Poisson's ratio unit and two-dimensional and three-dimensional programmable Poisson's ratio mechanical metamaterial

Abstract

The invention discloses a Poisson's ratio unit and a two-dimensional and three-dimensional programmable Poisson's ratio mechanical metamaterial, relates to the technical field of mechanical metamaterials, and solves the problem that the Poisson's ratio is fixed and cannot be changed after a traditional mechanical metamaterial is designed. The negative Poisson's ratio units are obtained by adding the reverse arms on the two sides of the positive Poisson's ratio units, and the positive Poisson's ratio units and the reverse arms are continuously added on the basis of the negative Poisson's ratio units to obtain the positive and negative Poisson's ratio units; the negative Poisson's ratio units and the positive Poisson's ratio units are combined into an array to obtain a two-dimensional programmable Poisson's ratio mechanical metamaterial; the positive and negative Poisson's ratio units, the negative and negative Poisson's ratio units and the positive and positive Poisson's ratio units are mutually combined and arrayed to obtain the three-dimensional programmable Poisson's ratio mechanical metamaterial. According to the invention, programming design can be carried out on different Poisson's ratio units according to different use scenes, and the use scenes are further expanded by flexibly adjusting and optimizing the Poisson's ratio in each direction.

Description

Technical Field

[0001] The present invention relates to the technical field of mechanical metamaterials, and particularly to a Poisson's ratio unit and a two-dimensional and three-dimensional programmable Poisson's ratio mechanical metamaterial. Background Art

[0002] Mechanical metamaterials are a class of artificial materials with unconventional mechanical properties. By cleverly designing and programming internal repeating units, adjustable stiffness, adjustable Poisson's ratio, shape reconfigurability and other mechanical properties can be achieved. For most traditional materials, Poisson's ratio is positive. A negative Poisson's ratio structure produces a transverse expansion effect when axially tensioned and exhibits a transverse contraction characteristic when compressed. Its unique mechanical response endows the structure with excellent compression impedance, indentation resistance and shear strength. A zero Poisson's ratio structure is a structure in which, under force, the deformation of the material in one direction (such as tension or compression) does not cause deformation in the direction perpendicular to that direction. Zero Poisson's ratio materials have attracted much attention due to their unusual properties and potential applications in different fields such as medicine, tissue engineering and aviation. After traditional mechanical metamaterials are designed, Poisson's ratio is fixed and cannot be changed. Therefore, it is of great significance to program and adjust the Poisson's ratio of the structure according to different usage scenarios. Summary of the Invention

[0003] In order to solve the problem that the Poisson's ratio of traditional mechanical metamaterials is fixed and cannot be changed after design, the present invention hereby provides a Poisson's ratio unit and a two-dimensional and three-dimensional programmable Poisson's ratio mechanical metamaterial. The present invention can perform programming design on different Poisson's ratio units according to different usage scenarios, and further expand the usage scenarios by flexibly adjusting and optimizing the Poisson's ratio in each direction.

[0004] The present invention provides a negative Poisson's ratio unit, which specifically includes a positive Poisson's ratio unit and two reverse arms. The positive Poisson's ratio unit is a rectangular ring structure, and the two reverse arms are arranged at a pair of diagonal positions of the positive Poisson's ratio unit; the reverse arm is a U-shaped structure, the positive Poisson's ratio unit is arranged in the middle of the two side edges of the U-shaped structure and is connected to one of the side edges, and the hollow area of the positive Poisson's ratio unit faces the bottom edge of the U-shaped structure of the reverse arm, thus forming a negative Poisson's ratio unit.

[0005] Furthermore, chamfering is performed at the four corner positions of the positive Poisson's ratio unit.

[0006] A two-dimensional programmable Poisson's ratio mechanical metamaterial using the above-mentioned negative Poisson's ratio unit specifically includes a plurality of Poisson's ratio structures one arranged longitudinally; the Poisson's ratio structure one includes at least one negative Poisson's ratio unit and at least one positive Poisson's ratio unit and they are connected to each other, or only includes a plurality of negative Poisson's ratio units.

[0007] A positive-negative Poisson's ratio unit specifically includes a positive Poisson's ratio unit and one of the above-mentioned negative Poisson's ratio units. The positive Poisson's ratio unit in the negative Poisson's ratio unit and another positive Poisson's ratio unit cross each other to form a positive-positive Poisson's ratio unit; the reverse arm of the negative Poisson's ratio unit passes through the annular center of another positive Poisson's ratio unit to form a positive-negative Poisson's ratio unit.

[0008] Furthermore, the positive-positive Poisson's ratio unit is an octahedral structure.

[0009] A three-dimensional programmable Poisson's ratio mechanical metamaterial using the above-mentioned positive-negative Poisson's ratio unit specifically includes a plurality of Poisson's ratio structures two arranged in an array; the Poisson's ratio structure two includes at least one positive-negative Poisson's ratio unit and at least one positive-positive Poisson's ratio unit and they are connected to each other, or only includes a plurality of positive-negative Poisson's ratio units.

[0010] A negative-negative Poisson's ratio unit specifically includes one of the above-mentioned positive-negative Poisson's ratio units and two reverse arms two; the two reverse arms two are obliquely arranged at both ends of the middle part of the positive Poisson's ratio unit of the positive-negative Poisson's ratio unit where there is no reverse arm, and pass through the center of another positive Poisson's ratio unit to form a negative-negative Poisson's ratio unit.

[0011] A three-dimensional programmable Poisson's ratio mechanical metamaterial using the above-mentioned negative-negative Poisson's ratio unit specifically includes a plurality of Poisson's ratio structures three arranged in an array; the Poisson's ratio structure three includes at least one negative-negative Poisson's ratio unit and at least one positive-positive Poisson's ratio unit and they are connected to each other, or only includes a plurality of negative-negative Poisson's ratio units.

[0012] A three-dimensional programmable Poisson's ratio mechanical metamaterial using the above-mentioned positive-negative Poisson's ratio unit and negative-negative Poisson's ratio unit specifically includes a plurality of Poisson's ratio structures four arranged in an array; the Poisson's ratio structure four includes at least one positive-negative Poisson's ratio unit and at least one negative-negative Poisson's ratio unit and they are connected to each other.

[0013] Furthermore, the positive-negative Poisson's ratio units and negative-negative Poisson's ratio units of the Poisson's ratio structure four are arranged alternately, and the reverse arm two of the negative-negative Poisson's ratio unit is connected to the positive-positive Poisson's ratio unit at the center of the positive-negative Poisson's ratio unit.

[0014] The beneficial effects of the Poisson's ratio unit and two-dimensional and three-dimensional programmable Poisson's ratio mechanical metamaterials of the present invention are as follows:

[0015] (1) A Poisson ratio unit and a two-dimensional and three-dimensional programmable Poisson ratio mechanical metamaterial according to the present invention solve the problem that the Poisson ratio of traditional mechanical metamaterials is fixed and cannot be changed after design. By adding reverse arms on both sides of the positive Poisson ratio unit to become a negative Poisson ratio unit, and by combining the positive Poisson ratio unit and the negative Poisson ratio unit, a programmable design of the Poisson ratio in the two-dimensional direction is realized. Compared with traditional mechanical metamaterials with a fixed Poisson ratio after design, the present invention has programmability and scalability, a wider range of application scenarios, and broad application prospects in the fields of shock and vibration isolation, energy absorption, shape reconstruction, and so on.

[0016] (2) A Poisson ratio unit and a two-dimensional and three-dimensional programmable Poisson ratio mechanical metamaterial according to the present invention, by further adding a positive Poisson ratio unit and a reverse arm two on the basis of the negative Poisson ratio unit, respectively obtain a positive-negative Poisson ratio unit and a negative-negative Poisson ratio unit, and realize a programmable design of the Poisson ratio in the three-dimensional direction by different combinations of the positive-negative Poisson ratio unit and the negative-negative Poisson ratio unit, thus having a higher design freedom, that is, the Poisson ratio in each direction can be flexibly adjusted and optimized to further expand the application scenarios, and has broad application prospects in the fields of shock and vibration isolation, energy absorption, shape reconstruction, and so on. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0018] In the drawings:

[0019] Figure 1 is an axonometric view of the positive Poisson ratio unit of a Poisson ratio unit and a two-dimensional and three-dimensional programmable Poisson ratio mechanical metamaterial according to the present invention;

[0020] Figure 2 is an axonometric view of the negative Poisson ratio unit of a Poisson ratio unit and a two-dimensional and three-dimensional programmable Poisson ratio mechanical metamaterial according to the present invention;

[0021] Figure 3 is an axonometric view of a +4 Poisson ratio mechanical metamaterial of a Poisson ratio unit and a two-dimensional and three-dimensional programmable Poisson ratio mechanical metamaterial according to the present invention;

[0022] Figure 4 is an axonometric view of a +2 Poisson ratio mechanical metamaterial of a Poisson ratio unit and a two-dimensional and three-dimensional programmable Poisson ratio mechanical metamaterial according to the present invention;

[0023] Figure 5 is an axonometric view of a 0 Poisson ratio mechanical metamaterial of a Poisson ratio unit and a two-dimensional and three-dimensional programmable Poisson ratio mechanical metamaterial according to the present invention;

[0024] Figure 6 Is an axonometric view of a -2 Poisson's ratio mechanical metamaterial of a Poisson's ratio unit and a two-dimensional and three-dimensional programmable Poisson's ratio mechanical metamaterial according to the present invention;

[0025] Figure 7 Is an axonometric view of a -4 Poisson's ratio mechanical metamaterial of a Poisson's ratio unit and a two-dimensional and three-dimensional programmable Poisson's ratio mechanical metamaterial according to the present invention;

[0026] Figure 8 Is an axonometric view of a positive-positive Poisson's ratio unit of a Poisson's ratio unit and a two-dimensional and three-dimensional programmable Poisson's ratio mechanical metamaterial according to the present invention;

[0027] Figure 9 Is an axonometric view of a positive-negative Poisson's ratio unit of a Poisson's ratio unit and a two-dimensional and three-dimensional programmable Poisson's ratio mechanical metamaterial according to the present invention;

[0028] Figure 10 Is an axonometric view of a negative-positive Poisson's ratio mechanical metamaterial of a Poisson's ratio unit and a two-dimensional and three-dimensional programmable Poisson's ratio mechanical metamaterial according to the present invention;

[0029] Figure 11 Is an axonometric view of a zero-positive Poisson's ratio mechanical metamaterial of a Poisson's ratio unit and a two-dimensional and three-dimensional programmable Poisson's ratio mechanical metamaterial according to the present invention;

[0030] Figure 12 Is an axonometric view of a negative-negative Poisson's ratio unit of a Poisson's ratio unit and a two-dimensional and three-dimensional programmable Poisson's ratio mechanical metamaterial according to the present invention;

[0031] Figure 13 Is an axonometric view of a negative-negative Poisson's ratio mechanical metamaterial of a Poisson's ratio unit and a two-dimensional and three-dimensional programmable Poisson's ratio mechanical metamaterial according to the present invention;

[0032] Figure 14 Is an axonometric view of a zero-zero Poisson's ratio mechanical metamaterial of a Poisson's ratio unit and a two-dimensional and three-dimensional programmable Poisson's ratio mechanical metamaterial according to the present invention;

[0033] Figure 15 Is an axonometric view of a negative-zero Poisson's ratio mechanical metamaterial of a Poisson's ratio unit and a two-dimensional and three-dimensional programmable Poisson's ratio mechanical metamaterial according to the present invention;

[0034] Wherein: 1: positive Poisson's ratio unit; 2: negative Poisson's ratio unit; 201: reverse arm; 3: end plate; 301: upper plate; 302: lower plate; 4: +4 Poisson's ratio mechanical metamaterial; 5: +2 Poisson's ratio mechanical metamaterial; 6: 0 Poisson's ratio mechanical metamaterial; 7: -2 Poisson's ratio mechanical metamaterial; 8: -4 Poisson's ratio mechanical metamaterial; 9: positive-positive Poisson's ratio unit; 10: positive-negative Poisson's ratio unit; 11: negative-negative Poisson's ratio unit; 1101: reverse arm two; 12: negative-negative Poisson's ratio mechanical metamaterial; 13: positive-negative Poisson's ratio mechanical metamaterial; 14: zero-zero Poisson's ratio mechanical metamaterial; 15: zero-positive Poisson's ratio mechanical metamaterial; 16: negative-zero Poisson's ratio mechanical metamaterial. Detailed implementation manners

[0035] The technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0036] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0037] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0038] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0039] Detailed implementation manner one: Refer to Figures 1 - 7Specifically describe this embodiment. A negative Poisson's ratio unit described in this embodiment specifically includes a positive Poisson's ratio unit 1 and two reverse arms 201. The positive Poisson's ratio unit 1 is a rectangular ring structure, and chamfering is performed at the four corner positions to form a platform structure, as Figure 1 shown; the two reverse arms 201 are arranged at a pair of diagonal positions of the positive Poisson's ratio unit 1; the reverse arm 201 is a U-shaped structure, and the positive Poisson's ratio unit 1 is arranged in the middle of the two side edges of the U-shaped structure and connected to one of the side edges, so that each reverse arm 201 is reversely connected from one side of the positive Poisson's ratio unit 1 to the other side; the hollow area of the positive Poisson's ratio unit 1 faces the bottom edge of the U-shaped structure of the reverse arm 201, constituting a negative Poisson's ratio unit 2, as Figure 2 shown. Under a compressive load, the positive Poisson's ratio unit 1 exhibits a positive Poisson's ratio deformation, while the two ends of the reverse arm 201 contract, so that the negative Poisson's ratio unit 2 as a whole exhibits a negative Poisson's ratio deformation. It should be noted that since the negative Poisson's ratio unit 2 only changes the deformation direction of the positive Poisson's ratio unit 1, the two have the same Poisson's ratio value, only the positive and negative directions are different. Here, the Poisson's ratio of the positive Poisson's ratio unit 1 is defined as +1, and the Poisson's ratio of the negative Poisson's ratio unit 2 is defined as -1.

[0040] A two-dimensional programmable Poisson's ratio mechanical metamaterial using the above-mentioned negative Poisson's ratio unit 2 specifically includes an end plate 3 and a number of longitudinally arranged Poisson's ratio structures I; the end plate 3 includes an upper plate 301 and a lower plate 302, and a number of longitudinally arranged Poisson's ratio structures I are arranged between the upper plate 301 and the lower plate 302; the Poisson's ratio structure I includes at least one negative Poisson's ratio unit 2 and at least one positive Poisson's ratio unit 1 and they are connected to each other, or is completely composed of interconnected negative Poisson's ratio units 2, or is completely composed of interconnected positive Poisson's ratio units 1; the structures between adjacent rows are the same, and the rows are connected by positive Poisson's ratio units 1; by adjusting the number and arrangement of the negative Poisson's ratio units 2 and the positive Poisson's ratio units 1, the Poisson's ratio of the two-dimensional mechanical metamaterial can be programmed and designed to obtain different two-dimensional programmable Poisson's ratio mechanical metamaterials to meet the Poisson's ratio requirements under different working conditions.

[0041] As Figure 3 shown, when the Poisson's ratio structure I is completely composed of positive Poisson's ratio units 1, four identical positive Poisson's ratio units 1 are connected in sequence in the transverse direction, and a +4 Poisson's ratio mechanical metamaterial 4 is obtained by arraying the positive Poisson's ratio units 1. Under a compressive load, the Poisson's ratio of the +4 Poisson's ratio mechanical metamaterial 4 is +4.

[0042] As Figure 4As shown, when Poisson ratio structure one includes a negative Poisson ratio unit 2 and three positive Poisson ratio units 1, a +2 Poisson ratio mechanical metamaterial 5 is obtained through an array of Poisson ratio structure one. The negative Poisson ratio unit 2 is connected to the apex position of the positive Poisson ratio unit 1 through the reverse arm 201, and the positive Poisson ratio units 1 are directly connected; the structures of adjacent rows are the same and are connected up and down through the platform of the positive Poisson ratio unit 1. Under compressive load, the Poisson ratio of the +2 Poisson ratio mechanical metamaterial 5 is +2.

[0043] As Figure 5 shown, when Poisson ratio structure one includes two negative Poisson ratio units 2 and two positive Poisson ratio units 1, that is, when the number of negative Poisson ratio units 2 and positive Poisson ratio units 1 is equal, a 0 Poisson ratio mechanical metamaterial 6 is obtained through an array. When two negative Poisson ratio units 2 are adjacent, they are directly connected through the reverse arm 201; when a negative Poisson ratio unit 2 and a positive Poisson ratio unit 1 are adjacent, the reverse arm 201 of the negative Poisson ratio unit 2 is connected to the apex position of the positive Poisson ratio unit 1; the structures of adjacent rows are the same and are connected up and down through the platform of the positive Poisson ratio unit 1. Under compressive load, the Poisson ratio effects of the positive Poisson ratio unit 1 and the negative Poisson ratio unit 2 cancel each other out, and the overall shows zero Poisson ratio deformation.

[0044] As Figure 6 shown, when Poisson ratio structure one includes three negative Poisson ratio units 2 and one positive Poisson ratio unit 1, a -2 Poisson ratio mechanical metamaterial 7 is obtained through an array. When two negative Poisson ratio units 2 are adjacent, they are directly connected through the reverse arm 201; when a negative Poisson ratio unit 2 and a positive Poisson ratio unit 1 are adjacent, the reverse arm 201 of the negative Poisson ratio unit 2 is connected to the apex position of the positive Poisson ratio unit 1; the structures of adjacent rows are the same and are connected up and down through the platform of the positive Poisson ratio unit 1. Under compressive load, the Poisson ratio of the -2 Poisson ratio mechanical metamaterial 7 is -2.

[0045] As Figure 7 shown, when Poisson ratio structure one is completely composed of negative Poisson ratio units 2, a -4 Poisson ratio mechanical metamaterial 8 is obtained through an array. The negative Poisson ratio units 2 are directly connected through the reverse arm 201; the structures of adjacent rows are the same and are connected up and down through the platform of the positive Poisson ratio unit 1. Under compressive load, the Poisson ratio of the -4 Poisson ratio mechanical metamaterial 8 is -4.

[0046] Specific implementation method two: Refer to Figures 8 - 11 Specifically illustrate this implementation method. A positive and negative Poisson ratio unit 10 described in this implementation method specifically includes a positive Poisson ratio unit 1 and a negative Poisson ratio unit 2 described in the first specific implementation method. The positive Poisson ratio unit 1 in the negative Poisson ratio unit 2 and another positive Poisson ratio unit 1 cross to form a positive-positive Poisson ratio unit 9. The positive-positive Poisson ratio unit 9 is an octahedral structure, as Figure 8As shown; the reverse arm 201 of the negative Poisson's ratio unit 2 passes through the annular center of another positive Poisson's ratio unit 1 to form a positive and negative Poisson's ratio unit 10, such as Figure 9 shown. Under the compressive load, the positive Poisson's ratio effect is presented in both the x and y directions of the positive-positive Poisson's ratio unit 9. Under the compressive load, the negative Poisson's ratio effect is presented in the x direction of the positive-negative Poisson's ratio unit 10, and the positive Poisson's ratio effect is presented in the y direction; taking Figure 9 as an example, Figure 9 the direction where the reverse arm 201 is located in

[0047] A three-dimensional programmable Poisson's ratio mechanical metamaterial using the above positive-negative Poisson's ratio unit 10 specifically includes end plates 3 and several Poisson's ratio structures II; the end plates 3 include an upper plate 301 and a lower plate 302, and several arrayed Poisson's ratio structures II are arranged between the upper plate 301 and the lower plate 302; the Poisson's ratio structure II includes at least one positive-negative Poisson's ratio unit 10 and at least one positive-positive Poisson's ratio unit 9 and they are connected to each other; or the Poisson's ratio structure II is completely composed of positive-negative Poisson's ratio units 10, and the positive-negative Poisson's ratio units 10 are connected to each other. By adjusting the number and arrangement of the positive-negative Poisson's ratio units 10 and the positive-positive Poisson's ratio units 9 in each row and then arraying them, the Poisson's ratio of the three-dimensional mechanical metamaterial can be programmatically designed to obtain different three-dimensional programmable Poisson's ratio mechanical metamaterials to meet the Poisson's ratio requirements under different working conditions.

[0048] As Figure 10 shown, when the Poisson's ratio structure II is completely composed of positive-negative Poisson's ratio units 10, the positive-negative Poisson's ratio units 10 are arrayed to obtain a positive-negative Poisson's ratio mechanical metamaterial 13; each positive-negative Poisson's ratio unit 10 in the row is connected to each other in the x direction through the reverse arm 201; in the y direction, that is, between adjacent rows in the same layer, they are connected through the platforms of the positive-positive Poisson's ratio units 9 inside the positive-negative Poisson's ratio units 10; in the z direction, all the units have the same configuration and are connected end to end. Under the compressive load, the positive-negative Poisson's ratio mechanical metamaterial 13 shows a negative Poisson's ratio effect in the x direction and a positive Poisson's ratio effect in the y direction.

[0049] As Figure 11As shown, the Poisson's ratio structure two includes two positive and negative Poisson's ratio units 10 and two positive and positive Poisson's ratio units 9. The positive and negative Poisson's ratio units 10 and the positive and positive Poisson's ratio units 9 are arranged alternately in a row; in the x direction, the reverse arms 201 of the positive and negative Poisson's ratio units 10 in a row are connected to the platforms of the positive and positive Poisson's ratio units 9; in the y direction, that is, between adjacent rows on the same layer, they are connected through the positive and positive Poisson's ratio units 9 inside the positive and negative Poisson's ratio units 10 and the platforms of the separate positive and positive Poisson's ratio units 9; in the z direction, all the units have the same configuration and are connected end to end; by arraying the Poisson's ratio structure two, a zero positive Poisson's ratio mechanical metamaterial 15 is obtained. Under compressive load, the zero positive Poisson's ratio mechanical metamaterial 15 exhibits a zero Poisson's ratio effect in the x direction and a positive Poisson's ratio effect in the y direction.

[0050] Specific Embodiment Three: Refer to Figure 8 、 Figures 12 - 14 This specific embodiment will be described in detail. A negative and negative Poisson's ratio unit 11 described in this embodiment includes a positive and negative Poisson's ratio unit 10 described in Specific Embodiment Two and two reverse arms two 1101; the two reverse arms two 1101 are obliquely arranged at both ends of the middle part of the positive Poisson's ratio unit 1 of the positive and negative Poisson's ratio unit 10 where the reverse arm 201 is not provided, and pass through the center of another positive Poisson's ratio unit 1 to form the negative and negative Poisson's ratio unit 11. The inclination angle of the reverse arm two 1101 is 45 degrees to avoid interference with another pair of reverse arms 201. Under compressive load, the negative and negative Poisson's ratio unit 11 exhibits a negative Poisson's ratio effect in both the x and y directions.

[0051] A three-dimensional programmable Poisson's ratio mechanical metamaterial of the above-mentioned negative and negative Poisson's ratio unit 11 specifically includes end plates 3 and several Poisson's ratio structures three; the end plates 3 include an upper plate 301 and a lower plate 302, and several arrayed Poisson's ratio structures three are arranged between the upper plate 301 and the lower plate 302; the Poisson's ratio structure three includes at least one negative and negative Poisson's ratio unit 11 and at least one positive and positive Poisson's ratio unit 9 and they are connected to each other; or the Poisson's ratio structure three is completely composed of several negative and negative Poisson's ratio units 11, and several negative and negative Poisson's ratio units 11 are connected to each other. By adjusting the number and arrangement mode of the negative and negative Poisson's ratio units 11 and the positive and positive Poisson's ratio units 9 in each row and then arraying, the Poisson's ratio of the three-dimensional mechanical metamaterial can be programmably designed to obtain different three-dimensional programmable Poisson's ratio mechanical metamaterials to meet the Poisson's ratio requirements under different working conditions.

[0052] Such as Figure 13As shown, when the Poisson's ratio structure three is completely composed of the negative-negative Poisson's ratio units 11, an array thereof gives a negative-negative Poisson's ratio mechanical metamaterial 12; wherein, in the x direction, the negative-negative Poisson's ratio units 11 in the same row are connected to each other through the reverse arm two 1101; in the y direction, the rows are connected through the reverse arm 201; in the z direction, all the units have the same configuration and are connected end to end. Under a compressive load, the negative-negative Poisson's ratio mechanical metamaterial 12 exhibits a negative Poisson's ratio effect in both the x and y directions.

[0053] As Figure 14 shown, the Poisson's ratio structure three includes two negative-negative Poisson's ratio units 11 and two positive-positive Poisson's ratio units 9; in the x direction and the y direction, the negative-negative Poisson's ratio units 11 and the positive-positive Poisson's ratio units 9 are alternately arranged, and an array of the Poisson's ratio structure three gives a zero-zero Poisson's ratio mechanical metamaterial 14; in the z direction, all the units have the same configuration and are connected end to end. Under a compressive load, the zero-zero Poisson's ratio mechanical metamaterial 14 exhibits a zero Poisson's ratio effect in both the x and y directions.

[0054] Specific implementation manner four: Refer to Figure 8 、 Figure 9 、 Figure 12 and Figure 15 to specifically illustrate this implementation manner. A three-dimensional programmable Poisson's ratio mechanical metamaterial using the above-mentioned positive-negative Poisson's ratio unit 10 and negative-negative Poisson's ratio unit 11 described in this implementation manner specifically includes an end plate 3 and a plurality of Poisson's ratio structures four; the end plate 3 includes an upper plate 301 and a lower plate 302, and a plurality of Poisson's ratio structures four arranged in an array are provided between the upper plate 301 and the lower plate 302; the Poisson's ratio structure four includes at least one positive-negative Poisson's ratio unit 10 and at least one negative-negative Poisson's ratio unit 11, and the positive-negative Poisson's ratio unit 10 and the negative-negative Poisson's ratio unit 11 are connected. By adjusting the number and arrangement of the negative-negative Poisson's ratio units 11 and the positive-negative Poisson's ratio units 10 in each row and then making an array, the Poisson's ratio of the three-dimensional mechanical metamaterial can be programmably designed to obtain different three-dimensional programmable Poisson's ratio mechanical metamaterials to meet the Poisson's ratio requirements under different working conditions.

[0055] As Figure 15 shown, the Poisson's ratio structure four includes two positive-negative Poisson's ratio units 10 and two negative-negative Poisson's ratio units 11; in the y direction, the negative-negative Poisson's ratio units 11 in the same row are connected to the platform of the positive-positive Poisson's ratio unit 9 inside the positive-negative Poisson's ratio unit 10 through the reverse arm two 1101; in the x direction, the adjacent rows are connected through the reverse arm 201; in the z direction, all the units have the same configuration and are connected end to end; an array of the Poisson's ratio structure four gives a negative-zero Poisson's ratio mechanical metamaterial 16. Under a compressive load, the negative-zero Poisson's ratio mechanical metamaterial 16 exhibits a negative Poisson's ratio effect in the x direction and a zero Poisson's ratio effect in the y direction.

[0056] Summarizing the above embodiments, a Poisson ratio unit and a two-dimensional and three-dimensional programmable Poisson ratio mechanical metamaterial according to the present invention solve the problem that the Poisson ratio of traditional mechanical metamaterials is fixed and cannot be changed after design. By adding reverse arms 201 on both sides of the positive Poisson ratio unit 1 to become a negative Poisson ratio unit 2, and by combining the positive Poisson ratio unit 1 and the negative Poisson ratio unit 2, a Poisson ratio programming design in the two-dimensional direction is realized. Compared with traditional mechanical metamaterials having a fixed Poisson ratio after design, the present invention has programmability and scalability, and has a wider range of application scenarios, and has broad application prospects in fields such as shock and vibration isolation, energy absorption, shape reconstruction, and so on. A Poisson ratio unit and a two-dimensional and three-dimensional programmable Poisson ratio mechanical metamaterial according to the present invention, by further adding a positive Poisson ratio unit 1 and a reverse arm two 1101 on the basis of the negative Poisson ratio unit 2, respectively obtain a positive-negative Poisson ratio unit 10 and a negative-negative Poisson ratio unit 11, and realize a Poisson ratio programming design in the three-dimensional direction by different combinations of the positive-negative Poisson ratio unit 10 and the negative-negative Poisson ratio unit 11, thereby having a higher design freedom, that is, by flexibly adjusting and optimizing the Poisson ratio in each direction, the application scenario is further expanded, and it has broad application prospects in fields such as shock and vibration isolation, energy absorption, shape reconstruction, and so on.

[0057] In the specific embodiments described above, the purpose, technical solutions, and beneficial effects of the present invention have been further described in detail. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the invention. It can also be a reasonable combination of the features described in the above embodiments. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A negative Poisson's ratio unit, characterized in that: It includes a positive Poisson's ratio unit (1) and two reverse arms (201). The positive Poisson's ratio unit (1) is a rectangular ring structure, and the two reverse arms (201) are arranged at a pair of diagonal positions of the positive Poisson's ratio unit (1); the reverse arm (201) is a U-shaped structure, and the positive Poisson's ratio unit (1) is arranged in the middle of the two side edges of the U-shaped structure and connected to one of the side edges. The hollow area of the positive Poisson's ratio unit (1) faces the bottom edge of the U-shaped structure of the reverse arm (201), forming a negative Poisson's ratio unit (2).

2. The negative Poisson's ratio unit according to claim 1, characterized in that: Chamfering treatment is performed on the four corner positions of the positive Poisson's ratio unit (1).

3. A two-dimensional programmable Poisson's ratio mechanical metamaterial using the negative Poisson's ratio unit described in claim 2, characterized in that: It includes a number of Poisson's ratio structures one arranged longitudinally; the Poisson's ratio structure one includes at least one negative Poisson's ratio unit (2) and at least one positive Poisson's ratio unit (1) and they are connected to each other, or only includes a number of negative Poisson's ratio units (2).

4. A unit with positive and negative Poisson's ratios, characterized in that: It includes a positive Poisson's ratio unit (1) and a negative Poisson's ratio unit (2) as described in claim 2. The positive Poisson's ratio unit (1) in the negative Poisson's ratio unit (2) and the other positive Poisson's ratio unit (1) cross each other to form a positive-positive Poisson's ratio unit (9); the reverse arm (201) of the negative Poisson's ratio unit (2) passes through the ring center of the other positive Poisson's ratio unit (1), forming a positive-negative Poisson's ratio unit (10).

5. The positive and negative Poisson's ratio unit according to claim 4, wherein: The positive-positive Poisson's ratio unit (9) is an octahedron structure.

6. A three-dimensional programmable Poisson's ratio mechanical metamaterial using the positive and negative Poisson's ratio unit described in claim 5, characterized in that: It includes a number of Poisson's ratio structures two arranged in an array; the Poisson's ratio structure two includes at least one positive-negative Poisson's ratio unit (10) and at least one positive-positive Poisson's ratio unit (9) and they are connected to each other, or only includes a number of positive-negative Poisson's ratio units (10).

7. A negative-negative Poisson's ratio unit, characterized in that: It includes a positive-negative Poisson's ratio unit (10) as described in claim 5 and two reverse arms two (1101); the two reverse arms two (1101) are inclined and arranged at both ends of the middle of the positive Poisson's ratio unit (1) of the positive-negative Poisson's ratio unit (10) where the reverse arm (201) is not provided, and pass through the center of the other positive Poisson's ratio unit (1), forming a negative-negative Poisson's ratio unit (11).

8. A three-dimensional programmable Poisson's ratio mechanical metamaterial using the negative-negative Poisson's ratio unit described in claim 7, characterized in that: It includes a number of Poisson's ratio structures three arranged in an array; the Poisson's ratio structure three includes at least one negative-negative Poisson's ratio unit (11) and at least one positive-positive Poisson's ratio unit (9) and they are connected to each other, or only includes a number of negative-negative Poisson's ratio units (11).

9. A three-dimensional programmable Poisson's ratio mechanical metamaterial using the positive-negative Poisson's ratio unit and negative-negative Poisson's ratio unit described in claim 7, characterized in that: It includes a number of Poisson's ratio structures four arranged in an array; the Poisson's ratio structure four includes at least one positive-negative Poisson's ratio unit (10) and at least one negative-negative Poisson's ratio unit (11) and they are connected to each other.

10. The three-dimensional programmable Poisson's ratio mechanical metamaterial according to claim 9, characterized in that: The positive-negative Poisson's ratio unit (10) and the negative-negative Poisson's ratio unit (11) of the Poisson's ratio structure four are arranged alternately, and the reverse arm two (1101) of the negative-negative Poisson's ratio unit (11) is connected to the positive-positive Poisson's ratio unit (9) at the center of the positive-negative Poisson's ratio unit (10).

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