A non-woven cloth trans-scale sound absorption-bearing integrated material based on a bionic turtle shell structure and a preparation method thereof

Abstract

The present application relates to a kind of nonwoven cloth across scale sound-absorbing-carrying integrated material based on bionic turtle shell structure and its preparation method, the material includes successively from top to bottom: surface layer plane nonwoven cloth, first bionic turtle shell arc nonwoven cloth layer, second bionic turtle shell arc nonwoven cloth layer and bottom layer plane nonwoven cloth;The first and second bionic turtle shell arc nonwoven cloth layer surface has periodic arrangement arc unit, and the convex surface of the arc unit of two bionic turtle shell arc nonwoven cloth layer is opposite and adheres, forms the core layer with hollow rhombic cavity array;The surface layer, bottom layer plane nonwoven cloth are respectively adhered to the concave surface of the arc unit of first and second bionic turtle shell arc nonwoven cloth layer, constitute semicircular cavity.The present application is through bionic turtle shell structure and hollow rhombic cavity, synergistically improves the lightweight, high carrying and cross-scale wideband sound-absorbing performance of material, applicable to building acoustics, traffic noise reduction and industrial protection and other fields.

Description

Technical Field

[0001] This invention belongs to the field of sound-absorbing materials and structural acoustics, and specifically relates to a nonwoven fabric cross-scale sound-absorbing and load-bearing integrated material based on a biomimetic turtle shell structure and its preparation method. Background Technology

[0002] With the acceleration of urbanization, environmental noise has become a significant source of pollution affecting residents' quality of life and health. To address the severe challenge of noise pollution, there is an urgent need to develop new sound-absorbing materials and noise reduction technologies that offer superior performance, lighter weight, and wider applicability. Existing sound-absorbing materials mainly rely on the frictional energy dissipation mechanism of porous media, such as nonwoven fabrics, foam materials, and fiber composites. Their sound absorption performance is highly dependent on microscale inter-fiber friction, making it difficult to actively control acoustic impedance and resulting in insufficient sound absorption capacity in the mid-to-low frequency range. Furthermore, traditional nonwoven fabrics have a loose structure and are prone to collapse, making it difficult to meet the integrated application requirements that need to balance mechanical load-bearing capacity and sound absorption performance.

[0003] In recent years, the introduction of acoustic metamaterials and biomimetic structural concepts has enabled the absorption of low-frequency sound waves on a small scale by constructing Helmholtz cavities, labyrinth structures, or local resonant units, breaking through the mass-thickness law of traditional materials. However, existing metamaterials mostly use rigid, dense materials to achieve precise structures, making it difficult to simultaneously meet the requirements of lightweight, flexible conformability, and multi-mechanism synergistic broadband sound absorption.

[0004] Existing technologies, such as Chinese patent CN120206925A, propose a sound-absorbing needle-punched nonwoven composite material and its preparation method. This material achieves synergistic sound absorption through the stacking of porous layers, resonant layers, and damping layers. However, the overall structure remains a macroscopic interlayer stack of different materials, without active acoustic design of the internal structure of the nonwoven fabric, resulting in limited improvement in low-frequency sound absorption. Chinese patent CN221446801U proposes a low-frequency sound-absorbing and insulating structure using an ultra-wideband bow-shaped local resonant acoustic metamaterial. This structure constructs a mass-spring resonant unit using a plastic bow-shaped spring and an aluminum block scatterer, mounted on an acrylic substrate. However, this structure relies on the precise geometric configuration and mechanical resonance of rigid materials, exhibiting a dense and rigid overall structure with a single sound absorption mechanism. It is difficult to bend or fit onto complex surfaces and struggles to achieve both lightweight material and wideband sound absorption. Therefore, a novel sound-absorbing system is urgently needed that can overcome the limitations of traditional porous materials while possessing both structural robustness and active acoustic control capabilities. Summary of the Invention

[0005] The technical problem to be solved by this invention is to address the shortcomings of existing nonwoven sound-absorbing materials, such as insufficient mechanical load-bearing capacity, poor low-frequency sound absorption performance, and narrow sound absorption bandwidth. This invention provides a nonwoven fabric with a biomimetic turtle shell structure that integrates sound absorption and load-bearing capacity across scales, and its preparation method. The aim is to achieve the integration of lightweight, wide-band high-efficiency sound absorption and high mechanical load-bearing capacity.

[0006] This invention provides a nonwoven fabric cross-scale sound absorption-load-bearing integrated material based on a biomimetic turtle shell structure. The material has a laminated structure, comprising, from top to bottom: a surface planar nonwoven fabric, a first biomimetic turtle shell arc-shaped nonwoven fabric layer, a second biomimetic turtle shell arc-shaped nonwoven fabric layer, and a bottom planar nonwoven fabric. The surfaces of the first and second biomimetic turtle shell arc-shaped nonwoven fabric layers have periodically arranged arc-shaped units, and the convex surfaces of the arc-shaped units of the two biomimetic turtle shell arc-shaped nonwoven fabric layers are relatively attached to each other to form a core layer with a hollow rhomboid cavity array. The surface and bottom planar nonwoven fabrics are respectively attached to the concave surfaces of the arc-shaped units of the first and second biomimetic turtle shell arc-shaped nonwoven fabric layers to form a semi-circular cavity.

[0007] Preferably, the arc-shaped unit is a spherical or quasi-spherical structure, and the ratio of its arc height h to its bottom radius R, h / R, is 0.2 to 1.0. The cavity volume and acoustic performance can be controlled by adjusting this ratio.

[0008] Preferably, the total thickness of the material ranges from 3 to 20 mm.

[0009] Preferably, the thickness of the nonwoven fabric of the surface layer, core layer, and bottom layer is 1~8 mm.

[0010] Preferably, the hollow rhomboid cavity array of the core layer can be an equally spaced array, a gradually changing array, or a multi-scale composite array of large and small units superimposed. By adjusting the cavity arrangement, the sound absorption bandwidth can be broadened and the sound absorption frequency distribution can be adjusted.

[0011] Preferably, the first and second biomimetic tortoise shell arc-shaped nonwoven fabric layers are made of thermoplastic fiber nonwoven fabric by hot pressing; wherein, the substrate of the thermoplastic nonwoven fabric is thermoplastic polymer fiber, including but not limited to polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyamide (PA6, PA66), polyurethane (TPU), polylactic acid (PLA), ethylene-vinyl acetate copolymer (EVA) or any combination thereof.

[0012] Preferably, the porosity of the nonwoven fabrics of the surface layer, core layer and bottom layer is designed to have a gradient distribution to achieve acoustic impedance matching, and the overall gradient porosity range is 50%~90%; wherein, the porosity of the surface nonwoven fabric is 75%~90%, the porosity of the core nonwoven fabric is 65%~85%, and the porosity of the bottom nonwoven fabric is 50%~75%.

[0013] This invention also provides a method for preparing a nonwoven multi-scale sound-absorbing and load-bearing integrated material based on a biomimetic tortoise shell structure, comprising the following steps:

[0014] (1) Preparation of nonwoven fabric substrate

[0015] The fiber raw materials are processed into a fiber web through opening, carding and web forming processes. The fiber web is then reinforced. Based on the porosity gradient design, surface, core and bottom nonwoven fabrics are prepared respectively.

[0016] (2) Forming of biomimetic turtle shell structure

[0017] A biomimetic turtle shell structure was constructed using software, and a punch and a die for hot pressing were prepared by 3D printing. The core layer nonwoven fabric was placed into the mold for hot pressing, so that the fibers rearranged and shaped, resulting in a biomimetic turtle shell structure with periodic arc units.

[0018] (3) Construction of the hollow cavity core layer

[0019] Two arc-shaped units of the biomimetic turtle shell structure described in step (2) are placed face to face and bonded together by local point bonding to form a core layer with an array of hollow rhomboid cavities inside.

[0020] (4) Assembly of laminated structures

[0021] In step (1), the surface nonwoven fabric and the bottom nonwoven fabric are respectively bonded to the concave surfaces of the upper and lower arc-shaped units of the core layer in step (3), thereby obtaining a material consisting of a surface planar nonwoven fabric, a first biomimetic tortoise shell arc-shaped nonwoven fabric, a second biomimetic tortoise shell arc-shaped nonwoven fabric, and a bottom planar nonwoven fabric from top to bottom.

[0022] Preferably, the reinforcement method in step (1) includes needle punching, melt spraying, hot air or hot rolling processes.

[0023] Preferably, step (1) achieves a gradient distribution of porosity by adjusting the areal density, needle punching density, or hot rolling degree of the surface, bottom, and core nonwoven fabrics.

[0024] Preferably, before hot pressing in step (2), the core nonwoven fabric is preheated or pre-impregnated with a low-concentration adhesive to improve its structural shaping accuracy and mechanical load-bearing capacity.

[0025] Preferably, the hot pressing parameters in step (2) are: the hot pressing temperature is higher than the glass transition temperature of the fiber and lower than the melting point of the fiber by 10~50 ℃, the hot pressing pressure is 0.2~0.8 MPa, and the holding time is 1~5 min.

[0026] Preferably, the material used for 3D printing in step (2) is a photocurable resin or a high-precision polymer to ensure the geometrical accuracy of the arc-shaped unit.

[0027] Preferably, the bonding method in steps (3) and (4) is selected from dot hot melt bonding, ultrasonic welding or adhesive dot bonding; the bonding medium is biodegradable hot melt adhesive, TPU hot melt film or low melting point fiber; the dot pattern is round dots, grid or elliptical dot matrix; the bonding area accounts for 20% to 60% to take into account both structural stability and cavity acoustic performance.

[0028] Beneficial effects

[0029] (1) This invention successfully integrates sound absorption function and mechanical load-bearing function into the same material system, realizing functional integration. The hollow tortoise shell cavity core layer endows the material with excellent compressive and bending resistance, overcoming the defects of poor mechanical properties of traditional non-woven sound-absorbing materials.

[0030] (2) This invention achieves cross-scale broadband sound absorption. Macroscopically, the hollow tortoise-shell cavity array can serve as a Helmholtz resonator array. By adjusting the geometric dimensions of the spherical cap shell, efficient absorption of low and mid-frequency sound waves can be achieved. Microscopically, the porous fiber network of the nonwoven fabric itself provides dissipative sound absorption of mid and high-frequency sound waves through viscous loss. The synergistic effect of macroscopic and microscopic mechanisms significantly broadens the sound absorption bandwidth of the material.

[0031] (3) The present invention optimizes acoustic impedance matching by designing a porosity gradient for the surface, core and bottom nonwoven fabrics, so that sound waves can enter the interior of the material more smoothly, reduce interface reflection, and further improve sound absorption efficiency.

[0032] (4) The present invention adopts hot pressing molding process, which is suitable for thermoplastic nonwoven fabric and has high preparation efficiency; combined with 3D printing mold, it realizes accurate and low-cost replication of complex biomimetic structures.

[0033] (5) Under the premise of ensuring excellent sound absorption and mechanical properties, the material structure obtained by the present invention is thin and light, which is particularly suitable for fields with strict requirements on space and weight, such as aerospace, automotive interior, and building sound insulation. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the nonwoven fabric multi-scale sound absorption-load-bearing integrated material based on a biomimetic turtle shell structure, according to the present invention.

[0035] Figure 2This is a front view of the nonwoven fabric multi-scale sound absorption-load-bearing integrated material based on a biomimetic turtle shell structure, according to the present invention.

[0036] Reference numerals: 1-Surface planar nonwoven fabric; 2-First biomimetic tortoise shell arc-shaped nonwoven fabric layer; 3-Second biomimetic tortoise shell arc-shaped nonwoven fabric layer; 4-Bottom planar nonwoven fabric; 5-First semi-circular cavity; 6-Second semi-circular cavity; 7-Hollow rhomboid cavity array. Detailed Implementation

[0037] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0038] The structure of the nonwoven multi-scale sound-absorbing and load-bearing integrated material based on the biomimetic turtle shell structure in this invention is as follows: Figure 1 , Figure 2 As shown, it includes: a surface planar nonwoven fabric 1, a first biomimetic tortoise shell arc-shaped nonwoven fabric layer 2, a second biomimetic tortoise shell arc-shaped nonwoven fabric layer 3, and a bottom planar nonwoven fabric 4; the first and second biomimetic tortoise shell arc-shaped nonwoven fabric layers are made of thermoplastic fiber nonwoven fabric by hot pressing, and their surfaces have periodically arranged arc-shaped units; the arc-shaped units have convex and concave surfaces, and the convex surfaces of the arc-shaped units of the first and second biomimetic tortoise shell arc-shaped nonwoven fabrics are relatively attached to each other to form a core layer with a hollow rhombic cavity array 7; the surface and bottom planar nonwoven fabrics are respectively attached to the concave surfaces of the arc-shaped units of the first and second biomimetic tortoise shell arc-shaped nonwoven fabric layers to form a first semi-circular cavity 5 and a second semi-circular cavity 6, thereby constructing an overall laminated structure.

[0039] Example 1

[0040] This embodiment provides a nonwoven fabric multi-scale sound absorption-load-bearing integrated material based on a biomimetic tortoise shell structure, comprising: a surface layer, a core layer, and a bottom layer. Each layer is made of nonwoven fabric prepared from PET single fibers, but with different thicknesses, porosities, and areal densities to optimize structural and acoustic performance. The thickness is determined according to GB / T 24218.2-2009 "Textiles—Nonwoven Fabrics—Test Methods—Part 2: Determination of Thickness", and the porosity is determined according to GB / T 42697-2023 "Nonwoven Fabrics—Porosity Test Method". The parameters are as follows: the surface layer is a planar nonwoven fabric with a thickness of 2 mm and a porosity of 90%; the core layer includes first and second biomimetic tortoise shell arc-shaped nonwoven fabric layers, each with a thickness of 3 mm and a porosity of 85%; the bottom layer is a planar nonwoven fabric with a thickness of 3 mm and a porosity of 80%. The ratio of the arc height h to the bottom radius R of the arc unit in the first and second biomimetic tortoise shell arc-shaped nonwoven fabric layers is h / R = 0.2.

[0041] The preparation method of the above-mentioned nonwoven multi-scale sound-absorbing and load-bearing integrated material includes the following steps:

[0042] (1) Preparation of nonwoven fabric substrate

[0043] PET fibers are opened, carded, and web-formed to prepare a nonwoven fabric substrate consisting of a surface layer, a core layer, and a bottom layer. The surface and bottom layers are reinforced by needle punching, while the core layer is reinforced by hot air processing to achieve the required thickness and porosity.

[0044] (2) Forming of biomimetic turtle shell structure

[0045] A periodic spherical crown-shaped unit structure model was established using CAD software, and the punch and die were prepared by photopolymerization 3D printing. Before hot pressing, the core layer PET nonwoven substrate was placed in an oven and preheated at 90 ℃ for 3 min to soften the fibers and eliminate internal stress. Subsequently, the core layer PET nonwoven substrate was arranged in the mold and hot-pressed at 240 ℃ and 0.4 MPa for 3 min to form a biomimetic tortoise shell structure with an equally spaced array of spherical crown-shaped units.

[0046] (3) Construction of the hollow cavity core layer

[0047] Two pieces of biomimetic turtle shell structure nonwoven fabric are hot-pressed together, with their convex surfaces facing each other. They are then bonded together with a dotted TPU hot melt mesh film to form a core layer with a hollow diamond-shaped cavity array. The bonding area is 40%, and the bonding points are distributed in a dotted array.

[0048] (4) Assembly of laminated structures

[0049] The top and bottom PET nonwoven fabrics are respectively bonded to the concave surfaces of the upper and lower arc-shaped units of the core layer, and then bonded by dotted TPU hot melt mesh film, with a bonding area of ​​40%, forming a four-layer composite sound-absorbing structure.

[0050] Example 2

[0051] This embodiment provides a nonwoven fabric multi-scale sound absorption-load-bearing integrated material based on a biomimetic turtle shell structure, comprising: a surface layer, a core layer, and a bottom layer. Each layer is made of nonwoven fabric prepared from PET single fibers, but with different thicknesses, porosities, and areal densities to optimize structural and acoustic performance. The parameters measured using the same method as in Embodiment 1 are as follows: the surface layer is a planar nonwoven fabric with a thickness of 3 mm and a porosity of 90%; the core layer includes first and second biomimetic turtle shell arc-shaped nonwoven fabric layers, each with a thickness of 3 mm and a porosity of 80%; the bottom layer is a planar nonwoven fabric with a thickness of 2 mm and a porosity of 70%. The ratio of the arc height h to the bottom radius R of the arc-shaped units in the first and second biomimetic turtle shell arc-shaped nonwoven fabric layers is h / R = 0.5.

[0052] The preparation method of the above-mentioned nonwoven multi-scale sound-absorbing and load-bearing integrated material includes the following steps:

[0053] (1) Preparation of nonwoven fabric substrate

[0054] PET fibers are opened, carded, and web-formed to prepare a nonwoven fabric substrate consisting of a surface layer, a core layer, and a bottom layer. The surface and bottom layers are reinforced by needle punching, while the core layer is reinforced by hot air processing to achieve the required thickness and porosity.

[0055] (2) Forming of biomimetic turtle shell structure

[0056] A periodic spherical crown-shaped unit structure model was established using CAD software, and the punch and die were prepared by photopolymerization 3D printing. Before hot pressing, the core layer PET nonwoven substrate was placed in an oven and preheated at 90 ℃ for 3 min to soften the fibers and eliminate internal stress. Subsequently, the core layer PET nonwoven substrate was arranged in the mold and hot-pressed at 240 ℃ and 0.5 MPa for 3 min to form a biomimetic tortoise shell structure with an equally spaced array of spherical crown-shaped units.

[0057] (3) Construction of the hollow cavity core layer

[0058] Two pieces of biomimetic turtle shell structure nonwoven fabric are hot-pressed together, with the convex surfaces facing each other. They are then bonded together with a dotted TPU hot melt mesh film to form a core layer with a hollow diamond-shaped cavity array. The bonding area is 40%, and the bonding points are distributed in a grid pattern.

[0059] (4) Assembly of laminated structures

[0060] The top and bottom PET nonwoven fabrics are respectively bonded to the concave surfaces of the upper and lower arc-shaped units of the core layer, and then bonded by dotted TPU hot melt mesh film, with a bonding area of ​​40%, forming a four-layer composite sound-absorbing structure.

[0061] Example 3

[0062] This embodiment provides a nonwoven fabric multi-scale sound absorption-load-bearing integrated material based on a biomimetic turtle shell structure, comprising: a surface layer, a core layer, and a bottom layer. Each layer is made of nonwoven fabric prepared from PET single fibers, but with different thicknesses, porosities, and areal densities to optimize structural and acoustic performance. Referring to the same method as in Embodiment 1, the parameters are as follows: the surface layer planar nonwoven fabric has a thickness of 2.5 mm and a porosity of 90%; the core layer includes first and second biomimetic turtle shell arc-shaped nonwoven fabric layers, each with a thickness of 3 mm and a porosity of 75%; the bottom layer planar nonwoven fabric has a thickness of 3 mm and a porosity of 60%. The ratio of the arc height h to the bottom radius R of the arc-shaped unit in the first and second biomimetic turtle shell arc-shaped nonwoven fabric layers is h / R = 0.8.

[0063] The preparation method of the above-mentioned nonwoven multi-scale sound-absorbing and load-bearing integrated material includes the following steps:

[0064] (1) Preparation of nonwoven fabric substrate

[0065] PET fibers are opened, carded, and web-formed to prepare a nonwoven fabric substrate consisting of a surface layer, a core layer, and a bottom layer. The surface and bottom layers are reinforced by needle punching, while the core layer is reinforced by hot air processing to achieve the required thickness and porosity.

[0066] (2) Forming of biomimetic turtle shell structure

[0067] A periodic spherical crown-shaped unit structure model was established using CAD software, and the punch and die were prepared by photopolymerization 3D printing. Before hot pressing, the core layer PET nonwoven substrate was placed in an oven and preheated at 90 ℃ for 3 min to soften the fibers and eliminate internal stress. Subsequently, the core layer PET nonwoven substrate was arranged in the mold and hot-pressed at 240 ℃ and 0.6 MPa for 3 min to form a biomimetic tortoise shell structure with an equally spaced array of spherical crown-shaped units.

[0068] (3) Construction of the hollow cavity core layer

[0069] Two pieces of biomimetic turtle shell structure nonwoven fabric are hot-pressed together, with the convex surfaces facing each other. They are then bonded together with a dotted TPU hot melt mesh film to form a core layer with a hollow rhomboid cavity array. The bonding area is 40%, and the bonding points are distributed in an elliptical dot matrix pattern.

[0070] (4) Assembly of laminated structures

[0071] The top and bottom PET nonwoven fabrics are respectively bonded to the concave surfaces of the upper and lower arc-shaped units of the core layer, and then bonded by dotted TPU hot melt mesh film, with a bonding area of ​​40%, forming a four-layer composite sound-absorbing structure.

[0072] Comparative Example 1

[0073] This comparative example provides a conventional planar nonwoven fabric laminate material, in which each layer is made of PET nonwoven fabric. The surface layer is 2 mm thick with a porosity of 90%; the core layer consists of two layers, each 3 mm thick with a porosity of 85%; and the bottom layer is 3 mm thick with a porosity of 80%. The core layer remains planar, without arc-shaped unit structures or hollow rhomboid cavity arrays.

[0074] The above-mentioned method for preparing traditional planar nonwoven laminate materials includes the following steps:

[0075] (1) Preparation of nonwoven fabric substrate

[0076] PET fibers are opened, combed, and web-formed to prepare nonwoven fabrics of various layers. The surface and bottom layers are needle-punched for reinforcement, and the core layer is hot-air reinforced.

[0077] (2) Core layer bonding

[0078] Two planar core layers are bonded together using a dotted TPU hot melt mesh film, with a bonding area of ​​approximately 40% and the bonding points distributed in a circular dot array.

[0079] (3) Assembly of laminated structures

[0080] The surface layer, core layer and bottom layer are stacked and bonded together with a dotted TPU hot melt mesh film, with a bonding area of ​​about 40%, forming a traditional planar sound-absorbing structure.

[0081] The following performance tests were performed on the nonwoven materials prepared in Examples 1-3 and Comparative Example 1:

[0082] 1) Sound absorption performance test

[0083] The test was conducted according to GB / T 18696.2-2002 "Acoustics - Measurement of absorption coefficient and acoustic impedance in impedance tubes - Part 2: Transfer function method", with the frequency range set to 800-6300 Hz.

[0084] 2) Cyclic compression and elastic recovery test

[0085] Using a universal testing machine, the maximum compressive strain was set to 50%, and 100 cycles of compression testing were performed at a speed of 2 mm / min. The thickness recovery rate after the 100th cycle was recorded.

[0086] The test results are shown in Table 1. Under the same test conditions, the material described in this invention achieves an average sound absorption coefficient of up to 0.75 in the 800-6300 Hz frequency band, a 74% improvement over traditional planar structures, with a maximum sound absorption coefficient of 0.95. In terms of mechanical stability, after 100 cycles of compression, the material maintains a thickness recovery rate of over 88%, approximately 29% higher than traditional methods, and the maximum compressive stress is more than doubled. This invention, while maintaining the lightweight and flexible characteristics of nonwoven fabrics, significantly outperforms traditional planar laminated materials, achieving a cross-scale synergistic improvement in sound absorption performance and mechanical robustness.

[0087] Table 1 Performance test results of the nonwoven materials prepared in Examples 1-3 and Comparative Example 1

[0088]

Claims

1. A nonwoven cloth cross-scale sound-absorbing-carrying integrated material based on a bionic turtle shell structure, characterized in that, The material has a laminated structure, comprising, from top to bottom: a surface planar nonwoven fabric, a first biomimetic tortoise shell arc-shaped nonwoven fabric layer, a second biomimetic tortoise shell arc-shaped nonwoven fabric layer, and a bottom planar nonwoven fabric; the surfaces of the first and second biomimetic tortoise shell arc-shaped nonwoven fabric layers have periodically arranged arc-shaped units, and the convex surfaces of the arc-shaped units of the two biomimetic tortoise shell arc-shaped nonwoven fabric layers are fitted together to form a core layer with a hollow rhomboid cavity array; the surface and bottom planar nonwoven fabrics are respectively fitted to the concave surfaces of the arc-shaped units of the first and second biomimetic tortoise shell arc-shaped nonwoven fabric layers to form a semi-circular cavity.

2. The nonwoven sound-absorbing-carrying integrated material based on the bionic turtle shell structure according to claim 1, characterized in that, The arc-shaped unit is a spherical or quasi-spherical structure, and the ratio of its arc height h to its bottom radius R, h / R, is 0.2 to 1.

0. 3.The nonwoven sound-absorbing and load-carrying integrated material based on the bionic turtle shell structure according to claim 1, wherein, The total thickness of the material ranges from 3 to 20 mm; the thickness of the nonwoven fabric of the surface layer, core layer, and bottom layer is 1 to 8 mm.

4. The nonwoven sound-absorbing-carrying integrated material based on the bionic turtle shell structure according to claim 1, characterized in that, The first and second biomimetic tortoise shell arc-shaped nonwoven fabric layers are made by hot pressing of thermoplastic fiber nonwoven fabric; wherein, the substrate of the thermoplastic nonwoven fabric is thermoplastic polymer fiber, including any one or a combination of several of polypropylene, polyethylene, polyethylene terephthalate, polybutylene terephthalate, polyamide, polyurethane, polylactic acid, and ethylene-vinyl acetate copolymer.

5. The nonwoven sound-absorbing-carrying integrated material based on the bionic turtle shell structure according to claim 1, characterized in that, The porosity of the nonwoven fabrics in the surface layer, core layer, and bottom layer is designed to have a gradient distribution, with an overall gradient porosity range of 50% to 90%; specifically, the porosity of the surface nonwoven fabric is 75% to 90%, the porosity of the core nonwoven fabric is 65% to 85%, and the porosity of the bottom nonwoven fabric is 50% to 75%.

6. A method for preparing a nonwoven multi-scale sound-absorbing and load-bearing integrated material based on a biomimetic tortoise shell structure, comprising the following steps: (1) The fiber raw material is opened, combed and formed into a fiber web, and the fiber web is reinforced. According to the porosity gradient design, the surface layer, core layer and bottom layer nonwoven fabrics are prepared respectively. (2) The structure of a turtle shell was simulated using software, and the punch and die for hot pressing were prepared by 3D printing. The core nonwoven fabric is placed into a mold and hot-pressed to rearrange and shape the fibers, thus producing a biomimetic tortoise shell structure with periodic arc units. (3) The two arc-shaped units of the biomimetic turtle shell structure described in step (2) are placed face to face and bonded together by local point bonding to form a core layer with a hollow rhomboid cavity array inside. (4) The surface nonwoven fabric and the bottom nonwoven fabric in step (1) are respectively bonded to the concave surface of the upper and lower arc-shaped units of the core layer in step (3), thereby obtaining a material consisting of a surface planar nonwoven fabric, a first biomimetic tortoise shell arc-shaped nonwoven fabric, a second biomimetic tortoise shell arc-shaped nonwoven fabric, and a bottom planar nonwoven fabric from top to bottom.

7. The preparation method according to claim 6, characterized in that, The reinforcement methods in step (1) include needle punching, melt spraying, hot air or hot rolling processes.

8. The preparation method according to claim 6, characterized in that, Before hot pressing in step (2), the core nonwoven fabric is preheated or pre-impregnated with a low-concentration adhesive.

9. The preparation method according to claim 6, characterized in that, The hot-pressing parameters in step (2) are that the hot-pressing temperature is 10-30 DEG C higher than the glass transition temperature of the fiber, the hot-pressing pressure is 0.2-0.8 MPa, and the pressure maintaining time is 1-5 min; and the material used in 3D printing is a photocuring resin or a high-precision polymer.

10. The method of claim 6, wherein, The bonding mode in steps (3) and (4) is selected from point-like hot-melt bonding, ultrasonic welding or adhesive point bonding; the bonding medium is a degradable hot-melt adhesive, a TPU hot-melt film or a low-melting-point fiber; the bonding area ratio is 20%-60%; and the point bonding pattern is a dot, a grid or an elliptical dot array.

Images