A Bistable Composite Material Torsion Structure Expansion and Retraction Method

Abstract

The present invention relates to a method for folding and unfolding a bistable composite material torsion structure, which includes the following steps: Folding: Applying an axial displacement in opposite directions to the rigid spokes located at both ends of the bistable composite material torsion structure, causing the rigid spokes at both ends to rotate relative to each other, and the bistable composite material torsion structure starts to twist; subsequently, a jump occurs, and the bistable composite material torsion structure is in a folded stable configuration; Unfolding: Applying an axial displacement in opposite directions to the rigid spokes located at both ends of the bistable composite material torsion structure, causing the rigid spokes at both ends to rotate relative to each other, and the bistable composite material torsion structure unfolds along the axial direction, and then jumps to the unfolded stable configuration. The present invention realizes the repeated jump between stable configurations of the torsion structure under the action of relative displacement, and can achieve stable torsional deformation of the structure without continuous energy input, providing necessary guidance for the application of the bistable composite material torsion structure in the fields of aerospace torsion mechanisms, energy harvesting systems, etc.

Description

Technical Field:

[0001] The present invention relates to a method for deploying and retracting a bistable composite material torsion structure. Background Art:

[0002] Torsion, as one of the basic forms of force on structural members, is very common in nature and daily life. Existing torsion structures are mostly metal hinge and rigid connecting rod structures, which are complex and heavy, and require regular lubrication and maintenance. With the continuous improvement of the requirements for lightweight design of structures, there is an urgent need to design a torsion structure that is lightweight, high-strength, and simple in structure. Summary of the Invention:

[0003] The purpose of the present invention is to provide a method for deploying and retracting a bistable composite material torsion structure.

[0004] To achieve the above purpose, the technical solution adopted by the present invention is: a method for deploying and retracting a bistable composite material torsion structure, comprising the following steps:

[0005] Retraction: Apply an axial displacement in opposite directions to the rigid spokes at both ends of the bistable composite material torsion structure, so that the rigid spokes at both ends rotate relative to each other. At this time, the bistable composite material torsion structure begins to twist; then a jump occurs, and the bistable composite material torsion structure is in a retracted stable configuration.

[0006] Deployment: Under the retracted stable configuration, apply an axial displacement in opposite directions to the rigid spokes at both ends of the bistable composite material torsion structure, so that the rigid spokes at both ends rotate relative to each other. The bistable composite material torsion structure unfolds along the axial direction, and then jumps to the deployed stable configuration.

[0007] Furthermore, the bistable composite material torsion structure includes two composite material thin shells with the same geometric configuration, and at least two rigid spokes arranged side by side and spaced apart along the axis direction of the composite material thin shells. The at least two rigid spokes are symmetrically distributed on both sides of the composite material thin shells. The two composite material thin shells are arranged with a spacing equal to the length of the rigid spokes and with their concave surfaces facing each other. The rigid spokes are perpendicular to the axis of the composite material thin shells, and the ends of the rigid spokes are fixed on the concave surfaces of the composite material thin shells.

[0008] Furthermore, the central angle of the unfolded cross-section of the composite material thin shell is β, the radius is r, the length is L, and the following conditions are satisfied: πr ≤ L, π / 6 < β < 2π - arcsin(d0 / 2r), where: d0 is the diameter of the rigid spoke.

[0009] Furthermore, the composite material thin shell adopts a unidirectional anti-symmetric ply or plain symmetric ply method, and the ply angle is α, where: π / 6 ≤ α ≤ π / 3.

[0010] Furthermore, the ratio of the thickness δ to the radius of curvature r of the composite thin shell is less than 1 / 20.

[0011] Furthermore, the length of the rigid spoke is 2R, the spacing is a, and it satisfies:

[0012] where: d0 is the diameter of the rigid spoke, and d0 < 2rsin(β / 2).

[0013] Furthermore, the spacing between two adjacent rigid spokes is a, where:

[0014] Furthermore, the relative rotation angle between the rigid spoke and the composite thin shell is θ, where: -π / 2 ≤ θ ≤ π / 2.

[0015] Furthermore, the fixed connection between the rigid spoke and the composite thin shell adopts point contact.

[0016] Furthermore, the bistable composite torsion structure has two torsion modes: left-handed and right-handed.

[0017] Compared with the prior art, the present invention has the following effects: The present invention is reasonably designed, realizing the repeated jump between the stable configurations of the bistable composite torsion structure under the action of relative displacement, and achieving stable torsional deformation of the structure without continuous energy input, providing necessary guidance for the application of the bistable composite torsion structure in fields such as aerospace torsion mechanisms and energy harvesting systems. Description of the Drawings:

[0018] Figure 1 is a schematic structural diagram of the embodiment of the present invention in the deployed stable configuration;

[0019] Figure 2 is a schematic structural diagram of the embodiment of the present invention during the torsion process;

[0020] Figure 3 is a schematic structural diagram of the embodiment of the present invention in the retracted stable configuration;

[0021] Figure 4 is a schematic diagram of the deployment of the composite thin shell in the embodiment of the present invention;

[0022] Figure 5 is a characteristic diagram of the axial force change during one expansion - retraction - expansion deformation cycle of the bistable composite torsion structure in the embodiment of the present invention.

[0023] In the figure:

[0024] 1 - composite thin shell; 2 - rigid spoke. Detailed Embodiments:

[0025] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0026] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0027] As Figures 1 to 4 shown, a method for deploying and retracting a bistable composite material torsion structure of the present invention. The bistable composite material torsion structure includes two composite material thin shells 1 with the same geometric configuration, and at least two rigid spokes 2 provided between the two composite material thin shells 1. The at least two rigid spokes 2 are arranged side by side and spaced apart along the central axis direction of the composite material thin shell 1. The cross-section of the composite material thin shell 1 is arc-shaped. The two composite material thin shells 1 are symmetrically distributed on both sides of the rigid spokes 2, and the two composite material thin shells 1 are arranged with the length of the rigid spokes 2 as the spacing and the concave surfaces facing each other. The rigid spokes 2 are perpendicular to the central axis of the composite material thin shell 1, and the ends of the rigid spokes 2 are fixed on the concave surfaces of the composite material thin shells 1. The deploying and retracting method includes the following steps:

[0028] Retraction: When the bistable composite material torsion structure is in the deployed stable configuration, as Figure 1 shown, during retraction, an axial displacement in the opposite direction is applied to the rigid spokes at both ends of the bistable composite material torsion structure, causing the rigid spokes at both ends to rotate relative to each other. At this time, the bistable composite material torsion structure begins to twist, as Figure 2 shown; subsequently, a jump occurs, and the bistable composite material torsion structure is in the retracted stable configuration, as Figure 3 shown;

[0029] Deployment: In the retracted stable configuration, as Figure 3 shown, an axial displacement in the opposite direction is applied to the rigid spokes at both ends of the bistable composite material torsion structure, causing the rigid spokes at both ends to rotate relative to each other. The bistable composite material torsion structure unfolds along the axial direction, as Figure 2 shown, and then jumps to the deployed stable configuration as Figure 1 shown.

[0030] In this embodiment, the axial force change characteristics during one deployment-retraction-deployment deformation cycle of the bistable composite material torsion structure are as Figure 5As shown, the bistable composite torsion structure realizes the jump between stable configurations under the action of relative displacement, and can achieve stable torsional deformation of the structure without continuous energy input.

[0031] In this embodiment, the central angle of the unfolded section of the composite thin shell is β, the radius is r, and the length is L, and the following conditions are satisfied: πr ≤ L, π / 6 < β < 2π - arcsin(d0 / 2r), where: d0 is the diameter of the rigid spoke.

[0032] In this embodiment, the composite thin shell adopts a unidirectional anti-symmetric ply or a plain symmetric ply, and the ply angle is α, where: π / 6 ≤ α ≤ π / 3. It should be noted that the unidirectional anti-symmetric ply means that the composite thin shell is prepared by using unidirectional fiber prepreg through an anti-symmetric ply method; while the plain symmetric ply means that the composite thin shell is prepared by using plain woven fabric fiber prepreg through a symmetric ply method.

[0033] In this embodiment, the ratio of the thickness δ of the composite thin shell to the radius of curvature r is less than 1 / 20.

[0034] In this embodiment, the length of the rigid spoke is 2R, the spacing is a, and the following conditions are satisfied:

[0035] where: d0 is the diameter of the rigid spoke, and d0 < 2rsin(β / 2), and R is the radius of the bistable torsion structure.

[0036] In this embodiment, the spacing between two adjacent rigid spokes is a, where:

[0037] In this embodiment, the relative rotation angle between the rigid spoke and the composite thin shell is θ, where: -π / 2 ≤ θ ≤ π / 2.

[0038] In this embodiment, the bistable composite torsion structure has two torsional modes: left-handed and right-handed.

[0039] In this embodiment, the bistable composite torsion structure has two stable configurations: unfolded and folded. When the bistable composite torsion structure is in the initial unfolded stable configuration in the extended state, the axial distance between the rigid spokes at both ends of the bistable composite torsion structure is l1 at this time; when the bistable composite torsion structure is twisted until the ends of all the rigid spokes are in contact with the side of the composite thin shell, the bistable composite torsion structure is in the folded stable configuration, and the axial distance between the rigid spokes at both ends of the bistable composite torsion structure is l2 at this time. The maximum axial displacement Δl of the bistable composite torsion structure = l1 - l2.

[0040] In this embodiment, the fixed connection between the rigid spoke and the composite thin shell adopts point contact to avoid stress concentration in the bistable torsion structure during the deployment and retraction process as much as possible.

[0041] In this embodiment, the materials and geometric dimensions of each rigid spoke are the same.

[0042] In this embodiment, the composite material used for the composite thin shell is carbon fiber-epoxy composite material. In some preferred embodiments, the matrix material can be any one of unsaturated polyester, vinyl ester resin, polyethylene, polypropylene, and polylactic acid resin; the reinforcing material can be any one of glass fiber, polyethylene, polypropylene, silk protein, and hemp plant fiber, and the raw material sources are extensive.

[0043] Embodiment: The central angle β of the deployed cross-section of the composite thin shell is 114°, the radius r is 12.5 mm, the thickness δ is 0.18 mm, and the length L is 330 mm. There are five rigid spokes, which are evenly and equidistantly distributed on the central axis of the composite thin shell. The length of the rigid spoke is 2R = 50 mm, the diameter d0 is 10 mm, and the distance a between the rigid spokes in the bistable composite torsion structure is 80 mm. The composite thin shell adopts a ±45° plain symmetric lay-up method.

[0044] The advantages of the present invention are as follows: The bistable composite torsion structure prepared by using composite materials has the advantages of light weight, high strength, simple structure form, large torsional deformation, and good fatigue resistance. The deployment and retraction method of the bistable torsion structure prepared by composite materials realizes the repeated jump between stable configurations under the action of relative displacement, and the stable torsional deformation of the structure can be realized without continuous energy input, providing necessary guidance for the application of the bistable composite torsion structure in fields such as aerospace torsion mechanisms and energy harvesting systems.

[0045] If the present invention discloses or involves components or structural parts that are fixedly connected to each other, then, unless otherwise stated, the fixed connection can be understood as: a detachable fixed connection (such as using bolts or screws), or it can also be understood as: a non-detachable fixed connection (such as riveting, welding). Of course, the mutual fixed connection can also be replaced by an integral structure (such as manufactured by integral casting process) (except when it is obviously impossible to adopt the integral forming process).

[0046] In addition, the terms used to represent the positional relationship or shape in any of the technical solutions disclosed in the present invention, unless otherwise stated, include states or shapes that are approximate, similar, or close to it.

[0047] Any component provided by the present invention can either be assembled from multiple separate components or be a single component manufactured by an integral forming process.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that: it is still possible to modify the specific implementation manners of the present invention or perform equivalent replacements on some technical features; without departing from the spirit of the technical solutions of the present invention, they should all be covered within the scope of the technical solutions claimed by the present invention.

Claims

1. A bistable composite material torsion structure unfolding and folding method, characterized in that: The bistable composite material torsion structure includes two composite material thin shells with the same geometric configuration, and at least two rigid spokes arranged side by side and spaced apart along the axial direction of the composite material thin shells. The at least two rigid spokes are symmetrically distributed on both sides of the composite material thin shells. The cross-section of the composite material thin shell is arc-shaped. The two composite material thin shells are arranged with the length of the rigid spoke as the spacing and the concave surfaces facing each other. The rigid spokes are perpendicular to the axis of the composite material thin shell, and the ends of the rigid spokes are fixed on the concave surfaces of the composite material thin shells. It includes the following steps: Folding: Apply an axial displacement in the opposite direction to the rigid spokes at both ends of the bistable composite material torsion structure, so that the rigid spokes at both ends rotate relative to each other. At this time, the bistable composite material torsion structure begins to twist; then a jump occurs, and the bistable composite material torsion structure is in the folded stable configuration. Unfolding: In the folded stable configuration, apply an axial displacement in the opposite direction to the rigid spokes at both ends of the bistable composite material torsion structure, so that the rigid spokes at both ends rotate relative to each other. The bistable composite material torsion structure unfolds along the axial direction and then jumps to the unfolded stable configuration.

2. A bistable composite torsion structure expansion and contraction method according to claim 1, characterized in that: The central angle of the unfolded cross-section of the composite material thin shell is β, the radius of curvature is r, and the length is L, and the following conditions are satisfied: πr ≤ L, π / 6 < β < 2π - arcsin(d0 / 2r), where: d0 is the diameter of the rigid spoke.

3. A bistable composite material torsion structure unfolding and folding method according to claim 1, characterized in that: The composite material thin shell adopts a unidirectional anti-symmetric ply or a plain symmetric ply method, and the ply angle is α, where: π / 6 ≤ α ≤ π / 3.

4. A bistable composite torsion structure deployment and retraction method according to claim 1, characterized in that: The ratio of the thickness δ of the composite material thin shell to the radius of curvature r is less than 1 / 20.

5. A bistable composite torsion structure expansion and contraction method according to claim 1, characterized in that: The length of the rigid spoke is 2R, the spacing is a, and it satisfies: where: d0 is the diameter of the rigid spoke, and d0 < 2r sin(β / 2).

6. A bistable composite material torsion structure expansion and contraction method according to claim 1, characterized in that: The distance between two adjacent rigid spokes is a, where:

7. A method for expanding and contracting a bistable composite material torsion structure according to claim 1, characterized in that: The relative rotation angle between the rigid spoke and the composite material thin shell is θ, where: -π / 2 ≤ θ ≤ π / 2.

8. A bistable composite material torsion structure unfolding and folding method according to claim 1, characterized in that: The fixed connection between the rigid spoke and the composite material thin shell adopts point contact.

9. A bistable composite material torsion structure expansion and contraction method according to claim 1, characterized in that: The bistable composite material torsion structure has two torsion modes: left-handed and right-handed.

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