A coupled lightweight, high-strength, impact-resistant biomimetic multi-scale multi-cellular sandwich structure

Abstract

The present invention belongs to the technical field of high-performance protective structures, specifically a coupled lightweight, high-strength, impact-resistant biomimetic multi-scale multicellular sandwich structure. The structure comprises a surface layer, an adhesive layer, and an intermediate layer, wherein the intermediate layer is sequentially provided with an adhesive layer and a surface layer on either side. The intermediate layer is composed of a plurality of biomimetic multi-scale multicellular structures, each comprising a first-level cylindrical filled multicellular structure, a novel composite multicellular structure, and a non-Newtonian fluid filled between the outer wall of the first-level cylindrical filled multicellular structure and the inner wall of the novel composite multicellular structure. Compared with traditional methods, the present invention aims to improve the compressive strength, impact resistance, and energy absorption performance of the protective structure while achieving a lightweight design.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-performance protection, and in particular relates to a bionic multi-cellular sandwich protection structure. Background Art

[0002] Multicellular sandwich protective structures are widely used in transportation engineering, aerospace, military equipment, ship engineering and other fields due to their excellent characteristics such as high specific strength, specific energy absorption and light weight. However, with the increasing requirements for the crashworthiness of structures in high-tech fields such as automobiles, high-speed trains, high-speed ships, aerospace vehicles and return capsules, the existing sandwich protective structures commonly used at home and abroad have problems with impact resistance, shock absorption and buffering, and insufficient energy absorption in the event of high-speed collisions, thus posing a safety hazard. At the same time, with the progress of society, humans are paying more and more attention to the environment and sustainable development, and thus realizing lightweight design of structures to reduce fuel consumption has become a focus of increasing attention. Therefore, the development of a sandwich protective structure with light weight, better energy absorption effect, stronger impact resistance and better mechanical properties has become a more urgent need in various fields.

[0003] Researchers have discovered a novel multi-scale, multi-cellular sandwich structure based on microscopic observations of natural Thousand-Eyed Bodhi wood. This structure exhibits low density, excellent compressive and impact resistance, and energy absorption, while also possessing multi-level reinforcement and toughening mechanisms. Therefore, the present invention, inspired by the natural Thousand-Eyed Bodhi wood structure, employs a biomimetic design to create a coupled, lightweight, high-strength, and impact-resistant biomimetic multi-scale multi-cellular sandwich structure. Summary of the Invention

[0004] In order to solve the problems existing in the above-mentioned prior art, the present invention provides a coupled lightweight, high-strength, impact-resistant bionic multi-scale multi-cellular sandwich structure. The bionic multi-scale multi-cellular sandwich structure aims to solve the bottleneck problem that lightweighting and its compression resistance, impact resistance and energy absorption performance cannot be improved together.

[0005] A bionic multi-scale multicellular sandwich protective structure comprises a surface layer, an adhesive layer and an intermediate layer, wherein the adhesive layer and the surface layer are arranged on both sides of the intermediate layer in sequence; the intermediate layer is composed of a plurality of bionic multi-scale multicellular cellular structures, and the bionic multi-scale multicellular cellular structure comprises a first-level cylindrical filled multicellular cellular structure and a novel composite multicellular structure, and a non-Newtonian fluid filled between the outer wall of the first-level cylindrical filled multicellular cellular structure and the inner wall of the novel composite multicellular structure.

[0006] Preferably, from the perspective of the macroscopic, mesoscopic and microscopic scales in natural science, the intermediate layer multi-scale polycellular structure is composed of a first-level cylindrical filled polycellular structure on the macroscopic scale, a second-level square closed-pore polycellular structure on the mesoscopic scale, and a second-level combined polycellular structure consisting of the second-level square closed-pore polycellular structure and the third-level circular pore polycellular structure on the microscopic scale.

[0007] Preferably, the inner wall of the novel composite multicellular structure is composed of a second-level closed-cell multicellular structure and a secondary combined multicellular structure, and the thickness of the cell wall of the square tubular novel composite multicellular structure is equal to the sum of 1 times the thickness of the second-level closed-cell multicellular structure and 9 times the thickness of the secondary combined multicellular structure. The inner wall of the cell wall of the square tubular novel composite multicellular structure is composed of an array of second-level closed-cell multicellular structures, and all other components are composed of secondary combined multicellular structures.

[0008] Preferably, the secondary combined multicellular structure is composed of multiple cells in a linear array, the second-level closed-cell multicellular cell structure adopts a square hollow structure, and the open-cell multicellular structure on its cell wall adopts a ring array distribution, which can achieve a lightweight design.

[0009] Preferably, the multi-scale multi-cellular sandwich structure is composed of a first-level cylindrical filling multi-cellular structure vertically penetrating the novel composite multi-cellular structure and tangentially connecting the cell walls to form a multi-scale multi-cellular structure, and a non-Newtonian fluid filling the space between the cylindrical filling multi-cellular structure and the novel composite multi-cellular structure. This combination creates a hierarchical coupling effect that can achieve lightweight design while improving its compressive, impact, and energy absorption performance.

[0010] Preferably, the side length of the square through hole in the center of the novel composite multicellular structure is equal to the circumference of the outer circle of the first-level cylindrical filled multicellular structure.

[0011] Preferably, the surface layer includes an upper surface layer and a lower surface layer, which is a sufficient mixture of A and B structural adhesives, carbon fiber and Kevlar fiber. The carbon fiber has low density, high specific strength and specific modulus, and its specific strength, that is, the ratio of the strength of the material to its density, can reach 2000MPa / (g / cm 3 ) or above. Kevlar fiber, as a synthetic fiber, has excellent impact absorption properties and can dissipate energy by stretching and deforming under the action of force. Adhere these two materials as the upper and lower surface materials to significantly improve the strength, toughness, and impact resistance of the structure through a synergistic effect, while also reducing mass and increasing fatigue resistance.

[0012] Preferably, the intermediate layer multi-scale multi-cellular sandwich structure is prepared by 3D printing of lightweight alloy powder.

[0013] Preferably, the bionic sandwich protective structure is formed by bonding the middle layer to the surface layer on both sides through adhesive layers, and is hot-pressed into one piece using a hot-pressing process.

[0014] Preferably, the bionic multi-scale multicellular sandwich structure of the present invention resists damage from external loads. First, the microscopic third-level open-cell multicellular structure induces the appearance of microcracks; as the external load increases, the microcracks further expand, and the second-level closed-cell multicellular structure on the mesoscopic scale exhibits energy absorption mechanisms such as cell wall bending, plastic buckling, and multiple cracks; at the same time, the first-level filled multicellular structure exhibits energy absorption mechanisms such as bending, crack expansion, fiber pullout, and tearing. The combination of the first-level filled multicellular structure on the macroscopic scale with the second-level and third-level multicellular structures produces a hierarchical coupling effect, which improves energy absorption performance and load-bearing capacity while reducing mass.

[0015] Preferably, the relationship between different scales of the bionic multi-scale sandwich multicellular structure is microscopic scale (10 - 3 mm)<mesoscopic scale (10 -1 mm)<macroscale(10 2 mm).

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. The upper and lower surface layers of the bionic multi-scale cellular sandwich structure in the present invention are made of carbon fiber and Kevlar fiber. The first-level filling cellular structure adopts carbon fiber material, which not only meets the requirements of material energy absorption and impact resistance but also has excellent compressive resistance. It not only plays a certain supporting role in the vertical direction, but also does not undergo huge deformation when the structure faces large energy. The structural stability is good, which reduces the probability of deformation of the structure due to excessive impact energy and extends the life of the structure.

[0018] 2. The multi-scale multi-cellular interlayer of the present invention adopts a cavity structure, such as the cavity structure of the second-level closed-cell multi-cellular structure and the square through-hole and filled circular tubular multi-cellular structure adopted in the new composite multi-cellular structure, which reduces the mass and, to a certain extent, also reduces the cost and saves raw materials.

[0019] 3. The non-Newtonian fluid filled in the multi-scale multi-cellular structure of the present invention undergoes a shear thickening effect as the impact velocity increases, thereby improving the impact resistance of the sandwich structure.

[0020] 4. The materials selected in the present invention, such as carbon fiber and aluminum alloy, all meet the requirements of lightweight.

[0021] 5. The multi-scale multi-cellular structure of the present invention is formed in one go through 3D printing technology, and the processing is convenient and flexible.

[0022] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 It is a schematic diagram of the bionic multi-scale multi-cellular sandwich structure of the present invention.

[0025] Figure 2 It is a schematic structural diagram of the bionic multi-scale multi-cellular sandwich layer of the present invention.

[0026] Figure 3 It is a schematic diagram of the multi-scale multi-cell structure of the present invention.

[0027] Figure 4 It is a schematic diagram of the secondary combined multicellular structure of the present invention.

[0028] Figure 5 This is a partially enlarged view of the multi-scale multi-cellular structure of the present invention.

[0029] In the figure: 1. Surface layer, 2. Adhesive layer, 3. Middle layer, 4. First-level cylindrical filled multicellular structure, 5. New composite multicellular structure, 6. Non-Newtonian fluid, 7. Second-level square closed-cell multicellular structure, 8. Third-level circular open-cell multicellular structure. DETAILED DESCRIPTION

[0030] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0031] like Figure 1-2As shown, the bionic multi-scale multicellular sandwich structure includes a surface layer 1, an adhesive layer 2 and an intermediate layer 3, wherein the adhesive layer 2 and the surface layer 1 are arranged on both sides of the intermediate layer 3 in sequence; the intermediate layer 3 is composed of a plurality of bionic multi-scale multicellular cell structures, and the bionic multi-scale multicellular cell structure includes a first-level cylindrical filled multicellular cell structure 4 and a novel composite multicellular structure 5 and a non-Newtonian fluid 6 filled between the outer wall of the first-level cylindrical filled multicellular cell structure 4 and the inner wall of the novel composite multicellular structure 5.

[0032] The following is a method for preparing the biomimetic multi-scale multi-cellular sandwich structure, comprising the following steps:

[0033] Step 1: After the carbon fiber and Kevlar fiber are fully mixed with A and B structural adhesives to form an overall surface layer, it is placed at room temperature for five hours to cure, thereby forming an overall upper and lower surface layer 1, that is, the upper and lower panels of the bionic multi-scale multi-cellular sandwich structure.

[0034] Step 2: The first-level cylindrical filling multicellular element 4 in the middle layer 3 multi-scale multicellular structure is made of carbon fiber reinforced material and is extruded into a cylindrical tubular structure.

[0035] Step 3: The multi-scale multi-cellular structure of the middle layer 3 is printed using 3D printing technology, and the 3D printing material can be lightweight materials such as aluminum alloy and magnesium aluminum alloy.

[0036] like Figure 4-5 As shown, the ratio of the diameter (d) of the third-level circular open-cell multicellular structure 8 to the thickness (t) of the second-level square closed-cell multicellular structure 7 is controlled to be 3-4, that is, 3≤t / d≤4, and the diameter (d) is 50-100μm. The third-level circular open-cell multicellular structure 8 is first located at the center of the second-level square closed-cell multicellular structure 7. Then, with this cell as the array center, an array of 12 cells with equal spacing and an array radius of 4d is formed. Then, a circular array is formed again with an array radius of 8d and 12 cells, distributed on the second-level square closed-cell multicellular structure 7.

[0037] The dimensions of the second-stage square closed-cell multicellular structure 7 are equal to those of the second-stage assembled multicellular structure in terms of length (l), width (w), height (h), and thickness (t). Furthermore, the length:width:height ratio of the second-stage assembled multicellular structure is 1:1:1, and the length-to-thickness ratio is controlled within the range of 5-7.5, i.e., 5≤l / t≤7.5.

[0038] The wall thickness (T) of the novel composite multicellular structure 5 is equal to 3-5 times the length (l) of the second-stage square closed-cell multicellular structure 7, that is, 3l≤T≤5l, and the innermost wall thickness of the cell wall of the novel composite multicellular structure 5 is equal to the length of the second-stage square closed-cell multicellular structure 7, and the remaining cell wall is composed of the combined multicellular structure. The ratio of its wall thickness to the length of the combined multicellular structure is controlled at 2-3, that is, 2l≤T 剩 ≤4l.

[0039] like Figure 3 As shown, the length (L) and width (W) of the novel composite multicellular structure 5 are equal, i.e., L / W=1, the ratio of its height (H) to width is controlled between 2-3, i.e., 2≤H / L≤3, and the ratio of its length to thickness is controlled between 5-6, i.e., 5≤L / T≤6.

[0040] like Figure 3 As shown, the outer diameter (D1) of the first-level cylindrical filled multicellular structure 4 is equal to the circumference of the inner wall of the new composite multicellular structure 5. In addition, the difference between its outer diameter (D1) and inner diameter (D2) is only 1 mm, that is, D1-D2=2 mm, and the height of the first-level cylindrical filled multicellular structure 4 is equal to the height of the new composite multicellular structure 5.

[0041] The outer cell walls of the first-stage cylindrical filled multicellular structure 4 are tangential to the inner cell walls of the new composite multicellular structure 5. They are bonded using structural adhesives A and B. The structure is then placed in a vacuum environment for three hours to remove air bubbles and solidify. The carbon fiber filling provides vertical support for the unit cells, while also strengthening and toughening them. After solidification, the structure is filled with a non-Newtonian fluid 6 and placed in a vacuum environment for five hours to remove air bubbles.

[0042] Step 4: Use a hot pressing process to stick the upper and lower panels and the middle layer 3 formed by 3D printing together to obtain the target structure.

Claims

1. A bionic sandwich protective structure, comprising a surface layer (1), an adhesive layer (2) and an intermediate layer (3), wherein the adhesive layer (2) and the surface layer (1) are sequentially arranged on both sides of the intermediate layer (3), characterized in that: The intermediate layer (3) is composed of a plurality of biomimetic multi-scale multi-cellular structures, wherein the biomimetic multi-scale multi-cellular structures include a first-level cylindrical filled multi-cellular structure (4) and a square tubular novel composite multi-cellular structure (5) on a macroscopic scale, and a non-Newtonian fluid (6) filled between the outer wall of the first-level cylindrical filled multi-cellular structure (4) and the inner wall of the novel composite multi-cellular structure (5); the inner wall of the novel composite multi-cellular structure (5) is composed of a second-level square closed-pore multi-cellular structure (7) on a mesoscopic scale, and the remaining wall thickness is composed of a second-level combined cell structure array distribution, wherein the second-level square closed-pore multi-cellular structure (7) is a cavity structure having a cube-shaped cavity inside; the second-level combined cell structure is composed of a second-level square closed-pore multi-cellular structure (7) and a third-level circular open-pore multi-cellular structure (8) on a microscopic scale distributed in a ring array on the cell wall of the second-level square closed-pore multi-cellular structure (7).

2. The bionic sandwich protective structure according to claim 1, characterized in that: The intermediate layer (3) is distributed in a linear array using a bionic multi-scale multi-cellular structure as a basic unit.

3. The bionic sandwich protective structure according to claim 1, characterized in that: The surface layer (1) comprises an upper surface layer and a lower surface layer, and is a sufficient mixture of A and B structural adhesives, carbon fibers and Kevlar fibers.

4. The bionic sandwich protective structure according to claim 1, characterized in that: The intermediate layer (3) is prepared by 3D printing of light alloy powder.

5. The bionic sandwich protective structure according to any one of claims 1 to 4, characterized in that: Both sides of the intermediate layer (3) are bonded to the surface layer (1) via adhesive layers (2) and are integrally formed by hot pressing using a hot pressing process.

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