Mechanical metamaterial structure with anisotropic Poisson's ratio

Abstract

The invention discloses a mechanical metamaterial structure with an anisotropic Poisson ratio, and belongs to the technical field of mechanical metamaterials. The structure is achieved through modular connection of the multiple zero-Poisson-ratio tensioning cell elements and the rapid connection buckle components. The zero-Poisson-ratio tensioning cell comprises an upper bottom plate, a lower bottom plate, an elastic body, a claw nail, a flexible hinge connecting block, a thick flexible hinge and a thin flexible hinge, and the zero-Poisson-ratio tensioning cell has the zero-Poisson-ratio characteristic, self-adaptability, self-stability and self-recovery performance in the axial direction by means of the synergistic effect of the components. Through cross-shaped arrangement and connection, the overall structure keeps the axial zero Poisson's ratio macroscopically, the transverse negative Poisson's ratio effect is achieved, remarkable Poisson's ratio anisotropy is formed, and meanwhile the overall structure has good self-recovery performance in the transverse direction. The modular structure facilitates local maintenance and performance regulation and control, and can adapt to complex load environments in the fields of aerospace, flexible robots and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of mechanical metamaterials, and particularly relates to a mechanical metamaterial structure with anisotropic Poisson's ratio. BACKGROUND

[0002] As a kind of artificial composite material, the physical properties of metamaterials mainly come from the unique structural unit and its spatial arrangement, rather than the intrinsic properties of the constituent material. Through the ordered design of its micro or meso geometry, metamaterials can achieve unique properties that natural materials do not possess.

[0003] Among them, mechanical metamaterials can break through the limitations of conventional materials in mechanical properties through reasonable configuration design. Poisson's ratio, as a key parameter to describe the relationship between lateral deformation and axial deformation of materials, is usually positive, that is, the material shrinks laterally when stretched and expands laterally when compressed. However, with the help of concave hexagons, chiral structures, rotating polygons and other special periodic or hinged configurations, there are now precedents for mechanical metamaterials with negative Poisson's ratio (i.e. auxetic effect). Such structures perform outstandingly in energy absorption, pore adjustment, curved surface fitting, etc., and are widely used in aerospace, biomedical and flexible robots, etc.

[0004] Although negative Poisson's ratio metamaterials have been intensively studied, existing technologies are mostly focused on achieving extreme Poisson's ratio in a single direction or isotropy. For example, patent CN202411632809.6 discloses a device for treating bridge head bump based on negative Poisson's ratio inner hexagon reinforced soil, which has negative Poisson's ratio characteristics due to its hollow inner hexagonal cross-section. However, this structure is only suitable for single-direction stress and energy absorption, and is difficult to cope with multi-directional load scenarios. Another patent CN202510801870.7 proposes a two-way auxetic honeycomb blast-resistant protective structure and a bending and welding integrated preparation method, which realizes two-way negative Poisson's ratio effect and higher two-way bearing capacity by combining concave hexagons and double-arrow honeycomb configurations. However, since its mechanical response is still isotropic, it is difficult to achieve direction-dependent fine deformation in complex and variable stress fields. In addition, due to the plastic properties of the preparation material, the structure is prone to cumulative plastic deformation under repeated loading, resulting in insufficient durability and difficulty in meeting the needs of long-term or repeated use in engineering scenarios. In fact, in many advanced application scenarios, such as directional energy management, non-uniform deformation flexible devices, and bionic tissue scaffolds, it is often required that the material have differential Poisson's response in different directions, i.e. achieve anisotropic Poisson's ratio. In addition, existing mechanical metamaterial structures are usually prepared by integral and integrated forming process, and the internal cells are mutually fixed, forming a continuous whole. When a small number of cells in the structure fail due to impact or fatigue, this strong connection method will cause the damage to spread rapidly, seriously affecting the overall integrity, mechanical properties and functional reliability of the structure. SUMMARY

[0005] The present application provides a mechanical metamaterial structure with anisotropic Poisson's ratio to overcome the deficiencies in the prior art. The structure is based on the synergistic effect of elastomers, thin flexible hinges and thick flexible hinges to achieve the self-adaptive deformation capability, mechanical stability and good shape recovery characteristics of the structure, while having outstanding durability. In addition, the fast buckle components are used to connect the zero Poisson's ratio tensile cells, and when the local zero Poisson's ratio tensile cells degrade or fail, they can be quickly replaced, facilitating maintenance and extending the service life of the overall structure. In terms of mechanical properties, a single zero Poisson's ratio tensile cell exhibits zero Poisson's ratio characteristics in the axial direction (i.e., the ratio of lateral strain to axial strain is zero), and through a cross-shaped spatial arrangement, the overall structure exhibits a negative Poisson's ratio effect in the lateral direction, thereby achieving anisotropy in the Poisson's ratio at the macro level.

[0006] It should be understood that in the present application, all terms related to components, orientations, etc. are named and defined only for the purpose of describing the present application. The relevant terms can be replaced or adjusted in direction according to the actual situation, and should not be understood as limiting the present application.

[0007] The present application provides a mechanical metamaterial structure with anisotropic Poisson's ratio, which mainly includes four zero Poisson's ratio tensile cells and eight fast connection buckle components. The upper and lower bottom plates of the zero Poisson's ratio tensile cell are provided with a clamping groove at both corners on the same side. Through the interlocking of the corresponding clamping groove and the matching fast connection buckle component, the fast and reliable butt joint between each zero Poisson's ratio tensile cell can be achieved to form a modular assembly structure. This design not only facilitates local maintenance and replacement, but also significantly improves the maintainability and service life of the overall structure. At the same time, under the action of lateral load, the force and displacement are transmitted between each zero Poisson's ratio tensile cell through this buckle type connection, causing the overall structure to produce coordinated torsional deformation, so that it has a negative Poisson's ratio characteristic at the macro level.

[0008] The zero-Poisson's ratio tensile unit comprises an upper bottom plate, a lower bottom plate, four elastic bodies, eight flexible hinge connecting blocks, twelve thick flexible hinges, twenty-four thin flexible hinges and eight horn pegs. The upper bottom plate and the lower bottom plate are square, each of the four corners of which is provided with a horn peg. The four elastic bodies are axially connected and tensed through the corresponding horn pegs on the upper bottom plate and the lower bottom plate. On the inner side of the upper bottom plate and the lower bottom plate opposite to each other, along the midpoint positions of the four side lines, one thick flexible hinge and two thin flexible hinges are arranged respectively and connected with one flexible hinge connecting block. The corresponding flexible hinge connecting blocks on the upper bottom plate and the lower bottom plate are further connected through one thick flexible hinge and two thin flexible hinges, thereby forming a complete zero-Poisson's ratio tensile unit structure. The main mechanical properties of the zero-Poisson's ratio tensile unit are derived from the coupling mechanism of the elastic body, the thick flexible hinge and the thin flexible hinge. The zero-Poisson's ratio tensile unit has certain self-adaptability, self-stability and self-recovery, and also ensures the reliability of long-term use, and realizes the mechanical property of zero Poisson's ratio in the axial direction.

[0009] The quick connection buckle component comprises two quick connection buckles, one thick flexible hinge and two thin flexible hinges. The two quick connection buckles are symmetrically arranged and connected with each other through the thick flexible hinge and the two thin flexible hinges. The component is matched with the preset clamping grooves of the upper bottom plate and the lower bottom plate of the zero-Poisson's ratio tensile unit through the protruding part thereof, so as to realize the quick assembly and reliable connection between multiple units, thereby forming a complete mechanical metamaterial overall structure. Based on the elastic recovery characteristics of the thick flexible hinge and the thin flexible hinge, the connection mode enables the overall structure to have good self-recovery performance in the transverse direction. In addition, since the quick connection buckle component is arranged in the transverse direction, the connection mechanism does not affect the axial mechanical behavior of the zero-Poisson's ratio tensile unit itself. Therefore, the overall structure can maintain the zero-Poisson's ratio characteristic in the axial direction and realize the negative Poisson's ratio effect in the transverse direction, thereby forming a Poisson's ratio anisotropy with significant directional difference. At the same time, the overall structure shows good self-recovery, self-adaptability and self-stability in the axial and transverse directions.

[0010] It should be noted that by adjusting the elastic modulus or stiffness coefficient of the elastic body, the thick flexible hinge and the thin flexible hinge, the load-bearing capacity and shape recovery capacity of the overall structure can be adjusted in direct proportion within a certain range.

[0011] Technical effects: The mechanical metamaterial structure with anisotropic Poisson's ratio provided by the application realizes the anisotropic characteristics of axial zero Poisson's ratio and transverse negative Poisson's ratio on a macro level through the cross-shaped arrangement of the zero Poisson's ratio tensile unit and the cooperation of the quick connection buckle part; the modular design facilitates local replacement and maintenance, and significantly improves the service life; meanwhile, the overall structure has good self-adaptation, self-stabilization and self-recovery performance under the synergistic action of the elastic body, the thick flexible hinge and the thin flexible hinge, and by adjusting the elastic modulus or the stiffness coefficient of the elastic body, the thick flexible hinge and the thin flexible hinge, the mechanical performance of the overall structure can be adjusted in direct proportion within a certain range, so that the overall structure can better adapt to complex types of load environment. BRIEF DESCRIPTION OF DRAWINGS

[0012] To clearly show the embodiments of the application and related technical solutions, the drawings involved in the embodiments will be briefly described below. It should be understood that the following drawings are only used to illustrate some embodiments of the application. Those skilled in the art can also obtain other related technical solutions and drawings based on these drawings without creative labor.

[0013] Figure 1 The overall schematic view of the mechanical metamaterial structure with anisotropic Poisson's ratio provided by the embodiments of the application.

[0014] Figure 2 The partial exploded view of the mechanical metamaterial structure with anisotropic Poisson's ratio provided by the embodiments of the application.

[0015] Figure 3 The zero Poisson's ratio tensile unit structure schematic view of the mechanical metamaterial structure with anisotropic Poisson's ratio provided by the embodiments of the application.

[0016] Figure 4 The zero Poisson's ratio tensile unit exploded view of the mechanical metamaterial structure with anisotropic Poisson's ratio provided by the embodiments of the application.

[0017] Figure 5 The zero Poisson's ratio tensile unit detail exploded view of the mechanical metamaterial structure with anisotropic Poisson's ratio provided by the embodiments of the application.

[0018] Figure 6 The axial compression deformation schematic view of the zero Poisson's ratio tensile unit of the mechanical metamaterial structure with anisotropic Poisson's ratio provided by the embodiments of the application.

[0019] Figure 7 The quick connection buckle part structure schematic view of the mechanical metamaterial structure with anisotropic Poisson's ratio provided by the embodiments of the application.

[0020] Figure 8The axial compression deformation and lateral torsion deformation schematic diagram of the mechanical metamaterial structure with anisotropic Poisson's ratio provided by the embodiment of the present application.

[0021] Label description: 1, zero Poisson's ratio tensile cell; 101, upper bottom plate; 102, lower bottom plate; 103, elastomer; 104, horned nail; 105, flexible hinge connecting block; 2, quick connection buckle part; 201, quick connection buckle; 3, thick flexible hinge; 4, thin flexible hinge. DETAILED DESCRIPTION

[0022] For the purpose of clearly illustrating the embodiments of the present application, the following will be described in detail with reference to the accompanying drawings. The same or similar reference signs in the drawings represent the same or similar components or components having the same or similar functions. It should be understood that the following description with reference to the drawings is only exemplary and is intended to explain the present application, but should not be understood as limiting the present application.

[0023] It should be noted that the same reference signs or numbers may be repeatedly used in different embodiments or drawings. The repetition is only to simplify the description and the drawings, and does not necessarily indicate a specific relationship between the embodiments or structures.

[0024] In the description of the present application, the "upper", "lower", "inner side", "same side", "symmetry", "center", "two corners", "four corners", "axial", "lateral", "clockwise", "counterclockwise" and other orientation or position relationships are defined based on the orientation or position shown in the drawings. These definitions are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the components referred to must have a specific orientation, nor should they constitute a limitation on the present application. In addition, unless otherwise explicitly and specifically limited, the meaning of "multiple" in the present application is two or more.

[0025] The different structures of the present application will be illustrated below through specific embodiments and examples of the drawings, in which the components in a specific example and their arrangement will be described. It should be understood that these examples are only for the purpose of clearly illustrating the present application, and should not constitute a limitation on the present application.

[0026] Please refer to Figures 1 to 3The application provides a mechanical metamaterial structure with anisotropic Poisson's ratio. The structure mainly consists of four zero-Poisson's ratio tensile units 1 and eight fast connection buckle components 2. Each zero-Poisson's ratio tensile unit 1 is provided with a clamping groove (i.e. the part enclosed by the dashed line frame I) at two corners on the same side of the upper bottom plate 101 and the lower bottom plate 102. By matching and locking the fast connection buckle components 2 with the clamping grooves, the four zero-Poisson's ratio tensile units 1 can be stably connected to form a complete and coordinated metamaterial whole. The modular connection design not only realizes the rapid assembly and disassembly of the structure, but also facilitates the independent maintenance and replacement of the zero-Poisson's ratio tensile units 1 with local failure or performance degradation in actual use, thereby significantly improving the maintainability, service life and practical value of the whole structure.

[0027] Referring to Figures 3 to 5 , the zero-Poisson's ratio tensile unit 1 mainly includes an upper bottom plate 101, a lower bottom plate 102, four elastic bodies 103, eight horn nails 104, eight flexible hinge connecting blocks 105, twelve thick flexible hinges 3 and twenty-four thin flexible hinges 4. The upper bottom plate 101 and the lower bottom plate 102 are symmetrically arranged. On the inner side opposite to each other, four horn nails 104 are arranged at each corner, and the four elastic bodies 103 are connected by the corresponding horn nails 104 up and down. At the same time, on the inner side opposite to each other of the upper bottom plate 101 and the lower bottom plate 102, a thick flexible hinge 3 and two thin flexible hinges 4 are arranged at the midpoint position along the four edge lines, and are connected with a flexible hinge connecting block 105 respectively. The corresponding flexible hinge connecting blocks 105 up and down are further connected by a thick flexible hinge 3 and two thin flexible hinges 4, thereby forming a complete zero-Poisson's ratio tensile unit 1. In this structure, the elastic body 103 provides an initial pretension, so that the zero-Poisson's ratio tensile unit 1 maintains a stable initial shape, laying a foundation for subsequent load bearing and energy absorption deformation. In addition, the elastic body 103, the thick flexible hinge 3 and the thin flexible hinge 4 cooperate to give the zero-Poisson's ratio tensile unit 1 good adaptability, structural stability and deformation self-recovery ability, thereby ensuring excellent service life and reliability.

[0028] Referring to Figures 3 to 6 , further referring to Figure 6 When the zero-Poisson's ratio tensile unit 1 is compressed in the axial direction (i.e. compressed in the direction A), the zero-Poisson's ratio tensile unit 1 only shrinks in the force direction, and the transverse dimension remains stable, i.e. it exhibits typical zero-Poisson's ratio characteristics in the axial direction.

[0029] Please refer to Figure 1 , Figure 2 , Figure 3 and Figure 7The quick connection buckle component 2 mainly comprises two quick connection buckles 201, one thick flexible hinge 3 and two thin flexible hinges 4. The two quick connection buckles 201 are symmetrically arranged and connected with each other through the thick flexible hinge 3 and the two thin flexible hinges 4. In addition, the quick connection buckle component 2 is locked with the corresponding clamping grooves (i.e. the dashed box I selected part) arranged on the upper bottom plate 101 and the lower bottom plate 102 of the zero Poisson's ratio tensile unit 1 through the protruding part (i.e. the dashed box II selected part) on the quick connection buckle 201, so as to realize the quick assembly and reliable connection between the plurality of zero Poisson's ratio tensile units 1, and together form a complete mechanical metamaterial structure.

[0030] Referring to Figures 1 to 8 Further referring to Figure 8 The four zero Poisson's ratio tensile units 1 are connected with each other through the four quick connection buckle components 2, and are assembled into a complete mechanical metamaterial structure with anisotropic Poisson's ratio. When the overall structure is subjected to a clockwise torsional force (i.e. along the B direction), the overall structure presents a clockwise (i.e. along the C direction) torsional deformation posture. Conversely, when the overall structure is subjected to a counterclockwise torsional force (i.e. along the D direction), the overall structure presents a counterclockwise (i.e. along the E direction) torsional deformation posture. In the above two directions of torsional deformation, the overall structure shows negative Poisson's ratio characteristics. In addition, based on the elastic effect of the thick flexible hinge 3 and the thin flexible hinge 4 in the quick connection buckle component 2, the overall structure also has good self-recovery performance in the transverse direction. At the same time, since the quick connection buckle component 2 is arranged in the transverse direction, such a connection mode does not affect the axial zero Poisson's ratio property of the zero Poisson's ratio tensile unit 1, so that the overall structure can still maintain the axial zero Poisson's ratio property at the macro level, and show negative Poisson's ratio effect in the transverse direction, forming significant Poisson's ratio anisotropy, so as to better adapt to various types of complex load application scenarios.

[0031] It should be noted that by adjusting the elastic modulus or stiffness coefficient of the elastic body 103, the thick flexible hinge 3 and the thin flexible hinge 4, the self-recovery, self-stability and self-adaptability of the overall structure can be adjusted in a certain range in direct proportion.

[0032] In summary, although the present application has been described in detail above in combination with specific embodiments, the protection scope of the present application is not limited to the specific embodiments described. Those skilled in the art can modify, deform or adapt these embodiments without departing from the principles of the present application, and these changes or replacements based on the technical concept of the present application should be covered within the protection scope of the present application.

Claims

1. A mechanical metamaterial structure having an anisotropic Poisson's ratio, characterized in that, The application relates to a zero-poisson-ratio tensile cell (1) and a quick-connection buckle component (2), wherein corresponding positions of an upper bottom plate (101) and a lower bottom plate (102) of the zero-poisson-ratio tensile cell (1) are provided with clamping grooves; the quick-connection buckle component (2) can be matched with the clamping grooves to realize detachable connection between the zero-poisson-ratio tensile cells (1), so that a modular overall structure is assembled; the zero-poisson-ratio tensile cell (1) comprises the upper bottom plate (101), the lower bottom plate (102), an elastic body (103), a horned nail (104), a flexible hinge connecting block (105), a thick flexible hinge (3) and a thin flexible hinge (4); the upper bottom plate (101) and the lower bottom plate (102) are symmetrically arranged; the elastic body (103) is axially tensioned through the horned nails (104) arranged at four corners of the upper bottom plate (101) and the lower bottom plate (102); thick flexible hinges (3) and thin flexible hinges (4) are arranged on inner sides of the upper bottom plate (101) and the lower bottom plate (102) and are connected through the flexible hinge connecting block (105); the quick-connection buckle component (2) comprises two symmetrically arranged quick-connection buckles (201), and the two quick-connection buckles (201) are connected with each other through a thick flexible hinge (3) and two thin flexible hinges (4). The elastic body (103), the thick flexible hinge (3) and the thin flexible hinge (4) in the zero-poisson-ratio tensile cell (1) jointly act to make the zero-poisson-ratio tensile cell (1) have self-adaptability, self-stability and self-recovery and have zero poisson's ratio characteristics in a single axial direction.

2. The mechanical metamaterial structure with anisotropic Poisson's ratio of claim 1, wherein, The quick-connection buckle component (2) is arranged in a transverse direction, and the connecting mechanism does not affect the axial mechanical characteristics of the zero-poisson-ratio tensile cell (1).

3. The mechanical metamaterial structure with anisotropic Poisson's ratio of claim 1, wherein, The thick flexible hinge (3) and the thin flexible hinge (4) in the quick-connection buckle component (2) make the overall structure have self-recovery performance in the transverse direction.

4. The mechanical metamaterial structure with anisotropic Poisson's ratio of claim 1, wherein, Under the action of transverse load, the overall structure can be coordinately deformed in torsion, so that a negative poisson's ratio effect is realized in a macroscopic aspect.

5. The mechanical metamaterial structure with anisotropic Poisson's ratio of claim 1, wherein, Through the cross-shaped spatial arrangement and connection of the zero-poisson-ratio tensile cells (1), the overall structure can keep the axial zero poisson's ratio characteristics in a macroscopic aspect and can present the negative poisson's ratio effect in the transverse direction, so that anisotropic poisson's ratio characteristics are formed.

6. The mechanical metamaterial structure with anisotropic Poisson's ratio of claim 1, wherein, By adjusting the elastic modulus or rigidity coefficient of the elastic body (103), the thick flexible hinge (3) and the thin flexible hinge (4), at least one of the load-carrying capacity, shape recovery capacity, self-recovery, self-stability and self-adaptability of the overall structure can be proportionally adjusted.

7. The mechanical metamaterial structure with anisotropic Poisson's ratio of claim 1, wherein, ​

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