CN219976111U - Metamaterial cell and structure with simultaneously controllable thermal expansion and poisson ratio - Google Patents

Abstract

The utility model relates to a metamaterial cell and a structure whose thermal expansion and Poisson's ratio can be controlled simultaneously. The metamaterial cell whose thermal expansion and Poisson's ratio can be controlled simultaneously includes a main unit and a plurality of thermal expansion units; the main unit includes a plurality of arc segments. , multiple arc-shaped segments are arranged at circumferential intervals, and the opening of each arc-shaped segment faces outward, and a connecting segment is connected between two adjacent arc-shaped segments; multiple thermal expansion units are arranged in one-to-one correspondence with the multiple arc-shaped segments , and each thermal expansion unit includes two adjusting sections connected at an angle, and a matching section connected to the two adjusting sections at the same time. The matching section and the two adjusting sections have different thermal expansion coefficients, where the connection between the two adjusting sections Recesses connected to corresponding arc segments. The cells provided by this solution can simultaneously control thermal expansion and Poisson's ratio, which enhances stability and practicality, and the setting of arc segments can also reduce stress concentration and meet the need for precision instruments working in harsh environments to maintain shape stability.

Description

Metamaterial cells and structures whose thermal expansion and Poisson's ratio can be controlled simultaneously

Technical field

The utility model relates to the technical field of metamaterials, and in particular to a metamaterial cell and structure whose thermal expansion and Poisson's ratio can be controlled simultaneously.

Background technique

Mechanical metamaterials with reasonable structural design can have special properties that traditional materials cannot have, and have important engineering application value. Properties such as adjustable thermal expansion coefficient, adjustable Poisson's ratio and lightweight and high stiffness can be widely used in engineering practice. On the one hand, in an environment with drastic temperature changes, materials and structures will bear large thermal stress and undergo thermal deformation, which will reduce the working accuracy of precision instruments and even cause damage. For example, when the thermal protection system of a hypersonic aircraft enters the atmosphere, aerodynamic heat generates higher temperatures on its surface. Therefore, designing a thermal protection system with a minimal thermal expansion coefficient will help reduce thermal stress and avoid thermal coupling failure and damage. Satellites in orbit during operation will experience huge temperature differences, and large thermal deformations will affect imaging accuracy. Mechanical metamaterials with adjustable thermal expansion properties are expected to maintain the working stability of precision instruments in environments with severe temperature changes.

On the other hand, adjustable Poisson's ratio metamaterials have many applications in many fields due to their special auxetic properties. The active deformation negative Poisson's ratio honeycomb structure can be used to drive the thickness adjustment of the morphing wing, and brings the characteristics of active deformation, smooth and continuous deformation, lightweight and space saving to the morphing wing. In the medical field, zero Poisson's ratio structures can be used to make vascular stents to protect vascular tissue. In the aerospace field, the loose and porous characteristics can also be used to produce lightweight and high-strength sandwich negative Poisson's ratio structures for energy absorption to protect space deployment mechanisms. For example, patent CN 114888949 A discloses a bidirectional negative Poisson's ratio structure, which can achieve negative Poisson's ratio effects in two directions by changing the geometric parameters of the deformed triangle, the elastic modulus of inclusions, and the number of inclusion holes. However, this structure lacks the ability to cope with thermal deformation induced by temperature fields. Therefore, it is necessary to design metamaterials with simultaneous control of thermal expansion and Poisson's ratio.

Utility model content

In view of this, it is necessary to provide a metamaterial cell and structure whose thermal expansion and Poisson's ratio can be controlled simultaneously to solve the problem that metamaterials in the existing technology cannot simultaneously respond to thermal deformation caused by a temperature field and deformation caused by a force field. To achieve effective control, it is urgent to design metamaterials with thermal expansion and Poisson's ratio that can be controlled simultaneously.

The utility model provides a metamaterial cell whose thermal expansion and Poisson's ratio can be controlled simultaneously. The metamaterial cell whose thermal expansion and Poisson's ratio can be controlled simultaneously includes:

The main unit includes a plurality of arc-shaped segments. The plurality of arc-shaped segments are arranged at circumferential intervals, and the openings of each arc-shaped segment face outward. A connecting segment is connected between two adjacent arc-shaped segments. , so that the main unit has a negative Poisson's ratio effect; and,

A plurality of thermal expansion units are arranged in one-to-one correspondence with the plurality of arc-shaped segments, and each thermal expansion unit includes two adjustment segments connected at an included angle, and a mating segment connected to the two adjustment segments at the same time, so The thermal expansion coefficients of the matching section and the two adjustment sections are different, wherein the connection point of the two adjustment sections is connected to the recess of the corresponding arc section.

Optionally, the connection point of the two adjustment sections is connected to the midpoint of the corresponding arc section.

Optionally, the matching section and the two adjustment sections are jointly surrounded to form a triangular structure, and the high line at the connection of the two adjustment sections of the triangular structure is the control high line;

The radial line passing through the midpoint of the corresponding arc segment is the control radial line, and the control radial line coincides with the control high line.

Optionally, the lengths of the two adjustment sections are the same, and the matching section is connected to the two adjustment sections end to end.

Optionally, one end of each adjustment section away from the corresponding arc section is an extension end, and the extension end extends outside the opening of the corresponding arc section;

Each matching section is connected to the corresponding extending end.

Optionally, there are four arc-shaped segments, and the four arc-shaped segments are arranged at equal intervals around the circumference;

Each connecting section includes two connecting rods connected vertically, and the two connecting rods connect two adjacent arc-shaped segments correspondingly.

Optionally, each of the arc segments is arranged in a semicircle.

Optionally, the plurality of arc segments and the plurality of connecting segments have the same thermal expansion coefficient.

Optionally, the main body unit is made of aluminum alloy.

In addition, the present invention also provides a metamaterial structure whose thermal expansion and Poisson's ratio can be controlled simultaneously, which includes a plurality of metamaterial cells whose thermal expansion and Poisson's ratio can be controlled simultaneously as described in any one of the above, wherein a plurality of the The metamaterial cells whose thermal expansion and Poisson's ratio can be controlled simultaneously are body-centered and orthogonally connected.

Compared with the existing technology, in the metamaterial cells provided by the present utility model whose thermal expansion and Poisson's ratio can be controlled at the same time, when the cell is subjected to a tensile load in the transverse direction, the corresponding arc segment will expand longitudinally; and when the cell is subjected to a tensile load, the corresponding arc segment will expand longitudinally; When a cell is subjected to a compressive load in the transverse direction, the corresponding arc segment will shrink longitudinally, causing the cell to have a negative Poisson's ratio effect. The negative Poisson's ratio can be controlled by rationally designing the length of the connecting segment and the radius of the arc segment. size, so that it can effectively cope with the deformation caused by the force field to maintain the shape stability of the structure.

At the same time, the thermal expansion coefficient (α1) of the adjustment section and the thermal expansion coefficient (α2) of the fitting section are set to be unequal, so that when the external temperature changes, the adjustment section and the fitting section undergo coordinated thermal deformation to offset the deformation caused by the expansion of the material itself. When the outside temperature rises and α1>α2, the elongation of the fitting section is less than the elongation of the adjustment section, causing the height of the thermal expansion unit to increase, showing a positive thermal expansion effect; when the outside temperature rises and α1< At α2, the elongation of the fitting section is greater than the elongation of the adjusting section, causing the height of the thermal expansion unit to become smaller, showing a negative thermal expansion effect; the thermal expansion coefficient can be controlled by changing the angle between the adjusting section and the fitting section. Realized, or through materials. Therefore, the cells provided by this solution can simultaneously control thermal expansion and Poisson's ratio, which enhances stability and practicality, and the setting of arc segments can also reduce stress concentration and meet the need for precision instruments working in harsh environments to maintain shape stability. .

The above description is only an overview of the technical solutions of the present utility model. In order to understand the technical means of the present utility model more clearly and implement them according to the contents of the specification, the preferred embodiments of the present utility model are described in detail below with reference to the accompanying drawings. The specific implementation mode of the present invention is given in detail by the following examples and accompanying drawings.

Description of the drawings

The drawings described here are used to provide a further understanding of the present utility model and constitute a part of the present application. The schematic embodiments of the present utility model and their descriptions are used to explain the present utility model and do not constitute an improper limitation of the present utility model. In the attached picture:

Figure 1 is a schematic structural diagram of an embodiment of a metamaterial cell in which thermal expansion and Poisson's ratio can be controlled simultaneously provided by the present invention;

Figure 2 is a schematic front view of the metamaterial cell in Figure 1 whose thermal expansion and Poisson's ratio can be controlled simultaneously;

Figure 3 is a schematic structural diagram of the main unit in Figure 2;

Figure 4 is a schematic structural diagram of the thermal expansion unit in Figure 2;

Figure 5 is a schematic structural diagram of an embodiment of a metamaterial structure in which thermal expansion and Poisson's ratio can be controlled simultaneously provided by the present invention.

Explanation of reference symbols:

100-Metamaterial cell with simultaneous control of thermal expansion and Poisson's ratio, 1-main unit, 11-arc section, 12-connection section, 121-connecting rod, 2-thermal expansion unit, 21-adjustment section, 211-extension End, 22-fitting section, 200-metamaterial structure whose thermal expansion and Poisson's ratio can be controlled simultaneously.

Detailed ways

The preferred embodiments of the present utility model will be described in detail below in conjunction with the accompanying drawings. The accompanying drawings constitute a part of this application and are used together with the embodiments of the present utility model to explain the principles of the present utility model and are not intended to limit the scope of the present utility model. scope.

Please refer to Figures 1 to 4. The metamaterial cell 100 whose thermal expansion and Poisson's ratio can be controlled simultaneously includes a main unit 1 and a plurality of thermal expansion units 2; the main unit 1 includes a plurality of arc segments 11, and a plurality of arc segments 11 They are arranged at circumferential intervals, and the openings of each arc-shaped segment 11 face outward, and a connecting segment 12 is connected between two adjacent arc-shaped segments 11 so that the main unit 1 has a negative Poisson's ratio effect; a plurality of thermal expansion units 2 Each thermal expansion unit 2 includes two adjusting sections 21 connected at an angle, and a matching section 22 connected to the two adjusting sections 21 at the same time. The matching section 22 is connected to the two adjusting sections 21 . The thermal expansion coefficients of the segments 21 are different, wherein the connection point of the two adjustment segments 21 is connected to the recess of the corresponding arc segment 11 .

In the metamaterial cell 100 whose thermal expansion and Poisson's ratio can be controlled simultaneously provided by the utility model, when the cell is subjected to a tensile load in the transverse direction, the corresponding arc segment 11 will expand in the longitudinal direction; and when the cell is subjected to a compressive load in the transverse direction, When , the corresponding arc segment 11 will shrink in the longitudinal direction, causing the cell to have a negative Poisson's ratio effect, and the size of the negative Poisson's ratio can be controlled by reasonably designing the length of the connecting segment 12 and the radius of the arc segment 11 , which can effectively cope with the deformation caused by the force field to maintain the shape stability of the structure.

At the same time, the thermal expansion coefficient (α1) of the adjustment section 21 and the thermal expansion coefficient (α2) of the fitting section 22 are set to be unequal, so that when the external temperature changes, the adjustment section 21 and the fitting section 22 undergo coordinated thermal deformation to offset the expansion of the material itself. deformation caused. When the outside temperature rises and α1>α2, the elongation of the fitting section 22 is less than the elongation of the adjustment section 21, so that the height of the thermal expansion unit 2 becomes larger, showing a positive thermal expansion effect; when the outside temperature rises, And when α1<α2, the elongation of the fitting section 22 is greater than the elongation of the adjusting section 21, so that the height of the thermal expansion unit 2 becomes smaller, showing a negative thermal expansion effect; the thermal expansion coefficient can be controlled by changing the adjusting section 21 and the fitting section. 22 to achieve the angle size, or through the material. Therefore, the cells provided by this solution can simultaneously control thermal expansion and Poisson's ratio, which enhances stability and practicality, and the setting of the arc segment 11 can also reduce stress concentration, meeting the requirements of maintaining shape stability of precision instruments working in harsh environments. need.

Furthermore, in this embodiment, the connection point of the two adjustment sections 21 is connected to the midpoint of the corresponding arc section 11 . Specifically, the matching section 22 and the two adjustment sections 21 are surrounded together to form a triangular structure. The height line of the triangular structure through the connection of the two adjustment sections 21 is the adjustment height line; the corresponding arc section 11 passes through the radial line at its midpoint. For the control diameter line, the control diameter line coincides with the control high line. That is to say, in this solution, each thermal expansion unit 2 is connected to the midpoint of the corresponding arc segment 11 , and the matching segment 22 and the two adjustment segments 21 form a triangular structure. The triangular structure is connected with the corresponding arc segment 11 When the connection point is used as the vertex, its high line coincides with the radial line of the corresponding arc segment 11 at the midpoint, which further increases the stability of the cell. Furthermore, the lengths of the two adjustment sections 21 are the same, and the matching section 22 is connected to the two adjustment sections 21 end to end. That is, the triangular structure is configured as an isosceles triangular structure.

It should be noted that in the example of the drawing, the control height line of the triangular structure is shown as h, and the control radius line of the arc segment 11 is shown as r.

Furthermore, one end of each adjustment section 21 away from the corresponding arc section 11 is an extension end 211, and the extension end 211 extends out of the opening of the corresponding arc section 11; each matching section 22 is connected to the corresponding extension end. 211. In this embodiment, the fitting section 22 is located outside the opening of the corresponding arc section 11 so that the thermal expansion unit 2 has sufficient deformation space.

Furthermore, in this embodiment, there are four arc-shaped segments 11 , and the four arc-shaped segments 11 are arranged at equal intervals around the circumference; each connecting segment 12 includes two vertically connected connecting rods 121 , and the two connecting rods 121 Correspondingly connect two adjacent arc segments 11. Specifically, each arc segment 11 is arranged in a semicircle. In this way, the main unit 1 is arranged centrally symmetrically, thereby enhancing the stability of the overall structure. In order to avoid the influence of temperature on the negative Poisson's ratio effect of the main unit 1, in this solution, the thermal expansion coefficients of the multiple arc segments 11 and the multiple connecting segments 12 are the same. Specifically, the main body unit 1 is made of aluminum alloy.

In addition, please refer to Figure 5. The present invention also provides a metamaterial structure 200 whose thermal expansion and Poisson's ratio can be controlled simultaneously. The metamaterial structure 200 whose thermal expansion and Poisson's ratio can be controlled simultaneously includes a plurality of thermal expansion structures as described in any one of the above. and a metamaterial cell 100 whose thermal expansion and Poisson's ratio can be simultaneously controlled, wherein multiple metamaterial cells 100 whose thermal expansion and Poisson's ratio can be controlled simultaneously are connected in a body-center orthogonal manner.

It should be noted that the detailed structure of the metamaterial cell 100 whose thermal expansion and Poisson's ratio can be simultaneously regulated of the metamaterial structure 200 whose thermal expansion and Poisson's ratio can be simultaneously regulated can refer to the above-mentioned metamaterial cell 100 whose thermal expansion and Poisson's ratio can be simultaneously regulated. The embodiments will not be repeated here; since the above-mentioned metamaterial cell 100 whose thermal expansion and Poisson's ratio can be simultaneously controlled is used in the metamaterial structure 200 of the present invention whose thermal expansion and Poisson's ratio can be controlled simultaneously, therefore, the present invention The embodiments of the new metamaterial structure 200 with simultaneous controllable thermal expansion and Poisson's ratio include all the technical solutions of all the embodiments of the above-mentioned metamaterial cell 100 with simultaneous controllable thermal expansion and Poisson's ratio, and the technical effects achieved are exactly the same. This will not be described again.

Specifically, in this embodiment, there are three metamaterial cells 100 whose thermal expansion and Poisson's ratio can be controlled simultaneously, and the three metamaterial cells 100 whose thermal expansion and Poisson's ratio can be controlled simultaneously are body-centered and orthogonal. The connection makes the overall structure isotropic in the three coordinate axes, further improving the stability and practicality of the structure.

The above are only preferred specific implementations of the present utility model, but the protection scope of the present utility model is not limited thereto. Any person familiar with the technical field can easily imagine that within the technical scope disclosed by the present utility model, Any changes or replacements shall be covered by the protection scope of the present utility model.

Claims (10)

1. A metamaterial cell whose thermal expansion and Poisson's ratio can be controlled simultaneously, characterized in that it includes: The main unit includes a plurality of arc-shaped segments. The plurality of arc-shaped segments are arranged at circumferential intervals, and the openings of each arc-shaped segment face outward. A connecting segment is connected between two adjacent arc-shaped segments. , so that the main unit has a negative Poisson's ratio effect; and, A plurality of thermal expansion units are arranged in one-to-one correspondence with the plurality of arc-shaped segments, and each thermal expansion unit includes two adjustment segments connected at an included angle, and a mating segment connected to the two adjustment segments at the same time, so The thermal expansion coefficients of the matching section and the two adjustment sections are different, wherein the connection point of the two adjustment sections is connected to the recess of the corresponding arc section. 2. The metamaterial cell whose thermal expansion and Poisson's ratio can be controlled simultaneously according to claim 1, characterized in that the connection point of the two adjustment sections is connected to the midpoint of the corresponding arc section. 3. The metamaterial cell whose thermal expansion and Poisson's ratio can be controlled simultaneously according to claim 2, characterized in that the matching section and the two adjustment sections are jointly surrounded to form a triangular structure, and the triangular structure is formed by two The high line at the connection of each of the adjustment sections is the high regulating line; The radial line passing through the midpoint of the corresponding arc segment is the control radial line, and the control radial line coincides with the control high line. 4. The metamaterial cell whose thermal expansion and Poisson's ratio can be controlled simultaneously according to claim 3, characterized in that the lengths of the two adjustment sections are the same, and the matching section is connected to the two adjustment sections end to end. . 5. The metamaterial cell whose thermal expansion and Poisson's ratio can be controlled simultaneously according to claim 1, characterized in that one end of each adjustment section away from the corresponding arc section is an extension end, and the extension end is The end extends outside the opening of the corresponding arc segment; Each matching section is connected to the corresponding extending end. 6. The metamaterial cell whose thermal expansion and Poisson's ratio can be controlled simultaneously according to claim 1, characterized in that there are four arc-shaped segments, and the four arc-shaped segments are arranged at equal intervals around the circumference; Each connecting section includes two connecting rods connected vertically, and the two connecting rods connect two adjacent arc-shaped segments correspondingly. 7. The metamaterial cell whose thermal expansion and Poisson's ratio can be controlled simultaneously according to claim 6, characterized in that each of the arc segments is arranged in a semicircle. 8. The metamaterial cell whose thermal expansion and Poisson's ratio can be controlled simultaneously according to claim 1, characterized in that the thermal expansion coefficients of the plurality of arc segments and the plurality of connecting segments are the same. 9. The metamaterial cell whose thermal expansion and Poisson's ratio can be controlled simultaneously according to claim 1, characterized in that the material of the main unit is aluminum alloy. 10. A metamaterial structure whose thermal expansion and Poisson's ratio can be controlled simultaneously, characterized by comprising a plurality of metamaterial cells whose thermal expansion and Poisson's ratio can be controlled simultaneously according to any one of claims 1 to 9, wherein , multiple metamaterial cells whose thermal expansion and Poisson's ratio can be controlled simultaneously are connected in a body-center orthogonal manner.