JP2021130338A - Boom with bistability - Google Patents

Abstract

To provide a boom with bistability whose initial resistance in self-extension is small so that the boom can surely progress the self-extension even when the boom is held in a rolled-up form for a long time.SOLUTION: A boom main body comprises a plurality of lengthy divided boom parts extending parallely in a longitudinal direction, and a bendable connection part connecting the plurality of divided boom parts. The divided boom parts respectively have bistability with which, in an extending form, the parts extend straight in the longitudinal direction and cross sectional shapes thereof in a direction orthogonal to the longitudinal direction are held being bent into an open cross sectional shape, and in a rolled-up form, the cross sectional shapes in the direction orthogonal to the longitudinal direction extend linearly, then bend in the longitudinal direction to be kept rolled up. In the extending form, the plurality of divided boom parts respectively constitute part of the open cross sectional shape of the boom main body, and the open cross sectional shape of the boom main body as a whole is held by the connection part.SELECTED DRAWING: Figure 3

Description

The present invention relates to a boom used as a structural material of various structures such as a space structure such as an antenna of an artificial satellite or a spacecraft or a solar cell panel or a ground structure, and the present invention particularly relates to a winding form and an extension. It relates to a bi-stability boom that stably holds the morphology and is capable of self-extending from the winding morphology.

As a conventional bistability boom of this kind, for example, an elastic member as described in Patent Document 1 is known.
That is, the boom body is composed of a long plate material having elasticity, and is bent in an open cross-sectional shape in a direction orthogonal to the longitudinal direction (hereinafter referred to as a lateral direction), and on the other hand, is wound in a cylindrical shape in the longitudinal direction. It is bent into the taken winding form, and in the initial form, it is stably held in either the extended form or the winding form.
In the winding mode, the boom body has a linearly extended open cross-sectional shape in the lateral direction, and the elastic restoring force for returning to the open cross-sectional direction is held by the rigidity of the wound cylindrical shape. .. Further, in the extended form, the boom body has an open cross-sectional shape in the lateral direction, and the elastic restoring force in the winding direction is maintained by the rigidity in the longitudinal direction of the boom body having the open cross-sectional shape.
The boom body is mechanically unstable when it has two forms, an extension form and a take-up form, and when it is slightly extended in the extension direction from the take-up form, it self-extends and shifts to the extension form.

Special Table 2000-507890

However, when this boom is molded from a resin material such as fiber reinforced resin, if it is stored for a long period of time in a wound state, the cross-sectional shape of the boom body in the lateral direction tends to return to the open cross-sectional shape due to stress relaxation. There is a problem that the elastic restoring force is reduced and self-extension is not started, or even if extension is started, it is stopped in the middle of extension. Further, in the initial stage of extension, when the terminal is pulled out a little, the elastic restoring force returning to the open cross-sectional shape is concentrated near the boundary between the terminal portion deformed into the open cross-sectional shape and the winding form, and bending occurs. Flexion becomes the initial resistance of self-extension and is a factor that hinders self-extension.

The present invention has been made in view of such circumstances, and an object of the present invention is that the initial resistance of self-extension is small and self-extension can be reliably promoted even when the wounded form is maintained for a long period of time. It is to provide a stability boom.

In order to achieve the above object, the present invention
It has a long boom body that can stably hold two forms, an extended form and a take-up form.
In the extended form, the boom body is held in a form that extends linearly in the longitudinal direction and the cross-sectional shape in the direction orthogonal to the longitudinal direction is curved to an open cross-sectional shape, and in the winding form, the boom body is orthogonal to the longitudinal direction. In a bistable boom in which the cross-sectional shape extends linearly and is held in a wound form that is curved in the longitudinal direction.
The boom body includes a plurality of divided boom portions that are divided in the circumferential direction and extend in parallel in the longitudinal direction.
A bendable connecting portion for connecting the plurality of split boom portions is provided.
In the extended form, the split boom portions are held in a form that extends linearly in the longitudinal direction and the cross-sectional shape in the direction orthogonal to the longitudinal direction is curved to the open cross-sectional shape, and in the winding form, the split boom portions are held in the longitudinal direction. It has bi-stability in which the cross-sectional shape in the orthogonal direction extends linearly and is curved in the longitudinal direction and held in a wound form.
In the extended form, the plurality of divided boom portions each form a part of the open cross-sectional shape of the boom body, and the connecting portion holds the open cross-sectional shape of the boom body as a whole. It is a feature.
According to the present invention, the amount of strain in the winding form is dispersed in a plurality of split boom portions and becomes small, and even if stress relaxation occurs after a long period of time in the winding form, the degree of stress relaxation is small. The boom body can be self-extended by the elastic restoring force.
Further, by dividing into a plurality of divided boom portions, the internal stress of the divided booms of each extension form and the take-up form is small, so that the elastic restoring force returning to the open cross-sectional shape is small, and the pulled-out terminal portion and the take-up form portion. The bending that occurs at the boundary between the wind and the wind is also reduced, the initial resistance in the process of transitioning from the winding form to the extending form is reduced, and self-extension becomes easier.

The connecting portion can be composed of a connecting material joined to the split boom portion.
In this way, production becomes easy.
The connecting member may be configured to be completely joined to the split boom portion.
In this way, there is also an effect of protecting the split boom portion.
Further, the connecting member may be configured to be partially joined to the side edge of the split boom portion.
In this way, the material required for the connecting portion can be minimized.
Further, it is preferable that the split boom portion is made of a fiber reinforced resin in which a fiber base material is impregnated with a resin.
The fiber base material may have a structure in which the orientation directions of the fibers are obliquely intersected with each other in the directions opposite to the extension direction.
The split boom portion and the connecting portion may be based on a common fiber base material, the split boom portion may be impregnated with a hard resin, and the hinge element may be impregnated with a soft resin.

According to the bistability boom of the present invention, the initial resistance of self-extension is small, and even when the self-extension is held for a long period of time, the transition from the winding form to the extension form can be reliably advanced.

FIG. 1 shows a bistability boom according to the first embodiment of the present invention, (A) is a perspective view of an extended form, (B) is a perspective view of a winding form, and (C) is a boom main body in an extended form. (D) is a cross-sectional view showing the boom body of (C) disassembled, (E) is an enlarged cross-sectional view in the vicinity of the connecting portion, and (F) is another configuration of the connecting portion. A partially enlarged view showing an example by disassembling, and (G) is a partially enlarged view showing still another structural example of the connecting portion by disassembling. 2 (A) is a perspective view of an extended form of the split boom portion constituting the boom body of FIG. 1, (B) is a perspective view of a winding form of the split boom portion of (A), and (C) is (A). It is a perspective view of the state in the middle of transition from the winding form to the extended form of the split boom portion of. FIG. 1 shows a state in which the bistable boom is in the process of transition from the winding form to the extended form, (A) is a perspective view of the initial transition state, and (B) is a perspective view of a state in which the transition is further advanced. .. FIG. 4 shows an example of an FRP sheet constituting the boom body of FIG. 1, (A) is an explanatory view of a yarn orientation direction when a woven fabric structure is used as a fiber base material, and (B) is (A). It is a schematic cross-sectional view along the orientation direction of one thread of the woven fabric structure of. FIG. 5 shows an example of an FRP sheet using a UD material as a fiber base material, (A) is a schematic exploded view showing a plurality of FRP sheets to be laminated, and (B) is a schematic sectional view of a laminated structure. .. FIG. 6 shows a bistability boom according to the second embodiment of the present invention, (A) is a perspective view of an extended form, (B) is a perspective view of a winding form, and (C) is a perspective view of an initial extended state. FIG. 3D is a cross-sectional view of the extended boom body in the direction orthogonal to the longitudinal direction. FIG. 7 shows a bistability boom according to the third embodiment of the present invention, (A) is a perspective view of an extended form, (B) is a perspective view of a winding form, and (C) is a boom main body in an extended form. A cross-sectional view in the direction orthogonal to the longitudinal direction of the above, (D) is an enlarged cross-sectional view of the connecting portion. 8A and 8B show the extension process of FIG. 7, where FIG. 8A is a perspective view of an initial extension state, and FIG. 8B is a perspective view of a state in which the extension is further advanced. FIG. 9 is a cross-sectional view of the boom body in the direction orthogonal to the longitudinal direction showing another embodiment of FIG. 1 (C).

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[Embodiment 1]
FIG. 1 shows a bistability boom according to the first embodiment of the present invention, (A) is a perspective view of an extended form, (B) is a perspective view of a winding form, and (C) is a boom main body in an extended form. (D) is a cross-sectional view showing the boom body of (C) disassembled, and (E) is an enlarged cross-sectional view of the vicinity of the connecting portion.
That is, this bistability boom has a long boom body 10 that can stably hold two forms, the extension form shown in FIG. 1 (A) and the winding form shown in FIG. 1 (B). .. Hereinafter, if necessary, the winding boom main body 10 will be described with an A at the end of the reference numerals, and the extended boom main body 10 will be described with a B at the end of the reference numerals.
In the extended form, the boom body 10 is held in a form in which it extends linearly in the longitudinal direction X and the cross-sectional shape in the direction orthogonal to the longitudinal direction X is curved into an open cross-sectional shape. On the other hand, the winding form has bistability in which the cross-sectional shape in the direction orthogonal to the longitudinal direction extends linearly and is held in the winding form curved in the longitudinal direction.
Regarding the boom main body 10, if the concave surface side of the open cross-sectional shape in the extended form is the first surface 10a and the convex surface side is the second surface 10b, the first surface 10a side is the concave surface even in the winding form. It is curved in the direction and wound up.

The boom main body 10 includes two long split boom portions 11 and 11 that are divided in the circumferential direction and extend in parallel with the longitudinal direction X, and a bendable connecting portion 12 that connects the two split boom portions 11 and 11. , Is equipped. In the extended form, the plurality of divided boom portions 11 and 11 each form a part of the open cross-sectional shape of the boom main body 10, and the connecting portion 12 holds the open cross-sectional shape of the boom main body 10 as a whole. ..
As shown in FIG. 1C, the open cross-sectional shape of the boom body 10 is a cross-sectional arc shape that curves in a C shape so as to form a part of a circle, and is a line connecting both ends of the arc and the center of curvature O. The opening angle α formed by the above is not particularly limited, and for example, as shown in FIG. 9, the opening angle α may be set so that both edges overlap in the circumferential direction and α becomes negative.
The two divided boom portions 11 and 11 have a configuration in which the boom main body 10 is divided into two in the longitudinal direction and the orthogonal direction, and are long elastic thin plates having the same shape and the same dimensions, respectively. It has bi-stability that can stably hold the two forms.

In this embodiment, the connecting portion 12 includes a first connecting sheet 12a as a connecting material that is adhered over the first surfaces 11a and 11a on the concave side of the split boom portions 11 and 11 in the extended form, and the split boom portion. It is composed of a second connecting sheet 12b that is adhered over the second surfaces 11b and 11b on the convex side of the 11 and 11. A slight gap is provided between the side edges of the split boom portions 11 and 11 to be connected, and in this gap, as shown in an enlarged manner in FIG. 1 (E), the first connecting sheet 12a and the second connecting sheet 12b Is adhered to form a bendable connecting portion 12. In this embodiment, the first connecting sheet 12a is adhered so as to cover the entire surface of the first surfaces 11a, 11a of the two split boom portions 11, 11, and the second connecting sheet 12b is formed by the two split boom portions 11. , 11 is adhered so as to cover the entire surface of the second surfaces 11b and 11b.
For the first connecting sheet 12a and the second connecting sheet 12b constituting the connecting portion 12, for example, a film composed of a flexible soft elastomer can be used, and the film is further reinforced with a fiber base material. You may. Further, a bias tape or the like other than carbon can be used. The connecting portion 12 has a configuration that flexibly deforms into both an extended form and a winding form, but the initial form (no load state) of the connecting portion 12 retains the form of the boom body 10 in the extended form. It is composed. That is, with respect to the deformation in the direction of increasing the opening angle of the boom body 10, the surface of the divided boom portions 11 and 11 of the connecting portion 12 on the concave surface side is stretched and the tension in the direction of returning to the original state acts to reduce the opening angle. The deformation in the direction is restored to the original opening cross-sectional shape by the action of tension in the direction in which the convex surface side surfaces of the split boom portions 11 and 11 of the connecting portion 12 are stretched and returned to the original shape.

In the illustrated example, the first connecting sheet 12a and the second connecting sheet 12b are attached so as to cover the entire surfaces of the first surfaces 11a and 11a and the second surfaces 11b and 11b of the two split boom portions 11 and 11. However, it may be composed of only the first connecting sheet 12a and only the second connecting sheet 12b.
Further, as shown in FIG. 1 (F), the first connecting sheet 112a and the second connecting sheet 112b may be partially attached to the side edges of the split boom portions 11 and 11 to be connected. In this case as well, only the first surface 11a side and the second surface 11b side may be attached. Further, as shown in FIG. 1 (G), on at least one of the first connecting sheet 112a and the second connecting sheet 112b,
A reinforcing material 112d such as a fiber base material may be attached, or a sheet containing the reinforcing material may be used.
Further, if the gap between the side edges of the split boom portions 11 and 11 connected by the connecting portion 12 is too narrow, the resistance at the time of winding tends to increase, and if it is too wide, the rigidity at the time of extension tends to decrease, which is appropriate. It is set in the range.

Next, each split boom portion 11 will be described.
2 (A) is a perspective view of an extended form of one split boom portion constituting the boom body of FIG. 1, (B) is a perspective view of a winding form of the split boom portion of (A), and (C) is (C). It is a perspective view of the state in the middle of transition from the winding form to the extension form of the split boom part of A).
The split boom portion 11 is formed of an elastic long thin plate, is bent in an open cross-sectional shape in a direction orthogonal to the longitudinal direction X, and is wound in a cylindrical shape in the longitudinal direction X. In the initial form, it is stably held in either the extended form 11A shown in FIG. 2 (A) or the winding form 11B shown in FIG. 2 (B). Assuming that the surface of the split boom portion 11 that is the concave surface side of the open cross-sectional shape in the extended form is the first surface 11a and the surface that is the convex surface side is the second surface 11b, the first surface 11a side is the concave surface even in the winding form. It is in the form of being wound in a curved direction.

As shown in FIGS. 4A and 4B, each of the split boom portions 11 is a fiber reinforced resin sheet (FR).
It is composed of P sheet) 13. The fiber-reinforced resin sheet 13 has a structure in which the fiber base material 15 is impregnated with the matrix resin 16.
The fiber base material 15 is a biaxial woven fabric structure, and the first axial yarn 15a and the second axial yarn 15b are inclined by a predetermined angle θ (orientation angle) in opposite directions with respect to the long axis N1 along the longitudinal direction. It is configured to do. The orientation angle is 45 °.
In this embodiment, carbon fibers are used for the first shaft yarn 15a and the second shaft yarn 15b, and in particular, the first shaft yarn 15a and the second shaft yarn 15b are composed of open fiber yarns in which fiber bundles are bundled flatly. In this example, the fiber reinforced resin sheet 13 has a one-layer structure, but a plurality of sheets may be laminated to form a multi-layer structure.
As the biaxial woven fabric structure, either a plain weave bias cut material or a bias weave can be adopted.
The base material structure of the fiber base material 15 is not limited to the woven fabric structure, and a braided structure can also be applied, and a knitted structure, a net structure, and the like can also be applied.

Further, as shown in FIGS. 5 (A) and 5 (B), as a fiber reinforced resin sheet (FRP sheet), a UD material 23 in which a bundle of fibers 25 is obliquely oriented with respect to the long axis N1 as a fiber base material ( It is also possible to use a laminated material in which a plurality of fibers (fiber reinforced materials) in which fibers 25 are oriented in one direction on the matrix resin 26 are laminated. The UD material 23 may have a two-layer structure in which the UD material 23 is oriented in opposite directions with respect to the long axis N1, but the two layers tend to be twisted, and the orientation angle θ is set to −θ / + θ / + θ / −θ. Twisting can be prevented by forming a four-layer structure. Regarding the notation of + and-of the orientation angle θ, the counterclockwise direction is + and the clockwise direction is −. The orientation angle θ is preferably about 45 °.

Regarding the first shaft yarn 15a and the second shaft yarn 15b of the fiber base material 15 and the fiber 25 of the UD material 23, in addition to the carbon fiber, glass fiber, polyester fiber, fluorine fiber, aramid fiber, etc. Polypropylene fiber, polyethylene fiber, metal fiber and the like can be used. When used for an antenna or the like, conductive fibers can also be used.
The matrix resins 16 and 26 include polycarbonate resins, polyester resins such as PET and PBT, PA (polyamide), PEI (polyetherimide), and PEE.
Engineering plastics such as K (polyetheretherketone) and PPS (polyphenylene sulfide), heat-resistant resins such as EP (epoxy resin) and polyimide can be used.

Next, the operation of the bistability boom of the present embodiment will be described with reference to FIG.
In the winding mode, the boom main body 10 has two split boom portions 11 and 11 having an arcuate cross-sectional shape extending in a straight line in a direction orthogonal to the extension direction, and an open cross section of each split boom portion 11 and 11. The elastic restoring force that tends to return in the direction is held by the rigidity of the wound cylindrical shape of each of the split boom portions 11 and 11. The connecting portion 12 is elastically deformed following the deformation of the split boom portions 11 and 11.
When the terminal of the boom body 10 which is stable in the winding form is pulled out a little, as shown in FIG. 3A, in the transition region 10C where the winding form 10B shifts to the extension form, the short direction of the boom body 10 The cross-sectional shape of No.
In the initial stage of extension, the terminal portion does not completely return to the open cross-sectional shape, and initial resistance is generated. In the case of the present embodiment, since the boom body is divided into two divided boom portions 11 and 11, it is easy to return to the open cross-sectional shape, the initial resistance is reduced, and the boom body is smoothly self-extended.
In the transition region 10C, the winding form 10B first shifts to a W-shape in which the divided boom portions 11 and 11 are curved in parallel, and the connecting portion increases as the distance from the winding form increases. Due to the elastic restoring force of 12, the W-shaped boundary peak gradually becomes lower and shifts to one C-shaped curved shape.

In the first embodiment, since the boom main body 10 is divided into two divided boom portions 11 and 11, the amount of distortion in the winding mode is dispersed and reduced in the plurality of divided boom portions 11 and 11. Therefore, for example, in the winding mode, even if stress relaxation occurs after a long period of time on a monthly or yearly basis, the degree of stress relaxation is small and the boom body 10 is composed of two split boom portions 11 and 11. Can be reliably self-extended by the elastic restoring force of each of the split boom portions 11 and 11.

Example The self-extending performance of the boom body 10 varies depending on the fiber base material, matrix resin, diameter, number of divisions of the split boom portion, thickness, curvature, width, elastic modulus, etc. of the boom body 10, and is specific. It is appropriately selected according to the intended use.
As an example, when the boom body was manufactured under the following conditions, it was confirmed that the initial resistance was small and the boom body extended smoothly.
Diameter: φ20mm
Aperture angle: Almost 0 °
Fiber base material:
・ Plain weave bias cut (45 °),
・ Bias weave,
·braid
-UD laminate: -45 ° / + 45 ° / + 45 ° / -45 ° 4-layer constituent fiber: 24 ton grade carbon fiber matrix resin: epoxy resin resin content (Vf): 60 to 65 vol /%
Thickness: 0.08 mm to 0.35 mm
In the case of UD laminated lumber, 60 μm / ly, total thickness 240 μm
When the fiber base material is plain weave, the length is limited to 1.4 m due to bias cutting, but when the fiber base material is bias weave, UD laminated lumber, or braid, the length is not limited.

Next, other embodiments of the present invention will be described. In the following description, only the points different from the above-described embodiment will be mainly described, the same components will be designated by the same reference numerals, and the description thereof will be omitted.
[Embodiment 2]
First, the second embodiment of the present invention will be described with reference to FIG.
FIG. 6 shows a bistability boom according to the second embodiment of the present invention, (A) is a perspective view of an extended form, (B) is a perspective view of a winding form, and (C) is a perspective view of an initial extended form. FIG. 3D is a cross-sectional view of the extended boom body in the direction orthogonal to the longitudinal direction.
In the second embodiment, the open cross-sectional shape of the boom main body 210 in the extended form is different from that of the first embodiment, and the arc shapes of the divided boom portions 11 and 11 are connected in parallel to form a W shape. Such a modified cross-sectional shape is also included in the open cross-sectional shape of the present invention. The present invention is applicable as long as one surface of the cross section in the longitudinal direction and the orthogonal direction has a curved surface that is curved in a concave shape. In the present embodiment, the open cross-sectional shape is the first surface 1 of each of the divided boom portions 11, 11.
1a and 11a are curved in a concave shape.
In the extended form 210A, the boom main body 210 is held in a form in which the boom body 210 extends linearly in the longitudinal direction X and the cross-sectional shape in the direction orthogonal to the longitudinal direction X is curved in a W shape, as shown in FIG. Will be done. The W-shape of the extended form 210A is held by the connecting portion 212.
On the other hand, in the winding form 210B, as shown in FIG. 6B, the cross-sectional shape in the direction orthogonal to the longitudinal direction extends linearly, and the twin is held in a wound form curved in the longitudinal direction. Has stability.

Also in the second embodiment, when the boom main body 210 that is stable in the winding form 210B is partially pulled out, as shown in FIG. 6C, in the transition region 210C that shifts from the winding form 210B to the extended form. , The cross-sectional shape of the boom body 20 in the direction orthogonal to the longitudinal direction gradually shifts from the linear state to the open cross-sectional shape. Unlike the first embodiment, it self-extends in a W shape.
Also in the second embodiment, since the boom main body 210 is divided into the two divided boom portions 11 and 11, the amount of distortion in the winding mode is dispersed and reduced in the plurality of divided boom portions 11 and 11, and the winding is performed. Even if stress relaxation occurs after a long period of time in the form or the extension form, the degree of stress relaxation is small, and self-extension can be reliably performed by the elastic restoring force of each of the split boom portions 11 and 11.

[Embodiment 3]
Next, the third embodiment of the present invention will be described with reference to FIGS. 7 and 8.
FIG. 7 shows a bistability boom according to the third embodiment of the present invention, (A) is a perspective view of an extended form, (B) is a perspective view of a winding form, and (C) is a boom main body in an extended form. A cross-sectional view in a direction orthogonal to the longitudinal direction of the above, (D) is an enlarged cross-sectional view schematically showing a connecting portion.
In each of the above embodiments, the split boom portion and the connecting portion are composed of separate members, but in the third embodiment, the split boom portions 311 and 311 and the connecting portion 312 are based on a common fiber base material.
The split boom portions 311 and 311 are impregnated with a hard resin, and the connecting portion 312 is impregnated with a soft resin.
That is, the open cross-sectional shape of the boom main body 310 is an arc-shaped cross section curved in a C shape so as to form a part of a circle, as in the first embodiment, and the two divided boom portions 311, 311 are the boom main body. The 310 is divided into two in the longitudinal direction and the orthogonal direction. Each of the divided boom portions 311 and 311 is a long elastic plate having the same shape and the same dimensions, and each has bistability capable of stably holding two forms, an extended form and a wound form. doing.
The split boom portions 311 and 311 are composed of, for example, the fiber reinforced resin sheet 13 shown in FIG. As shown in FIG. 7D, the fiber base material 1 of each of the split boom portions 311 and 311
The fiber base material 15 is a common fiber base material 15 that straddles the divided boom portions 311 and 311 via the connecting portion 312 without dividing the 5. In the illustrated example, the fiber base material 15 impregnated with the resin is schematically shown, and the direction of the fiber yarn has an orientation angle of −45 ° / + 45 ° with respect to the long axis N1. .. As a hard resin, the portion corresponding to the split boom portions 311 and 311 of the fiber base material 15 is used.
The same matrix resin 16 as in the first embodiment is impregnated, and the soft resin 17 is impregnated in the portion corresponding to the connecting portion 312. As the soft resin 17, an elastomer such as TPU (thermoplastic polyurethane) is used.
The fiber base material is not limited to the fiber reinforced resin sheet 13 shown in FIG. 4, but the UD material 23 shown in FIG. 5 may be used, or another fiber base material such as a braided structure may be used. Can be done.

Also in the third embodiment, when the boom main body 310 which is stable in the winding form 310B is partially pulled out, as shown in FIG. 8A, in the transition region 310C which shifts from the winding form 310B to the extended form. , The cross-sectional shape of the boom body 310 in the direction orthogonal to the longitudinal direction shifts to a W shape. When further extended from this state, as shown in FIG. 8 (B), the W-shaped boundary peak gradually becomes lower, becomes one curved form, and shifts to the extended form having a predetermined open cross-sectional shape. ..
Also in the third embodiment, since the boom main body 310 is divided into two divided boom portions 311, 311, the amount of distortion in the winding form and the extended form is a plurality of divided boom portions 311,3.
Even if stress relaxation occurs after a long period of time in the winding form or the extending form, the stress relaxation is small, and the elastic restoring force of each of the split boom portions 21 and 21 ensures self-reliance. It can be extended or contracted.
In addition, in the configuration of the connecting portion 312 of the third embodiment, the open cross-sectional shape of the extended form may be a W shape as in the second embodiment.

In each of the above embodiments, the split boom portion constituting the boom body has been described as an example of two divisions, but in each embodiment, the split boom portion may be divided into three or more, and the peripheral length of each split boom portion may be described. May be different, and various changes can be made without departing from the gist of the present invention.

10 Boom body 10A Extended form, 10B Winding form, 10C Transition area 11 Divided boom part 11a 1st surface (concave surface in extended form), 11b 2nd surface 12 Connecting part, 12a 1st connecting sheet (connecting material), 12b 1st 2 Connecting sheet (connecting material)
13 Fiber reinforced plastic sheet,
15 Fiber Substrate, 15a 1st Axoneme, 15b 2nd Axoneme 16 Matrix Resin 23 UD Material, 25 Fibers, 26 Matrix Resin 210 Boom Body (Embodiment 2),
210A extension form, 210B take-up form, 210C transition area 212 connection part 310 boom body (embodiment 3)
310A extension form, 310B take-up form, 310C transition area 311 split boom part, 312 connection part 17 soft resin N1 long axis, O center of curvature,
X Longitudinal α Aperture angle, θ Orientation angle

Claims (7)

It has a long boom body that can stably hold two forms, an extended form and a take-up form.
In the extended form, the boom body is held in a form that extends linearly in the longitudinal direction and the cross-sectional shape in the direction orthogonal to the longitudinal direction is curved to an open cross-sectional shape, and in the winding form, the boom body is orthogonal to the longitudinal direction. In a bistable boom in which the cross-sectional shape extends linearly and is held in a wound form that is curved in the longitudinal direction.
The boom body includes a plurality of split boom portions that are divided in the circumferential direction and extend in parallel in the longitudinal direction, and a bendable connecting portion that connects the plurality of divided boom portions.
In the extended form, the split boom portions are held in a form that extends linearly in the longitudinal direction and the cross-sectional shape in the direction orthogonal to the longitudinal direction is curved to the open cross-sectional shape, and in the winding form, the split boom portions are held in the longitudinal direction. It has bi-stability in which the cross-sectional shape in the orthogonal direction extends linearly and is curved in the longitudinal direction and held in a wound form.
In the extended form, the plurality of divided boom portions each form a part of the open cross-sectional shape of the boom body, and the connecting portion holds the open cross-sectional shape of the boom body as a whole. The characteristic bi-stability boom. The bistability boom according to claim 1, wherein the connecting portion is composed of a connecting material joined to the split boom portion. The bistability boom according to claim 2, wherein the connecting material is entirely joined to the split boom portion. The bistability boom according to claim 2, wherein the connecting member is partially joined to a side edge portion of the split boom portion. The bistability boom according to any one of claims 1 to 4, wherein the split boom portion is made of a fiber reinforced resin in which a fiber base material is impregnated with a resin. The bistability boom according to claim 5, wherein the fiber base material is a structure in which the orientation directions of the fibers are obliquely intersected with each other in the direction opposite to the extension direction. A claim in which the split boom portion and the connecting portion are based on a common fiber base material, the split boom portion is impregnated with a hard resin, and the hinge element is impregnated with a soft resin. Item 2. The bistability boom according to item 1.

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