JP7454214B2 - bistable boom - Google Patents

Description

The present invention relates to a boom used as a structural material for various structures, such as space structures and ground structures such as antennas of artificial satellites and probes, solar panels, etc. The present invention relates to a bistable boom that maintains a stable configuration and is also capable of self-extending from a rolled-up configuration.

As a conventional bistable boom of this type, for example, an elastic member as described in Patent Document 1 is known.
In other words, the boom body is composed of an elastic long plate material, which is bent into an open cross-sectional shape in a direction perpendicular to the longitudinal direction (hereinafter referred to as the transverse direction), and is also rolled into a cylindrical shape in the longitudinal direction. The structure is such that it is bent into the rolled-up form and stably held in either the extended form or the rolled-up form in the initial form.
In the reeled-up form, the open cross-sectional shape of the boom body in the transverse direction is extended linearly, and the elastic restoring force that attempts to return to the open cross-sectional direction is maintained by the rigidity of the rolled-up cylindrical shape. . Further, in the extended configuration, the boom body has an open cross-sectional shape in the transverse direction, and the elastic restoring force in the winding direction is maintained by the longitudinal rigidity of the boom body having the open cross-sectional shape.
The boom body is dynamically unstable when it has two forms, an extended form and a retracted form, and when it is slightly extended in the extended direction from the retracted form, it self-extends and shifts to the extended form.

Special Publication No. 2000-507890

However, when this boom is molded from a resin material such as fiber-reinforced resin, if it is stored in a rolled-up state for a long period of time, the cross-sectional shape of the boom body in the short direction tends to return to the open cross-sectional shape due to stress relaxation. The elastic restoring force decreases, causing problems such as self-extension not starting, or even if extension starts, it stops mid-way. In addition, in the initial stage of extension, when the terminal is slightly pulled out, the elastic restoring force that returns to the open cross-sectional shape is concentrated near the boundary between the terminal portion that has deformed to the open cross-sectional shape and the rolled-up form, causing bending. Bending acts as an initial resistance to self-extension and is a factor that inhibits self-extension.

The present invention has been made in view of the above circumstances, and its purpose is to provide a double-sided product that has low initial resistance to self-extension and can reliably progress self-extension even when kept in a rolled-up form for a long period of time. Its purpose is to provide 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 retracted form,
In the extended form, the boom body extends linearly in the longitudinal direction and is held in a form in which the cross-sectional shape in the direction perpendicular to the longitudinal direction is curved into an open cross-sectional shape, and in the retracted form, the boom body extends in a straight line in the longitudinal direction. In a bistable boom whose cross-sectional shape extends in a straight line and is curved in the longitudinal direction and held in a rolled-up configuration,
The boom main body includes a plurality of divided boom parts that are divided in the circumferential direction and extend in parallel to the longitudinal direction, and a bendable connecting part that connects the plurality of divided boom parts,
In the extended form, each of the split boom parts extends linearly in the longitudinal direction and is held in a form in which the cross-sectional shape in the direction orthogonal to the longitudinal direction is curved into an open cross-sectional shape, and in the rolled-up form, the split boom parts extend linearly in the longitudinal direction. It has bistable properties in which the cross-sectional shape in the orthogonal direction extends in a straight line and is curved in the longitudinal direction and maintained in a wound form.
In the extension mode, each of the plurality of divided boom parts constitutes a part of the open cross-sectional shape of the boom main body, and the connecting part maintains the open cross-sectional shape of the boom main body as a whole ;
In the winding mode, the plurality of split boom portions are curved in a direction in which the concave side of the open cross-sectional shape in the extended mode is curved in the direction of the concave surface, without overlapping each other. It is characterized by
According to the present invention, the amount of strain in the winding form is distributed over the plurality of split boom parts 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 elastic restoring force allows the boom body to self-extend.
In addition, by dividing the boom into multiple split boom parts, the internal stress of the split boom in each extension form and take-up form is small, so the elastic restoring force to return to the open cross-sectional shape is small, and the pulled-out terminal part and the take-up form part The bending that occurs at the boundary between the two is also reduced, and the initial resistance during the transition from the rolled-up form to the stretched form is reduced, making it easier to self-extend.

The connecting portion may be formed by a connecting member joined to the split boom portion.
In this way, manufacturing becomes easy.
The connecting member may be entirely joined to the split boom portion.
This also has the effect of protecting the split boom section.
Further, the connecting member may be partially joined to a 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 section is made of fiber-reinforced resin in which a fiber base material is impregnated with resin.
The fiber base material may have a structure in which the orientation direction of the fibers is diagonally crossed in opposite directions to the stretching direction.
The split boom part and the connection part may be based on a common fiber base material, and the split boom part may be impregnated with a hard resin, and the connection part may be impregnated with a soft resin.

According to the bistable boom of the present invention, the initial resistance to self-extension is small, and even when the boom is kept in the rolled-up configuration for a long period of time, the transition from the rolled-up configuration to the extended configuration can be reliably progressed.

FIG. 1 shows a bistable boom according to Embodiment 1 of the present invention, in which (A) is a perspective view in an extended form, (B) is a perspective view in a retracted form, and (C) is a boom main body in an extended form. (D) is an exploded cross-sectional view of the boom body of (C), (E) is an enlarged cross-sectional view of the vicinity of the connecting part, (F) is another configuration of the connecting part. (G) is a partial enlarged view showing an exploded example, and (G) is a partial enlarged view showing still another configuration example of the connecting portion. 2 (A) is a perspective view of the extended form of the split boom part that constitutes the boom body in Fig. 1, (B) is a perspective view of the split boom part of (A) in the rolled-up form, and (C) is FIG. 6 is a perspective view of the split boom section of the split boom part in the middle of transition from the retracted form to the extended form. This figure shows the state of the bistable boom in FIG. 1 in the middle of transition from the retracted form to the extended form, where (A) is a perspective view of the initial transition state, and (B) is a perspective view of the state where the transition has further progressed. . Figure 4 shows an example of the FRP sheet that constitutes the boom body in Figure 1, where (A) is an explanatory diagram of the direction of yarn orientation when a textile structure is used as the fiber base material, and (B) is an illustration of the direction of yarn orientation when a textile structure is used as the fiber base material. FIG. 2 is a schematic cross-sectional view along the orientation direction of one of the yarns of the textile structure of FIG. Figure 5 shows an example of an FRP sheet using UD material as the fiber base material, where (A) is a schematic exploded view showing a plurality of laminated FRP sheets, and (B) is a schematic cross-sectional view of the laminated structure. . FIG. 6 shows a bistable boom according to Embodiment 2 of the present invention, in which (A) is a perspective view in an extended state, (B) is a perspective view in a retracted state, and (C) is a perspective view in an initial extended state. FIG. 2D is a sectional view taken in a direction orthogonal to the longitudinal direction of the boom main body in an extended state. FIG. 7 shows a bistable boom according to a third embodiment of the present invention, in which (A) is a perspective view of the extended form, (B) is a perspective view of the reeled form, (C) is a cross-sectional view perpendicular to the longitudinal direction of the boom body in the extended form, and (D) is an enlarged cross-sectional view of the connecting portion. 8 shows the extension process of FIG. 7, in which (A) is a perspective view of the initial extension state, and (B) is a perspective view of the state where the extension has further progressed. FIG. 9 is a sectional view taken in a direction orthogonal to the longitudinal direction of the boom body, showing another embodiment of FIG. 1(C).

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
[Embodiment 1]
FIG. 1 shows a bistable boom according to Embodiment 1 of the present invention, in which (A) is a perspective view in an extended configuration, (B) is a perspective view in a retracted configuration, and (C) is a boom body in an extended configuration. (D) is an exploded cross-sectional view of the boom main body of (C), and (E) is an enlarged cross-sectional view of the vicinity of the connecting portion.
That is, this bistable boom has a long boom body 10 that can stably hold two forms: the extended form shown in FIG. 1(A) and the retracted form shown in FIG. 1(B). . Hereinafter, the boom body 10 in the retracted form will be described with A added to the end of the reference numeral, and the boom main body 10 in the extended form will be described with the reference numeral B added at the end, as necessary.
In the extended state, the boom main body 10 is held in a form that extends linearly in the longitudinal direction X and has a cross-sectional shape in a direction orthogonal to the longitudinal direction X curved into an open cross-sectional shape. On the other hand, in the rolled form, the cross-sectional shape in the direction perpendicular to the longitudinal direction extends linearly, and has bistable properties such that it is curved in the longitudinal direction and maintained in the rolled form.
Regarding the boom body 10, if the concave surface of the open cross-sectional shape in the extended form is the first surface 10a, and the convex surface is the second surface 10b, the first surface 10a side will be the concave surface even in the retracted form. It has a shape that is curved in the direction and rolled up.

The boom body 10 includes two long divided boom parts 11, 11 that are divided in the circumferential direction and extend parallel to each other in the longitudinal direction X, and a bendable connecting part 12 that connects the two divided boom parts 11, 11. , is equipped with. In the extended form, the plurality of divided boom parts 11, 11 each constitute a part of the open cross-sectional shape of the boom main body 10, and the connecting part 12 maintains the open cross-sectional shape of the boom main body 10 as a whole. .
As shown in FIG. 1(C), the open cross-sectional shape of the boom body 10 is an arc-shaped cross section that curves in a C-shape to form part of a circle, and a line connecting both ends of the arc and the center of curvature O The aperture angle α formed by the opening angle α is not particularly limited, and for example, as shown in FIG. 9, the opening angle α may be set to be negative such that both side edges overlap in the circumferential direction.
The two divided boom parts 11, 11 have a configuration in which the boom body 10 is divided into two parts in the longitudinal direction and the orthogonal direction, and are long elastic thin plates having the same shape and the same dimensions, and each has an extension form and a winding form. It has bistability that allows it to stably maintain two forms.

In this embodiment, the connecting portion 12 includes a first connecting sheet 12a as a connecting material bonded across the first surfaces 11a, 11a which are the concave surfaces of the divided boom portions 11, 11 in the extended form, and a first connecting sheet 12a as a connecting material, and a divided boom portion. It is constituted by a second connecting sheet 12b that is bonded across the second surfaces 11b, 11b, which are the convex surfaces of the first and second surfaces 11, 11. A slight gap is provided between the side edges of the divided boom parts 11, 11 to be connected, and in this gap, as shown in an enlarged view in FIG. 1(E), the first connecting sheet 12a and the second connecting sheet 12b are bonded together to form a bendable connecting portion 12. In this embodiment, the first connecting sheet 12a is bonded so as to cover the entire first surfaces 11a, 11a of the two divided boom sections 11, 11, and the second connecting sheet 12b is bonded to cover the entire first surfaces 11a, 11a of the two divided boom sections 11, 11. , 11 so as to cover the entire second surfaces 11b, 11b.
For the first connecting sheet 12a and the second connecting sheet 12b constituting the connecting portion 12, for example, a film made of a flexible soft elastomer can be used, and the film can be further reinforced with a fiber base material. You can stay there. Furthermore, a bias tape or the like other than carbon may also be used. The connecting part 12 is configured to flexibly deform into either an extended form or a retracted form, but the initial form (no load state) of the connecting part 12 maintains the form of the boom body 10 in the extended form. The structure is as follows. That is, when the boom body 10 is deformed in the direction of increasing the opening angle, the concave side surfaces of the split boom parts 11, 11 of the connecting part 12 are stretched and tension is applied in the direction of returning to the original state, thereby reducing the opening angle. The deformation in this direction is caused by the action of tension in the direction in which the convex surfaces of the split boom parts 11, 11 of the connecting part 12 stretch and return to their original shape, returning them to their original opening cross-sectional shape.

In the illustrated example, the first connecting sheet 12a and the second connecting sheet 12b are attached so as to cover the entire first surfaces 11a, 11a and second surfaces 11b, 11b of the two divided boom parts 11, 11. However, it may be configured by 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 divided boom parts 11, 11 to be connected. Also in this case, only the first surface 11a side and only the second surface 11b side may be pasted. Further, as shown in FIG. 1(G), 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 a reinforcing material may be used.
In addition, if the gap between the side edges of the split boom parts 11, 11 connected by the connecting part 12 is too narrow, the resistance during winding will increase, and if it is too wide, the rigidity during extension will tend to decrease. is set within the range.

Next, each divided boom section 11 will be explained.
2(A) is a perspective view of the extended form of one split boom part constituting the boom body of FIG. 1, (B) is a perspective view of the split boom part of (A) in the retracted form, and (C) is It is a perspective view of the state in which the split boom part of A) is in the middle of transitioning from the retracted form to the extended form.
The split boom section 11 is composed of a long elastic thin plate, which is bent into an open cross-sectional shape in a direction perpendicular to the longitudinal direction X, and is wound into a cylindrical shape in the longitudinal direction X. It is configured to be stably held in either the extended form 11A shown in FIG. 2(A) or the rolled-up form 11B shown in FIG. 2(B) in the initial form. In the split boom section 11, if the concave surface of the open cross-sectional shape in the extended form is the first surface 11a, and the convex surface is the second surface 11b, the first surface 11a side is the concave surface even in the winding form. It has a shape that allows it to be wound up in a curved direction.

As shown in FIGS.
P sheet) 13. The fiber reinforced resin sheet 13 has a structure in which a fiber base material 15 is impregnated with a matrix resin 16.
The fiber base material 15 has a biaxial textile structure, and the first axis 15a and the second axis 15b are inclined at 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 this. The orientation angle is 45°.
In this embodiment, carbon fibers are used for the first axis 15a and the second axis 15b, and in particular, they are composed of spread yarns made by flatly bundling fiber bundles. In this example, the fiber-reinforced resin sheet 13 has a one-layer structure, but it may have a multi-layer structure in which a plurality of sheets are laminated together.
As the biaxial fabric structure, either plain weave bias cut material or bias weave can be adopted.
Note that the base material structure of the fiber base material 15 is not limited to a woven structure, and a braided structure can also be applied, as well as a knitted structure, a net structure, and the like.

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

Regarding the first axis 15a and second axis 15b of the fiber base material 15 described above and the fibers 25 of the UD material 23, in addition to carbon fiber, glass fiber, polyester fiber, fluorine fiber, aramid fiber, Polypropylene fibers, polyethylene fibers, metal fibers, etc. can be used. When used for antennas etc., 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, with reference to FIG. 3, the operation of the bistable boom of this embodiment will be explained.
In the winding form, the boom main body 10 has two split boom parts 11, 11 whose arcuate cross-sections in a direction orthogonal to the extension direction are extended linearly, and the open cross-section of each split boom part 11, 11 is extended linearly. The elastic restoring force that tends to return to the direction is maintained by the rigidity of the wound cylindrical shape of each split boom section 11, 11. The connecting portion 12 is elastically deformed following the deformation of the split boom portions 11, 11.
When the end of the boom body 10, which is stable in the retracted configuration, is slightly pulled out, as shown in FIG. The cross-sectional shape of the winding 10B gradually changes from a straight line state to an open cross-sectional shape due to the elastic restoring force that tends to curve it in the lateral direction, and the wound form 10B moves toward an extended form and self-extends.
At the initial stage of extension, the end portion cannot return to its open cross-sectional shape, and initial resistance occurs. In the case of this embodiment, since the boom body is divided into two divided boom parts 11, 11, it is easy to return to the open cross-sectional shape, the initial resistance is small, and the boom body extends smoothly by itself.
In the transition region 10C, the winding configuration 10B first transitions to a W-shape in which the divided boom parts 11, 11 are curved in parallel, and as the distance from the winding configuration increases, the connecting portion Due to the elastic restoring force of 12, the W-shaped boundary peak gradually becomes lower and shifts to a C-shaped curved form.

In the first embodiment, since the boom main body 10 is divided into two divided boom parts 11, 11, the amount of distortion in the winding form is distributed to the plurality of divided boom parts 11, 11 and becomes small. Therefore, for example, even if stress relaxation occurs after a long period of time (months or years) in the rolled form, the degree of stress relaxation is small, and the boom body 10 composed of the two divided boom parts 11, 11 can be reliably self-extended by the elastic restoring force of each divided boom section 11,11.

Example The self-extension performance of the boom body 10 varies depending on the fiber base material of the boom body 10, matrix resin, diameter, number of divisions of the divided boom section, thickness, curvature, width, elastic modulus, etc. It is selected as appropriate depending on the intended use.
As an example, when a boom body was manufactured under the following conditions, it was confirmed that the initial resistance was small and it self-extended smoothly.
Diameter: φ20mm
Aperture angle: almost 0°
Fiber base material:
・Plain weave bias cut (45°)
・Bias weave,
·braid
・UD laminated material: -45°/+45°/+45°/-45° 4-layer composition Fiber: 24ton grade carbon fiber Matrix resin: Epoxy resin Resin content (Vf): 60 to 65 vol/%
Thickness: 0.08mm~0.35mm
In the case of UD laminated material, 60μm/ply, total thickness 240μm
Note that when the fiber base material is plain weave, the length is limited to 1.4 m due to bias cutting, but in the case of bias weave, UD laminate material, and braided cord, there is no limit to the length.

Next, other embodiments of the present invention will be described. In the following description, only the points different from the above embodiment will be mainly explained, and the same components will be denoted by the same reference numerals and the description thereof will be omitted.
[Embodiment 2]
First, a second embodiment of the present invention will be described with reference to FIG.
FIG. 6 shows a bistable boom according to Embodiment 2 of the present invention, in which (A) is a perspective view of the extended configuration, (B) is a perspective view of the retracted configuration, and (C) is a perspective view of the initial extended configuration. FIG. 3(D) is a sectional view taken in a direction orthogonal to the longitudinal direction of the boom main body in an extended state.
In the second embodiment, the open cross-sectional shape of the boom main body 210 in the extended state is different from the first embodiment, and has a W-shape in which the arc shapes of the divided boom parts 11, 11 are connected in parallel. Such an irregular cross-sectional shape is also included in the open cross-sectional shape of the present invention. The present invention is applicable to any shape having a curved surface in which one surface of the cross section in the direction orthogonal to the longitudinal direction is curved concavely. In this embodiment, the open cross-sectional shape is the first surface 1 of each split boom section 11, 11.
1a and 11a are concavely curved.
In the extended state 210A, the boom main body 210 extends linearly in the longitudinal direction be done. The W-shape of this extended form 210A is held by the connecting portion 212.
On the other hand, in the winding form 210B, as shown in FIG. It has stability.

Also in the second embodiment, when the boom body 210, which is stable in the retracted configuration 210B, is partially pulled out, as shown in FIG. , the cross-sectional shape of the boom main body 20 in the direction orthogonal to the longitudinal direction gradually changes from a straight state to an open cross-sectional shape. Unlike Embodiment 1, it self-extends while maintaining its W-shape.
Also in the second embodiment, since the boom main body 210 is divided into two divided boom parts 11, 11, the amount of distortion in the winding form is distributed to the plurality of divided boom parts 11, 11 and becomes small. Even if stress relaxation occurs after a long period of time in the expanded configuration or extended configuration, the degree of stress relaxation is small and the elastic restoring force of each split boom section 11 can ensure self-extension.

[Embodiment 3]
Next, a third embodiment of the present invention will be described with reference to FIGS. 7 and 8.
FIG. 7 shows a bistable boom according to Embodiment 3 of the present invention, in which (A) is a perspective view in an extended configuration, (B) is a perspective view in a retracted configuration, and (C) is a boom body in an extended configuration. (D) is an enlarged sectional view schematically showing a connecting portion.
In each of the above embodiments, the split boom part and the connecting part are made of separate members, but in the third embodiment, the split boom parts 311, 311 and the connecting part 312 are based on a common fiber base material,
The split boom parts 311, 311 are impregnated with hard resin, and the connecting part 312 is impregnated with soft resin.
That is, the open cross-sectional shape of the boom main body 310 is an arcuate cross-sectional shape that is curved in a C-shape so as to constitute a part of a circle, as in the first embodiment, and the two divided boom parts 311, 311 are connected to the boom main body. 310 is divided into two in the longitudinal direction and the orthogonal direction. Each of the split boom parts 311, 311 is a long elastic plate with the same shape and size, and each has bistable properties that can stably hold two forms, an extended form and a rolled-up form. are doing.
The split boom parts 311, 311 are configured by, for example, the fiber-reinforced resin sheet 13 shown in FIG. 4. As shown in FIG. 7(D), the fiber base material 1 of each split boom part 311, 311
The fiber base material 15 is made into a common fiber base material 15 that straddles each of the divided boom parts 311, 311 via the connecting part 312 without dividing the fiber base material 5. The illustrated example schematically shows the fiber base material 15 impregnated with resin, 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, a portion of the fiber base material 15 corresponding to the split boom portions 311, 311,
The same matrix resin 16 as in the first embodiment is impregnated, and a portion corresponding to the connecting portion 312 is impregnated with a soft resin 17. As the soft resin 17, an elastomer such as TPU (thermoplastic polyurethane) is used.
Note that 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 can also be used, or other fiber base materials such as a braided structure can be used. I can do it.

Also in the third embodiment, when the boom body 310, which is stable in the retracted configuration 310B, is partially pulled out, as shown in FIG. , the cross-sectional shape of the boom body 310 in the direction orthogonal to the longitudinal direction transitions to a W-shape. When further extended from this state, as shown in FIG. 8(B), the boundary peak of the W-shape gradually becomes lower, forming a single curved form, and transitioning to an extended form with a predetermined open cross-sectional shape. .
Also in the third embodiment, since the boom main body 310 is divided into two divided boom parts 311, 311, the amount of distortion in the winding form and the extension form is different from that of the plural divided boom parts 311, 3.
Even if stress relaxation occurs after a long period of time in the rolled-up or extended form, the degree of stress relaxation is small and the elastic restoring force of each split boom section 21 ensures that the self-relaxation occurs. It can be expanded or contracted.
In addition, with the structure of the connecting part 312 of this Embodiment 3, the open cross-sectional shape of an extended form can also be made into W-shape like Embodiment 2.

In each of the above embodiments, an example was explained in which the split boom part constituting the boom body is divided into two parts, but in each embodiment, it may be divided into three or more parts, and the circumference of each split boom part may be 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 Split boom part 11a First surface (concave surface in extended form), 11b Second surface 12 Connecting part, 12a First connecting sheet (connecting material), 12b 2 connected sheets (connecting material)
13 Fiber reinforced resin sheet,
15 fiber base material, 15a first axis, 15b second axis 16 matrix resin 23 UD material, 25 fiber, 26 matrix resin 210 boom main body (Embodiment 2),
210A extension form, 210B winding form, 210C transition area 212 connecting part 310 boom main body (Embodiment 3)
310A extension form, 310B winding form, 310C transition area 311 split boom part, 312 connection part 17 soft resin N1 long axis line, O center of curvature,
X Longitudinal direction α Opening angle, θ Orientation angle

Claims (7)

It has a long boom body that can stably hold two forms, an extended form and a retracted form,
In the extended form, the boom body extends linearly in the longitudinal direction and is held in a form in which the cross-sectional shape in the direction perpendicular to the longitudinal direction is curved into an open cross-sectional shape, and in the retracted form, the boom body extends in a straight line in the longitudinal direction. In a bistable boom whose cross-sectional shape extends in a straight line and is curved in the longitudinal direction and held in a rolled-up configuration,
The boom main body includes a plurality of divided boom parts that are divided in the circumferential direction and extend in parallel to the longitudinal direction, and a bendable connecting part that connects the plurality of divided boom parts,
In the extended form, each of the split boom parts extends linearly in the longitudinal direction and is held in a form in which the cross-sectional shape in the direction orthogonal to the longitudinal direction is curved into an open cross-sectional shape, and in the rolled-up form, the split boom parts extend linearly in the longitudinal direction. It has bistable properties in which the cross-sectional shape in the orthogonal direction extends in a straight line and is curved in the longitudinal direction and maintained in a wound form.
In the extension mode, each of the plurality of divided boom parts constitutes a part of the open cross-sectional shape of the boom main body, and the connecting part maintains the open cross-sectional shape of the boom main body as a whole ;
In the winding mode, the plurality of split boom portions are curved in a direction in which the concave side of the open cross-sectional shape in the extended mode is curved in the direction of the concave surface, without overlapping each other. A bistable boom featuring: 2. The bistable boom of claim 1, wherein the connecting portion is constituted by a connecting member joined to the split boom portion. 3. The bistable boom of claim 2, wherein the tie is fully joined to the split boom section. 3. The bistable boom of claim 2, wherein the tie is partially joined to a side edge portion of the split boom section. The bistable boom according to any one of claims 1 to 4, wherein the split boom section is made of a fiber reinforced resin obtained by impregnating a fiber base material with resin. 6. The bistable boom according to claim 5, wherein the fiber base material has a structure in which the orientation direction of the fibers is diagonally crossed in opposite directions to the stretching direction. The divided boom part and the connecting part are based on a common fiber base material, and the divided boom part is impregnated with a hard resin, and the connecting part is impregnated with a soft resin. Bistable boom according to paragraph 1.

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