A negative poisson's ratio metamaterial incorporating face-centered cubic cells

Abstract

This invention discloses a negative Poisson's ratio metamaterial combining face-centered cubic (FCC) cells. The metamaterial consists of FCC cells and concave cells combined in a specific configuration. This configuration involves first arraying the concave cells into a honeycomb structure, then replacing some of the concave cells in the negative Poisson's ratio honeycomb structure with FCC cells in X- or rhomboid shapes and combining them with other concave cells. Compared to traditional negative Poisson's ratio honeycomb structures, the negative Poisson's ratio metamaterial designed in this invention exhibits a more stable deformation mode and higher energy absorption performance under axial and lateral loads. Furthermore, it maintains excellent mechanical properties under multi-angle impacts, overcoming the shortcomings of extremely unstable deformation and low lateral stiffness of negative Poisson's ratio structures under compressive loads, thus expanding the application prospects of negative Poisson's ratio metamaterials in the field of protective engineering.

Description

Technical Field

[0001] This invention relates to the field of new materials and new structures, specifically to a negative Poisson's ratio metamaterial that incorporates face-centered cubic cells. Background Technology

[0002] Conventional materials expand (contract) under compression (tension). However, materials with a negative Poisson's ratio exhibit the completely opposite deformation behavior; these materials were named "tensile dilatation" by Evans. Besides the negative Poisson's ratio effect, negative Poisson's ratio materials possess many other excellent properties, such as resistance to indentation, shear resistance, fracture resistance, unidirectional curvature, variable permeability, and energy absorption. With further research, negative Poisson's ratio materials and structures have been increasingly applied in civil engineering, medicine, smart materials, and protective engineering. Currently, many negative Poisson's ratio structures are emerging, such as concave structures, chiral structures, and perforated plate structures. Among these, concave structures are frequently studied as energy-absorbing structures. Star-shaped honeycombs, double-arrow honeycombs, and concave honeycombs are three classic examples of concave structures. Concave honeycombs have received particular attention due to their excellent energy absorption and manufacturability. However, this structure often exhibits unstable deformation modes under compressive loads, and its lateral stiffness is far from sufficient.

[0003] Like negative Poisson's ratio structures, face-centered cubic (FCC) lattices are also a type of mechanical metamaterial. Due to their lightweight and high strength, they are widely used in lightweight applications. Leveraging these properties, a novel negative Poisson's ratio hybrid structure is designed by combining FCC cells with concave cells. When the structure is subjected to compressive loads, the internal FCC cells act like the reinforcing ribs of a negative Poisson's ratio honeycomb, stabilizing structural deformation. Furthermore, as a positive Poisson's ratio structure, the FCC cell tends to expand outwards under compressive loads, which is the opposite of the deformation of a negative Poisson's ratio honeycomb. Therefore, the two types of unit cells generate interaction forces under compression, enhancing the energy absorption capacity of the entire structure.

[0004] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide a negative Poisson's ratio metamaterial that incorporates face-centered cubic (FCC) cells. Utilizing the lightweight and high-strength properties of FCC cells, this material is combined with concave cells to design a novel negative Poisson's ratio hybrid honeycomb structure. This overcomes the shortcomings of negative Poisson's ratio structures, such as easy buckling and low lateral stiffness.

[0006] To achieve the above objectives, the present invention provides a negative Poisson's ratio metamaterial incorporating face-centered cubic (FCC) cells, comprising concave cells and FCC cells; the FCC cells are arranged in an X-shape or rhombus shape, and the arrangement shape is consistent with the space occupied by the negative Poisson's ratio honeycomb composed of concave cells; the combination of FCC cells and concave cells forms The structure yields a negative Poisson's ratio metamaterial.

[0007] Preferably, in the above technical solution, the relationship between the length l1 of the upper and lower sides of the concave cell and the overall length l of the concave cell satisfies: 0.7≤l1 / l≤0.88.

[0008] Preferably, in the above technical solution, the thickness t of the concave cell is... r The relationship between the concave cell height h and the concave cell height h satisfies: 6.4 ≤ h / t r ≤20.

[0009] Preferably, in the above technical solution, the relationship between the overall length l of the concave cell and the height h satisfies: 0.7≤h / l≤1.2.

[0010] Preferably, in the above technical solution, the thickness t of the face-centered cubic cell is... F The relationship between the height h and the height h satisfies: 10 ≤ h / t F ≤20.

[0011] Preferably, in the above technical solution, the overall length l and height h of the concave cell must be consistent with the overall length l and height h of the face-centered cubic cell.

[0012] Preferably, in the above technical solution, the thickness t of the concave cell is... r The thickness t of the face-centered cubic cell F The relation satisfies: 0.83 ≤ t r / t F ≤2.

[0013] Preferably, in the above technical solution, the relationship between the overall length L of the structure and the thickness b in the tensile direction of the structure satisfies: 3.84≤L / b≤1.92.

[0014] A method for assembling negative Poisson's ratio metamaterials combining face-centered cubic cells, wherein concave cells and face-centered cubic cells within the structure are combined together according to the following steps: Step 1: Determine the dimensions of the concave cells and face-centered cubic cells, as well as the overall dimensions of the structure, based on the actual application scenario. Step 2, array the concave cells into A square negative Poisson's ratio honeycomb structure; Step 3: Arrange the face-centered cubic cells into an X-shape or a rhombus shape. The arrangement shape must be consistent with the space occupied by the negative Poisson's ratio honeycomb in Step 2. Step 4: Replace the concave cells at the same position in the negative Poisson's ratio honeycomb with the arranged face-centered cubic cells to form a negative Poisson's ratio metamaterial with combined face-centered cubic cells.

[0015] Preferably, the above technical solution further includes step 5, in which finite element software is used to perform mechanical analysis on the negative Poisson's ratio metamaterial with combined face-centered cubic cells to verify its mechanical properties.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The key to generating the negative Poisson's ratio effect in this invention lies in the combination of face-centered cubic (FCC) cells and concave cells. FCC cells need to be combined with concave cells in an X-shape or rhomboid shape to achieve optimal energy absorption characteristics. When the structure is subjected to compressive loads, the internal FCC cells act like reinforcing ribs in a negative Poisson's ratio honeycomb, stabilizing structural deformation. Furthermore, as a positive Poisson's ratio structure, the FCC cell tends to expand outwards under compressive loads, which is the opposite of the deformation of a negative Poisson's ratio honeycomb. Therefore, the two types of cells generate interaction forces under compression, enhancing the energy absorption of the entire structure. According to experiments and finite element analysis, under axial loads, the energy absorption performance of the negative Poisson's ratio metamaterial incorporating FCC cells can be improved by 84.8%; under lateral loads, the energy absorption performance can be improved by 207%.

[0017] The significant advantages of this invention are that it exhibits excellent energy absorption characteristics, stable mechanical response, and deformation mode when subjected to external loads.

[0018] Conventional negative Poisson's ratio structures often exhibit unstable deformation modes under compressive loads, making them prone to buckling. Furthermore, their lateral stiffness is far from sufficient to withstand lateral or oblique impacts.

[0019] The anti-collision structure designed in this invention, which combines face-centered cubic cells and concave cells, exhibits excellent mechanical properties under multi-directional loads. Attached Figure Description

[0020] Figure 1-2 This is an overall diagram of the negative Poisson's ratio metamaterial combining face-centered cubic cells according to the present invention; Figure 3 It is an X-shaped face-centered cubic cell; Figure 4 It is a rhombic face-centered cubic cell; Figure 5 This is a schematic diagram of the concave cell structure; Figure 6 This is a schematic diagram of a face-centered cubic cell structure. Detailed Implementation

[0021] The specific embodiments of the present invention will be described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0022] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0023] like Figure 1-6 As shown, a negative Poisson's ratio metamaterial combining face-centered cubic cells is fabricated using stainless steel (or other materials; generally, ductile metals such as aluminum can achieve good energy absorption). The energy absorption performance of the structure is related to the Young's modulus and yield strength of the material. If the Young's modulus or yield strength of the material is low, the energy absorption performance of the structure will be weaker. However, the deformation mode of the structure under compressive load can maintain a stable state. The metamaterial is prepared using 3D printing technology and includes an internal concave cell 1 and a face-centered cubic cell 2.

[0024] The present invention proposes a negative Poisson's ratio metamaterial combining face-centered cubic cells, wherein the concave cell 1 and face-centered cubic cell 2 within the structure are combined together in a specific form. The process includes the following steps: Step 1: Determine the dimensions of the concave cell and the face-centered cubic cell, as well as the overall dimensions of the structure, based on the actual application scenario. The relationship between the lengths of the top and bottom edges l1 of the concave cell and the overall length l of the concave cell satisfies: 0.7≤l1 / l≤0.88.

[0025] Thickness t of the concave cell r The relationship between the concave cell height h and the concave cell height h satisfies: 6.4 ≤ h / t r ≤20.

[0026] The relationship between the overall length l and height h of the concave cell satisfies: 0.7 ≤ h / l ≤ 1.2.

[0027] The thickness t of a face-centered cubic cell t The relationship between the height h and the height h satisfies: 10 ≤ h / t t ≤20.

[0028] The overall length l and height h of the concave cell must be consistent with the overall length l and height h of the face-centered cubic cell; Thickness t of the concave cell r The thickness t of the face-centered cubic cell t The relation satisfies: 0.83 ≤ t r / t t ≤2; The relationship between the overall length L of the structure and the thickness b in the tensile direction satisfies: 3.84≤L / b≤1.92.

[0029] Step 2, array the concave cells into n n-square negative Poisson's ratio honeycomb structure; Step 3: Arrange the face-centered cubic cells into an X-shape or a rhombus shape. The arrangement shape must be consistent with the space occupied by the negative Poisson's ratio honeycomb in Step 2. Step 4: Replace the concave cells in the same position in the negative Poisson's ratio honeycomb with the arranged face-centered cubic cells to form a negative Poisson's ratio metamaterial with combined face-centered cubic cells. Step 5: Use finite element method (FEM) software to perform mechanical analysis on the negative Poisson's ratio metamaterial with combined face-centered cubic cells to verify its mechanical properties.

[0030] The key to generating the negative Poisson's ratio effect in this invention lies in the combination of face-centered cubic (FCC) cells and concave cells. FCC cells need to be combined with concave cells in an X-shape or rhomboid shape to achieve optimal energy absorption characteristics. When the structure is subjected to compressive loads, the internal FCC cells act like reinforcing ribs in a negative Poisson's ratio honeycomb, stabilizing structural deformation. Furthermore, as a positive Poisson's ratio structure, the FCC cell tends to expand outwards under compressive loads, which is the opposite of the deformation of a negative Poisson's ratio honeycomb. Therefore, the two types of cells generate interaction forces under compression, enhancing the energy absorption of the entire structure. According to experiments and finite element analysis, under axial loads, the energy absorption performance of the negative Poisson's ratio metamaterial incorporating FCC cells can be improved by 84.8%; under lateral loads, the energy absorption performance can be improved by 207%.

Claims

1. A negative Poisson's ratio metamaterial incorporating face-centered cubic cells, characterized in that, Including face-centered cubic cells (2) embedded in concave cells (1) to form n n structure; the face-centered cubic cells (2) are arranged in an X shape or rhombus shape, and the arrangement shape is consistent with the negative Poisson's ratio honeycomb space formed by the occupies concave cells (1).

2. The negative Poisson's ratio supermaterial combining face-centered cubic cells according to claim 1, characterized in that: The relationship between the length l1 of the upper and lower sides of the concave cell and the overall length l of the concave cell satisfies: 0.7≤l1 / l≤0.

88.

3. The negative Poisson's ratio supermaterial combining face-centered cubic cells according to claim 1, characterized in that: The thickness t of the concave cell r The relationship between the concave cell height h and the concave cell height h satisfies: 6.4 ≤ h / t r ≤20.

4. The negative Poisson's ratio supermaterial combining face-centered cubic cells according to claim 1, characterized in that: The relationship between the overall length l and height h of the concave cell satisfies: 0.7 ≤ h / l ≤ 1.

2.

5. The negative Poisson's ratio supermaterial combining face-centered cubic cells according to claim 1, characterized in that: The thickness t of the face-centered cubic cell F The relationship between the height h and the height h satisfies: 10 ≤ h / t F ≤20.

6. The negative Poisson's ratio supermaterial combining face-centered cubic cells according to claim 1, characterized in that: The overall length l and height h of the concave cell must be consistent with the overall length l and height h of the face-centered cubic cell.

7. The negative Poisson's ratio supermaterial combining face-centered cubic cells according to claim 1, characterized in that: The thickness t of the concave cell r The thickness t of the face-centered cubic cell F The relation satisfies: 0.83 ≤ t r / t F ≤2.

8. The negative Poisson's ratio supermaterial combining face-centered cubic cells according to claim 1, characterized in that: The relationship between the overall length L of the structure and the thickness b in the tensile direction satisfies: 3.84≤L / b≤1.

92.

9. A method for assembling negative Poisson's ratio metamaterials combining face-centered cubic cells, characterized in that: The concave cell (1) and face-centered cubic cell (2) inside the structure are combined together according to the following steps: Step 1: Determine the dimensions of the concave cells and face-centered cubic cells, as well as the overall dimensions of the structure, based on the actual application scenario. Step 2, array the concave cells into n n-square negative Poisson's ratio honeycomb structure; Step 3: Arrange the face-centered cubic cells into an X-shape or a rhombus shape. The arrangement shape must be consistent with the space occupied by the negative Poisson's ratio honeycomb in Step 2. Step 4: Replace the concave cells at the same position in the negative Poisson's ratio honeycomb with the arranged face-centered cubic cells to form a negative Poisson's ratio metamaterial with combined face-centered cubic cells.

10. The combination method according to claim 9, characterized in that: It also includes step 5, in which finite element software is used to perform mechanical analysis on the negative Poisson's ratio metamaterial with combined face-centered cubic cells to verify its mechanical properties.

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