Negative Poisson's ratio metamaterial structural member with double-layer concave hexagons

Abstract

The invention discloses a negative Poisson's ratio metamaterial structural member which is of a double-layer concave hexagonal structure and serves as a supporting piece of a deformable wing. The metamaterial structural members are arranged in a single-row array mode in the wing chord direction of the wing. The metamaterial structural member comprises 6 straight rods and 16 connecting rods, every two connecting rods are parallel to each other and are arranged between every two straight rods in the same inclined direction, and every two straight rods are spatially parallel to each other; the metamaterial structural members designed by the invention are connected through a linear array in a three-dimensional space to form a supporting structure. The deformation direction of the metamaterial structural member is more stable, and Poisson's ratio adjustability within a certain range is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of negative Poisson's ratio metamaterials, and more particularly to a negative Poisson's ratio metamaterial structure constructed by double-layer concave hexagons, which can be used as a support mechanism for a deformable wing, and the elastic stiffness of the deformable wing reaches 1×10 5 N / m 。 Background Art

[0002] Mechanical metamaterials refer to artificial materials that have special functions based on geometric structures to achieve extraordinary properties. Negative Poisson's ratio mechanical metamaterials are a typical type of mechanical metamaterial. Under the action of uniaxial tension, this type of negative Poisson's ratio metamaterial expands in the direction perpendicular to the load. This type of negative Poisson's ratio metamaterial can improve the lateral and vertical bearing capacity of the material. Compared with traditional materials, negative Poisson's ratio metamaterials have more advantages than traditional materials in deformation performance, shear performance, energy absorption performance, fracture toughness and indentation resistance. Therefore, this material has a good application prospect in the direction of deformation structure.

[0003] The wing is the main part of an aircraft that can be reconfigured in flight. Purposefully changing the wing shape in flight (such as wing sweep, changing the span and camber, etc.) can effectively increase the efficiency of the wing. Among them, changing the span and wing area has the most prominent effect. For example, when the aircraft is cruising, the wing usually requires a high aspect ratio and a large wing area, while in order to fly at high speed, a low aspect ratio and a small wing area are required. The morphing wing allows the wing area to change between 50% and 150%, respectively, to meet the needs of cruising and high-speed flight, and provide more lift for the aircraft. However, this mechanically moving flap and slat are bulky, complex, and inefficient. Therefore, it is necessary to find a method that can effectively change the wing shape in flight without mechanical action, so that the aircraft has ideal performance at all speeds.

[0004] Hyeonu Heo published "Compliant cellular structures application to a passive morphing airfoil" in 2013, which introduced the airfoil of concave hexagonal honeycomb core. Daochun Li published "A review of modelling and analysis of morphing wings" in 2018, which introduced the modeling and analysis of morphing wings, and concluded from the morphing structure to the aerodynamic analysis that morphing wings have great potential in improving the overall performance of aircraft. Summary of the invention

[0005] The present invention designs a negative Poisson's ratio metamaterial structure with double-layer concave hexagons for use as a support body for a deformable wing, which is arranged in a single row array along the chord direction of the wing. The metamaterial structure of the present invention is a three-dimensional negative Poisson's ratio metamaterial constructed with double-layer concave hexagons, which is connected in a linear array in three-dimensional space. The metamaterial structure is composed of two vertically arranged double-layer concave hexagonal structures and two connecting rods. The double-layer concave hexagonal structure is composed of 6 straight rods and 16 connecting rods; the connecting rods are parallel to each other and are arranged between the two straight rods in the same inclination direction, and the two straight rods are arranged vertically and parallel in space; the metamaterial structure designed by the present invention is connected in a linear array in three-dimensional space to form a support structure.

[0006] There is a distance between the first central straight rod (21) and the second central straight rod (22) placed in the same horizontal direction.

[0007] A first outer straight rod (11), a second outer straight rod (12), a third outer straight rod (13) and a fourth outer straight rod (14) are evenly distributed around the first central straight rod (21) and the second central straight rod (22);

[0008] An AA connecting rod (11A) and an AB connecting rod (11B) are arranged between the first outer straight rod (11) and the second center straight rod (22) and are inclined toward the inner end of the second center straight rod (22), and the AA connecting rod (11A) and the AB connecting rod (11B) remain parallel; an AC connecting rod (11C) and an AD connecting rod (11D) are arranged between the first outer straight rod (11) and the first center straight rod (21) and are inclined toward the inner end of the first center straight rod (21), and the AC connecting rod (11C) and the AD connecting rod (11D) remain parallel.

[0009] A BA connecting rod (12A) and a BB connecting rod (12B) are arranged between the second outer straight rod (12) and the second center straight rod (22) and are inclined toward the inner end of the second center straight rod (22), and the BA connecting rod (12A) and the BB connecting rod (12B) remain parallel; a BC connecting rod (12C) and a BD connecting rod (12D) are arranged between the second outer straight rod (12) and the first center straight rod (21) and are inclined toward the inner end of the first center straight rod (21), and the BC connecting rod (12C) and the BD connecting rod (12D) remain parallel.

[0010] A CA connecting rod (13A) and a CB connecting rod (13B) are arranged between the third outer straight rod (13) and the second center straight rod (22) and are inclined toward the inner end of the second center straight rod (22), and the CA connecting rod (13A) and the CB connecting rod (13B) remain parallel; a CC connecting rod (13C) and a CD connecting rod (13D) are arranged between the third outer straight rod (13) and the first center straight rod (21) and are inclined toward the inner end of the first center straight rod (21), and the CC connecting rod (13C) and the CD connecting rod (13D) remain parallel.

[0011] A DA connecting rod (14A) and a DB connecting rod (14B) are arranged between the fourth outer straight rod (14) and the second center straight rod (22) and are inclined toward the inner end of the second center straight rod (22), and the DA connecting rod (14A) and the DB connecting rod (14B) remain parallel; a DC connecting rod (14C) and a DD connecting rod (14D) are arranged between the fourth outer straight rod (14) and the first center straight rod (21) and are inclined toward the inner end of the first center straight rod (21), and the DC connecting rod (14C) and the DD connecting rod (14D) remain parallel.

[0012] The metamaterial structure of the present invention is a negative Poisson's ratio material. In the air static load test, a force of 100N is applied, using T6061 aluminum alloy. The maximum deformation displacement is 1mm, indicating that the deformable wing loaded with the metamaterial structure of the present invention has good stability. The maximum stress is 107MPa, which is less than the yield strength of the aluminum alloy. The metamaterial structure can be used as a supporting mechanism for the deformable wing, and the elastic stiffness of the deformable wing reaches 1×10 5 N / m 。

[0013] The three-dimensional negative Poisson's ratio metamaterial structure with double-layer concave hexagons as the support body of the deformable wing has the following technical effects:

[0014] ① The deformation stability of the metamaterial structure of the present invention is better than that of the traditional concave hexagonal negative Poisson's ratio metamaterial. The flexible parallelogram structure is combined with the traditional concave hexagonal negative Poisson's ratio metamaterial to improve the deformation stability of the structure.

[0015] ② The Poisson's ratio of the three-dimensional Poisson's ratio structure of the present invention can be adjusted as parameters change, and can be adjusted for different environments. Poisson's ratios of different sizes can be obtained by adjusting the length ratio of the rods and the angles between the rods.

[0016] ③ The negative Poisson's ratio material of the present invention is integrally formed by additive manufacturing, and the joints are seamless, which effectively reduces stress concentration; the material has a semi-hollow structure, which can effectively reduce the mass compared to a solid structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of a deformable wing mid-support body formed by arranging in an array in the chord direction of the wing a three-dimensional negative Poisson's ratio metamaterial structural member having double layers of concave hexagons designed by the present invention.

[0018] Figure 1A yes Figure 1 Another perspective structure diagram.

[0019] Figure 2It is a structural diagram of a three-dimensional negative Poisson's ratio metamaterial structural component with double-layer concave hexagons designed by the present invention.

[0020] Figure 2A yes Figure 2 Another perspective structure diagram.

[0021] Figure 2B yes Figure 2 AA section view.

[0022] Figure 2C yes Figure 2 Front view of .

[0023] Figure 2D yes Figure 2C Another perspective structure diagram.

[0024] Figure 2E yes Figure 2 Left view of .

[0025] Figure 2F yes Figure 2E Another perspective structure diagram.

[0026] Figure 3 It is a dimensioning schematic diagram of a three-dimensional negative Poisson's ratio metamaterial structure with double-layer concave hexagons designed by the present invention.

[0027] Figure 4 It is a deformation schematic diagram of a three-dimensional negative Poisson's ratio metamaterial structure with double-layer concave hexagons designed by the present invention.

[0028] Figure 4A This is a diagram showing the simulation results of the deformation of the metamaterial structure of the present invention in the XZ plane.

[0029] Figure 4B This is a diagram showing the simulation results of the deformation of the metamaterial structure of the present invention in the XY plane.

[0030] Figure 4C This is a diagram showing the simulation results of the deformation of the metamaterial structure of the present invention in the ZY plane.

[0031] Figure 5 It is a schematic diagram of negative Poisson's ratio metamaterial structures arranged in a single row array.

[0032] Figure 6 It is the deformation displacement diagram of the deformable wing loaded with metamaterial structure.

[0033] Figure 7 It is the stress distribution diagram of the deformable wing loaded with metamaterial structural components.

[0034] DETAILED DESCRIPTION

[0035] The present invention will be further described in detail below with reference to the accompanying drawings. The various parameter demonstrations listed are only preferred embodiments of the present invention. It should be noted that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention, and these improvements and modifications should also be considered as the protection scope of the present invention.

[0036] Metamaterial Structural Parts

[0037] See also Figure 2 , Figure 2A , Figure 2B , Figure 2C , Figure 2D , Figure 2E , Figure 2F , Figure 3 The present invention shown in the figure designs a three-dimensional negative Poisson's ratio metamaterial structure with double-layer concave hexagons suitable for use as a wing support. The negative Poisson's ratio metamaterial structure is manufactured using an integrated processing technology, such as 3D printing technology and wire cutting technology. Figure 2C The shape of the left side of the negative Poisson's ratio metamaterial structure is a cross configuration (as shown in Figure 2E shown).

[0038] See also Figure 2 , Figure 2A , Figure 2D , Figure 2F , Figure 3 The negative Poisson's ratio metamaterial structural component designed by the present invention includes 6 straight rods and 16 connecting rods; the connecting rods are arranged in pairs parallel and in the same inclination direction between the pairs of straight rods, and the pairs of straight rods are arranged vertically.

[0039] The six straight rods are a first outer straight rod 11 , a second outer straight rod 12 , a third outer straight rod 13 , a fourth outer straight rod 14 , a first central straight rod 21 , and a second central straight rod 22 .

[0040] The 16 connecting rods refer to the AA connecting rod 11A, AB connecting rod 11B, AC connecting rod 11C and AD connecting rod 11D arranged between the first outer straight rod 11 and the first center straight rod 21 and the second center straight rod 22; the BA connecting rod 12A, BB connecting rod 12B, BC connecting rod 12C and BD connecting rod 12D between the second outer straight rod 12 and the first center straight rod 21 and the second center straight rod 22; the CA connecting rod 13A, CB connecting rod 13B, CC connecting rod 13C and CD connecting rod 13D between the third outer straight rod 13 and the first center straight rod 21 and the second center straight rod 22; the DA connecting rod 14A, DB connecting rod 14B, DC connecting rod 14C and DD connecting rod 14D between the fourth outer straight rod 14 and the first center straight rod 21 and the second center straight rod 22.

[0041] like Figure 2 As shown, a first central straight rod 21 and a second central straight rod 22 are arranged along the center line, and a distance D exists between the inner end of the first central straight rod 21 and the inner end of the second central straight rod 22 .

[0042] Four outer straight rods are arranged around the first central straight rod 21 and the second central straight rod 22, that is, the first outer straight rod 11 is arranged above the first central straight rod 21 and the second central straight rod 22; the third outer straight rod 13 is arranged below the first central straight rod 21 and the second central straight rod 22; and the first outer straight rod 11 and the third outer straight rod 13 are kept parallel to the first central straight rod 21 and the second central straight rod 22. The fourth outer straight rod 14 is arranged in front of the first central straight rod 21 and the second central straight rod 22; the second outer straight rod 12 is arranged behind the first central straight rod 21 and the second central straight rod 22; and the fourth outer straight rod 14 and the second outer straight rod 12 are kept parallel to the first central straight rod 21 and the second central straight rod 22.

[0043] An AA connecting rod 11A and an AB connecting rod 11B are arranged between the first outer straight rod 11 and the second center straight rod 22, tilted toward the inner end of the second center straight rod 22, and the AA connecting rod 11A and the AB connecting rod 11B remain parallel; an AC connecting rod 11C and an AD connecting rod 11D are arranged between the first outer straight rod 11 and the first center straight rod 21, tilted toward the inner end of the first center straight rod 21, and the AC connecting rod 11C and the AD connecting rod 11D remain parallel.

[0044] A BA connecting rod 12A and a BB connecting rod 12B are arranged between the second outer straight rod 12 and the second center straight rod 22, tilted toward the inner end of the second center straight rod 22, and the BA connecting rod 12A and the BB connecting rod 12B remain parallel; a BC connecting rod 12C and a BD connecting rod 12D are arranged between the second outer straight rod 12 and the first center straight rod 21, tilted toward the inner end of the first center straight rod 21, and the BC connecting rod 12C and the BD connecting rod 12D remain parallel.

[0045] A CA connecting rod 13A and a CB connecting rod 13B are arranged between the third outer straight rod 13 and the second center straight rod 22, tilted toward the inner end of the second center straight rod 22, and the CA connecting rod 13A and the CB connecting rod 13B remain parallel; a CC connecting rod 13C and a CD connecting rod 13D are arranged between the third outer straight rod 13 and the first center straight rod 21, tilted toward the inner end of the first center straight rod 21, and the CC connecting rod 13C and the CD connecting rod 13D remain parallel.

[0046] A DA link 14A and a DB link 14B are provided between the fourth outer straight rod 14 and the second center straight rod 22, tilted toward the inner end of the second center straight rod 22, and the DA link 14A and the DB link 14B remain parallel; a DC link 14C and a DD link 14D are provided between the fourth outer straight rod 14 and the first center straight rod 21, tilted toward the inner end of the first center straight rod 21, and the DC link 14C and the DD link 14D remain parallel.

[0047] In the present invention, the first outer straight rod 11, the second outer straight rod 12, the third outer straight rod 13 and the fourth outer straight rod 14 have the same structure.

[0048] In the present invention, the first central straight rod 21 and the second central straight rod 22 have the same structure.

[0049] In the present invention, the structures of the connecting rods (11A, 11B, 11C, 11D, 12A, 12B, 12C, 12D, 13A, 13B, 13C, 13D, 14A, 14B, 14C, 14D) obliquely arranged between the four outer straight rods (11, 12, 13, 14) and the two central straight rods (21, 22) are the same.

[0050] Dimensional design of metamaterial structures

[0051] The rod length and related parameters of the metamaterial structure can be adjusted within a certain range according to the spatial size of the application scenario and the negative Poisson's ratio required by the application scenario, so as to adapt to different application scenarios. Figure 3 The dimensions of the three-dimensional negative Poisson's ratio metamaterial structure with double-layer concave hexagons are designed based on the negative Poisson's ratio characteristics of the non-interference metamaterial, with the length C of the first outer straight rod 11 being 11 As a benchmark, and meet

[0052] θ=30°~60° 。

[0053] The length of the first central straight rod 21 is denoted by C 21 , K 21 、Thick is G 21 The first central straight rod 21 and the second central straight rod 22 have the same structure. The distance between the inner end of the first central straight rod 21 and the inner end of the second central straight rod 22 is denoted as D 。

[0054] The length of the first outer straight rod 11 is denoted by C 11 , K 11 、Thick is G 11 The first outer straight rod 11, the second outer straight rod 12, the third outer straight rod 13 and the fourth outer straight rod 14 have the same structure.

[0055] The length of the AD connecting rod 11D is c, the width is k, the thickness is g, and the distance between the two connecting rods is d (i.e., the distance between the AC connecting rod 11C and the AD connecting rod 11D). The structures of the 16 connecting rods are the same. The distance between the lower end of the AC connecting rod 11C and the inner end of the first central straight rod 21 is a. The inclination angle between the AD connecting rod 11D and the first central straight rod 21 is θ, and θ=30° to 60°.

[0056] The present invention has a double-layer concave hexagonal negative Poisson's ratio metamaterial structure. Compared with the previous concave hexagonal negative Poisson's ratio metamaterial, the metamaterial structure adopts a double-layer concave hexagonal structure composed of parallel double oblique connecting rods as a basic unit, and this structure can increase the stability of deformation. The parallel double oblique connecting rods and the part between the straight rods can be regarded as a flexible parallelogram mechanism. The advantage of the flexible parallelogram mechanism is that the four-sided straight rods can be approximately regarded as translation. Here, the use of the flexible parallelogram mechanism can make the straight rods between the double oblique connecting rods approximately translate, thereby reducing the bending degree of the entire straight rod and increasing the stability of deformation.

[0057] Stress deformation of metamaterial structures

[0058] The stress deformation of a metamaterial structure is as follows: Figure 4 As shown, when the outer straight rods (first outer straight rod 11 and third outer straight rod 13) of the metamaterial structure in the up-down direction are contracted toward the center by an external force (large black arrow), the central straight rods (first central straight rod 21 and second central straight rod 22) in the horizontal direction contract inward (small black arrow), and at the same time, the outer straight rods (second outer straight rod 12 and fourth outer straight rod 14) in the front-back direction are also driven to contract inward (small black arrow).

[0059] Figure 4A Deformation diagram for the front view. Figure 4B The deformation diagram of the top view is shown in Figure 2. Figure 4C Deformation diagram for the left view.

[0060] Figure 4 The deformation of the metamaterial structure shows that the deformation characteristics of the metamaterial structure conform to the negative Poisson's ratio, which is -0.64. Different colors in the figure represent lateral displacements of different sizes. It should be noted that in order to show the deformation effect more clearly, the deformation is magnified in the figure.

[0061] Example 1

[0062] The three-dimensional negative Poisson's ratio metamaterial structure with double-layer concave hexagons designed by the present invention is used as a support member of the deformable wing and is arranged along the chord direction of the wing.

[0063] The dimensions of the three-dimensional negative Poisson's ratio metamaterial structure with double-layer concave hexagons in the embodiment are:

[0064] The length C of the first outer straight rod 11 11 =40mm, width K 11 =2mm, thickness G 11 =1mm. The length C of the first central straight rod 21 21 =10mm, width K 21 =2mm, thickness G 21 =2mm. The length of the AD link 11D is c=17.68mm, the width is k=2mm, the thickness is g=1mm, and d=5mm. The distance between the inner end of the first center straight rod 21 and the inner end of the second center straight rod 22 is D=5mm, a=0.5mm, and the inclination angle between the AD link 11D and the first center straight rod 21 is θ=45°.

[0065] like Figure 1 As shown, in the wing cavity 100E, a maximum of 8 metamaterial structural members are arranged in a single row array along the chord direction, and the total length of the wing supporting members is 360 mm.

[0066] In ANSYS simulation software, the air static load test is simplified to point force for simulation test. Figure 1 A force of 100N is applied to the structure shown in the figure. The metamaterial structure is made of T6061 aluminum alloy. When the leading edge area of ​​the wing is fixed, the simulation results are as follows: Figure 6 , Figure 7 shown. Figure 6 The figure is a deformation displacement diagram of a deformable wing loaded with a metamaterial structural component. The maximum deformation in the figure is 1 mm, indicating that the deformable wing loaded with the metamaterial structural component of the present invention has good stability. Figure 7 The stress distribution diagram of the deformable wing loaded with the metamaterial structure. The maximum stress in the figure is 107MPa, which is less than the yield strength of aluminum alloy. The metamaterial structure can serve as the support mechanism of the deformable wing. The elastic stiffness of the deformable wing reaches 1×10 5 N / m 。

[0067] 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 aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned 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. A negative Poisson's ratio metamaterial structure with double-layer concave hexagons, which is used as a support body for a deformable wing; characterized in that: Negative Poisson's ratio metamaterial structural parts with double layers of concave hexagons are arranged in a single row array along the chord direction of the wing; The negative Poisson's ratio metamaterial structure with double-layer concave hexagons includes 6 straight rods and 16 connecting rods; the connecting rods are arranged between two straight rods in parallel and in the same tilt direction, and the two straight rods are arranged in parallel in space; There is a distance between the first central straight rod (21) and the second central straight rod (22) placed in the same horizontal direction; A first outer straight rod (11), a second outer straight rod (12), a third outer straight rod (13) and a fourth outer straight rod (14) are evenly distributed around the first central straight rod (21) and the second central straight rod (22); An AA connecting rod (11A) and an AB connecting rod (11B) are arranged between the first outer straight rod (11) and the second center straight rod (22) and are inclined toward the inner end of the second center straight rod (22), and the AA connecting rod (11A) and the AB connecting rod (11B) remain parallel; an AC connecting rod (11C) and an AD connecting rod (11D) are arranged between the first outer straight rod (11) and the first center straight rod (21) and are inclined toward the inner end of the first center straight rod (21), and the AC connecting rod (11C) and the AD connecting rod (11D) remain parallel; A BA connecting rod (12A) and a BB connecting rod (12B) are arranged between the second outer straight rod (12) and the second center straight rod (22) and are inclined toward the inner end of the second center straight rod (22), and the BA connecting rod (12A) and the BB connecting rod (12B) remain parallel; a BC connecting rod (12C) and a BD connecting rod (12D) are arranged between the second outer straight rod (12) and the first center straight rod (21) and are inclined toward the inner end of the first center straight rod (21), and the BC connecting rod (12C) and the BD connecting rod (12D) remain parallel; A CA connecting rod (13A) and a CB connecting rod (13B) are arranged between the third outer straight rod (13) and the second center straight rod (22) and are inclined toward the inner end of the second center straight rod (22), and the CA connecting rod (13A) and the CB connecting rod (13B) are kept parallel; a CC connecting rod (13C) and a CD connecting rod (13D) are arranged between the third outer straight rod (13) and the first center straight rod (21) and are inclined toward the inner end of the first center straight rod (21), and the CC connecting rod (13C) and the CD connecting rod (13D) are kept parallel; A DA connecting rod (14A) and a DB connecting rod (14B) are arranged between the fourth outer straight rod (14) and the second center straight rod (22) and are inclined toward the inner end of the second center straight rod (22), and the DA connecting rod (14A) and the DB connecting rod (14B) remain parallel; a DC connecting rod (14C) and a DD connecting rod (14D) are arranged between the fourth outer straight rod (14) and the first center straight rod (21) and are inclined toward the inner end of the first center straight rod (21), and the DC connecting rod (14C) and the DD connecting rod (14D) remain parallel.

2. The negative Poisson's ratio metamaterial structure having double-layer concave hexagons according to claim 1, characterized in that The optimized structural dimensions are: The length C of the first outer straight rod (11) 11 As a benchmark, and meet θ=30°~60° ； The length of the first central straight rod (21) is denoted by C 21 , K 21 、Thick is G 21 The distance between the inner end of the first center straight rod (21) and the inner end of the second center straight rod (22) is denoted as D ； The length of the first outer straight rod (11) is denoted by C 11 , K 11 、Thick is G 11 ; The length of the AD connecting rod (11D) is c 、 宽记为 k 、 厚记为 g 、 两个连杆之间的间距记 is d ； AC连杆(11 The distance between the lower end of the first central straight rod (21) and the inner end of the first central straight rod (21) is denoted as a ； AD The inclination angle between the connecting rod (11D) and the first central straight rod (21) is denoted as θ ， And θ=30°~60° ； 3. The negative Poisson's ratio metamaterial structure with double-layer concave hexagons according to claim 1, characterized in that: The metamaterial structure can be used as a support mechanism for a deformable wing, and the elastic stiffness of the deformable wing reaches 1×10 5 N / m 。

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