer, and the nanofiber layer is a polyacrylonitrile fiber layer or a polyvinyl alcohol fiber layer. They have different average pore sizes and porosities under different gradients.
[0029] The thin film in the thin-film acoustic metamaterial layer is a polyimide film, a polyvinyl chloride film, or a polyethylene film; the shapes of the through holes and metal blocks in the thin-film acoustic metamaterial layer can be square or circular, but are not limited to square and circular, and the shapes of the through holes and metal blocks can be the same or different. There can be one or more through holes.
[0030] The sound absorption and sound insulation performance of the composite structure can be controlled and adjusted by changing the total thickness, gradient, porosity, and average pore size of the micro- and nano-gradient fiber layers (including the gradient micro- and nano-fibers in the n-layer micro- and nano-gradient fiber layers and the m-layer thin-film acoustic metamaterial layer), the through-hole size and shape of the thin-film acoustic metamaterial, the size and shape of the metal pieces on the thin-film material, the value of the number of layers n or the value of the number of layers m, or by changing two or more of these parameters.
[0031] The porosity of the micro / nano gradient fiber layer ranges from 80% to 95%; the average pore size of the microfiber layer is 2-10 μm, and the average pore size of the nanofiber layer is 5-10 nm.
[0032] This composite structure can achieve good sound absorption and insulation effects across a wide frequency range, from low to high.
[0033] Example 1
[0034] To more intuitively compare the performance of the composite structure of this invention with other materials, experiments were conducted in an impedance tube to test the invention and two comparative materials. Specifically, the transmission loss and absorption coefficient were measured using the composite structure of this invention, ordinary fiber materials, and traditional thin-film acoustic metamaterials, respectively.
[0035] For the composite structure of the present invention used in the experiment:
[0036] In this experiment, the composite structure of the present invention was prepared using existing technology. The preparation method is as follows: PP (polypropylene) fiber nonwoven material is attached to an electrospinning metal roller as a substrate material. Randomly oriented PAN nanofibers are collected and directly deposited onto the PP nonwoven material to form 1 mm micro-nano gradient fibers. These gradient fibers are then composited layer by layer using hot pressing. The resulting micro-nano gradient fiber material of the composite structure of the present invention is obtained.
[0037] like Figure 3As shown, the composite structure of this invention in the experiment is a cuboid with a square base of 29 mm on each side and a height of 10.2 mm. It comprises 10 layers of micro / nano gradient fibers, each 1 mm thick with a two-stage gradient. The two stages in each layer are made of polyacrylonitrile (PAN) with an average pore size of 6.9 nm and polypropylene (PP) with an average pore size of 8.6 μm, respectively. Both PAN and PP have a porosity of 85%. The two materials in each of the 10 gradient fiber layers are arranged identically, with PP on top and PAN on the bottom. A cylindrical cavity with a bottom diameter of 23 mm and a height of 6 mm is centrally located between the third to eighth layers. A taut PI film 6 is placed between the fifth and sixth layers, with a small cylindrical lead block 7, 3 mm in diameter and 1.5 mm high, adhered to the center of the film. The film has a thickness of 0.2 mm.
[0038] The density of the PI film is 1200 kg / m³. 3 The Young's modulus is 0.36 x 10⁻⁶. 9 Pa, Poisson's ratio is 0.32. A small cylindrical lead block with a diameter of 3 mm and a height of 1.5 mm is attached to the center of the PI film. The density of the lead block is 11340 kg / m³. 3 The Young's modulus is 16 x 10⁻⁶. 9 Pa, Poisson's ratio is 0.44.
[0039] The first and second layers form a gradient fiber layer; the ninth and tenth layers form a gradient fiber layer; and the third to eighth layers form a thin-film acoustic metamaterial layer.
[0040] The following are the comparative materials used in the experiment:
[0041] The ordinary fiber material used in the experiment was a cuboid: its base was a square with a side length of 29 mm and a height of 10 mm. It was polypropylene (PP) with an average pore size of 8.6 μm and a porosity of 85%. Ordinary fibers do not have tiers.
[0042] The traditional thin-film acoustic metamaterial used in the experiment was a cuboid: its base was a square with a side length of 29 mm and a height of 6 mm. The material was ABS resin with a density of 1160 kg / m³. 3 The Young's modulus is 2.3 x 10⁻⁶. 9 Pa, Poisson's ratio is 0.375. There is a cylindrical through-hole with a diameter of 23 mm in the center. A taut PI film is horizontally arranged 3 mm from the bottom surface. The density of the PI film is 1200 kg / m³. 3 The Young's modulus is 0.36 x 10⁻⁶. 9 Pa, Poisson's ratio is 0.32. A small cylindrical lead block with a diameter of 3 mm and a height of 1.5 mm is attached to the center of the PI film. The density of the lead block is 11340 kg / m³.3 The Young's modulus is 16 x 10⁻⁶. 9 Pa, Poisson's ratio is 0.44. The PI film and small lead blocks used in the conventional thin-film acoustic metamaterials in the experiment are the same materials used in the composite structure of the present invention in the experiment.
[0043] like Figure 4 As shown, the horizontal axis represents the frequency range of 0-6400Hz, and the vertical axis represents sound transmission loss. A higher sound transmission loss indicates better sound insulation. Traditional thin-film acoustic metamaterials have better sound insulation performance than ordinary fibers in the low-frequency range, but at other frequencies, their sound insulation performance is weaker than that of ordinary fibers. It can be seen that the sound insulation effect of traditional thin-film acoustic metamaterials is significant in the 0-1000Hz range. The structure of this invention, however, exhibits better sound insulation performance than both comparative materials across all frequency ranges.
[0044] like Figure 5 As shown, the horizontal axis represents the frequency range of 500-6000Hz, and the vertical axis represents the sound absorption coefficient. A higher sound absorption coefficient indicates better sound absorption. In the 500-1500Hz range, ordinary fiber materials and traditional thin-film acoustic metamaterials have similar effects. In the 1500-3000Hz and 3500-6000Hz ranges, ordinary fiber materials show significantly higher sound absorption than traditional thin-film acoustic metamaterials. In the 3000-3500Hz range, traditional thin-film acoustic metamaterials outperform ordinary fibers. It can be seen that in the 5000-6000Hz range, ordinary fiber materials exhibit significant sound absorption. The structure of this invention combines the advantages of both materials, achieving better sound absorption at all frequencies except for a slightly lower sound absorption effect than ordinary fibers in the 4500-5500Hz range.
[0045] Therefore, the composite structure of the present invention exhibits excellent sound insulation and sound absorption performance, making it highly suitable for various applications requiring efficient sound insulation and sound absorption.
Claims
1. A composite structure of micro / nano gradient fibers and thin-film acoustic metamaterials, characterized in that: It includes a first gradient fiber layer, a second gradient fiber layer, and a thin-film acoustic metamaterial layer disposed between the first gradient fiber layer and the second gradient fiber layer, wherein: The first gradient fiber layer and the second gradient fiber layer are each composed of several layers of micro-nano gradient fiber layers; The thin-film acoustic metamaterial layer has a three-layer structure, including two outer layers and an intermediate layer disposed between the two outer layers. Each outer layer is a micro-nano gradient fiber layer with uniformly spaced through holes, and there are several layers of the micro-nano gradient fiber layer. The intermediate layer is a thin film, and a metal block is bonded to the center of the thin film located in the through holes. Low-frequency noise is absorbed by the vibration of the metal block on the thin film. The micro-nano gradient fiber layers that make up the first gradient fiber layer and the second gradient fiber layer, as well as the micro-nano gradient fiber layers in the thin film acoustic metamaterial layer, are all micro-nano fiber layers with an average pore size gradient distribution, used to absorb high-frequency noise. The micro-nano fiber layers are composed of micron fiber layers and nano fiber layers. The porosity of the micro-nano gradient fiber layer is 80%-95%; the average pore size of the micron fiber layer is 2-10 μm, and the average pore size of the nanofiber layer is 5-10 nm.
2. The composite structure of micro / nano gradient fibers and thin-film acoustic metamaterials according to claim 1, characterized in that: The micron fiber layer is a polypropylene fiber layer, a polyester fiber layer, or a polyethylene fiber layer, and the nanofiber layer is a polyacrylonitrile fiber layer or a polyvinyl alcohol fiber layer.
3. The composite structure of micro / nano gradient fibers and thin-film acoustic metamaterials according to claim 1, characterized in that: The film is a polyimide film, a polyvinyl chloride film, or a polyethylene film.
4. The composite structure of micro / nano gradient fibers and thin-film acoustic metamaterials according to claim 1, characterized in that: The through-holes and small metal blocks are square or circular in shape.
5. The micro / nano gradient fiber and thin-film acoustic metamaterial composite structure according to any one of claims 1-4, characterized in that: There are one or more through holes.