Hinge and deployment structure

Abstract

A hinge (100) includes: a film-like member (111) composed of a first fiber material having two fiber orientations; and a film-like member (112) composed of a second fiber material having two fiber orientations. The two fiber orientations of the first fiber material are symmetrical with respect to a longitudinal direction of the film-like member (111). The two fiber orientations of the second fiber material are symmetrical with respect to a longitudinal direction of the film-like member (112). An angle between each of the two fiber orientations of the first fiber material and the longitudinal direction of the film-like member (111) is different from an angle between each of the two fiber orientations of the second fiber material and the longitudinal direction of the film-like member (112).

Description

Hinge and deployable structure

[0001] The present disclosure relates to a hinge and a deployment structure using the hinge.

[0002] Artificial satellites are equipped with many deployable structures, including solar array paddles. Hinges are mainly used to connect the components of deployable structures. Hinges are required to have a mechanism that provides the driving force for deployment. Hinges are also required to have sufficient rigidity as structural members after deployment. Furthermore, hinges are required to be lightweight.

[0003] Patent Document 1 discloses a technology for improving the bending radius by using a hinge made of flexible composite fibers. Prior Art Document 2 discloses a technology for using a flexible tape as a hinge.

[0004] Publication of Utility Model Publication No. 61-50100 Special Publication No. 3-502566

[0005] When a hinge used in a deployable structure for a satellite is realized using a flexible tape-shaped member, there is a problem of low rigidity. Tape spring hinges, which can increase rigidity by increasing the cross section, must avoid collisions between the tapes and unstable deployment behavior due to differences in the inner and outer diameters of the two opposing tapes. For this reason, tape spring hinges are subject to significant structural constraints, such as lengthening the tape portion and narrowing the tape spacing. Therefore, tape spring hinges have a problem of limited design freedom. Tape spring hinges also have a problem of large size. Furthermore, tape spring hinges have problems such as a small hinge deployment angle and a small thickness of the associated structure. Thus, conventional technology has the problem of being unable to realize a lightweight hinge that has deployment force and high rigidity after deployment.

[0006] One of the main objectives of the present disclosure is to solve the above-mentioned problems. Specifically, the main objective of the present disclosure is to realize a lightweight hinge that has deployment force and high rigidity after deployment.

[0007] The hinge according to the present disclosure comprises a first elastic plate-like body made of a first fiber material having two fiber orientations, and a second elastic plate-like body made of a second fiber material having two fiber orientations, wherein the two fiber orientations of the first fiber material are symmetrical with respect to the longitudinal direction of the first elastic plate-like body, the two fiber orientations of the second fiber material are symmetrical with respect to the longitudinal direction of the second elastic plate-like body, and the angle formed by each of the two fiber orientations of the first fiber material with the longitudinal direction of the first elastic plate-like body is different from the angle formed by each of the two fiber orientations of the second fiber material with the longitudinal direction of the second elastic plate-like body.

[0008] According to the present disclosure, it is possible to realize a lightweight hinge that stores elastic energy to have deployment force and has high rigidity after deployment.

[0009] 1 is a diagram showing an example of a hinge according to embodiment 1. FIG. 2 is a diagram showing an example of a hinge according to embodiment 1. FIG. 3 is a diagram showing an example of fiber orientation of a membrane member according to embodiment 1. FIG. 4 is a diagram showing an example of a cross section of a hinge in a folded state according to embodiment 1. FIG. 5 is a diagram showing the radius of curvature of a deployed state according to embodiment 1. FIG. 6 is a diagram showing the radius of curvature of a single tip according to embodiment 1. FIG. 7 is a diagram showing the radius of curvature of a hinge tip according to embodiment 1. FIG. 8 is a diagram showing an example of a hinge according to embodiment 2. FIG. 9 is a diagram showing an example of a solar cell paddle according to embodiment 3.

[0010] In the description of the embodiments and the drawings, the same elements and corresponding elements are denoted by the same reference numerals, and the description of the elements denoted by the same reference numerals will be omitted or simplified as appropriate.

[0011] Embodiment 1. In this embodiment, a hinge that is used by bending will be described. The hinge according to this embodiment has at least two membrane-like members made of a fiber-reinforced composite material. At least two of the membrane-like members are opposed to each other. Furthermore, the two or more opposed membrane-like members have at least two types of fiber orientation. For example, when two membrane-like members are opposed to each other, the fiber orientation of each membrane-like member is different. Furthermore, when three membrane-like members are opposed to each other, the fiber orientation of one membrane-like member is different from the fiber orientation of the other two membrane-like members. Similarly, when four or more membrane-like members are opposed to each other, at least two types of fiber orientation are present. The hinge according to this embodiment stores elastic energy to provide deployment force. Furthermore, the hinge according to this embodiment is lightweight and has high rigidity after deployment.

[0012] ***Description of Configuration*** FIGS. 1 and 2 show a hinge 100 according to this embodiment in an unfolded state.

[0013] The hinge 100 is used as a connecting member for deployable structures such as solar cell panels. For example, as shown in FIG. 1 , the hinge 100 is composed of membrane members 111, 112, and fasteners 113. Alternatively, as shown in FIG. 2 , the hinge 100 may be composed of only the membrane members 111 and 112 without using the fasteners 113. The membrane members 111 and 112 face each other. The fiber-reinforced composite material of the membrane member 111 has a fiber orientation 121. The fiber-reinforced composite material of the membrane member 112 has a fiber orientation 122. Details of the fiber orientation 121 and the fiber orientation 122 will be described later. Also, A in FIG. 1 indicates the longitudinal direction of the membrane members 111 and 112.

[0014] The membrane member 111 and the membrane member 112 are each made of a fiber-reinforced composite material and use plain woven fibers. The membrane member 111 and the membrane member 112 are each an elastic plate-like body. The longitudinal direction of the membrane member 111 and the membrane member 112 is significantly longer than the lateral direction. The cross section of the membrane member 111 perpendicular to the longitudinal direction of the membrane member 111 is curved with both sides of the cross section protruding. The cross section of the membrane member 112 perpendicular to the longitudinal direction of the membrane member 112 is also curved with both sides of the cross section protruding. The membrane member 111 corresponds to a first elastic plate-like body. The membrane member 112 corresponds to a second elastic plate-like body. The fiber-reinforced composite material constituting the membrane member 111 corresponds to a first fiber material. The fiber-reinforced composite material constituting the membrane member 112 corresponds to a second fiber material.

[0015] In the hinge 100 shown in FIG. 1 , one end of the membrane member 111 and one end of the membrane member 112 are fixed by a fixing device 113a. The other end of the membrane member 111 and the other end of the membrane member 112 are fixed by a fixing device 113b. When there is no need to distinguish between the fixing device 113a and the fixing device 113b, they are collectively referred to simply as fixing device 113. Furthermore, the fixing device 113a in FIG. 1 corresponds to the first fixing portion. The fixing device 113b in FIG. 1 corresponds to the second fixing portion. The following description will be given assuming a hinge 100 configured with the membrane member 111, the membrane member 112, and the fixing device 113 shown in FIG. 1 ; however, the description in this embodiment also applies to the hinge 100 configured with the membrane member 111 and the membrane member 112 shown in FIG. 2.

[0016] 3 shows a fiber orientation 121 of the membrane member 111 and a fiber orientation 122 of the membrane member 112. (a) of Fig. 3 shows the fiber orientation 121 of the membrane member 111. (b) of Fig. 3 shows the fiber orientation 122 of the membrane member 112.

[0017] The fiber-reinforced composite material of the membrane member 111 has two fiber orientations as the fiber orientation 121. The fiber-reinforced composite material of the membrane member 112 has two fiber orientations as the fiber orientation 122. The fiber orientation angles shown in FIG. 3 are based on the longitudinal direction A of the membrane members 111 and 112. The two fiber orientations of the membrane member 111 are symmetrical with respect to the longitudinal direction A. In the example of FIG. 3( a), the membrane member 111 has two fiber orientations as the fiber orientation 121, that is, "56 degrees" and "-56 degrees" with respect to the longitudinal direction A. The two fiber orientations of the membrane member 112 are symmetrical with respect to the longitudinal direction A. In the example of FIG. 3( b), the membrane member 112 has two fiber orientations as the fiber orientation 122, that is, "45 degrees" and "-45 degrees" with respect to the longitudinal direction A. In this embodiment, the angle that each of the two fiber orientations of the membrane member 111 makes with the longitudinal direction A is different from the angle that each of the two fiber orientations of the membrane member 112 makes with the longitudinal direction A. In the example of Figure 3, the angle that each of the two fiber orientations of the membrane member 111 makes with the longitudinal direction A is larger than the angle that each of the two fiber orientations of the membrane member 112 makes with the longitudinal direction A.

[0018] In this embodiment, it is assumed that carbon fiber reinforced plastic is used as the fiber of the fiber reinforced composite material. Specifically, it is assumed that the fiber is carbon fiber (T300 manufactured by Toray), the resin is epoxy resin, and the fiber volume fraction is 50%. However, the fiber reinforced composite material fiber is not limited to this.

[0019] FIG. 4 is a schematic cross-sectional view of the hinge 100 according to the present embodiment in a retracted state.

[0020] In FIG. 4 , the membrane member 111 is on the compression side (inside) and the membrane member 112 is on the tension side (outside). That is, in FIG. 4 , the membrane member 111 and the membrane member 112 are bent in the longitudinal direction A of FIG. 1 so that the membrane member 111 is on the compression side and the membrane member 112 is on the tension side. By bending the membrane member 111 and the membrane member 112 in this manner, the membrane member 111 and the membrane member 112 elastically deform, accumulating elastic energy. When the hinge 100 begins to bend, the compression side undergoes large deformation and bends first. Next, the compression side collides with the tension side, and the membrane member 111 and the membrane member 112 begin to come into contact with each other. After that, the tension side also undergoes large deformation. In this embodiment, the radius of curvature of the single tip of the membrane member 111 is different from the radius of curvature of the single tip of the membrane member 112. In this embodiment, the radius of curvature of the single tip of film-like member 111 is smaller than the radius of curvature of the single tip of film-like member 112. In this embodiment, film-like member 111 and film-like member 112 can be bent without plastic deformation or destruction until fixing device 113a and fixing device 113b come into contact. Plastic deformation and destruction occur due to large repulsion or buckling caused by contact between film-like member 111 and film-like member 112. In this embodiment, the radius of curvature of the single tip of film-like member 111 and the radius of curvature of the single tip of film-like member 112 are different, so plastic deformation and destruction do not occur.

[0021] For example, the radius of curvature of the single tip of the membrane member 111 and the membrane member 112 will be the same in any of the following cases: (1) When the material of the membrane member 111 and the membrane member 112 is a fiber-reinforced composite material with only orthogonal fiber orientation found in general woven fabrics, and the radius of curvature of the membrane member 111 and the membrane member 112 in the expanded state is the same. (2) When the material of the membrane member 111 and the membrane member 112 is a fiber-reinforced composite material with the same fiber orientation even if it is not orthogonal, and the radius of curvature of the membrane member 111 and the membrane member 112 in the expanded state is the same. (3) When the material of the membrane member 111 and the membrane member 112 is metal, and the radius of curvature of the membrane member 111 and the membrane member 112 in the expanded state is the same. If the individual tip curvature radii of the membrane-like members 111 and 112 are the same, the membrane-like members 111 and 112 will collide while bending the hinge, and will be strongly repelled by restraining each other, causing the membrane-like members 111 and 112 to enter an unstable deformed state.

[0022] Here, the radius of curvature in the unfolded state is the radius of curvature in a direction perpendicular to the longitudinal direction A of the membrane members 111 and 112 in the unfolded state. Specifically, the radius of curvature in the unfolded state is the radius of curvature corresponding to the curved surface indicated by the reference numeral 201 in FIG. 5 .

[0023] The radius of curvature in the longitudinal direction A is the tip radius of curvature. The radius of curvature of the tip when the membrane member 111 and the membrane member 112 are folded individually is the single tip radius of curvature. Specifically, the single tip radius of curvature is the radius of curvature corresponding to the curved surface indicated by reference numeral 202 in FIG. 6. The single tip radius of curvature is a radius of curvature that can be theoretically calculated once the material and shape of the membrane member are determined. The single tip radius of curvature can be calculated using the formula of J. C. H. Yee et al. (American Institute of Aeronautics and Astronautics Paper 2004-1819, formula (24)). The radius of curvature of the tip when the membrane member 111 and the membrane member 112 are folded as a hinge is the hinge tip radius of curvature. Specifically, the radius of curvature of the hinge tip is the radius of curvature corresponding to the curved surface indicated by the reference numeral 203 in Fig. 7. The radius of curvature of the hinge tip is the radius of curvature near the center 114 of the bent portion where the membrane-like members 111 and 112 come into contact. In other words, the radius of curvature of the hinge tip is the radius of curvature in the longitudinal direction of the hinge when the hinge is bent. The radius of curvature of the hinge tip is affected by the radius of curvature of the individual membrane-like members 111 and 112 until they collide, and after the collision, is affected by the hinge bending angle when stored.

[0024] In this embodiment, the radius of curvature of membrane member 111 in the unfolded state is 15 mm. The radius of curvature of membrane member 112 in the unfolded state is 12.5 mm. The radius of curvature of the tip of membrane member 111 alone is 8.6 mm. The radius of curvature of the tip of membrane member 112 alone is 12.5 mm. In addition, the distance between the ridge lines of membrane members 111 and 112 is 12 mm, and the length of fixing device 113, which affects bending, is 66 mm.

[0025] For example, consider the case of bending a hinge using two membrane-like members with the same radius of curvature at the tip of each member. If the two membrane-like members are bent until the two fixing devices come into contact, the resistance at the contact point increases, requiring a large load for bending. If the two membrane-like members are unable to deform uniformly due to the contact constraint, large localized deformation occurs. This results in fracture or plastic deformation due to the load exceeding the yield strength. If fracture or plastic deformation occurs, the shape after deployment cannot be restored, impairing the hinge's functionality. Furthermore, the significantly larger load required for bending necessitates larger restraining devices to maintain the folded state. This results in the problem of the hinge becoming heavier.

[0026] It is also possible to differentiate the radius of curvature of the two membrane-like members in their unfolded state, thereby differentiating the radius of curvature of the individual tips of the two membrane-like members. However, if the radius of curvature of the two membrane-like members in their unfolded state is differentiated to the extent that the individual tips' radii of curvature are different, the membrane-like member with the smaller radius of curvature of the individual tip will have higher rigidity in its unfolded state. As a result, the membrane-like member will be more difficult to bend. This will increase the rebound at the bending point, which will increase instability.

[0027] In contrast, this embodiment uses two membrane-like members with different fiber orientations. That is, in this embodiment, the angle between the fiber orientation of membrane-like member 111 and the longitudinal direction A is different from the angle between the fiber orientation of membrane-like member 112 and the longitudinal direction A. Because the angles between the two membrane-like members are different, the radii of curvature of the individual tips of the two membrane-like members are different when they are bent. This significantly reduces the constraint caused by contact between the two membrane-like members when they are bent. This reduces the stress generated in each membrane-like member, and also reduces the load required for bending. As a result, the hinge can be bent without impairing its function as a hinge.

[0028] ***Explanation of the Effects of the Embodiment*** In this way, in this embodiment, by using two membrane-like members with different fiber orientations, it is possible to realize a lightweight hinge that accumulates elastic energy, has deployment force, and has high rigidity after deployment.

[0029] ***Modifications*** In this embodiment, the respective ends of the membrane-like members 111 and 112 are clamped between fasteners 113 and fixed by screws at the fasteners 113. The membrane-like members 111 and 112 may be fixed by other methods. The membrane-like members 111 and 112 may be fixed by other mechanical fastening methods, such as rivets or joints. The membrane-like members 111 and 112 may also be fixed by adhesive. Furthermore, this embodiment assumes a configuration in which the membrane-like members 111 and 112 are connected to the solar cell panel via the fasteners 113. Alternatively, the membrane-like members 111 and 112 may be connected directly to the solar cell panel without using the fasteners 113.

[0030] In this embodiment, a woven fabric with biaxially oriented fibers is used as the fiber-reinforced composite material of the membrane members 111 and 112. The fiber-reinforced composite material of the membrane members 111 and 112 may also be a woven fabric with two or more axes, such as a triaxial fabric. Furthermore, the woven fabric used as the fiber-reinforced composite material may be two-dimensionally planar or braided. Furthermore, in the fiber-reinforced composite material, fiber orientation may be obtained by stacking materials oriented in one direction.

[0031] In this embodiment, the membrane members 111 and 112 are made of prepregs, which are plain-woven carbon fiber cloths in which biaxial carbon fibers are woven orthogonally and impregnated with epoxy resin. The membrane member 111 is obtained by applying a tensile load to the prepreg to deform it until the fiber orientation of the membrane member 111 (56 degrees and -56 degrees) is obtained. One layer of prepreg is laminated, and the prepreg is shaped into a pipe-shaped mold so as to obtain the fiber orientation of the membrane member 111. The prepreg is then heated and cured, and machined to obtain the membrane member 111. Because the biaxial carbon fibers in the prepreg are orthogonal, the fiber orientation of the membrane member 112 (45 degrees and -45 degrees) is already obtained from the beginning. Therefore, the prepreg is used as is for the membrane member 112.

[0032] In this embodiment, prepreg is used as the material for the membrane members 111 and 112, but a method of injecting resin after shaping fibers may also be used. For example, RTM (Resin Transfer Molding) may be used. Furthermore, as the fiber cloth, twill weave and satin weave may also be used in addition to plain weave. Furthermore, in this embodiment, tensile deformation is assumed as a method for obtaining fiber orientation in the membrane member 111, but fiber orientation in the membrane member 111 may also be obtained by a weaving method.

[0033] In this embodiment, carbon fiber is used as the fiber-reinforced composite material of the membrane members 111 and 112. Alternatively, inorganic fibers such as glass fiber and basalt fiber may be used. Also, organic fibers such as aramid fiber may be used.

[0034] In this embodiment, a thermosetting epoxy resin is used as the base material of the fiber-reinforced composite material of the membrane members 111 and 112. Alternatively, other thermosetting resins such as cyanate resin and vinyl ester resin may be used. Thermoplastic resins such as PEEK (polyether ether ketone) and PA (polyamide) may also be used. Metals such as aluminum and copper may also be used. The combinations of fibers and base materials of the fiber-reinforced composite material of the membrane members 111 and 112 may also be different.

[0035] In this embodiment, two film-like members are assumed, but three or more film-like members may be used. When three or more film-like members are used, for example, a state in which an additional film-like member is disposed between film-like member 111 and film-like member 112 is considered. Also, a state in which additional film-like members are disposed in parallel beside film-like member 111 and film-like member 112 is considered.

[0036] Embodiment 2 In this embodiment, differences from embodiment 1 will be described with reference to the drawings. Items not described below are the same as in embodiment 1. In this embodiment, film member 111 and film member 112 are integrated.

[0037] 8 shows the hinge 100 according to this embodiment in an unfolded state. The hinge 100 according to this embodiment is made up of a membrane member 111, a membrane member 112, an end 131a, and an end 131b. The membrane member 111, the membrane member 112, the end 131a, and the end 131b are made of a fiber-reinforced composite material and are integrated together. In this embodiment, the end 131a corresponds to the first fixing portion, and the end 131b corresponds to the second fixing portion. When there is no need to distinguish between the end 131a and the end 131b, they are collectively simply referred to as end 131.

[0038] In the first embodiment, the fixing portion that fixes the membrane member 111 and the membrane member 112 is a fixing device 113 that is independent from the membrane member 111 and the membrane member 112. In the present embodiment, the fixing portion that fixes the membrane member 111 and the membrane member 112 is an end portion 131 that is integrally molded with the membrane member 111 and the membrane member 112. In the present embodiment, carbon fiber and thermosetting epoxy resin are used for the membrane member 111, the membrane member 112, and the end portion 131. The carbon fiber and thermosetting epoxy resin are continuously molded at the boundary between the membrane member 111 and the end portion 131. The carbon fiber and thermosetting epoxy resin are also continuously molded at the boundary between the membrane member 112 and the end portion 131. The shape and fiber orientation of the membrane member 111 and the membrane member 112 are the same as those in the first embodiment.

[0039] The hinge 100 according to this embodiment is fabricated using the same prepreg as in embodiment 1. The same prepreg piece is shaped and molded near the boundary between the film member 111 and the end 131, and near the boundary between the film member 112 and the end 131. This results in the hinge 100 in which the film member 111, the film member 112, and the end 131 are integrated.

[0040] In this embodiment, the carbon fiber and thermosetting epoxy resin are continuously molded at the boundary between the film member 111 and the end portion 131 and at the boundary between the film member 112 and the end portion 131. However, it is not necessary for both the carbon fiber and the thermosetting epoxy resin to be continuous. The carbon fiber may be partial, or only the thermosetting epoxy resin may be continuous. The types of fiber and resin used at the end portion 131a and the end portion 131b may be different.

[0041] Embodiment 3 This embodiment shows a deployable structure connected by the hinges 100 shown in Embodiments 1 and 2. Figure 9 shows a solar paddle 000 equipped with a solar cell panel 001. In Figure 9, the solar cell panel 001 is a deployable structure connected by the hinges 100 according to Embodiments 1 or 2. A deployable structure using the hinges 100 according to Embodiments 1 or 2 is lightweight, has a deploying force, and has high rigidity after deployment.

[0042] Although the first to third embodiments have been described above, two or more of these embodiments may be combined and implemented. Alternatively, one of these embodiments may be partially implemented. Alternatively, two or more of these embodiments may be partially combined and implemented. Furthermore, the configurations and procedures described in these embodiments may be modified as necessary.

[0043] 100 hinge, 111 membrane member, 112 membrane member, 113 fixing device, 113a fixing device, 113b fixing device, 114 center of bent portion, 121 fiber orientation, 122 fiber orientation, 131 end portion, 131a end portion, 131b end portion.

Claims

1. A hinge comprising a first elastic plate made of a first fiber material having two fiber orientations, and a second elastic plate made of a second fiber material having two fiber orientations, wherein the two fiber orientations of the first fiber material are symmetrical with respect to the longitudinal direction of the first elastic plate, and the two fiber orientations of the second fiber material are symmetrical with respect to the longitudinal direction of the second elastic plate, and wherein the angle between each of the two fiber orientations of the first fiber material and the longitudinal direction of the first elastic plate is different from the angle between each of the two fiber orientations of the second fiber material and the longitudinal direction of the second elastic plate.

2. A hinge as described in claim 1, wherein the angle formed by each of the two fiber orientations of the first fiber material with the longitudinal direction of the first elastic plate-like body is larger than the angle formed by each of the two fiber orientations of the second fiber material with the longitudinal direction of the second elastic plate-like body.

3. The hinge according to claim 1, wherein the radius of curvature of the tip of the first elastic plate member is different from the radius of curvature of the tip of the second elastic plate member.

4. A hinge according to claim 3, wherein the radius of curvature of the tip of said first elastic plate is smaller than the radius of curvature of the tip of said second elastic plate.

5. The hinge according to claim 1, wherein the radius of curvature of the first elastic plate-like body in an expanded state is different from the radius of curvature of the second elastic plate-like body in an expanded state.

6. The hinge according to claim 5, wherein the radius of curvature of said first elastic plate in an expanded state is greater than the radius of curvature of said second elastic plate in an expanded state.

7. The hinge according to claim 1, wherein the first elastic plate and the second elastic plate are disposed opposite each other.

8. A hinge according to claim 7, wherein the first elastic plate and the second elastic plate are bent so that the first elastic plate is on the inside and the second elastic plate is on the outside.

9. A hinge as described in claim 7, comprising a first fixing portion that fixes one end of the first elastic plate-like body and one end of the second elastic plate-like body that are arranged opposite each other, and a second fixing portion that fixes the other end of the first elastic plate-like body and the other end of the second elastic plate-like body that are arranged opposite each other.

10. The hinge according to claim 9, wherein the first fixing portion and the second fixing portion are integrally formed with the first elastic plate-like body and the second elastic plate-like body.

11. A hinge as described in claim 1, wherein the cross section of the first elastic plate perpendicular to the longitudinal direction of the first elastic plate is curved with both sides of the cross section protruding, and the cross section of the second elastic plate perpendicular to the longitudinal direction of the second elastic plate is curved with both sides of the cross section protruding.

12. A deployable structure using the hinge according to any one of claims 1 to 11.

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