A novel negative Poisson's ratio structure combining a concave stepped edge structure and a chiral structure.

Abstract

This invention relates to the field of mechanical metamaterials technology, specifically to a novel negative Poisson's ratio structure combining a concave stepped edge structure and a chiral structure. The structure includes a concave stepped edge structure and a chiral structure. The frame structure comprises a first horizontal wall and a second horizontal wall, respectively configured as upper and lower frames and parallel to each other, and a first concave stepped platform and a second concave stepped platform, respectively configured as left and right side frames and symmetrical to each other. The chiral structure includes a chiral structural nodal circle; at least two chiral structural ribs, one end of which is fixed to the outer wall of the chiral structural nodal circle, and the other end of which is fixed to the inner wall of either the first or second horizontal wall. At least one pair of chiral structural ribs, with their ends parallel to each other and away from the chiral structural nodal circle, are moved away from each other in opposite directions. The novel negative Poisson's ratio structure provided by this invention has significant advantages in terms of weight reduction, increased strength, and improved compressive strength.

Description

Technical Field

[0001] This invention relates to the field of mechanical metamaterials technology, and more specifically, to a novel negative Poisson's ratio structure that combines a concave stepped edge structure with a chiral structure. Background Art

[0002] With the continuous development of materials science and engineering technology, negative Poisson's ratio materials have attracted much attention due to their unique mechanical properties. Negative Poisson's ratio materials exhibit independent lateral expansion and longitudinal contraction under stress, displaying deformation characteristics that are drastically different from traditional materials. This property makes negative Poisson's ratio materials promising for broad applications in impact resistance, energy absorption, and vibration damping.

[0003] Traditional negative Poisson's ratio structures often employ a single geometric shape or material design. While these achieve the negative Poisson's ratio effect to some extent, they still have limitations in terms of strength and energy absorption performance. Therefore, how to further improve the performance of negative Poisson's ratio materials, especially in enhancing their strength and energy absorption capacity, has become a research hotspot.

[0004] In recent years, chiral structures have gradually attracted the attention of researchers due to their unique geometric characteristics and mechanical properties. Chiral structures refer to materials or structures with chiral geometric features, capable of exhibiting asymmetric deformation behavior under stress. Through rational design, researchers have discovered that chiral structures have good potential in terms of negative Poisson's ratio properties. Summary of the Invention

[0005] The purpose of this invention is to provide a negative Poisson's ratio structure that combines a concave stepped edge structure with a chiral structure. By combining the concave stepped edge structure with the chiral structure, this structure can enhance the strength and energy absorption capacity of the structure while maintaining excellent mechanical properties.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0007] A novel negative Poisson's ratio structure combining a concave stepped edge structure and a chiral structure includes a concave stepped edge structure configured as a frame structure and a chiral structure installed within the frame structure.

[0008] The frame structure includes a first horizontal wall and a second horizontal wall that are configured as upper and lower frames and are parallel to each other, and a first concave step platform and a second concave step platform that are configured as left and right side frames and are symmetrical to each other. Both the first concave step platform and the second concave step platform are in the shape of concave steps.

[0009] The chiral structure includes a chiral structure nodal circle; at least two chiral structure ribs arranged along the tangent direction of the chiral structure nodal circle, one end of the chiral structure rib is fixed to the outer wall of the chiral structure nodal circle, and the other end of the chiral structure rib is fixed to the inner wall of the first horizontal wall or the inner wall of the second horizontal wall, and at least one pair of chiral structure ribs are parallel to each other and their ends away from the chiral structure nodal circle are away from each other in opposite directions.

[0010] Specifically, the present invention provides a novel negative Poisson's ratio structure combining a concave stepped edge structure and a chiral structure. The concave stepped edge structure includes two horizontal walls, two vertical walls, and four stepped walls. The two ends of the two horizontal walls are connected to the stepped walls, and the two stepped walls on the same side are connected to the vertical walls, forming a concave shape and an axisymmetric, concave-sided closed structure. The chiral structure, through a specific geometric arrangement, connects its ribs to the ends of the horizontal walls of the concave stepped edge structure, allowing the material's lateral expansion and longitudinal contraction to change independently when external force is applied. Furthermore, the ribs cause the overall structure to generate more strain during deformation, further improving its compressive strength. The design of the novel negative Poisson's ratio structure ensures that the overall structure exhibits negative Poisson's ratio characteristics when subjected to external force.

[0011] The horizontal wall is connected to the stepped edge at both ends, forming a concave shape, which constitutes an axisymmetric, concave closed structure. This design can effectively disperse external forces and enhance the overall stability of the material.

[0012] In a preferred embodiment, the first concave stepped platform has a first vertical wall, which is perpendicular to the first horizontal wall. The two ends of the first vertical wall are symmetrically provided with a first stepped wall and a second stepped wall. The end of the first stepped wall away from the first vertical wall is fixed to the end of the first horizontal wall, and the end of the second stepped wall away from the first vertical wall is fixed to the end of the second horizontal wall.

[0013] The second concave stepped platform has a second vertical wall, which is perpendicular to the first horizontal wall. A third stepped wall and a fourth stepped wall are symmetrically arranged at both ends of the second vertical wall. The end of the third stepped wall away from the second vertical wall is fixed to the end of the first horizontal wall, and the end of the fourth stepped wall away from the second vertical wall is fixed to the end of the second horizontal wall.

[0014] In the preferred embodiment, the length L of the first and second horizontal walls is 20mm, the height H of the frame structure is 16mm, the height l of each step of the first, second, third, and fourth stepped walls is equal in the vertical direction, and the width d of each step of the first, second, third, and fourth stepped walls is equal in the horizontal direction, and 1mm≤d<l≤1.5mm.

[0015] The design parameters for the concave stepped edge structure include the horizontal wall length L, structural height H, step height l, step width d, and wall thickness t1. These parameters are designed as follows: L = 20mm, H = 16mm, and 1mm ≤ d < l ≤ 1.5mm. The aim is to enhance the overall energy absorption characteristics of the structure through the optimized combination of these parameters. The flexibility in design, not limited to a specific number of steps, is a major advantage of this structure, allowing the number of steps to be adjusted according to actual applications and needs.

[0016] In the preferred embodiment, the radius of the chiral structure nodal circle is R, where 1mm ≤ R ≤ 3mm.

[0017] The chiral structure has a rotational geometry with a pitch circle radius of R, determined by the number of structural steps, typically 1mm ≤ R ≤ 3mm. This ensures that during load-bearing, the ribs transfer the force to the pitch circle, causing it to rotate. Simultaneously, the ribs are rolled up, resulting in a smaller compressive cross-section and a larger tensile cross-section, exhibiting a negative Poisson's ratio characteristic to enhance the material's energy absorption capacity under external forces.

[0018] In the preferred embodiment, the angle θ between the chiral rib wall and the horizontal direction satisfies the condition 30° < θ < 90°.

[0019] In the preferred scheme, the wall thickness of the frame structure is greater than or equal to the wall thickness of the chiral rib wall. That is, if the wall thickness of the concave stepped edge structure is t1 and the wall thickness of the chiral rib wall is t2, then t1≥t2.

[0020] In the preferred embodiment, the number of chiral ribs is 2 or 4.

[0021] In the preferred embodiment, the novel negative Poisson's ratio structure is used in the aerospace, automotive, and construction fields.

[0022] In the preferred embodiment, the novel negative Poisson's ratio structure can be made of polymer plastics, metals or composite materials, and manufactured using additive manufacturing technology. Additive manufacturing technology is recommended to achieve efficient production of complex structures.

[0023] Under the preferred design, the novel negative Poisson's ratio structure can be applied in aerospace, automotive, and construction fields to improve the structure's strength, impact resistance, and energy absorption performance.

[0024] The beneficial effects of the present invention are:

[0025] This invention provides a novel negative Poisson's ratio structure that combines a concave stepped edge structure with a chiral structure. This structure, through its concave stepped edge design combined with a chiral structure, exhibits a negative Poisson's ratio effect when subjected to external forces. Compared with existing technologies, this novel negative Poisson's ratio structure offers significant advantages in terms of weight reduction, increased strength, and improved compressive strength.

[0026] The novel negative Poisson's ratio structure component provided by this invention is composed of two structures. The model produced by additive manufacturing technology has a high surface precision and is easier to remove the printed support structure during the manufacturing process, thereby making the model making simpler and improving the yield rate.

[0027] The novel negative Poisson's ratio chiral structure provided by this invention is connected to both ends of the horizontal wall of the concave stepped edge structure through a specific geometric arrangement. Under external force, the ribs of the chiral structure can expand laterally and contract longitudinally independently of the concave stepped edge structure, thereby enhancing the material's strain capacity. This design allows the overall structure to generate greater strain during deformation, improving its compressive strength. Attached Figure Description

[0028] Figure 1 This is a planar schematic diagram of the novel negative Poisson's ratio structure in an embodiment of the present invention.

[0029] Figure 2 This is a schematic diagram of the structural parameters of the novel negative Poisson's ratio in an embodiment of the present invention.

[0030] Figure 3 This is a three-dimensional schematic diagram of the novel negative Poisson's ratio structure in an embodiment of the present invention.

[0031] Figure 4 This is a planar schematic diagram of a novel negative Poisson's ratio structure with different numbers of chiral structural ribs in this invention.

[0032] In the figure, 1 is the first horizontal wall; 2 is the second horizontal wall; 3 is the first stepped wall; 4 is the second stepped wall; 5 is the third stepped wall; 6 is the fourth stepped wall; 7 is the first vertical wall; 8 is the second vertical wall; 9 is the chiral nodal circle; 10 is the first chiral rib wall; and 11 is the second chiral rib wall. Detailed Implementation

[0033] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0034] This invention proposes a novel negative Poisson's ratio structure combining a concave stepped edge structure and a chiral structure, aiming to further improve the mechanical properties of materials by combining the advantages of these two structures. The concave stepped edge structure can effectively change the local stress distribution of the material, while the chiral structure can enhance the overall strength and energy absorption characteristics of the material. Through this composite structure, not only can excellent negative Poisson's ratio characteristics be achieved, but good stability can also be maintained under multi-directional stress.

[0035] A novel negative Poisson's ratio structure combining a concave stepped edge structure and a chiral structure, comprising a concave stepped edge structure and a chiral structure;

[0036] The concave stepped edge structure consists of two horizontal walls, two vertical walls, and four stepped walls. The two ends of the two horizontal walls are connected to the stepped edge, and the two stepped walls on the same side are connected to the vertical wall, forming a concave shape and creating an axially symmetrical, concave closed structure.

[0037] The chiral structure, through a specific geometric arrangement, connects its ribs to the horizontal walls of the concave stepped edge structure at both ends, allowing the material's lateral expansion and longitudinal contraction to change independently when external forces are applied. Furthermore, the ribs enable the overall structure to generate more strain during deformation, further enhancing its compressive strength. The design of the novel negative Poisson's ratio structure causes the overall structure to exhibit negative Poisson's ratio characteristics when subjected to external forces.

[0038] like Figure 1 As shown, the concave stepped edge structure has two horizontal walls, four stepped walls, and two vertical walls, which are respectively: first horizontal wall 1, second horizontal wall 2, first stepped wall 3, second stepped wall 4, third stepped wall 5, fourth stepped wall 6, first vertical wall 7, and second vertical wall 8; chiral structure nodal circle 9, first chiral structure rib wall 10, and second chiral structure rib wall 11.

[0039] In this structure, one end of the first horizontal wall 1 is connected to the first stepped wall 3, and the other end is connected to the first chiral structural rib wall 10 and the third stepped wall 5; one end of the second horizontal wall 2 is connected to the fourth stepped wall 6, and the other end is connected to the second chiral structural rib wall 11 and the second stepped wall 4; the first stepped wall 3 and the second stepped wall 4 on the left are connected to the first vertical wall 7 and are concave in shape; the third stepped wall 5 and the fourth stepped wall 6 on the right are connected to the second vertical wall 8 and are also concave in shape. The first chiral structural rib wall 10 and the second chiral structural rib wall 11 are tangent to the chiral structural nodal circle 9, forming an axially symmetrical, concave closed structure on both sides.

[0040] like Figure 2As shown, the design parameters of the concave stepped edge structure include the horizontal wall length L, structural height H, step height l, step width d, and wall thickness t1. Specifically, L = 20mm, H = 16mm, and 1mm ≤ d < l ≤ 1.5mm. These parameters are optimized to enhance the overall structure's energy absorption characteristics, ensuring effective response under external forces. The overall deformation pattern of the concave stepped edge structure is basically the same as that of the concave straight edge and concave star-shaped structures, all exhibiting a significant compressive concave deformation process. The stepped edge structure generates local bending deformation in the step bending area, thereby improving the structure's energy absorption characteristics. Not limited to a specific number of steps, the design flexibility is a major advantage of this structure; the number of steps can be adjusted according to actual applications and needs.

[0041] The chiral structure rib wall thickness is t2, where t1 ≥ t2; the angle θ between the chiral structure rib wall and the horizontal surface satisfies the condition 30° < θ < 90°. The chiral structure pitch circle radius R is determined based on the number of structural steps, typically 1mm ≤ R ≤ 3mm; these parameters are optimized to enhance the overall energy absorption characteristics of the structure. The flexibility in design, not limited to a specific number of steps, is a major advantage of this structure, allowing the number of steps to be adjusted according to actual applications and needs.

[0042] The radius of the chiral structure nodal circle 9 is R, which is determined based on the number of structural steps, typically 1mm ≤ R ≤ 3mm. The ribs adopt a rotational design, which can effectively transfer the force to the chiral structure nodal circle 9 during load-bearing, promoting the rotational tendency of the chiral structure nodal circle 9. At the same time, the roll-up effect of the chiral structure ribs reduces the compressive section and increases the tensile section, thereby further exhibiting negative Poisson's ratio characteristics.

[0043] like Figure 1 and 4 As shown, a novel negative Poisson's ratio structure combining a concave stepped edge structure and a chiral structure can have 2 or 4 chiral ribs. The wall thickness t1 of the concave stepped edge structure should be equal to or greater than the wall thickness t2 of the chiral ribs to ensure the strength and stability of the structure.

[0044] like Figure 3 As shown, the cross-sections of each wall in the novel negative Poisson's ratio structure are rectangular with a width of b. The range of values ​​for b can be adjusted according to actual engineering needs.

[0045] As a specific embodiment, the filling material of the novel negative Poisson's ratio structure, which is a composite of a concave stepped edge structure and a chiral structure, provided by the present invention is a polymer plastic, a metal, or a composite material, and is manufactured using additive manufacturing technology.

[0046] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A novel negative Poisson's ratio structure combining a concave stepped edge structure and a chiral structure, characterized in that, It includes a concave stepped edge structure configured as a frame structure; and a chiral structure installed within the frame structure; The frame structure includes a first horizontal wall (1) and a second horizontal wall (2) that are configured as upper and lower frames and are parallel to each other, and a first concave step platform and a second concave step platform that are configured as left and right frames and are symmetrical to each other. The first concave step platform and the second concave step platform are both concave step-shaped. The chiral structure includes a chiral structure nodal circle (9); at least two chiral structure ribs are arranged along the tangent direction of the chiral structure nodal circle (9), one end of the chiral structure rib is fixed to the outer wall of the chiral structure nodal circle (9), and the other end of the chiral structure rib is fixed to the inner wall of the first horizontal wall (1) or the inner wall of the second horizontal wall (2), and at least one pair of chiral structure ribs are parallel to each other and their ends away from the chiral structure nodal circle (9) are away from each other in opposite directions.

2. The novel negative Poisson's ratio structure combining the concave stepped edge structure and the chiral structure according to claim 1, characterized in that, The first concave stepped platform has a first vertical wall (7), which is perpendicular to the first horizontal wall (1). The first vertical wall (7) has a first stepped wall (3) and a second stepped wall (4) symmetrically arranged at both ends. The end of the first stepped wall (3) away from the first vertical wall (7) is fixed to the end of the first horizontal wall (1), and the end of the second stepped wall (4) away from the first vertical wall (7) is fixed to the end of the second horizontal wall (2). The second concave stepped platform has a second vertical wall (8), which is perpendicular to the first horizontal wall (1). A third stepped wall (5) and a fourth stepped wall (6) are symmetrically arranged at both ends of the second vertical wall (8). The end of the third stepped wall (5) away from the second vertical wall (8) is fixed to the end of the first horizontal wall (1), and the end of the fourth stepped wall (6) away from the second vertical wall (8) is fixed to the end of the second horizontal wall (2).

3. The novel negative Poisson's ratio structure combining the concave stepped edge structure and the chiral structure according to claim 2, characterized in that, The length L of the first horizontal wall (1) and the second horizontal wall (2) is 20 mm, the height H of the frame structure is 16 mm, the height l of each step of the first stepped wall (3), the second stepped wall (4), the third stepped wall (5) and the fourth stepped wall (6) in the vertical direction is equal, and the width d of each step of the first stepped wall (3), the second stepped wall (4), the third stepped wall (5) and the fourth stepped wall (6) in the horizontal direction is equal, and 1 mm ≤ d < l ≤ 1.5 mm.

4. The novel negative Poisson's ratio structure combining the concave stepped edge structure and the chiral structure according to claim 1, characterized in that, The radius of the chiral structure nodal circle (9) is R, 1mm≤R≤3mm.

5. The novel negative Poisson's ratio structure combining the concave stepped edge structure and the chiral structure according to claim 1, characterized in that, The acute angle between the chiral rib wall and the horizontal direction is θ, where 30° < θ < 90°.

6. The novel negative Poisson's ratio structure combining the concave stepped edge structure and the chiral structure according to claim 1, characterized in that, The wall thickness of the frame structure is greater than or equal to the wall thickness of the chiral structure rib.

7. The novel negative Poisson's ratio structure combining the concave stepped edge structure and the chiral structure according to claim 1, characterized in that, The number of chiral structural ribs is two or four.

8. The novel negative Poisson's ratio structure combining the concave stepped edge structure and the chiral structure according to claim 1, characterized in that, Made of polymer plastics, metals or composite materials.

9. The novel negative Poisson's ratio structure combining the concave stepped edge structure and the chiral structure according to claim 1, characterized in that, Used in aerospace, automotive, and construction industries.

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