A two-dimensional metamaterial unit cell with tunable thermal expansion and poisson's ratio and combinations thereof

Abstract

The present application relates to a kind of metamaterials, specifically, a kind of thermal expansion and poisson ratio integrated controllable two-dimensional metamaterial cell and its combination.The purpose is to provide a kind of thermal expansion and poisson ratio integrated controllable metamaterial cell, the material should have the characteristics of thermal expansion coefficient controllable, poisson ratio controllable.The technical scheme is a kind of thermal expansion and poisson ratio integrated controllable two-dimensional metamaterial cell, it is characterized in that: the two-dimensional metamaterial cell includes four-side unit by two first connecting rods and two second connecting rods sequentially connected head to tail and two half-arrow units formed by the one end of third connecting rod and the one end of fourth connecting rod are connected respectively;Wherein: the connecting point of first connecting rod and second connecting rod also connects the other end of third connecting rod, the two fourth connecting rods are coaxially arranged and pass through the connecting point of two second connecting rods, first connecting rod, second connecting rod, third connecting rod and fourth connecting rod are coplanar.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of metamaterials, specifically to a kind of two-dimensional metamaterial cell with integrated adjustable thermal expansion and poisson's ratio and its combination. BACKGROUND

[0002] Negative thermal expansion metamaterials can be widely used in aerospace, such as satellite antennas and spacecraft thermal deformation control; in addition, in the engineering field of precision instruments, electronics, etc., the structure is easily affected by temperature fluctuations and requires high precision itself, so materials with negative expansion or even zero expansion coefficient have high application value. Negative poisson's ratio metamaterials can be used as the bottom plate of a bomb-proof vehicle. When the explosive at the bottom of the bomb-proof vehicle explodes, the huge shock wave will cause the negative poisson's ratio material to rapidly gather at the impact point, increase in density and strength, resist deformation and thus ensure the safety of the people inside the vehicle. In addition, negative poisson's ratio materials can also be used as car tires, seat belts and safety helmets, all of which benefit from their excellent energy absorption and buffering performance. Therefore, designing and developing more new metamaterials to integrate multiple mechanical properties and functions into one material so that the material itself can serve in multiple field integrated working conditions for a long time is a key way to further improve the performance limit of the material. SUMMARY

[0003] The purpose of the present application is to overcome the shortcomings in the background art, and to provide a two-dimensional metamaterial cell with integrated adjustable thermal expansion and poisson's ratio. The material should have the characteristics of adjustable thermal expansion coefficient and adjustable poisson's ratio.

[0004] The technical solution provided by the present application is:

[0005] A two-dimensional metamaterial cell with integrated adjustable thermal expansion and poisson's ratio, characterized in that: the two-dimensional metamaterial cell comprises a quadrilateral unit formed by two first connecting rods and two second connecting rods connected end to end in sequence, and two half-arrow units each formed by one end of a third connecting rod connected to one end of a fourth connecting rod; wherein: the connecting points of the first connecting rod and the second connecting rod also connect the other end of the third connecting rod, the two fourth connecting rods are coaxially arranged and pass through the connecting points of the two second connecting rods, and the first connecting rod, the second connecting rod, the third connecting rod and the fourth connecting rod are coplanar.

[0006] The quadrilateral unit is symmetrical about a diagonal line, and the two half-arrow units are symmetrical about the diagonal line; the diagonal line is the line connecting the connecting points of the two first connecting rods to the connecting points of the two second connecting rods.

[0007] The two fourth connecting rods are perpendicular to the diagonal line.

[0008] The included angle θ1 between the first connecting rod and the fourth connecting rod is less than 90 degrees; the included angle θ3 between the second connecting rod and the fourth connecting rod is less than 90 degrees; and the included angle θ2 between the third connecting rod and the fourth connecting rod is greater than the included angle θ3 between the second connecting rod and the fourth connecting rod and less than the supplementary angle of the included angle θ1 between the first connecting rod and the fourth connecting rod.

[0009] The first connecting rod, the third connecting rod and the fourth connecting rod are made of a low-thermal-expansion-coefficient material; and the second connecting rod is made of a high-thermal-expansion-coefficient material.

[0010] The adjustable three-dimensional metamaterial unit cell is formed by using the thermal expansion and Poisson ratio integrated adjustable two-dimensional metamaterial unit cell, and has the characteristics that the three-dimensional metamaterial unit cell structure is constructed by two two-dimensional metamaterial unit cell structures sharing a vertex and a bottom point, planes formed by four edge elements in the two two-dimensional metamaterial unit cell structures are perpendicular to each other, the vertex is a connecting point of two first connecting rods, and the bottom point is a connecting point of two second connecting rods.

[0011] The adjustable three-dimensional metamaterial unit cell is formed by using the thermal expansion and Poisson ratio integrated adjustable two-dimensional metamaterial unit cell, and has the characteristics that the three-dimensional metamaterial unit cell structure is a quasi-right square pyramid structure constructed by four two-dimensional metamaterial unit cell structures sharing a vertex, and four pyramid faces are all two-dimensional metamaterial unit cell structures.

[0012] The pyramid face is a plane formed by the four edge elements, and two adjacent four edge elements share a first connecting rod, so as to form a pyramid edge of the quasi-right square pyramid structure.

[0013] The thermal expansion and Poisson ratio integrated adjustable metamaterial unit cell has the advantages that the thermal expansion coefficient and the Poisson ratio are integrated, so that the material itself can serve for a long time under the working condition of temperature field and mechanical field coupling. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 It is a front view structural schematic diagram of the embodiment 1 of the present application.

[0015] Figure 2 It is a three-dimensional structural schematic diagram of the embodiment 2 of the present application.

[0016] Figure 3 It is a three-dimensional structural schematic diagram of the embodiment 3 of the present application.

[0017] In the figure, the reference numerals are as follows: first connecting rod 1, second connecting rod 2, third connecting rod 3 and fourth connecting rod 4. DETAILED DESCRIPTION

[0018] The present application is further described below in combination with the embodiments shown in the accompanying drawings, but the present application is not limited to the following embodiments.

[0019] Embodiment 1

[0020] Figure 1 The thermal expansion and Poisson ratio integration can regulate the two-dimensional metamaterial unit cell, which includes a quadrilateral unit formed by two first links 1, two second links 2 connected end to end in sequence, and two half-arrow units formed by one end of a third link 3 and one end of a fourth link 4; wherein: the connection points of the two first links 1 are the top points, and the connection points of the two second links 2 are the bottom points; the line from the top point to the bottom point is one diagonal of the quadrilateral unit, and one first link 1 and one second link are symmetrically arranged on the left and right sides of the diagonal; the connection points of the first link and the second link also connect the other end of the third link 3; the two fourth links are coaxially arranged and pass through the bottom point, and are perpendicular to the diagonal; the first link, the second link, the third link and the fourth link are coplanar.

[0021] Obviously, the quadrilateral unit is symmetrical about the diagonal; the two half-arrow units are symmetrical about the diagonal; Figure 1 In the center, the center line of the two-dimensional metamaterial unit cell coincides with the diagonal.

[0022] The included angle θ1 between the first link 1 and the fourth link 4 is less than 90 degrees; the included angle θ3 between the second link 2 and the fourth link 4 is less than 90 degrees; the included angle θ2 between the third link 3 and the fourth link 4 is greater than the included angle θ3 between the second link 2 and the fourth link 4 and less than the supplement of the included angle θ1 between the first link and the fourth link.

[0023] The first link 1, the third link 3 and the fourth link 4 are made of low-thermal-expansion-coefficient materials, and the low-thermal-expansion-coefficient materials are recommended to be PVA materials, and the thermal expansion coefficient thereof is about 21e-6 / ℃; the second link 2 is made of high-thermal-expansion-coefficient materials, and the high-thermal-expansion-coefficient materials are recommended to be nylon materials, and the thermal expansion coefficient thereof is about 166e-6 / ℃.

[0024] Embodiment 2

[0025] Figure 2 The three-dimensional metamaterial unit cell structure shown is formed by two two-dimensional metamaterial unit cell structures sharing top points and bottom points, wherein the fourth link is a bottom edge perpendicular to the diagonal of the quadrilateral unit (referred to as vertical type), and the planes formed by the quadrilateral units in the two two-dimensional metamaterial unit cell structures are perpendicular to each other.

[0026] Embodiment 3

[0027] Figure 3Another three-dimensional metamaterial unit cell structure shown is a regular tetrapod structure constructed by four two-dimensional metamaterial unit cell structures sharing vertices, and the four pyramid surfaces are all two-dimensional metamaterial unit cell structures (referred to as tetrapod-like). It is shown in the figure that: the pyramid surface is a plane formed by the four-edge unit in each two-dimensional metamaterial unit cell structure, and two adjacent four-edge units share a first connecting rod, thereby forming the pyramid edge of the regular tetrapod structure.

Claims

1. A thermally expandable and poisson's ratio integrated tunable two-dimensional metamaterial unit cell, characterized in that: The two-dimensional metamaterial unit cell comprises a quadrilateral unit formed by two first connecting rods (1) and two second connecting rods (2) connected end to end in sequence, and two half-arrow units each formed by one end of a third connecting rod (3) connected to one end of a fourth connecting rod (4); wherein: the connecting points of the first connecting rod and the second connecting rod also connect the other end of the third connecting rod, the other end of the fourth connecting rod is located on the extension line of the first connecting rod, the two fourth connecting rods are coaxially arranged and pass through the connecting points of the two second connecting rods, and the first connecting rod, the second connecting rod, the third connecting rod and the fourth connecting rod are coplanar; The quadrilateral unit is symmetric about a diagonal line, and the two half-arrow units are symmetric about the diagonal line; the diagonal line is a line connecting the connecting points of the two first connecting rods to the connecting points of the two second connecting rods; The two fourth connecting rods are perpendicular to the diagonal line; The included angle θ1 between the first connecting rod and the fourth connecting rod is less than 90 degrees; the included angle θ3 between the second connecting rod and the fourth connecting rod is less than 90 degrees; the included angle θ2 between the third connecting rod and the fourth connecting rod is greater than the included angle θ3 between the second connecting rod and the fourth connecting rod and less than the supplement of the included angle θ1 between the first connecting rod and the fourth connecting rod.

2. The thermally expandable and poisson's ratio integrated tunable metamaterial unit cell of claim 1, wherein: The first connecting rod, the third connecting rod and the fourth connecting rod are made of a low-thermal-expansion-coefficient material; and the second connecting rod is made of a high-thermal-expansion-coefficient material.

3. A tunable three-dimensional metamaterial unit cell formed using the tunable two-dimensional metamaterial unit cell of claim 1 having integrated thermal expansion and Poisson's ratio, characterized in that: The three-dimensional metamaterial unit cell structure is constructed by two two-dimensional metamaterial unit cell structures sharing a vertex and a bottom point, the planes formed by the quadrilateral units in the two two-dimensional metamaterial unit cell structures are perpendicular to each other; the vertex is the connecting point of the two first connecting rods, and the bottom point is the connecting point of the two second connecting rods.

4. The tunable three-dimensional metamaterial unit cell formed by the thermal expansion and Poisson's ratio integrated tunable two-dimensional metamaterial unit cell of claim 1, wherein: The three-dimensional metamaterial unit cell structure is a quasi-right quadrangular pyramid structure constructed by four two-dimensional metamaterial unit cell structures sharing a vertex, and the four pyramid faces are two-dimensional metamaterial unit cell structures.

5. The tunable three-dimensional metamaterial unit cell formed by integrating tunable two-dimensional metamaterial unit cells with thermal expansion and Poisson's ratio according to claim 4, wherein: The pyramid faces are the planes formed by the quadrilateral units, and two adjacent quadrilateral units share a first connecting rod, thereby forming the pyramid edges of the quasi-right quadrangular pyramid structure.

Images