Novel negative Poisson's ratio structure compounded by concave step edge structure and chiral structure

Abstract

The invention relates to the technical field of mechanical metamaterials, in particular to a novel negative Poisson's ratio structure compounded by a concave stepped edge structure and a chiral structure, which comprises the concave stepped edge structure and the chiral structure, the frame structure comprises a first horizontal wall and a second horizontal wall which are respectively configured as an upper frame and a lower frame and are parallel to each other, and a first concave step table and a second concave step table which are respectively configured as a left frame and a right frame and are symmetrical to each other; the chiral structure comprises a chiral structure pitch circle; one end of each chiral structure rib wall is fixed on the outer wall of the corresponding chiral structure pitch circle, and the other end of each chiral structure rib wall is fixed on the inner wall of the first horizontal wall or the inner wall of the second horizontal wall; at least one pair of chiral structure rib walls are parallel to each other, and one ends far away from the chiral structure pitch circle are far away from each other along the opposite direction. The novel negative Poisson's ratio structure provided by the invention has obvious advantages in the aspects of reducing the weight, improving the strength, improving the compression resistance and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of mechanical metamaterials, and more specifically to a novel negative Poisson's ratio structure which is a composite of an inwardly concave step edge structure and 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 can achieve independence of lateral expansion and longitudinal contraction when subjected to force, showing deformation characteristics that are completely different from traditional materials. This characteristic makes negative Poisson's ratio materials have broad application prospects in the fields of impact resistance, energy absorption, and shock absorption.

[0003] Traditional negative Poisson's ratio structures mostly adopt a single geometric shape or material design. Although they have achieved the negative Poisson's ratio effect to a certain extent, they still have certain limitations in terms of strength and energy absorption performance. Therefore, how to further improve the performance of negative Poisson's ratio materials, especially in terms of improving their strength and energy absorption capacity, has become a hot topic of research.

[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 characteristics in geometric shape, which can exhibit asymmetric deformation behavior when subjected to force. Through the rational design of chiral structures, researchers have found that they have good potential in negative Poisson's ratio characteristics. Summary of the invention

[0005] The purpose of the present invention is to provide a negative Poisson's ratio structure of a composite of an inward-concave step edge structure and a chiral structure, which can enhance the strength and energy absorption capacity of the structure while maintaining excellent mechanical properties by combining the inward-concave step edge structure and the chiral structure.

[0006] In order to achieve the above object, the present invention is implemented by the following technical solutions:

[0007] A novel negative Poisson's ratio structure composed of an inward-concave step-edge structure and a chiral structure, comprising the inward-concave step-edge structure configured as a frame structure; and a chiral structure installed in the frame structure;

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

[0009] The chiral structure includes a chiral structure pitch circle; at least two chiral structure rib walls are arranged along the tangent direction of the chiral structure pitch circle, one end of the chiral structure rib wall is fixed to the outer wall of the chiral structure pitch circle, and the other end of the chiral structure rib wall 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 rib walls are parallel to each other and the ends away from the chiral structure pitch circle are away from each other in opposite directions.

[0010] Specifically, the present invention provides a novel negative Poisson's ratio structure of a composite of a concave step edge structure and a chiral structure, including a concave step edge structure and a chiral structure; the concave step edge structure includes two horizontal walls, two vertical walls and four step walls; the two ends of the two horizontal walls are respectively connected to the step walls, and the two step walls on the same side are connected to the vertical wall, showing a concave shape, forming an axisymmetric, closed structure with concave sides; the chiral structure is connected to the two ends of the horizontal wall of the concave step edge structure through a specific geometric arrangement, so that when an external force is applied, the lateral expansion and longitudinal contraction of the material can change independently, and the rib walls enable the overall structure to generate more strain during the deformation process, further improving the compression resistance; the design of the novel negative Poisson's ratio structure enables the overall structure to exhibit a negative Poisson's ratio characteristic when subjected to an external force.

[0011] The two ends of the horizontal wall are connected to the stepped edges to form a concave shape, constituting an axisymmetric, closed structure with concave sides. 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, the first vertical wall is perpendicular to the first horizontal wall, the first vertical wall is symmetrically provided with a first stepped wall and a second stepped wall at both ends, one end of the first stepped wall away from the first vertical wall is fixed to the end of the first horizontal wall, and one 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 step platform has a second vertical wall, the second vertical wall is perpendicular to the first horizontal wall, and a third stepped wall and a fourth stepped wall are symmetrically arranged at both ends of the second vertical wall. One end of the third stepped wall away from the second vertical wall is fixed to the end of the first horizontal wall, and one end of the fourth stepped wall away from the second vertical wall is fixed to the end of the second horizontal wall.

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

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

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

[0017] The chiral structure has a rotational geometry, and the pitch radius of the chiral structure is R, which is determined by the number of structural steps, usually 1mm≤R≤3mm, so that during the load-bearing process, the rib wall will transfer the force to the pitch circle of the chiral structure, thereby causing the pitch circle to rotate. At the same time, the rib wall will also be rolled up, resulting in a reduction in the compression cross section and an increase in the tension cross section, showing a negative Poisson's ratio characteristic to improve the energy absorption capacity of the material under the action of external forces.

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

[0019] In the preferred embodiment, the wall thickness of the frame structure is greater than or equal to the wall thickness of the chiral structure rib wall, that is, assuming that the wall thickness of the concave step edge structure is t1 and the wall thickness of the chiral structure rib wall is t2, then t1≥t2.

[0020] In a preferred embodiment, the number of rib walls of the chiral structure is 2 or 4.

[0021] Under the preferred embodiment, the new negative Poisson's ratio structure is used in the fields of aerospace, automobile and construction.

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

[0023] Under the preferred scheme, the new negative Poisson's ratio structure can be applied to aerospace, automobile, construction and other fields to improve the strength, impact resistance and energy absorption performance of the structure.

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

[0025] The present invention provides a novel negative Poisson's ratio structure of a concave step edge structure and a chiral structure. The structure can exhibit a negative Poisson's ratio effect when subjected to external force by combining the concave step edge design with the chiral structure. Compared with the prior art, the novel negative Poisson's ratio structure of the present invention has obvious advantages in reducing weight, increasing strength, improving compressive performance, etc.

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

[0027] The novel negative Poisson's ratio chiral structure provided by the present invention is connected to the two ends of the horizontal wall of the concave step edge structure through a specific geometric arrangement. The rib wall of the chiral structure can expand laterally and contract longitudinally independently of the concave step edge structure under the action of external force, thereby enhancing the strain capacity of the material. This design enables the overall structure to generate greater strain during deformation and improves the compression resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic plan view of a novel negative Poisson's ratio structure in an embodiment of the present invention.

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

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

[0031] Figure 4 It is a schematic plan view of a novel negative Poisson's ratio structure with different numbers of chiral structural rib walls in the present invention.

[0032] In the figure, 1, first horizontal wall; 2, second horizontal wall; 3, first stepped wall; 4, second stepped wall; 5, third stepped wall; 6, fourth stepped wall; 7, first vertical wall; 8, second vertical wall; 9, chiral structure pitch circle; 10, first chiral structure rib wall; 11, second chiral structure rib wall. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0034] The present invention proposes a new negative Poisson's ratio structure of a composite of a concave step edge structure and a chiral structure, aiming to further improve the mechanical properties of the material by combining the advantages of the two structures. The concave step 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 also good stability can be maintained under multi-directional forces.

[0035] A new type of negative Poisson's ratio structure of a composite of an inward-concave step-edge structure and a chiral structure, comprising the inward-concave step-edge structure and the chiral structure;

[0036] The concave step edge structure includes two horizontal walls, two vertical walls and four step-shaped walls; the two ends of the two horizontal walls are respectively connected to the step edge, and the two step-shaped walls on the same side are connected to the vertical wall, forming a concave shape, forming an axisymmetric closed structure with concave sides;

[0037] The chiral structure is connected to the two ends of the horizontal wall of the concave step-edge structure through a specific geometric arrangement, so that when external force is applied, the lateral expansion and longitudinal contraction of the material can change independently, and the rib walls make the overall structure produce more strain during the deformation process, further improving the compression resistance. The design of the new negative Poisson's ratio structure makes the overall structure exhibit a negative Poisson's ratio characteristic when subjected to external force.

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

[0039] Among them, 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 structure 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 structure 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 structure rib wall 10 and the second chiral structure rib wall 11 are tangent to the chiral structure pitch circle 9, forming an axisymmetric, closed structure with concave sides.

[0040] like Figure 2As shown in the figure, the design parameters of the concave step edge structure include the horizontal wall length L, the structure height H, the step height l, the step width d and the wall thickness t1. Among them, L = 20mm, H = 16mm, 1mm≤d<l≤1.5mm; these parameters are optimized and combined to enhance the energy absorption characteristics of the overall structure and ensure effective response under external forces. The overall deformation form of the concave step edge structure is basically the same as that of the concave straight edge and the concave star shape. They all have obvious compression and concave deformation processes. The step edge structure will produce local bending deformation in the step bending area, thereby improving the energy absorption characteristics of the structure. Not limited to a specific number of steps, the flexibility of design is a major advantage of this structure, and the number of steps can be adjusted according to actual applications and needs.

[0041] The thickness of the chiral structure rib wall is t2, t1≥t2; the angle θ between the chiral structure rib wall and the horizontal satisfies the condition 30°<θ<90°. The radius R of the chiral structure pitch circle 9 is determined according to the number of structural steps, usually 1mm≤R≤3mm; these parameters are optimized and combined to enhance the energy absorption characteristics of the overall structure. Not limited to a specific number of steps, the flexibility of design is a major advantage of this structure, and the number of steps can be adjusted according to actual applications and needs.

[0042] The radius of the chiral structure pitch circle 9 is R, which is determined according to the number of structural steps, and is usually 1mm≤R≤3mm; the rib wall adopts a rotational design, which can effectively transfer the force to the chiral structure pitch circle 9 during the load-bearing process, and promote the rotation trend of the chiral structure pitch circle 9. At the same time, the rolling effect of the chiral structure rib wall reduces the compression cross section and increases the tension cross section, thereby further showing the negative Poisson's ratio characteristics.

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

[0044] like Figure 3 As shown, the cross-sections of the walls of the new negative Poisson's ratio structure are all rectangular, with a width of b. The value range of b can be adjusted according to actual engineering needs.

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

[0046] The above are only preferred specific implementation modes of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and inventive concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A novel negative Poisson's ratio structure composed of an inward-concave step-edge structure and a chiral structure, characterized in that: It includes a concave step edge structure configured as a frame structure; and a chiral structure installed in the frame structure; The frame structure comprises a first horizontal wall (1) and a second horizontal wall (2) which are respectively configured as upper and lower frames and are parallel to each other, and a first concave step platform and a second concave step platform which are respectively configured as left and right frames and are symmetrical to each other, wherein the first concave step platform and the second concave step platform are both in the shape of concave steps; The chiral structure comprises a chiral structure pitch circle (9); at least two chiral structure rib walls arranged along the tangent direction of the chiral structure pitch circle (9); one end of the chiral structure rib wall is fixed to the chiral structure pitch circle (9) and to the outer wall of the chiral structure pitch circle (9); the other end of the chiral structure rib wall is fixed to the inner wall of the first horizontal wall (1) or the inner wall of the second horizontal wall (2); at least one pair of the chiral structure rib walls are parallel to each other and the ends away from the chiral structure pitch circle (9) are away from each other in opposite directions.

2. According to claim 1, the novel negative Poisson's ratio structure of the composite of the concave step edge structure and the chiral structure is characterized in that: The first concave stepped platform has a first vertical wall (7), the first vertical wall (7) is perpendicular to the first horizontal wall (1), and the first stepped wall (3) and the second stepped wall (4) are symmetrically arranged at two ends of the first vertical wall (7), 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), the second vertical wall (8) is perpendicular to the first horizontal wall (1), and a third stepped wall (5) and a fourth stepped wall (6) are symmetrically arranged at both ends of the second vertical wall (8), and 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 of the composite of the concave step 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, 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 of the composite of the concave step edge structure and the chiral structure according to claim 1, characterized in that: The radius of the chiral structure pitch circle (9) is R, 1mm≤R≤3mm.

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

6. The novel negative Poisson's ratio structure of the composite of the concave step 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 rib wall of the chiral structure.

7. The novel negative Poisson's ratio structure of the composite of the concave step edge structure and the chiral structure according to claim 1, characterized in that: The number of the chiral structure rib walls is two or four.

8. The novel negative Poisson's ratio structure of the composite of the concave step edge structure and the chiral structure according to claim 1, characterized in that: Made of polymer plastic, metal or composite material.

9. The novel negative Poisson's ratio structure of the composite of the concave step edge structure and the chiral structure according to claim 1, characterized in that: Used in aerospace, automotive and construction fields.

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