Mechanical metamaterial structure with anisotropic poisson's ratio

Abstract

The application discloses a mechanical metamaterial structure with anisotropic Poisson's ratio, and belongs to the technical field of mechanical metamaterials. The structure is realized through the modular connection of a plurality of zero-Poisson's ratio tensile units and fast connection buckle components. The zero-Poisson's ratio tensile unit comprises an upper bottom plate, a lower bottom plate, an elastomer, a horned nail, a flexible hinge connecting block, a thick flexible hinge and a thin flexible hinge. The synergistic effect of these components enables the zero-Poisson's ratio characteristic, self-adaptability, self-stability and self-recovery in the axial direction. Through the cross arrangement and connection, the overall structure maintains the axial zero-Poisson's ratio and realizes the lateral negative Poisson's ratio effect in the macroscopic aspect, forms the significant Poisson's ratio anisotropy, and meanwhile, the overall structure also has good self-recovery in the lateral direction. The modular structure is convenient for local maintenance and performance regulation and control, and can adapt to the complex load environment in the fields of aerospace and flexible robots.

Description

Technical Field

[0001] This invention relates to the field of mechanical metamaterials technology, and more particularly to a mechanical metamaterial structure with an anisotropic Poisson's ratio. Background Technology

[0002] Metamaterials, as a type of artificial composite material, derive their physical properties primarily from their unique structural units and spatial arrangement, rather than from the intrinsic properties of the constituent materials themselves. Through the ordered design of their microscopic or mesoscopic geometric configurations, metamaterials can achieve unique properties that natural materials do not possess.

[0003] Among them, mechanical metamaterials, through rational configuration design, can overcome the limitations of conventional materials in terms of mechanical properties. Poisson's ratio, a key parameter describing the relationship between lateral and axial deformation of a material, is usually a positive value, meaning that the material contracts laterally under tension and expands laterally under compression. However, by utilizing special periodic or hinged configurations such as concave hexagons, chiral structures, and rotating polygons, there are now precedents for the design of mechanical metamaterials with negative Poisson's ratio characteristics (i.e., the tensile expansion effect). Such structures exhibit outstanding performance in energy absorption, porosity regulation, and surface fitting, and are widely used in aerospace, biomedicine, and flexible robotics fields.

[0004] Although negative Poisson's ratio metamaterials have been extensively studied, existing technologies largely focus on achieving extreme Poisson's ratios in a single direction or isotropically. For example, patent CN202411632809.6 discloses a device for treating bridge approach slabs based on negative Poisson's ratio hexagonal reinforced soil. Because its unit cell cross-section is a hollow hexagon, it possesses negative Poisson's ratio characteristics. However, this structure is only suitable for unidirectional force application and energy absorption, making it difficult to handle multidirectional load scenarios. Another patent, CN202510801870.7, proposes a bidirectional tensile expansion honeycomb explosion-proof protective structure and an integrated bending and welding fabrication method. By combining concave hexagons and double-arrow honeycomb configurations, it achieves a bidirectional negative Poisson's ratio effect and higher bidirectional load-bearing capacity. However, because its mechanical response is still isotropic, it is difficult to achieve directionally related fine deformation in complex and variable stress fields. Furthermore, limited by the plasticity of the fabricated material, this structure is prone to cumulative plastic deformation under repeated loads, resulting in insufficient durability and making it unsuitable for engineering scenarios requiring long-term or repeated use. In practice, many advanced applications, such as directional energy management, non-uniformly deformable flexible devices, and biomimetic tissue scaffolds, often require materials to exhibit differentiated Poisson responses in different directions, i.e., achieving Poisson ratio anisotropy. Furthermore, existing mechanical metamaterial structures are typically fabricated using a monolithic molding process, where internal cells are interconnected to form a continuous whole. When a few cells fail locally due to impact or fatigue, this strong connection leads to rapid damage propagation, severely impacting the overall integrity, mechanical properties, and functional reliability of the structure. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, this invention provides a mechanical metamaterial structure with anisotropic Poisson's ratio. Based on the synergistic effect of an elastomer, thin flexible hinges, and thick flexible hinges, this structure achieves adaptive deformation capability, mechanical stability, and excellent shape recovery characteristics, while also exhibiting outstanding durability. Furthermore, the zero Poisson's ratio tensile cells are connected using quick-locking components, allowing for rapid replacement when local zero Poisson's ratio tensile cells experience performance degradation or failure, facilitating maintenance and extending the overall structure's service life. In terms of mechanical properties, individual zero Poisson's ratio tensile cells exhibit zero Poisson's ratio characteristics in the axial direction (i.e., the ratio of transverse strain to axial strain is zero), while the cross-shaped spatial arrangement causes the overall structure to exhibit a negative Poisson's ratio effect in the transverse direction, thus achieving macroscopic Poisson's ratio anisotropy.

[0006] It should be understood that, in this invention, all naming and definitions of terms involving components, orientations, etc., are used solely for describing this invention. Related terms may be equivalently replaced or directionally adjusted according to actual circumstances, and should not be construed as limiting the invention.

[0007] This invention proposes a mechanical metamaterial structure with anisotropic Poisson's ratio, mainly comprising four zero Poisson's ratio tensile cells and eight quick-connect snap-fit ​​components. The upper and lower base plates of each zero Poisson's ratio tensile cell have slots at two corners on the same side. By interlocking the matching quick-connect snap-fit ​​components with their corresponding slots, rapid and reliable docking between the zero Poisson's ratio tensile cells can be achieved, forming 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. Simultaneously, under lateral loads, the snap-fit ​​connections between the zero Poisson's ratio tensile cells transmit force and displacement, inducing coordinated torsional deformation in the overall structure, giving it negative Poisson's ratio characteristics at the macroscopic level.

[0008] The zero Poisson's ratio tension cell includes an upper base plate, a lower base plate, four elastic bodies, eight flexible hinge connecting blocks, twelve thick flexible hinges, twenty-four thin flexible hinges, and eight claw nails. Both the upper and lower base plates are square, with a claw nail at each of their four corners. The four elastic bodies are axially connected and tensioned via corresponding claw nails. On the inner surfaces of the upper and lower base plates, along the midpoints of the four sides, one thick flexible hinge and two thin flexible hinges are positioned, each connected to a flexible hinge connecting block. The corresponding flexible hinge connecting blocks are further connected via one thick flexible hinge and two thin flexible hinges, thus forming a complete zero Poisson's ratio tension cell structure. The main mechanical properties of the zero Poisson's ratio tension cell originate from the coupling mechanism of the elastic bodies, thick flexible hinges, and thin flexible hinges. This gives the zero Poisson's ratio tensile cell a certain degree of self-adaptability, self-stability, and self-recovery, while also ensuring its long-term reliability and achieving the mechanical property of zero Poisson's ratio in the axial direction.

[0009] The quick-connecting snap-fit ​​component consists of two quick-connecting snaps, a thick flexible hinge, and two thin flexible hinges. The two quick-connecting snaps are symmetrically arranged and interconnected with the two thin flexible hinges via the thick flexible hinge. This component, through its protruding portion engaging with pre-set slots in the upper and lower base plates of the zero Poisson's ratio tensile cell, achieves rapid assembly and reliable connection between multiple cells, thus forming a complete mechanical metamaterial monolithic structure. Based on the elastic recovery characteristics of the thick and thin flexible hinges, this connection method gives the overall structure good self-healing performance in the lateral direction. Furthermore, since the quick-connecting snap-fit ​​component is arranged laterally, its connection mechanism does not affect the axial mechanical behavior of the zero Poisson's ratio tensile cell itself. Therefore, the overall structure can maintain the axial zero Poisson's ratio characteristic macroscopically and achieve a negative Poisson's ratio effect in the lateral direction, forming a Poisson's ratio anisotropy with significant directional differences. Simultaneously, the overall structure exhibits good self-healing, self-adaptive, and self-stability in both the axial and lateral directions.

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

[0011] Technical Effects: This invention provides a mechanical metamaterial structure with anisotropic Poisson's ratio. Through the cross-shaped arrangement of zero Poisson's ratio tensile cells and the cooperation of quick-connect snap-fit ​​components, it achieves macroscopic anisotropy of axial zero Poisson's ratio and lateral negative Poisson's ratio. Its modular design facilitates local replacement and maintenance, significantly improving service life. At the same time, the overall structure has good self-adaptive, self-stabilizing, and self-recovering properties under the synergistic effect of the elastomer, thick flexible hinge, and thin flexible hinge. Furthermore, by adjusting the elastic modulus or stiffness coefficient of the elastomer, thick flexible hinge, and thin flexible hinge, the mechanical properties of the overall structure can be proportionally adjusted within a certain range, thereby better adapting to complex load environments. Attached Figure Description

[0012] To clearly illustrate the embodiments and related technical solutions of the present invention, the accompanying drawings involved in the embodiments will be briefly described below. It should be understood that the following drawings are only for illustrating some embodiments of the present invention. Those skilled in the art can also obtain other related technical solutions and drawings based on these drawings without any inventive effort.

[0013] Figure 1 This is an overall schematic diagram of a mechanical metamaterial structure with an anisotropic Poisson's ratio, provided as an embodiment of the present invention.

[0014] Figure 2 This is a partial exploded view of a mechanical metamaterial structure with anisotropic Poisson's ratio provided in an embodiment of the present invention.

[0015] Figure 3 A schematic diagram of a zero Poisson's ratio tensile cell structure of a mechanical metamaterial structure with anisotropic Poisson's ratio provided in an embodiment of the present invention.

[0016] Figure 4 The zero Poisson's ratio tensile cell explosion diagram of a mechanical metamaterial structure with anisotropic Poisson's ratio provided in an embodiment of the present invention.

[0017] Figure 5 Exploded view of the zero Poisson's ratio tensile cell detail of a mechanical metamaterial structure with anisotropic Poisson's ratio provided in an embodiment of the present invention.

[0018] Figure 6 A schematic diagram of axial compression deformation of a zero Poisson's ratio tensile cell in a mechanical metamaterial structure with anisotropic Poisson's ratio provided in an embodiment of the present invention.

[0019] Figure 7 A schematic diagram of a quick-connect snap-fit ​​component with an anisotropic Poisson's ratio mechanical metamaterial structure provided in an embodiment of the present invention.

[0020] Figure 8This is a schematic diagram of the axial compression deformation and transverse torsional deformation of a mechanical metamaterial structure with anisotropic Poisson's ratio provided for an embodiment of the present invention.

[0021] Labeling Explanation: 1. Zero Poisson's Ratio Tension Cell; 101. Upper Base Plate; 102. Lower Base Plate; 103. Elastomer; 104. Claw Nail; 105. Flexible Hinge Connector Block; 2. Quick Connect Buckle Component; 201. Quick Connect Buckle; 3. Thick Flexible Hinge; 4. Thin Flexible Hinge. Detailed Implementation

[0022] To clearly illustrate the embodiments of the present invention, a detailed description will be provided below in conjunction with the accompanying drawings. The same or similar reference numerals 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 in conjunction with the accompanying drawings is merely exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0023] It should be noted that the same reference numerals or numbers may be used repeatedly in different embodiments or figures. This repetition is only for simplifying the text description and figure indication, and does not in itself indicate that there is necessarily a specific relationship between the various embodiments or structures.

[0024] In the description of this invention, the terms "upper," "lower," "inner side," "same side," "symmetric," "center," "two corners," "four corners," "axial," "lateral," "clockwise," and "counterclockwise," etc., are defined based on the orientations or positions shown in the accompanying drawings. These definitions are merely for the convenience of describing and simplifying the invention, and do not indicate or imply that the components referred to must have a specific orientation, nor should they constitute a limitation on the invention. Furthermore, unless otherwise explicitly specified, "a plurality of" in this invention means two or more.

[0025] The following description illustrates different structures of the present invention through specific embodiments and accompanying drawings, with particular examples focusing on the components and their arrangement. It should be understood that these examples are merely illustrative and should not be construed as limiting the invention.

[0026] Please see Figures 1 to 3This invention provides a mechanical metamaterial structure with an anisotropic Poisson's ratio. The structure mainly consists of four zero Poisson's ratio tensile cells 1 and eight quick-connect snap-fit ​​components 2. Each zero Poisson's ratio tensile cell 1 has a slot (the portion highlighted by the dashed box I) at two corners on the same side of its upper base plate 101 and lower base plate 102. By locking the quick-connect snap-fit ​​components 2 into these slots, the four zero Poisson's ratio tensile cells 1 can be securely connected, forming a complete and coordinated metamaterial assembly. This modular connection design not only enables rapid assembly and disassembly of the structure but also facilitates independent maintenance and replacement of zero Poisson's ratio tensile cells 1 that experience localized failure or performance degradation during practical use, thereby significantly improving the maintainability, service life, and practical value of the overall structure.

[0027] See Figures 3 to 5 The zero Poisson's ratio tension cell 1 mainly includes an upper base plate 101, a lower base plate 102, four elastic bodies 103, eight spur nails 104, eight flexible hinge connecting blocks 105, twelve thick flexible hinges 3, and twenty-four thin flexible hinges 4. The upper base plate 101 and the lower base plate 102 are arranged symmetrically. On their opposing inner surfaces, each corner has a spur nail 104, and the four elastic bodies 103 are tensioned and connected via corresponding upper and lower spur nails 104. Simultaneously, on the opposing inner surfaces of the upper base plate 101 and the lower base plate 102, along the midpoint of each of the four sides, one thick flexible hinge 3 and two thin flexible hinges 4 are respectively provided and connected to a flexible hinge connecting block 105. The corresponding upper and lower flexible hinge connecting blocks 105 are further connected via one thick flexible hinge 3 and two thin flexible hinges 4, thus forming the complete zero Poisson's ratio tension cell 1. In this structure, the elastomer 103 provides initial pretension, enabling the zero Poisson's ratio tensioned cell 1 to maintain a stable initial shape, laying the foundation for its subsequent load-bearing and energy-absorbing deformation. Furthermore, the elastomer 103, the thick flexible hinge 3, and the thin flexible hinge 4 work synergistically to endow the zero Poisson's ratio tensioned cell 1 with excellent self-adaptability, structural stability, and deformation self-recovery capability, thereby ensuring its superior service life and reliability.

[0028] See Figures 3 to 6 For further information Figure 6 When the zero Poisson's ratio tensile cell 1 is compressed along the axial direction (i.e., along the A direction), the zero Poisson's ratio tensile cell 1 only contracts in the direction of the force, while remaining stable in the transverse dimension. That is, it exhibits typical zero Poisson's ratio characteristics in the axial direction.

[0029] Please see Figure 1 , Figure 2 , Figure 3 and Figure 7The quick-connecting buckle component 2 mainly includes two quick-connecting buckles 201, a thick flexible hinge 3, and two thin flexible hinges 4. The two quick-connecting buckles 201 are symmetrically arranged and are interconnected through the thick flexible hinge 3 and the two thin flexible hinges 4. In addition, the quick-connecting buckle component 2 uses the protrusions on its quick-connecting buckles 201 (i.e., the portion selected by dashed box II) to engage and lock with the corresponding slots (i.e., the portions selected by dashed box I) provided on the upper base plate 101 and lower base plate 102 of the zero Poisson's ratio tensile cell 1, thereby realizing the rapid assembly and reliable connection between multiple zero Poisson's ratio tensile cells 1, which together constitute a complete mechanical metamaterial integral structure.

[0030] See Figures 1 to 8 For further information Figure 8 Four zero Poisson's ratio tensile cells 1 are interconnected by four quick-connect snap-fit ​​components 2, assembling 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 direction B), the overall structure exhibits a clockwise torsional deformation posture (i.e., along direction C). Conversely, when the overall structure is subjected to a counterclockwise torsional force (i.e., along direction D), the overall structure exhibits a counterclockwise torsional deformation posture (i.e., along direction E). During the torsional deformation process in both directions, the overall structure exhibits negative Poisson's ratio characteristics. Furthermore, based on the elastic effect of the thick flexible hinge 3 and the thin flexible hinge 4 in the quick-connect snap-fit ​​components 2, the overall structure also has good self-restoring performance in the lateral direction. Meanwhile, since the quick-connect buckle component 2 is arranged in the transverse direction, this connection method does not affect the axial zero Poisson's ratio property of the zero Poisson's ratio tensile cell 1. Therefore, the overall structure can still maintain the axial zero Poisson's ratio characteristic at the macroscopic level, and exhibit a negative Poisson's ratio effect in the transverse direction, forming a significant Poisson's ratio anisotropy, thus better adapting 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-restoring, self-stability and self-adaptive properties of the overall structure can be adjusted proportionally within a certain range.

[0032] In summary, although the present invention has been described in detail above with reference to specific embodiments, the scope of protection of the present invention is not limited to the specific embodiments described. Those skilled in the art can modify, alter, or adapt these embodiments without departing from the principles of the present invention. All such changes or substitutions based on the inventive concept should be covered within the scope of protection of the present invention.

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 in an up-down mode through the flexible hinge connecting block (105); the quick-connection buckle component (2) comprises two symmetrically arranged quick-connection buckles (201), the two quick-connection buckles (201) are connected with each other through a thick flexible hinge (3) and two thin flexible hinges (4); cross-shaped space arrangement and connection of the zero-poisson-ratio tensile cell (1) make the overall structure have the zero-poisson-ratio characteristic in the axial direction and have the negative poisson's ratio effect in the transverse direction, so that the poisson's ratio characteristic of anisotropy is formed. 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 on the zero-poisson-ratio tensile cell (1), so that the zero-poisson-ratio tensile cell (1) has self-adaptability, self-stability and self-recovery and has the zero-poisson-ratio characteristic 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 the transverse direction, and the connection mechanism does not affect the axial mechanical characteristic 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 the 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 the transverse load, the overall structure can be coordinately deformed in torsion, so that the negative poisson's ratio effect is realized in the macroscopic level.

5. The mechanical metamaterial structure with anisotropic Poisson's ratio of claim 1, wherein, By adjusting the elastic modulus or the 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, the shape recovery capacity, the self-recovery performance, the self-stability and the self-adaptability of the overall structure can be proportionally adjusted.

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

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