JPH0762484B2 - CFRP joint - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CFRP joint used for a joint between primary structural members of a frame structure.

Conventional technology CFRP (carbon fiber reinforced plastic) is expected to be a promising material in the field of aerospace because of its high mechanical properties such as specific strength and specific rigidity, and its excellent thermal dimensional stability method. ing. In addition, not only the primary structural members of frame structures (truss or rigid frame type) used in outer space but also the joints used for connecting the primary structures are attempted to be CFRP.

In this case, the primary structural member has a simple shape such as a pipe shape or a flat plate shape, whereas the joint has to be combined with a plurality of members, so the shape must be extremely complicated. . for that reason,
In molding the joint as described above, a molded product in which a chopped strand of carbon fiber is contained in a predetermined resin and a laminated molded product obtained by laminating carbon fiber cloth are proposed (for example, 32nd International SAM
PE Symposium Proceedings April 6-9, 1987 P.772-P.781).

Problems to be Solved by the Invention Molded products using the chopped strands of carbon fibers as described above have good manufacturability, but on the other hand, the fibers are not continuous, so that the original strength and elasticity of the fibers cannot be fully utilized. ,
In addition to low mechanical properties as a molded product, it is difficult to achieve arbitrary specific strength and specific rigidity depending on the shape of the molded product.

Further, regarding the laminated molded product, it becomes more difficult to adapt the load load direction and the fiber direction as the product shape becomes more complicated, and it is necessary to partially bear only the adhesive strength of the cloth against the tensile load, for example. Get lost. As a result, similarly to the above, the strength of the fiber body cannot be fully utilized, and sufficient strength cannot be obtained as a product.

INDUSTRIAL APPLICABILITY The present invention provides a CFRP joint having excellent mechanical properties by utilizing the original strength of the fiber.

Means for Solving the Problems In the joint of the present invention, a plurality of CFRP box-shaped cells are combined to form a skeletal structure of the joint, and carbon fibers are wound in a circular shape along the open end face of each cell. To form a frame body, and a plurality of cells are integrated with each other.

The box-shaped cell as a basic element is, for example, rectangular or substantially funnel-shaped as shown in Examples, and the cell is formed by stacking carbon fiber cloths. Therefore,
The fiber orientation is the planar orientation of the cell walls. The fibers of each cell are not continuous just by combining a plurality of cells. Therefore, in order to compensate for this, the carbon fiber is wound around the end face of each cell by the filament winding method.

In addition, a coupling hole is formed in the wall portion of each cell as needed for connection with the primary structural member of the frame structure.

Action According to the above structure, assuming that the mating primary structural member is pin-coupled to the wall of the cell, for example, the compressive load is borne by the wall surface of each cell, while the tensile load is circular. The frame body portion, which is the secondary molding layer wound around, bears the burden.

Example FIG. 1 is a structural explanatory view showing an example of the joint of the present invention, and the joint 1 is formed into a spherical shape as a whole as if the five discs were combined in appearance.
As shown in FIG. 2, this joint 1 has a box-shaped cell 2 having a substantially funnel shape as a basic element, and a total of 16 cells 2 are combined with each other and bonded to each other to form a skeleton of the joint 1. The three-dimensional structure 3 is formed, and further, carbon fibers that are continuous along the joint end faces of the cells 2 in the intermediate assembly 3 are wound in a circular shape by the unidirectional filament winding method to form the frame body portion 4 as shown in FIG. Joint 1 is constructed.

The cell 2 is constructed by laminating and molding a carbon fiber cloth in advance and then subjecting it to a predetermined machining process, and the direction of the fiber has a so-called cross-ply shape as shown by a symbol Q in FIG. The wall portion 5 of each cell 2 is oriented in the plane direction. In this case, depending on the required strength, the fibers may be oriented in only one direction. Further, a groove 6 for molding the frame portion 4 is formed in advance on the open end surface of the cell 2, and the wall portion 5 is provided with a first groove as necessary for coupling with a mating primary structural member. A coupling hole 7 is formed as shown in FIG.

In the structure of the above embodiment, if the truss member 8 is connected to the wall portion 5 by the pin 9 as shown in FIG. 3, the bending load in this case can be neglected because it is extremely small. A load transmission system with only tensile and compression loads is required. Therefore, first, regarding the compressive load, the compressive load is input as the surface pressure of the inner peripheral surface of the coupling hole 7, becomes the in-plane compressive load of the wall portion 5, and is transmitted to the other wall portion 5. Further, the tensile load is input as the surface pressure of the inner peripheral surface of the coupling hole 7 and becomes the in-plane compressive load of the wall portion 5. This load is converted into the tensile load of the frame body portion 4 and is applied to the other wall portion 5. Transmitted.

That is, according to the above-described embodiment, all the load transmission is performed in the form of tension or compression, and the load transmission by bending that lowers the rigidity is not performed. And, the direction of the fiber can be always matched with the load direction without depending on the adhesive strength and the shear strength of the fiber layer constituting the joint 1,
You can maximize the strength of the fiber.

Here, as shown in FIG. 4 and FIG. 5, it is more preferable to embed a metal bush 11 with a flange 10 in the coupling hole 7 of the wall portion 5 to improve load (contact pressure) transferability. In particular, when the elastomer layer 12 is formed on the flange 10 as shown in FIG. 5, the distribution of the shear stress acting between the wall material and the bush 11 can be made smooth.

Further, when the mating member is screwed to the wall portion 5 instead of being pin-connected, a bush made of metal (for example, titanium) having a screw portion 13 from the back surface of the wall portion 5 as shown in FIG.
When 14 is fitted, the reinforcing effect of the joint can be expected.

Further, when it is necessary to connect the truss members 8 linearly, for example, joints as shown in FIGS. 7A, 7B and 8 are used.

In the case of the joint 15 of FIG. 7, as shown in FIG. 7B, after the bush 18 having the threaded portion 17 is positioned on the side surface of the core 16 made of foam material or the like, the threaded portion 17 is formed on the outer periphery of the bushing 18. The reinforcing fiber layer 19 is formed by winding fibers in parallel with the axis by, for example, a filament winding method. In addition, in the case of FIG. 8, it is different from that of FIG. 7 in that the whole is formed in a cylindrical shape, but in FIG. 7 in that the core 16, the bush 28 and the fiber reinforced layer 29 are the constituent elements. Is the same as.

FIG. 9 shows another embodiment of the present invention. In the first embodiment, a plurality of cells 2 having the same shape are combined to form a spherical joint 1, whereas the present embodiment has a different shape. The joint 21 is formed by combining three types of cells 22, 32, 42.

In the case of this embodiment, the frame member of the frame structure is inserted and connected to the rectangular cell 22 from the direction of the arrow e, while the above-described operation is performed on the wall portions 5 of the other cells 32 and 42. As in the example, the truss member is pin-connected through the connecting hole 7. Therefore, the effects of the cells 32 and 42 are similar to those of the first embodiment.

As described above, in the joint of the present invention, a plurality of CF
A box-shaped cell made of RP is combined to form the skeleton structure of the joint, and the carbon fiber is wrapped around the open end surface of each cell to form a frame part, which allows multiple cells to be integrated with each other. As a result, the direction of the fiber can be aligned with the load direction of the wall portion of each cell that bears the compressive load and the frame body portion that bears the tensile load. Therefore, it is possible to obtain a joint that is lightweight and has excellent mechanical properties by making the most of the strength and rigidity of the fiber.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the joint of the present invention,
2 is a perspective view of an intermediate assembly of the joint shown in FIG. 1, FIG. 3 is a sectional view taken in the direction X in FIG. 1, and FIGS. 4, 5, and 6 are all FIG. FIG. 7 (A) is a cross-sectional view showing an example of a joint used for linearly connecting truss members, and FIG. 7 (B) is the same figure (A). FIG. 8 is a sectional view showing another embodiment of the joint of FIG. 7 (A), and FIG. 9 is a perspective view showing another embodiment of the joint of the present invention. 1,21 ... Joint, 2,22,32,42 ... cell, 4 ... frame part, 5 ... wall part, 7 ... coupling hole, 8 ... truss member.

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Claims (1)

[Claims] 1. A CFRP joint used for a joint portion of a frame structure, wherein a plurality of CFRP box-shaped cells are combined to form a skeletal structure of the joint, and
A CFRP joint characterized in that a frame body is formed by winding carbon maintenance in a circular shape along the open end surface of each cell, and thereby a plurality of cells are integrated with each other.