Polyhedral cell element with multiple metamorphic configurations

Abstract

The invention discloses a polyhedral cell element with multiple metamorphic configurations. The polyhedral cell element comprises an upper contour surface, a middle contour surface and a lower contour surface, the upper contour surface comprises a regular n-polygon surface unit and n square surface units, the regular n-polygon surface unit is located in the center, and the n square surface units are connected with n edges of the regular n-polygon surface unit through common edges respectively; the lower contour surface is the same as the upper contour surface; the middle contour surface is located between the upper contour surface and the lower contour surface and comprises n square surface units and 2n rectangular surface units; the n square surface units of the middle contour surface respectively correspond to the n square surface units of the upper contour surface upwards and respectively correspond to the n square surface units of the lower contour surface downwards; in the middle contour surface, two rectangular surface units are arranged between two adjacent square surface units, the two rectangular surface units are connected through a common edge, and the two rectangular surface units are connected with the adjacent square surface units through common edges; each common edge relates to two face units, and all the common edges are provided with rotating pairs.

Description

Technical Field

[0001] The invention belongs to the field of space metamorphic mechanisms and foldable structures, and in particular relates to a polyhedral cell with multiple metamorphic configurations. Background Art

[0002] With the rapid development of the aerospace field, the cargo space of spacecraft faces severe challenges. As a structure that can be folded and unfolded to adapt to different working conditions, the foldable structure is widely used in spacecraft equipment such as extension arms, solar wings, and space-deployable antennas. The foldable structure can be unfolded to a predetermined large-scale form when in operation, and folded into a smaller form during transportation and storage, thereby meeting both large-scale working needs and small-volume transportation and storage needs.

[0003] The deployable structures in the prior art mainly include planar deployable structures, spatial mesh deployable structures, and polyhedral deployable structures. Planar deployable structures are constructed based on planar units, such as scissor-type mechanisms, parallelogram mechanisms, etc. Mesh spatial deployable structures are often constructed based on spatial over-constrained mechanism units, and the units are mainly rod-shaped. Polyhedral deployable structures are often constructed by combining rod-shaped and planar units, and a small number of them are constructed based on pure planar units with the help of complex spatial mechanisms.

[0004] In the prior art, the planar deployable structure has a single configuration and cannot meet the requirements of specific spatial configurations; the mesh deployable structure is usually constructed with rod-shaped units, so it is often necessary to manufacture a corresponding covering film to achieve specific requirements; and the polyhedral deployable structure often requires the use of a combination of units in various forms and the application of specially designed kinematic pairs to meet the kinematic compatibility conditions. Existing polyhedrons based on pure planar units and connected only by revolute pairs also have problems such as too many revolute pairs and complex constraints. In addition, existing polyhedral structures constructed based on pure planar units and revolute pairs are often difficult to form closed structures, and most of them only have one folding path.

[0005] Therefore, providing a polyhedral cell with a simple structure and multiple cell transformation paths has become a problem that the industry needs to solve. Summary of the invention

[0006] In order to solve the deficiencies in the prior art, the main purpose of the present invention is to provide a spatially foldable polyhedron cell with a simple structure, a single degree of freedom, and a large folding ratio, which has multiple cell transformation paths.

[0007] In order to achieve the above main purpose, the present invention discloses a polyhedral cell with multiple metamorphic cell configurations, which includes an upper contour surface, an intermediate contour surface, and a lower contour surface;

[0008] The upper contour surface includes a regular n-gon surface unit and n square surface units, the regular n-gon surface unit is located in the center, and the n square surface units are respectively connected to n edges of the regular n-gon surface unit through common edges;

[0009] The lower contour surface is the same as the upper contour surface;

[0010] The middle contour surface is located between the upper contour surface and the lower contour surface, and includes n square surface units and 2n rectangular surface units; the n square surface units of the middle contour surface correspond to the n square surface units of the upper contour surface upwards and correspond to the n square surface units of the lower contour surface downwards; two adjacent and corresponding square surface units are connected by a common edge;

[0011] In the middle contour surface, two rectangular surface units are arranged between two adjacent square surface units, the two rectangular surface units are connected by a common edge, and the two rectangular surface units are connected to the adjacent square surface units by a common edge;

[0012] Each common edge involves two surface elements, and all common edges are equipped with revolute pairs.

[0013] According to a specific implementation of the present invention, n≥3.

[0014] According to a specific implementation of the present invention, n=4, the center of the upper contour surface is a square surface unit, and the center of the lower contour surface is also a square surface unit.

[0015] According to a specific embodiment of the present invention, the side length of the square surface unit is l, and the long side and short side lengths of the rectangular surface unit are l and m respectively;

[0016]

[0017] According to a specific embodiment of the present invention, the polyhedral cell has a fully expanded state, at which time the five square surface units of the upper contour surface are in the same plane, the five square surface units of the lower contour surface are also in the same plane, and every two directly connected rectangular surface units are also in a coplanar state.

[0018] According to a specific embodiment of the present invention, depending on the driving mode, the 5 square face units on the upper contour surface and the 5 square face units on the lower contour surface are convex outward at the same time or concave inward at the same time. In the present invention, when the 5 square face units on the upper and lower contour surfaces are convex outward at the same time, it is defined as folding path I; when the 5 square face units on the upper and lower contour surfaces are concave inward at the same time, it is defined as folding path II. The polyhedral cell of the present invention forms an octagonal prism structure in a fully unfolded state. When folded along folding path I, it folds and gathers in the width and length directions, forming a closed quadrangular prism structure in a fully folded state. When folded along folding path II, it also folds and gathers inward in the width and length directions, and the height direction remains unchanged.

[0019] According to a specific implementation of the present invention, depending on the driving mode, the five square surface units on the upper contour surface are convex outward or concave inward, and the five square surface units on the lower contour surface are concave inward or convex outward.

[0020] In addition, for the rectangular surface units on the side, a plate-like unit of a certain thickness is pasted on the inside through a multi-layer material processing method, and physical interference is used to constrain it to be folded in one direction toward the inside of the polyhedron.

[0021] The foldable polyhedron cell of the present invention can be folded along multiple paths, each path corresponding to different motion characteristics. The foldable polyhedron structure has the advantages of single degree of freedom, simple structure, easy processing and manufacturing, easy modular expansion, etc., and has good application potential and broad application prospects in the fields of aerospace, construction engineering, modular robots, metamaterials, etc.

[0022] According to a specific implementation of the present invention, during the folding and unfolding process, two square surface units facing each other always remain parallel.

[0023] According to a specific implementation of the present invention, during the folding and unfolding process, the two square surface units in the center of the upper and lower contour surfaces always remain perpendicular to the four square surface units of the middle contour surface.

[0024] According to a specific implementation of the present invention, during the folding and unfolding process, every two square surface units connected by the rectangular surface units always remain vertical.

[0025] The present invention has the following beneficial effects:

[0026] 1. The polyhedral cell of the present invention is constructed only by a planar unit and a rotational pair structure, and has the characteristics of simple structure and easy production and processing;

[0027] 2. The polyhedral cell of the present invention has the characteristics of single degree of freedom, simple control, large folding and unfolding ratio, and can be folded into a closed and regular prismatic structure;

[0028] 3. The polyhedral cell of the present invention has multiple folding paths, which can realize different folding processes and size change characteristics;

[0029] 4. The polyhedral cell of the present invention has good symmetry in structure and motion characteristics, is easy to modularize and expand, and can be used as a basic module to construct mechanical metamaterials with adjustable characteristics or large-scale modular structures.

[0030] In order to more clearly illustrate the purpose, technical solutions and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a schematic diagram of the arrangement of square face units under a certain instantaneous configuration of the polyhedral cell of Example 1;

[0032] Figure 2 is a schematic diagram of the arrangement of rectangular surface units under a certain instantaneous configuration of the polyhedral cell of Example 1;

[0033] Figure 3 is a schematic diagram of structural design parameters of the polyhedron cell of Example 1;

[0034] Figure 4 is the fully folded state of the folding path I in embodiment 1;

[0035] Figure 5 is one of the intermediate states of folding path I in embodiment 1;

[0036] Figure 6 This is the second intermediate state of the folding path I in Example 1;

[0037] Figure 7 It is the third intermediate state of the folding path I in Example 1;

[0038] Figure 8 is the fully expanded state of Example 1;

[0039] Fig. 9 is the intermediate state of folding path II in Example 1;

[0040] Fig.10 is the fully folded state of folding path II in Example 1;

[0041] Figure 8-Figure 4 is the folding process of the polyhedral cell of Example 1 along the folding path I;

[0042] Figure 8-Figure 10 is the folding process of the polyhedral cell of Example 1 along the folding path II;

[0043] Fig.11 is a schematic structural diagram of a polyhedral cell in a certain instantaneous configuration of Example 2;

[0044] Fig.12 is a schematic structural diagram of a polyhedral cell in a certain instantaneous configuration of Example 3;

[0045] Fig.13 It is a schematic diagram of the structure of the polyhedron cell of Example 4 in a certain instantaneous configuration. DETAILED DESCRIPTION

[0046] In the following description, many specific details are explained in conjunction with the embodiments to facilitate a full understanding of the present invention. However, it should be understood that the following embodiments and detailed descriptions are only for illustrative purposes and do not limit the scope of protection of the present invention.

[0047] Example 1 (n=4)

[0048] This embodiment provides a polyhedral cell (foldable polyhedral unit), which includes an upper contour surface, an intermediate contour surface, and a lower contour surface. Figure 1 and Figure 8 As shown, the upper contour surface includes five square surface units S1-S5, and S2-S5 are respectively connected to the four sides of S1 through rotation pairs. Figure 8 In the figure, the notation in brackets indicates the surface unit number of the lower contour surface corresponding to the surface unit; for example, S2(S10) indicates that the surface unit number is S2, and the surface unit number of the lower contour surface corresponding to it is S10.

[0049] The lower contour surface includes five square surface units S10-S14; S10-S13 are respectively connected to the four sides of S14 through revolute pairs.

[0050] The middle contour surface is located between the upper contour surface and the lower contour surface, and includes 4 square surface units S6-S9 and 8 rectangular surface units R1-R8 (such as Figure 2 and Figure 8 ); the 4 square surface units of the middle contour surface correspond to the 4 square surface units of the upper contour surface upwards, and correspond to the 4 square surface units of the lower contour surface downwards; two adjacent and corresponding square surface units are connected by a common edge;

[0051] In the middle contour surface, two rectangular surface units are arranged between two adjacent square surface units, the two rectangular surface units are connected by a common edge, and the two rectangular surface units are connected to the adjacent square surface units by a common edge;

[0052] Each common edge involves two surface units, and all common edges are provided with revolute pairs. Specifically, R1 and R2, R3 and R4, R5 and R6, R7 and R8 are connected by revolute pairs respectively; S6 and R1 and R8, S7 and R2 and R3, S8 and R4 and R5, S9 and R6 and R7 are connected by revolute pairs respectively; S2 and S6, S3 and S7, S4 and S8, S5 and S9 are connected by revolute pairs respectively; S6 and S10, S7 and S11, S8 and S12, S9 and S13 are connected by revolute pairs respectively.

[0053] Figure 3 is a schematic diagram of the design parameters of the polyhedron structure, where the side length of the square surface unit is l, and the long side and short side lengths of the rectangular surface unit are l and m respectively. In order to achieve a fully unfolded configuration and avoid physical interference during folding, l and m must meet the following conditions:

[0054]

[0055] Right now,

[0056]

[0057] Therefore, the polyhedral cell has only one design parameter, and the selection of the design parameter only affects the scale of the structure but does not affect the folding, expansion and motion characteristics of the structure.

[0058] In the fully expanded state ( Figure 8 ), the first to fifth square face units S1-S5 of the upper contour surface are in the same plane, and the tenth to fourteenth square face units S10-S14 of the lower contour surface are also in the same plane. At this time, every two directly connected side rectangular face units are also in a coplanar state. For the side rectangular face units, a method of adding a patch of a certain thickness on the inside is adopted, and physical interference is used to constrain that it can only fold in one direction toward the inside of the polyhedron. For the square face units on the upper and lower contour surfaces, according to different driving methods, it can be realized that they convex outward at the same time ( Figure 7 ) or concave inwards at the same time ( Fig. 9 ), these two modes are defined as folding path I and folding path II, respectively.

[0059] H, L, and W represent the height, length, and width dimensions of the polyhedral cell, respectively. Figure 8-Figure 4 ) When folding, L and W are simultaneously folded inward and the size remains the same, while H gradually increases. Figure 8 Indicates the fully expanded state. Figure 4 represents the fully folded state of folding path I; when following folding path II ( Figure 8-Figure 10 ) When folded, L and W are folded inward and the size remains the same, and H remains unchanged. Fig.10Indicates the fully folded state of folding path II. By utilizing the scale variation characteristics of the foldable structural unit, a mechanical metamaterial with positive Poisson's ratio, negative Poisson's ratio and alternating positive and negative Poisson's ratio can be designed based on the unit.

[0060] During the movement of the foldable polyhedron, the relative square face units S1 and S14, S2 and S12, S3 and S13, S4 and S10, S5 and S11, S6 and S8, S7 and S9 always remain parallel to each other; S1 and S14 always remain perpendicular to S6-S9; S6 is perpendicular to S7 and S9, and S7 is perpendicular to S6 and S8.

[0061] In particular, when two directly connected rectangular face units (such as R1 and R2) move to a mutually perpendicular state, the H, L and W scales of the developable polyhedron structure are the same, and the polyhedron forms a small rhombic truncated semi-cube outline.

[0062] Example 2 (n=3)

[0063] like Fig.11 As shown, the difference between this embodiment and embodiment 1 is that the centers of the upper and lower contour surfaces are regular triangle surface units; and the number of rectangular surface units is 6.

[0064] Example 3 (n=5)

[0065] like Fig.12 As shown, the difference between this embodiment and embodiment 1 is that the centers of the upper and lower contour surfaces are regular pentagonal surface units; and the number of rectangular surface units is 10.

[0066] Example 4 (n=6)

[0067] like Fig.13 As shown, the difference between this embodiment and embodiment 1 is that the centers of the upper and lower contour surfaces are regular hexagonal surface units; and the number of rectangular surface units is 12.

[0068] Although the present invention has been described above through embodiments, the above embodiments are only used to exemplarily describe the feasible implementation schemes of the present invention, and are not used to limit the protection scope of the present invention. Any equivalent substitutions or changes made by those skilled in the art in accordance with the present invention should also be covered by the protection scope defined by the claims of the present invention.

Claims

1. A polyhedral cell having multiple cell configurations, characterized in that: The polyhedral cell comprises an upper contour surface, an intermediate contour surface, and a lower contour surface; The upper contour surface includes a regular n-gonal surface unit and n square surface units, the regular n-gonal surface unit is located in the center, and the n square surface units are respectively connected to the n sides of the regular n-gonal surface unit through common edges; The lower contour surface is identical to the upper contour surface; The intermediate contour surface is located between the upper contour surface and the lower contour surface, and includes n square surface units and 2n rectangular surface units; the n square surface units of the intermediate contour surface correspond to the n square surface units of the upper contour surface upwardly and correspond to the n square surface units of the lower contour surface downwardly; two adjacent and corresponding square surface units are connected by a common edge; In the intermediate contour surface, two rectangular surface units are arranged between two adjacent square surface units, the two rectangular surface units are connected by a common edge, and the two rectangular surface units and their adjacent square surface units are connected by a common edge; Each of the common edges involves two surface units, and all of the common edges are provided with a revolute pair.

2. The polyhedral cell according to claim 1, characterized in that: n≥3。 3. The polyhedral cell according to claim 1, characterized in that: n=4, the center of the upper contour surface is a square surface unit, and the center of the lower contour surface is also a square surface unit.

4. The polyhedral cell according to claim 3, characterized in that: The side length of the square surface unit is l, and the long side and short side lengths of the rectangular surface unit are l and m respectively; 5. The polyhedral cell according to claim 3, characterized in that: The polyhedral cell is in a fully expanded state, at which time the five square surface units of the upper contour surface are in the same plane, the five square surface units of the lower contour surface are also in the same plane, and every two directly connected rectangular surface units are also in a coplanar state.

6. The polyhedral cell according to claim 5, characterized in that: According to different driving modes, the five square surface units on the upper contour surface and the five square surface units on the lower contour surface are convex outward or concave inward at the same time.

7. The polyhedral cell according to claim 5, characterized in that: According to different driving modes, the five square surface units on the upper contour surface are convex outward or concave inward, and the five square surface units on the lower contour surface are concave inward or convex outward.

8. The polyhedral cell according to claim 6, characterized in that: During the folding and unfolding process, the two square surface units facing each other always remain parallel.

9. The polyhedral cell according to claim 8, characterized in that: During the folding and unfolding process, the two square surface units in the center of the upper and lower contour surfaces always remain perpendicular to the four square surface units of the middle contour surface.

10. The polyhedral cell according to claim 9, characterized in that: During the folding and unfolding process, every two of the square surface units connected by the rectangular surface units always remain vertical.

Images