Negative Poisson's ratio metamaterial cell element structure based on four-rod tension structure

Abstract

The invention relates to a negative Poisson's ratio metamaterial cell element structure based on a four-rod tension structure, which belongs to the field of mechanical metamaterials and comprises a four-rod tension integral structure component and a degree-of-freedom constraint component. Under the action of a four-rod twelve-cable tensioning integral structure, when the structure is not subjected to external load, the structure is balanced in a self-stabilizing state under the interaction of internal stress; and under the state of external load, the upper surface and the lower surface can generate a torsion effect, and the structure can recover to the initial state after the external load is removed again. The negative Poisson's ratio metamaterial cell element structure based on the four-rod tension structure has the advantages of self-adaptability, self-recovery, compression-torsion characteristic and the like. The tensegrity structure and the mechanical metamaterial structure are combined, the types of existing mechanical metamaterial cell element structures are enriched, and a brand new direction is opened up for design, analysis and application of the tensegrity mechanical metamaterial structure.

Description

Technical Field

[0001] The present invention belongs to the field of mechanical metamaterials and can be applied to the fields of robots, shock absorption, impact resistance, etc. More specifically, it relates to a negative Poisson's ratio metamaterial cell structure based on a four-bar tension structure. Background Art

[0002] Metamaterials are non-natural materials whose properties are derived from their structure rather than their chemical composition. They are artificial synthetic materials with special structures that exhibit very unique properties in the fields of mechanics, electromagnetic waves, sound waves, etc. According to the application field, metamaterials can be divided into four categories: electromagnetic metamaterials, acoustic metamaterials, thermal metamaterials, and mechanical metamaterials. Negative Poisson's ratio metamaterials are a branch of mechanical metamaterials. When subjected to pressure, the ratio of the lateral normal strain to the axial normal strain in a certain direction (Poisson's ratio) is negative. This material has many unique properties, such as highly controllable elasticity, light weight, high strength, etc., and can be used in various fields, such as robotics, medicine, aerospace, etc., making its research and application have great potential and has received widespread attention in recent years.

[0003] At present, the existing mechanical metamaterials have a single cell structure in terms of structural design, and negative Poisson's ratio metamaterials are mostly integrated structures with low reusability. In addition, many designs to date rely on the deformation or evolution of existing metamaterial structures, and it is impossible to systematically design geometric and topological shapes to obtain new metamaterial structures with negative Poisson's ratio effects.

[0004] Therefore, how to enrich the types of mechanical metamaterials and design a mechanical metamaterial that can be reused, has adjustable self-stiffness, and has adaptability, self-stability, and self-recovery is an urgent problem that technicians in this field need to solve. Summary of the invention

[0005] To this end, the present invention provides a negative Poisson's ratio metamaterial cell structure based on a four-bar tensioned structure. By combining the tensioned overall structure with the mechanical metamaterial structure, the types of negative Poisson's ratio metamaterial cells are enriched and the mechanical properties of traditional mechanical metamaterials are improved.

[0006] The present invention provides a negative Poisson's ratio metamaterial cellular structure based on a four-bar tensegrity structure, comprising: a degree of freedom constraint component and a four-bar tensegrity overall structure component.

[0007] The freedom constraint assembly includes a square frame, a sliding component, a rod connector and a connecting shaft; the four-rod tensile structure assembly includes a first tension elastic body, a second tension elastic body and a connecting rod.

[0008] There are two groups of square frames, which are respectively placed at the upper and lower ends of the entire structure. Hinge holes are arranged at the outer edge positions of the four corners of the square frame. Four regular quadrangular prism structures inside the structure are arranged in a 90° circular array. An octagonal structure is arranged at the center of the structure and fixedly connected to the regular quadrangular prism structure. The function of the hinge holes is to enable the cell structure to be hingedly connected through the hinge holes. The regular quadrangular prism structure plays a guiding role, and the octagonal structure in the middle plays a limiting role.

[0009] There are eight groups of sliding parts, which are respectively installed on the regular quadrangular prism structures of two groups of square frames, and a short axis is designed at the lower end of the sliding part; there are eight groups of rod connecting parts, and through holes are provided on the upper end faces of the structures to cooperate with the short axis at the lower end of the sliding parts to achieve free rotation; the four groups of sliding parts fixed on the regular quadrangular prism structures of the square frames below are arranged opposite to the four groups of sliding parts fixed on the regular quadrangular prism structures of the square frames above, and the four groups of rod connecting parts rotatably connected to the four groups of sliding parts below are arranged opposite to the four groups of rod connecting parts rotatably connected to the four groups of sliding parts above; there are eight groups of connecting shafts.

[0010] There are eight groups of the first tension elastic bodies, and two ends of each group of the first tension elastic bodies are respectively fixedly connected to the side surfaces of two adjacent groups of sliding components arranged on the same group of square frames.

[0011] The four-rod and twelve-cable tensegrity structure has two different connection methods, which can achieve different deformation effects during compression. The first end of the rod of the four-rod and twelve-cable tensegrity structure is connected to a vertex on the bottom surface of a regular tetrahedron in space, and the second end is connected to the diagonal vertex of the side rectangle of the regular tetrahedron, and each rod is spatially staggered and connected in sequence.

[0012] There are four groups of connecting rods, which are designed to be S-shaped to avoid interference. Both ends of each group of connecting rods are hinged to the rod connecting members through the connecting shaft. The spatial position of each group of connecting rods is the same as the spatial position of the four-rod and twelve-cable tensioned integral structure rods, and each group of connecting rods is spatially staggered and connected in sequence; there are four groups of second tension elastic bodies, and both ends of each group of the second tension elastic bodies are fixedly connected to the lower end of one group of connecting rods and the upper end of another adjacent group of connecting rods.

[0013] It can be known from the above technical solutions that, compared with the prior art, the present invention discloses a negative Poisson's ratio metamaterial cellular structure based on a four-bar tension structure. Under the action of the four-bar twelve-cable tension structure, when the structure is not subjected to external loads, the structure is subjected to the interaction of internal stresses and reaches equilibrium in a self-stable state; when subjected to external loads, the upper and lower surfaces will produce a torsional effect, and once the external load is removed, the structure will return to its initial state. A negative Poisson's ratio metamaterial cellular structure based on a four-bar tension structure has the advantages of adaptability, self-recovery, and compression-torsion characteristics. The present invention enriches the types of existing mechanical metamaterial cellular structures by combining the tension structure with the mechanical metamaterial structure, and opens up a new direction for the design, analysis, and application of tension mechanical metamaterial structures.

[0014] Another object of the present invention is to provide a negative Poisson's ratio metamaterial cellular structure based on a four-bar tensioned structure, and a second morphological structure with another connection method, including a device body and the above-mentioned negative Poisson's ratio metamaterial cellular structure based on a four-bar tensioned structure connected thereto. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0016] Figure 1 The accompanying drawing is a schematic diagram of a negative Poisson's ratio metamaterial cell structure based on a four-bar tension structure provided by the present invention.

[0017] Figure 2 The accompanying drawing is a front view of a negative Poisson's ratio metamaterial cell structure based on a four-bar tension structure provided by the present invention.

[0018] Figure 3 The accompanying drawing is a top view of a negative Poisson's ratio metamaterial cell structure based on a four-bar tension structure provided by the present invention.

[0019] Figure 4 The accompanying drawing is a schematic diagram of a local explosion of a negative Poisson's ratio metamaterial cell structure based on a four-bar tension structure provided by the present invention.

[0020] Figure 5 The accompanying drawing is a partial explosion schematic diagram of the connection part of the freedom constraint component of the negative Poisson's ratio metamaterial cell structure based on the four-bar tension structure provided by the present invention.

[0021] Figure 6The accompanying drawing is a schematic structural diagram of a negative Poisson's ratio metamaterial cell structure based on a four-bar tension structure provided by the present invention under a load state.

[0022] Figure 7 The accompanying drawing is a structural diagram of different connection modes of four-bar twelve-cable tensegrity structural members in a negative Poisson's ratio metamaterial cell structure based on a four-bar tensegrity structure provided by the present invention.

[0023] Figure 8 The accompanying drawing is a schematic diagram of the second form structure of a negative Poisson's ratio metamaterial cell structure based on a four-bar tension structure provided by the present invention.

[0024] Fig. 9 The accompanying drawing is a schematic diagram of a second form structure of a negative Poisson's ratio metamaterial cell structure based on a four-bar tension structure provided by the present invention under a loaded state.

[0025] Among them, 100-freedom constraint component; 101-square frame; 102-sliding component; 103-rod connector; 104-connecting shaft; 200-four-rod tension integral structure component; 201-first tension elastic body; 202-second tension elastic body; 203-connecting rod. DETAILED DESCRIPTION

[0026] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0027] In the description of the present invention, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are 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 understood as a limitation on the present invention.

[0028] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like 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 a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0030] In terms of structural design, existing mechanical metamaterials have a single cell structure, and negative Poisson's ratio metamaterials are mostly integrated structures with low reusability. In addition, many designs to date rely on the deformation or evolution of existing metamaterial structures, and it is impossible to systematically design geometric and topological shapes to obtain new metamaterial structures with negative Poisson's ratio effects.

[0031] In view of this, the embodiment of the present invention discloses a negative Poisson's ratio metamaterial cell structure based on a four-bar tension structure, see the attached Figure 1-9 , including: a degree of freedom constraint component 100 and a four-bar tensegrity structure component 200.

[0032] The freedom constraint assembly 100 includes a square frame 101 , a sliding component 102 , a rod connector 103 and a connecting shaft 104 ; the four-bar tensegrity structural assembly 200 includes a first tension elastic body 201 , a second tension elastic body 202 and a connecting rod 203 .

[0033] There are two groups of square frames 101, which are respectively placed at the upper and lower ends of the entire structure. Hinge holes are arranged at the outer edge positions of the four corners of the square frames 101. Four regular quadrangular prism structures inside the structure are arranged in a 90° circular array. An octagonal structure is arranged at the center of the structure and fixedly connected to the regular quadrangular prism structure. The function of the hinge holes is to enable the cell structure to be hingedly connected through the hinge holes. The regular quadrangular prism structure plays a guiding role, and the octagonal structure in the middle plays a limiting role.

[0034] See attached Figure 1-5In the embodiment of the present invention, there are eight groups of sliding components 102, which are respectively installed on the regular quadrangular prism structures of the two groups of square frames 101, and a short axis is designed at the lower end of the sliding component 102; there are eight groups of rod connectors 103, and a through hole is provided on the upper end surface of the structure to cooperate with the short axis at the lower end of the sliding component 102 to achieve free rotation; the four groups of sliding components 102 fixed on the regular quadrangular prism structure of the square frame 101 below are arranged opposite to the four groups of sliding components 102 fixed on the regular quadrangular prism structure of the square frame 101 above, and the four groups of rod connectors 103 rotatably connected to the four groups of sliding components 102 below are arranged opposite to the four groups of rod connectors 103 rotatably connected to the four groups of sliding components 102 above; there are eight groups of connecting shafts 104.

[0035] See attached Figure 4 There are eight groups of the first tension elastic bodies 201 , and both ends of each group of the first tension elastic bodies 201 are fixedly connected to the side surfaces of two adjacent groups of the sliding components 102 arranged on the same group of square frames 101 .

[0036] See attached Figure 7 The four-rod and twelve-cable tensegrity structure has two different connection methods, which can achieve different deformation effects during compression. The first end of the rod of the four-rod and twelve-cable tensegrity structure is connected to a vertex of the bottom surface of the regular tetrahedron in space, and the second end is connected to the diagonal vertex of the side rectangle of the regular tetrahedron, and each rod is connected in sequence in a staggered manner in space.

[0037] In a preferred embodiment of the present invention, there are four groups of connecting rods 203, and both ends of each group of connecting rods 203 are respectively hinged to the rod connecting members 103 through the connecting shaft 104. The spatial position of each group of connecting rods 203 is the same as the spatial position of the four-rod twelve-cable tensioned integral structure rods, and each group of connecting rods 203 is spatially staggered and connected in sequence.

[0038] Different deformation effects caused by different connection methods are: one is that the upper frame 101 rotates clockwise relative to the lower square frame 101 in the top view direction after being loaded; the other is that the upper square frame 101 rotates counterclockwise relative to the lower square frame 101 in the top view direction after being loaded.

[0039] In the embodiment provided by the present invention, when working, the four groups of sliding components 102 fixed on the regular tetrahedral prism structure of the square frame 101 below need to limit the sliding freedom. The rotation angle of the structure and the overall stiffness of the cell structure can be adjusted by adjusting the positions of the four groups of sliding components 102 on the regular tetrahedral prism structure of the square frame 101 below. The connecting rod 203 is designed to be S-shaped in order to avoid interference so that the cell structure can rotate at a larger angle.

[0040] In a preferred embodiment of the present invention, there are four groups of the second tension elastic bodies 202, and both ends of each group of the second tension elastic bodies 202 are fixedly connected to the lower end of one group of the connecting rods 203 and the upper end of another adjacent group of the connecting rods 203.

[0041] See attached Figure 1 and attached Figure 6 The working mode of the embodiment under the first connection mode provided by the present invention is mainly that the cellular structure is under the action of the four-bar twelve-cable tensioned overall structure. When the structure is not subjected to external loads, the structure is subjected to the interaction of internal stresses and reaches equilibrium in a self-stable state; when subjected to external loads, the upper and lower surfaces will produce a torsional effect, and after the external loads are removed, the structure will return to its initial state.

[0042] See attached Figure 8 and attached Fig. 9 The working mode of the second form structure embodiment under the second connection mode provided by the present invention is mainly that the cellular structure is under the action of the four-bar twelve-cable tensioned overall structure. When the structure is not subjected to external loads, the structure is subjected to the interaction of internal stresses and reaches equilibrium in a self-stable state; when subjected to external loads, the upper surface and the lower surface will produce a torsional effect, and the torsional direction is opposite to that of the embodiment under the first connection mode. After the external load is removed, the structure will return to its initial state.

[0043] The present invention provides a negative Poisson's ratio metamaterial cellular structure based on a four-bar tension structure, which has the advantages of adaptability, self-recovery, compression-torsion characteristics, etc. The present invention enriches the types of existing mechanical metamaterial cellular structures by combining the tensioned integral structure with the mechanical metamaterial structure, and opens up a new direction for the design, analysis and application of tensioned mechanical metamaterial structures. The present invention has important academic significance. The negative Poisson's ratio metamaterial cellular structure based on a four-bar tension structure provided by the present invention is simple in structure, is expected to be vigorously developed, and can realize its application value in many fields.

[0044] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification.

[0045] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A negative Poisson's ratio metamaterial cell structure based on a four-bar tension structure, characterized in that: include: A degree of freedom constraint component (100) and a four-bar tensegrity structural component (200); the degree of freedom constraint component (100) comprises a square frame (101), a sliding component (102), a rod connector (103) and a connecting shaft (104); the four-bar tensegrity structural component (200) comprises a first tension elastic body (201), a second tension elastic body (202) and a connecting rod (203); there are two groups of the square frame (101), which are respectively arranged at the upper and lower ends of the entire structure; hinge holes are respectively arranged at the outer edge positions of the four corners of the square frame (101); four regular quadrangular prism structures are arranged in a 90° annular array inside the structure; an octagonal structure is arranged at the center of the structure and is fixedly connected to the regular quadrangular prism structure.

2. According to claim 1, a negative Poisson's ratio metamaterial cell structure based on a four-bar tension structure is characterized in that: There are eight groups of sliding components (102) respectively mounted on the regular quadrangular prism structures of the two groups of square frames (101), and a short shaft is designed at the lower end of the sliding components (102); there are eight groups of rod connectors (103), and through holes are provided on the upper end surfaces of the structures to cooperate with the short shafts at the lower ends of the sliding components (102) to achieve free rotation. The four groups of sliding components (102) fixed on the regular quadrangular prism structures of the square frames (101) below and the four groups of sliding components fixed on the regular quadrangular prism structures of the square frames (101) above The four groups of rod connectors (103) rotatably connected to the four groups of sliding components (102) at the bottom are arranged opposite to each other, and the four groups of rod connectors (103) rotatably connected to the four groups of sliding components (102) at the top are arranged opposite to each other; there are eight groups of connecting shafts (104); there are eight groups of the first tension elastic bodies (201), and the two ends of each group of the first tension elastic bodies (201) are respectively fixedly connected to the side surfaces of two adjacent groups of sliding components (102) arranged on the same group of square frames (101).

3. The negative Poisson's ratio metamaterial cell structure based on a four-bar tension structure according to claim 2, characterized in that: There are four groups of connecting rods (203), and both ends of each group of connecting rods (203) are respectively hinged to the rod connecting members (103) through the connecting shaft (104). The spatial position of each group of connecting rods (203) is the same as the spatial position of the rods of the four-rod twelve-cable tensioned integral structure, and each group of connecting rods (203) are spatially staggered and connected in sequence. There are four groups of the second tension elastic bodies (202), and both ends of each group of the second tension elastic bodies (202) are respectively fixedly connected to the lower end of one group of connecting rods (203) and the upper end of another adjacent group of connecting rods (203).

4. The negative Poisson's ratio metamaterial cell structure based on a four-bar tension structure according to claim 3, characterized in that: The invention comprises a second form structure and a device of another connection mode of a negative Poisson's ratio metamaterial cell structure based on a four-bar tension structure.

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