An anisotropic chiral honeycomb structure
By designing an anisotropic chiral honeycomb structure and manufacturing it using 3D printing technology, the properties of negative Poisson's ratio and zero Poisson's ratio are achieved, which solves the problem of poor performance of the honeycomb structure in a single direction and improves the deformation ability and aerodynamic performance of the variant wing.
Patent Information
- Application Number
- CN202310523026.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-05-10
- Publication Date
- 2025-09-30
- Estimated Expiration
- 2043-05-10
AI Technical Summary
The existing honeycomb structure has excellent effects in one direction, but poor performance in another direction, making it difficult to meet the complex deformation requirements of the variant wing. It also has problems such as difficulty in coordinating with other components and reduced durability.
An anisotropic chiral honeycomb structure was designed and manufactured using 3D printing technology. The cell consists of centrosymmetric ligaments and through-hole cylinders. The properties of negative and zero Poisson's ratios are achieved through the bending and axial deformation of the ligaments, breaking through the isotropic limitations of traditional chiral honeycombs.
It achieves high out-of-plane stiffness, can carry large aerodynamic loads, maintain the aerodynamic shape of the wing, meet complex deformation requirements, improve aerodynamic performance, reduce drive output force, and reduce fuselage weight.
Smart Images
Figure CN116280169B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of variant wings, and in particular to an anisotropic chiral honeycomb structure. Background Art
[0002] Fighter aircraft have evolved from first-generation to fifth-generation aircraft to meet the demands of war, placing higher demands on the performance of future aircraft. During a mission, fighter aircraft must undergo three phases: accelerated climb, decelerated descent, and accelerated descent. Each phase places varying demands on the aircraft's aerodynamic performance. This has led to the concept of morphing aircraft, which can adaptively change their shape based on changes in the flight environment and mission requirements. As a key aerodynamic structure, the wings bear the majority of the deformation burden. To achieve even better aerodynamic performance, the research focus of morphing wings has shifted from the large-scale, overall mechanical deformation of fifth-generation aircraft wings to the localized, continuous, and smooth deformation of the leading and trailing edges and wingtips.
[0003] A key component of a morphing wing is its flexible honeycomb-based skin. This structure requires sufficient out-of-plane stiffness to maintain the wing's aerodynamic shape during deformation, while maintaining minimal in-plane stiffness to reduce actuator output forces during deformation.
[0004] A cutting-edge solution currently is a flexible skin based on a honeycomb structure. The properties of this skin are primarily dependent on the properties of the honeycomb structure. Conventional honeycomb structures offer excellent anisotropic properties, but often exhibit a uniform Poisson's ratio. For example, arrow-shaped honeycombs exhibit negative Poisson's ratios in both directions and relatively low out-of-plane stiffness. While both four-ligament and six-ligament chiral honeycombs have high out-of-plane stiffness, the four-ligament honeycomb exhibits isotropic Poisson's ratio, while the six-ligament honeycomb has a constant Poisson's ratio of -1 in all directions. Existing honeycombs constructed from single-cell structures exhibit excellent loading performance only in one direction, lacking performance in the other. Flexible skins fabricated using current honeycomb structures can often only achieve relatively simple deformations for morphing wings, such as varying span, trailing edge, or chord length. These simple deformations offer limited functionality, limited applications, and are difficult to meet practical needs. Furthermore, due to the limited deformation capabilities, they can be difficult to integrate with other components, making them difficult to use, and their durability can be reduced. Summary of the Invention
[0005] Based on the aforementioned technical problem that existing single-cell honeycomb structures only exhibit excellent performance when loaded in one direction, but lack good performance in the other, an anisotropic chiral honeycomb structure is provided. The honeycomb structure of the present invention achieves a negative Poisson's ratio in one direction and zero Poisson's ratio in the other. This also overcomes the limitation of four-ligament and six-ligament chiral honeycombs, which only have one Poisson's ratio.
[0006] The technical means adopted in the present invention are as follows:
[0007] An anisotropic chiral honeycomb structure comprises a plurality of cells periodically arranged in the same plane, wherein the cells are centrosymmetrical structures, wherein one cell comprises a ligament, four first through-hole cylinders, and four second through-hole cylinders, wherein the four second through-hole cylinders are arranged on the inner side of the first through-hole cylinders, and the ligaments comprise a first ligament, a second ligament, a third ligament, a fourth ligament, and a fifth ligament;
[0008] In the same cell, the right side of the first through-hole cylinder in the upper left corner is tangentially connected to the first ligament, and the tangent point is the lower end point of the first ligament. The other end of the first ligament is tangentially connected to the first through-hole cylinder of another cell; the lower side of the first through-hole cylinder in the upper left corner is tangentially connected to the second ligament, and the tangent point is the left end point of the second ligament. The right end point of the second ligament is tangentially connected to the lower side of the first through-hole cylinder in the upper right corner; the lower left side of the first through-hole cylinder in the upper left corner is tangentially connected to the third ligament, and the tangent point is the middle part of the third ligament; the second through-hole cylinder in the upper left corner is tangentially connected to the third ligament. The lower left side of the hole cylinder is tangently connected to the third ligament, and the tangent point is the lower end point of the third ligament; the angle between the third ligament and the horizontal line is α; the lower side of the second through-hole cylinder in the upper left corner is tangently connected to the fourth ligament, and the tangent point is the right end point of the fourth ligament, and the left end point of the fourth ligament is tangently connected to the lower side of the second through-hole cylinder of another cell; the right side of the second through-hole cylinder in the upper left corner is tangently connected to the fifth ligament, and the tangent point is the upper end point of the fifth ligament, and the lower end point of the fifth ligament is tangently connected to the right side of the second through-hole cylinder in the upper left corner.
[0009] Furthermore, the figure formed by connecting the centers of the four first through-hole cylinders is a rectangle, and the figure formed by connecting the centers of the four second through-hole cylinders is a rectangle.
[0010] Furthermore, the ratio of the wall thickness of the ligament to the ligament length is less than 1 / 5.
[0011] Furthermore, the cross-section of the ligament is rectangular.
[0012] Furthermore, the material of the cell is one of stainless steel, nylon or aluminum alloy.
[0013] Furthermore, the honeycomb structure is manufactured using 3D printing technology.
[0014] Furthermore, when the honeycomb structure is deformed, the first through-hole cylinder and the second through-hole cylinder do not deform, and the ligament undergoes bending deformation and axial deformation, causing the first through-hole cylinder and the second through-hole cylinder to undergo relative displacement and rotation.
[0015] Furthermore, the angle α satisfies the following formula:
[0016] α=arctan
(L2-L3) / (L1-L4)
[0017] Among them, L1 is the center distance between the first through-hole cylinder in the upper left corner and the first through-hole cylinder in the upper right corner of the same cell; L2 is the center distance between the first through-hole cylinder in the upper left corner and the first through-hole cylinder in the lower left corner of the same cell; L3 is the center distance between the second through-hole cylinder in the upper left corner and the second through-hole cylinder in the lower left corner of the same cell; L4 is the center distance between the second through-hole cylinder in the upper left corner and the second through-hole cylinder in the upper right corner of the same cell.
[0018] Compared with the prior art, the present invention has the following advantages:
[0019] The honeycomb structure of this invention has high out-of-plane stiffness, capable of carrying large aerodynamic loads and maintaining the wing's aerodynamic shape. It also overcomes the isotropy limitations of common four-ligament and six-ligament structures in chiral honeycombs, achieving a zero Poisson's ratio in one direction and a negative Poisson's ratio in the other. This allows for complex wing deformation requirements and improves the wing's aerodynamic performance under different conditions. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] 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 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 labor.
[0021] Figure 1 Schematic diagram of the honeycomb structure of the present invention.
[0022] Figure 2 Schematic diagram of a single cell of the present invention.
[0023] Figure 3 It is a schematic diagram of the present invention being subjected to force in the horizontal direction to achieve a negative Poisson's ratio.
[0024] Figure 4 It is a schematic diagram of the present invention being subjected to force in the vertical direction to achieve zero Poisson's ratio.
[0025] Figure 5It is a schematic diagram of the dimensions and angles of the present invention.
[0026] Figure 6 Schematic diagram of the mechanism of action of the present invention.
[0027] Figure 7 for Figure 6 Schematic diagram of the dotted line part.
[0028] Figure 8 for Figure 6 Schematic diagram of the solid line part.
[0029] In the figure: 1. First through-hole cylinder; 2. Second through-hole cylinder; 3. First ligament; 4. Second ligament; 5. Third ligament; 6. Fourth ligament; 7. Fifth ligament. DETAILED DESCRIPTION
[0030] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.
[0031] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.
[0032] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.
[0033] Unless otherwise specifically stated, the relative arrangement of the parts and steps, numerical expressions and numerical values described in these embodiments do not limit the scope of the present invention. At the same time, it should be clear that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The techniques, methods and equipment known to ordinary technicians in the relevant fields may not be discussed in detail, but where appropriate, the techniques, methods and equipment should be considered as part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following figures, so once an item is defined in one figure, it does not need to be further discussed in subsequent figures.
[0034] In the description of the present invention, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "horizontal, vertical, vertical, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention: the directional words "inside and outside" refer to the inside and outside relative to the outline of each component itself.
[0035] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used herein to describe the spatial positional relationship of a device or feature to other devices or features as shown in the figures. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figures. For example, if the device in the drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below their position devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.
[0036] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.
[0037] like Figure 1-Figure 4As shown, the present invention provides an anisotropic chiral honeycomb structure, comprising a plurality of cells periodically arranged in the same plane, wherein the cells are a centrally symmetrical structure, wherein one cell comprises a ligament, four first through-hole cylinders 1 and four second through-hole cylinders 2, wherein the four second through-hole cylinders 2 are arranged on the inner side of the first through-hole cylinder 1, and the ligament comprises a first ligament 3, a second ligament 4, a third ligament 5, a fourth ligament 6 and a fifth ligament 7; the figure formed by connecting the centers of the four first through-hole cylinders 1 is a rectangle, and the figure formed by connecting the centers of the four second through-hole cylinders 2 is a rectangle.
[0038] In the same cell, the right side of the first through-hole cylinder 1 in the upper left corner is tangentially connected to the first ligament 3, and the tangent point is the lower end point of the first ligament 3. The other end of the first ligament 3 is tangentially connected to the first through-hole cylinder 1 of another cell; the lower side of the first through-hole cylinder 1 in the upper left corner is tangentially connected to the second ligament 4, and the tangent point is the left end point of the second ligament 4. The right end point of the second ligament 4 is tangentially connected to the lower side of the first through-hole cylinder 1 in the upper right corner; the lower left side of the first through-hole cylinder 1 in the upper left corner is tangentially connected to the third ligament 5, and the tangent point is the middle part of the third ligament 5; the second through-hole cylinder 1 in the upper left corner is tangentially connected to the third ligament 5. The lower left side of the hole cylinder 2 is tangently connected to the third ligament 5, and the tangent point is the lower end point of the third ligament 5; the angle between the third ligament 5 and the horizontal line is α; the lower side of the second through-hole cylinder 2 in the upper left corner is tangently connected to the fourth ligament 6, and the tangent point is the right end point of the fourth ligament 6, and the left end point of the fourth ligament 6 is tangently connected to the lower side of the second through-hole cylinder 2 of another cell; the right side of the second through-hole cylinder 2 in the upper left corner is tangently connected to the fifth ligament 7, and the tangent point is the upper end point of the fifth ligament 7, and the lower end point of the fifth ligament 7 is tangently connected to the right side of the second through-hole cylinder 2 in the upper left corner.
[0039] Figure 5 In the equation, the angle α satisfies the following formula:
[0040] α=arctan
(L2-L3) / (L1-L4)
[0041] Among them, L1 is the center distance between the first through-hole cylinder in the upper left corner and the first through-hole cylinder in the upper right corner of the same cell; L2 is the center distance between the first through-hole cylinder in the upper left corner and the first through-hole cylinder in the lower left corner of the same cell; L3 is the center distance between the second through-hole cylinder in the upper left corner and the second through-hole cylinder in the lower left corner of the same cell; L4 is the center distance between the second through-hole cylinder in the upper left corner and the second through-hole cylinder in the upper right corner of the same cell.
[0042] The ratio of the ligament wall thickness to ligament length is less than 1 / 5. The cross-section of the ligament is rectangular. The cell is made of one of stainless steel, nylon, or aluminum alloy. The honeycomb structure is manufactured using 3D printing technology.
[0043] The theoretical basis of the present invention is as follows:
[0044] According to Castiglione's second theorem, the tensile modulus of the structure is derived. Assume that the honeycomb wall will bend and deform axially when subjected to force. Castiglione's second theorem calculates the external force F by the strain energy U. i The partial derivative of , we can get the displacement i under the action of this force,
[0045]
[0046] The deformation of the honeycomb wall is equivalent to the bending of a cantilever beam, which is mainly subjected to the bending load M(x) and the axial force F N (x), so its strain energy can be expressed as:
[0047]
[0048] The concept of a chiral honeycomb structure in the name of this invention is as follows: Chiral symmetry is widely present in nature and organic chemistry, representing an important symmetry characteristic in various disciplines. The chiral honeycomb structure is named based on this symmetry. In chemistry, a molecular structure is said to be "chiral" if its structure is different from its mirror image. The mirror image of a molecular structure cannot be superimposed on the original molecular structure, just as a person's left and right hands are mirror images of each other but cannot be superimposed. Objects that can be superimposed on their mirror images are called achiral.
[0049] like Figure 6-8 As shown, the mechanism of action of the present invention is as follows: when the second ligament 4 is subjected to longitudinal compression, the fifth ligament 7 will be concave inward, showing the typical negative Poisson's ratio material property; however, when the fifth ligament 7 is subjected to transverse compression, the second ligament 4 will protrude outward, but the degree of protrusion is very small, showing the properties of a positive Poisson's ratio material but close to zero Poisson's ratio. Under the constraints of the structure, zero Poisson's ratio can be achieved.
[0050] The honeycomb structure of the present invention has potential applications in advanced aircraft. For example, in a deformable fuel tank mechanism, replacing the outer skin with the honeycomb composite material can reduce the output force of the actuator, reduce the weight of the fuselage, maintain the fuel tank's shape, and improve aerodynamic performance. Another example is a flexible deformable air inlet. Using the honeycomb composite material to replace the outer skin can reduce the output force of the actuator, reduce the weight of the fuselage, maintain the air inlet's shape, and improve aerodynamic performance and stealth.
[0051] Table 1 shows various data of existing honeycomb structures. It can be seen that various types of existing honeycombs often have excellent effects only when loaded in one specific direction, or have the same properties in two directions but are relatively poor.
[0052] Table 1: Poisson's ratio of existing honeycombs
[0053] Cell name Young's modulus E(MPa) Poisson's ratio ν Star (isotropic) 12.08 -0.237 Arrow-shaped (anisotropic) 22.47 -1.268 Four ligaments with opposite chirality (anisotropy) 16.57 -2 Six-ligament reverse chirality (isotropic) 21.32 -1
[0054] Table 2 shows various data of two embodiments of the present invention. It can be seen that by adopting the structure of the present invention, the effects of approximately zero Poisson's ratio and negative Poisson's ratio can be achieved in the xy directions respectively.
[0055] Table 2 Honeycomb Poisson's ratio of the present invention
[0056]
[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. An anisotropic chiral honeycomb structure, characterized in that: The invention comprises a plurality of cells periodically arranged in the same plane, wherein the cells are of a centrally symmetrical structure, wherein one cell comprises a ligament, four first through-hole cylinders (1) and four second through-hole cylinders (2), wherein the four second through-hole cylinders (2) are arranged on the inner side of the first through-hole cylinder (1), and the ligament comprises a first ligament (3), a second ligament (4), a third ligament (5), a fourth ligament (6) and a fifth ligament (7); In the same cell, the right side of the first through-hole cylinder (1) in the upper left corner is tangentially connected to the first ligament (3), and the tangent point is the lower end point of the first ligament (3). The other end of the first ligament (3) is tangentially connected to the first through-hole cylinder (1) of another cell; the lower side of the first through-hole cylinder (1) in the upper left corner is tangentially connected to the second ligament (4), and the tangent point is the left end point of the second ligament (4). The right end point of the second ligament (4) is tangentially connected to the lower side of the first through-hole cylinder (1) in the upper right corner; the lower left side of the first through-hole cylinder (1) in the upper left corner is tangentially connected to the third ligament (5), and the tangent point is the middle part of the third ligament (5); the second through-hole cylinder (1) in the upper left corner is tangentially connected to the third ligament (5). The lower left side of the cylinder (2) is tangently connected to the third ligament (5), and the tangent point is the lower end point of the third ligament (5); the angle between the third ligament (5) and the horizontal line is α; the lower side of the second through-hole cylinder (2) in the upper left corner is tangently connected to the fourth ligament (6), and the tangent point is the right end point of the fourth ligament (6); the left end point of the fourth ligament (6) is tangently connected to the lower side of the second through-hole cylinder (2) of another cell; the right side of the second through-hole cylinder (2) in the upper left corner is tangently connected to the fifth ligament (7), and the tangent point is the upper end point of the fifth ligament (7); the lower end point of the fifth ligament (7) is tangently connected to the right side of the second through-hole cylinder (2) in the upper left corner; When the honeycomb structure is deformed, the first through-hole cylinder (1) and the second through-hole cylinder (2) are not deformed, and the ligament is bent and axially deformed, causing the first through-hole cylinder (1) and the second through-hole cylinder (2) to undergo relative displacement and rotation; When the second ligament (4) is compressed longitudinally, the fifth ligament (7) will be concave inwards, and when the fifth ligament (7) is compressed transversely, the second ligament (4) will be protruded outwards.
2. The anisotropic chiral honeycomb structure according to claim 1, characterized in that: The figure formed by connecting the centers of the four first through-hole cylinders (1) is a rectangle, and the figure formed by connecting the centers of the four second through-hole cylinders (2) is a rectangle.
3. The anisotropic chiral honeycomb structure according to claim 1, characterized in that: The ratio of the wall thickness of the ligament to the length of the ligament is less than 1 / 5.
4. The anisotropic chiral honeycomb structure according to claim 1, characterized in that: The cross section of the ligament is rectangular.
5. The anisotropic chiral honeycomb structure according to claim 1, characterized in that: The cell is made of stainless steel, nylon or aluminum alloy.
6. The anisotropic chiral honeycomb structure according to claim 1, characterized in that: The honeycomb structure is manufactured using 3D printing technology.
7. The anisotropic chiral honeycomb structure according to claim 1, characterized in that: The angle α satisfies the following formula: α=arctan【(L2-L3) / (L1-L4)】 Among them, L1 is the center distance between the first through-hole cylinder in the upper left corner and the first through-hole cylinder in the upper right corner of the same cell; L2 is the center distance between the first through-hole cylinder in the upper left corner and the first through-hole cylinder in the lower left corner of the same cell; L3 is the center distance between the second through-hole cylinder in the upper left corner and the second through-hole cylinder in the lower left corner of the same cell; L4 is the center distance between the second through-hole cylinder in the upper left corner and the second through-hole cylinder in the upper right corner of the same cell.