JP2001301043A - Bonded structure of fiber reinforced composite materials and method for bonding the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bonded structure of fiber reinforced composite materials capable of obtaining sufficient bonding strength and capable of effectively suppressing and preventing the generation of unevenness in a bonded part and the concentration of stress to a screw, and to provide a method for bonding the fiber reinforced composite materials. SOLUTION: The bonded structure of the fiber reinforced composite materials is provided with a plurality of the fiber reinforced composite materials 1, 2 opposed to each other through a bonding gap, the strands 4, 5 of fibers 3 exposed to the gap from the fiber reinforced composite materials 1, 2, a knot 7 formed by tying the strands 4, 5 of the fiber reinforced composite materials 1, 2 slightly loosely and the filler 6A charged in the exposed parts of the strands 4, 5 including the knot 7 to be solidified. Since the knot 7 is formed by entangling the strands 4, 5 and the filler 6A is charged even in the exposed parts of the strands 4, 5 including the knot 7 to be solidified, strong bonding and high strength near to an integrated molded article can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joining structure of a fiber-reinforced composite material and a joining method of the fiber-reinforced composite material.

[0002]

2. Description of the Related Art In recent years, materials that can be used in various fields have been developed. One of them is a fiber-reinforced composite material. This fiber-reinforced composite material is formed into a fixed shape by filling the periphery of a large number of fibers with a synthetic resin and hardening, utilizing the advantages of high-strength fibers. For example, carbon fiber (CF) made from polyacrylonitrile (PAN) is a high-strength yarn and has a length of about 3,400
It has a tensile strength of MPa (this value is an order of magnitude higher than that of hard steel). A material obtained by solidifying a large number of carbon fibers with a synthetic resin such as an epoxy resin and molding the same into a fixed shape is called carbon fiber reinforced plastic (CFRP). Applications are expanding to a wide range.

[0003] In order to maintain sufficient strength of the fiber-reinforced composite material, the entire final product must be integrally formed so that the fibers are not broken. To do this,
It is necessary that the shape of the final product is fixed, and as a result, a very expensive mold is indispensable. However, if you need such an expensive mold,
Unlike metals, application in various fields is extremely difficult.

Accordingly, in recent years, a method of forming a plurality of small fiber-reinforced composite materials and joining the plurality of fiber-reinforced composite materials together so as to obtain a strength close to that of an integrally molded product has been earnestly studied. . Specifically, as shown in FIG. 10A, end faces of a plurality of fiber-reinforced composite materials 1 and 2 are butt-joined to each other via an adhesive 11, or as shown in FIG. Are butt-joined via an adhesive 11 and a plurality of fiber-reinforced composite materials 1.
2 or a plurality of fiber reinforced composite materials 1.2 are butted together as shown in FIG. 10 (c), and the plurality of fiber reinforced composite materials 1.2 are joined together.
A method of joining the vicinity of the joint portion with a backing plate 12 and a fastener 13 such as a screw has been studied.

[0005]

However, FIG.
In the method (a), the strength of the joint depends only on the adhesive strength of the adhesive 11, and only an insufficient and unstable joint can be obtained. Further, in the method shown in FIG. 2B, although there is a possibility that the strength is increased, undesired steps and irregularities are generated at the joint. Further, in the method shown in FIG. 3 (c), not only a step or unevenness occurs at the joint, but also a big problem that stress is concentrated on the fastener 13 such as a screw is newly generated. As described above, in the related art, it has been extremely difficult to join a plurality of fiber-reinforced composite materials 1 and 2 to ensure strength close to that of an integrally molded product without any problem.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a sufficient bonding strength. Further, it is an object of the present invention to effectively suppress the occurrence of unevenness in a bonding portion and concentration of stress on a screw. It is an object of the present invention to provide a bonding structure of a fiber-reinforced composite material and a bonding method of the fiber-reinforced composite material.

[0007]

According to the first aspect of the present invention, in order to achieve the above object, a plurality of fiber reinforced composite materials, a plurality of fibers respectively exposed from the plurality of fiber reinforced composite materials, and a plurality of fiber reinforced composite materials are provided. It is characterized by comprising a knot formed by tying fibers and the like of the fiber-reinforced composite material, and a filler that fills and solidifies an exposed portion of the fiber and the like including the knot. It should be noted that an insertion material made of a material different from the filling material can be inserted into the knot to reduce the bending of the fiber or the like. Further, it is preferable that the inserting material is a fiber or a fiber strand. In addition, a plurality of small cavities located around the knot may be formed in the filler.

In order to achieve the above object, the present invention provides a method of joining a plurality of fiber-reinforced composite materials, the method comprising joining fibers and the like from the plurality of fiber-reinforced composite materials. The method is characterized in that a knot is formed by connecting the fibers and the like of the plurality of fiber-reinforced composite materials, and the exposed portion of the fiber and the like including the knot is filled with a filler and solidified. When tying together a plurality of fibers of the fiber-reinforced composite material, a knot can be formed while inserting an insertion material made of a material different from the filler, so that the bending of the fibers and the like can be weakened. Further, it is preferable that the inserting material is a fiber or a fiber strand. In addition, in the filler,
Preferably, a plurality of small cavities located around the knot are formed.

One of the present inventors used a plurality of fiber-reinforced composite materials (GFRP) having glass fibers in 1993, and exposed the glass fibers from the plurality of fiber-reinforced composite materials facing each other. The effectiveness of a joining method in which glass fibers of a plurality of fiber-reinforced composite materials are arranged in parallel, and a plurality of glass fiber portions are filled with a synthetic resin and solidified has been confirmed (increase in joining strength by a new joining method) 70th Ordinary General Meeting Lectures 1-625). The present inventors have further developed such a technical idea, and confirmed that if a knot is formed with fibers of a fiber-reinforced composite material having a strong bending force, a joint having high strength can be obtained, and the present invention has been completed. Was.

Here, the plurality of fiber-reinforced composite materials in the claims may be a pair, but are not necessarily limited to this, and may be three, four, five or more.
The fibers and the like refer to fibers or strands of fibers (1,000 to 12,000 fibers of several μm to several tens μm are bundled in parallel and aligned). The fiber may be a glass fiber or the like in addition to the carbon fiber as long as it can secure a certain level of strength. The filler is mainly composed of various synthetic resins, but is not necessarily limited thereto, and may be a fluid carbon, ceramics, metal or the like which can be filled.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1 and FIG. A plurality of fiber-reinforced composite materials 1 facing each other via a gap
2 and the strands 4.5 of the fibers 3 which are respectively exposed in the gap direction from the plurality of fiber-reinforced composite materials 1 and 2 and the strands 4.5 of the plurality of fiber-reinforced composite materials 1.2 are slightly loosely tied. And a filler 6A that fills and solidifies the exposed portions of the strands 4.5 containing the knot 7.

As shown in FIG. 1, each of the fiber-reinforced composite materials 1 and 2 has a plurality of strands 4.5 of fibers 3 and a filler (also called a matrix) filled between the plurality of strands 4.5. 6 are used as components. The strength of each fiber-reinforced composite material 1 and 2 in the fiber direction is
It depends on its own strength and on the content of fiber 3 with respect to the whole. The filler 6 is made of various synthetic resins or the like, and is filled not only between the plurality of strands 4 and 5 but also between the fibers 3. The filler 6 mainly plays a role in maintaining the shape and distribution of the fiber-reinforced composite materials 1 and 2 as a whole, and also has a function of dispersing stress on the surface of the fiber 3. However, it is not an element that increases the strength.

Next, a method for joining a plurality of fiber-reinforced composite materials 1 and 2 will be described with reference to FIG. 2. First, the strands 4.5 are projected from each of the fiber-reinforced composite materials 1.2 to form a plurality of fiber-reinforced composite materials. The composite materials 1.2 are butted from the left and right through a gap, and the different strands 4.5 of the plurality of fiber-reinforced composite materials 1.2 are entangled and tied to form a knot 7 loosely.
Thereafter, if the exposed portions of the strands 4 and 5 including the knot 7, in other words, the gap is filled with the fluid filler 6 A and solidified, the fiber reinforced composite materials 1 and 2 are firmly joined to each other to form an integral body. Can be

According to the above, the knots 7 are formed by tying the strands 4.5 together, and the filler 6A is also filled and solidified in the exposed portions of the strands 4.5 including the knots 7, so that the integrally molded article is formed. A very strong bond close to the above can be easily obtained. Therefore, the application can be remarkably expanded to aerospace equipment, automobiles, paving equipment, golf clubs, and the like. In addition, since the butt joining method can be used, there is no need for any fastener 13 such as a backing plate 12 or a screw. Therefore, there is no step or unevenness near the joint,
There is no problem that stress concentrates on the screw.

Next, FIG. 3 shows a second embodiment of the present invention. In this case, when the knot 7 is formed by tying, a fitting material 8 different from the filler material 6A is fitted. , The bending of the fibers 3 and the like is weakened. Insertion material 8
Is a fiber 3 or a strand of the fiber 3, and in the present embodiment, has a substantially circular cross section or a shape close thereto. The other parts are the same as those in the above-described embodiment, and a description thereof will be omitted.

In this embodiment, the same operation and effect as those of the above embodiment can be expected. In addition, since the fitting member 8 functions as a spacer and the bending of the strands 4 and 5 is weakened, the strength can be further improved. .

Next, FIG. 4 shows a third embodiment of the present invention. In this case, the fluid filler 6A before solidification is used.
A fluid such as air is allowed to flow into the stirrer, and the mixture is stirred and solidified.
In A, a plurality of small cavities 9 located around the knot 7 are formed. The other parts are the same as those in the above-described embodiment, and a description thereof will be omitted.

In this embodiment, the same operation and effect as those of the above embodiment can be expected. Further, since a plurality of small cavities 9 distributed around the knot 7 are formed in the filler 6A, the progress of the breaking line 10 is suppressed. be able to. Explaining this effect, the rupture most often occurs near the knot 7, but initially occurs near the surface of the filler 6A. From this, the rupture occurs from the vicinity of the surface of the filler 6A to the knot 7
If the progress of the rupture can be stopped in some way before reaching the vicinity, it can be greatly expected to avoid the final rupture. According to the present embodiment, since the plurality of small cavities 9 are distributed around the knot 7, the progress of the breaking line 10 from near the surface of the filler 6A can be easily stopped by the small cavities 9.

In the above embodiment, the strands 4 and 5 are respectively exposed from the plurality of fiber-reinforced composite materials 1 and 2,
Although the plurality of fiber-reinforced composite materials 1 and 2 are butted with a gap therebetween, the order of these operations may be reversed. Also,
As shown in FIG. 5, a plurality of strands 4.5 are exposed from each fiber-reinforced composite material 1.2, and a plurality of fiber-reinforced composite materials 1
The two strands 4 and 5 are butted together to form a plurality of knots 7 loosely, and then the exposed portions of the strands 4 and 5 including the knots 7 are filled with the filler 6A. May be solidified. At this time, the plurality of knots 7 can be shifted in the left-right direction in FIG. Furthermore, the butting may be in the left-right direction or the up-down direction.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the joint structure of a fiber-reinforced composite material and a method of joining a fiber-reinforced composite material according to the present invention will be described below. Production of Joint Structure Using the fiber-reinforced composite material, the joint structures shown in FIGS. 2, 7, and 8 were produced, respectively, and the most important tensile strength was compared. Although the structure shown in FIG. 6 is an integrated structure having no joint structure, it was intentionally manufactured for comparison with the joint structure. In this case, the strand 4 is continuously extended over the entire length of the fiber-reinforced composite material 1.

The joining structure of FIG. 2 exposes the strands 4.5 from each fiber reinforced composite material 1.2 and abuts the plurality of fiber reinforced composite materials 1.2 with a gap therebetween. 2 strands 4
After tying the knot 7 by loosening the knot 7, the filler 6A is filled and buried in the exposed portions of the strands 4.5 containing the knot 7, ie, the gap, and solidified. Produced. The joint structure of FIG. 7 Strands 4.5 are exposed from each fiber-reinforced composite material 1.2, and a plurality of fiber-reinforced composite materials 1.2 are abutted through a gap to form a strand of the plurality of fiber-reinforced composite materials 1.2. 4
5 were arranged so as to be vertically overlapped with a gap therebetween, and the exposed portions of the strands 4 and 5, that is, the gap were filled with the filler 6 </ b> A and solidified to prepare a joint structure for comparison.

The joining structure of FIG. 8 exposes the strands 4.5 from each of the fiber-reinforced composite materials 1.2 and bends their free ends into a J-shape to connect the plurality of fiber-reinforced composite materials 1.2 with a gap therebetween. After abutting and engaging the strands 4.5 of the plurality of fiber-reinforced composite materials 1.2 via the J-shaped portion, the filler 6A is inserted into the exposed portions of the strands 4.5 including the J-shaped portion, that is, the gaps. Was buried and solidified to prepare a joint structure for comparison.

Tensile Strength Test A tensile test was carried out using the joint structures of the examples shown in FIGS. 2, 7 and 8 and the comparative example, and the results shown in FIG. 9 were obtained. As the tensile test piece, a No. 13B tensile test piece (flat plate) specified in JIS Z2201 (metallic material tensile test piece) was used. The following materials and test equipment were used. Carbon fiber strands: Mitsubishi Rayon PAN TR50S
23L Filler: Epoxy resin (FPO-MIX manufactured by BUHLER) Tensile tester: Shimadzu Autograph DCS-25T Load cell: 98000N

The test was performed under the following conditions. Crosshead speed: 3 mm / min Load amplifier magnification: 5 times Test temperature: 12 ± 3 ° C. Relative temperature: 88 ± 6% Carbon fiber content (volume) in test piece: 14.9%
The knotted portion is about 30%

Fifteen test specimens of each type were prepared, and the maximum, average, and minimum measured values were obtained. The results are summarized in the graph of FIG. In FIG. 9, the standard test piece refers to the structure of FIG. 6, and the hook joint refers to the structure of FIG.
The fiber embedded bonding refers to the structure of FIG. Further, the final knot joint refers to the structure of FIG. 2 according to the present invention, and as shown in FIG. 5, the position of the knot 7 in the solidified state is shifted, and the distance L is set to 0 mm, 5 mm, and 10 mm. .

According to the test results, in the case of the joining method using the knot 7, although the strength is inferior to that of the integrally molded article having no joint, the strength of about 100-400 MPa for aluminum (150-500 MPa) or brass is obtained. It was confirmed that it was sufficiently stronger than the tensile strength (30 MPa) of the joint with the epoxy adhesive. Since the tensile strength of the fiber-reinforced composite materials 1 and 2 depends on the content of the carbon fiber, if the content of the test condition of 14.9% is further increased, the same strength as iron can be obtained. it can.

From the above test results, it was found that the broken knot 7 has a lower breaking force as the strands 4.5 are sharply bent. From this, it was found that it is effective to insert the insert 8 made of a different material from the filler 6A when forming the knot 7 to weaken the bending of the fibers 3 and the like.

In addition, according to the test results, the fracture was almost always generated near the knot 7, but initially the filler 6A
It was found to occur near the surface. From this,
If the progress of the break can be stopped by any method before the break reaches from the vicinity of the surface of the filler 6A to the vicinity of the knot 7, it can be expected that the final break is avoided. In view of this point, air is flowed into the fluid filler 6A before solidification and stirred, and the solidified filler 6A is tied to the knot 7A.
If a plurality of small cavities 9 located on the periphery are formed, the breaking line 1
It is possible to stop the progress of zero.

[0029]

As described above, according to the present invention, a sufficient joining strength can be obtained, and furthermore, unevenness such as a backing plate or the like is generated at the joining portion, and stress is concentrated on fasteners such as screws. Can be effectively suppressed and prevented.

[Brief description of the drawings]

FIG. 1 is an explanatory sectional view of a main part showing an embodiment of a joining structure of a fiber-reinforced composite material and a joining method of the fiber-reinforced composite material according to the present invention.

FIG. 2 is an explanatory sectional view showing an embodiment of a joining structure of a fiber-reinforced composite material and a joining method of the fiber-reinforced composite material according to the present invention.

FIG. 3 is an explanatory sectional view showing a second embodiment of the joining structure of the fiber-reinforced composite material and the joining method of the fiber-reinforced composite material according to the present invention.

FIG. 4 is a sectional explanatory view showing a third embodiment of the joining structure of the fiber-reinforced composite material and the joining method of the fiber-reinforced composite material according to the present invention.

FIG. 5 is an explanatory sectional view showing a fourth embodiment of the joining structure of the fiber-reinforced composite material and the joining method of the fiber-reinforced composite material according to the present invention.

FIG. 6 is an explanatory sectional view showing a comparative example of a joining structure of a fiber-reinforced composite material and a joining method of the fiber-reinforced composite material according to the present invention.

FIG. 7 is an explanatory sectional view showing a comparative example of a joining structure of a fiber-reinforced composite material and a joining method of the fiber-reinforced composite material according to the present invention.

FIG. 8 is an explanatory sectional view showing a comparative example of a joining structure of a fiber-reinforced composite material and a joining method of the fiber-reinforced composite material according to the present invention.

FIG. 9 is a graph showing an example of a bonding structure of a fiber-reinforced composite material and a bonding method of the fiber-reinforced composite material according to the present invention.

FIG. 10 is an explanatory view showing a conventional method for joining a fiber-reinforced composite material.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fiber-reinforced composite material 2 Fiber-reinforced composite material 3 Fiber 4 Strand 5 Strand 6 Filler 6A Filler 7 Knot 8 Filling material 9 Small cavity

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshinori Kanno 2-23-10 Myojincho, Hachioji-shi, Tokyo F-term (reference) 4F211 AD16 AD19 AD35 TA06 TA08 TA15 TC08 TC21 TD01 TH02 TH16 TJ30 TN71 TN81

Claims (8)

[Claims] 1. A plurality of fiber-reinforced composite materials, fibers and the like respectively exposed from the plurality of fiber-reinforced composite materials, a knot formed by tying the fibers and the like of the plurality of fiber-reinforced composite materials, and the knot And a filler that fills and solidifies the exposed portion of the fiber or the like containing the same. 2. The fiber-reinforced composite material joining structure according to claim 1, wherein an insertion material made of a material different from that of the filler is inserted into the knot to reduce bending of the fiber or the like. 3. The joint structure for a fiber-reinforced composite material according to claim 2, wherein the insertion material is a fiber or a fiber strand. 4. The fiber-reinforced composite material joining structure according to claim 1, wherein a plurality of small cavities located around the knot are formed in the filler. 5. A method of joining a plurality of fiber-reinforced composite materials, the method comprising joining fibers of the plurality of fiber-reinforced composite materials, and exposing fibers and the like from the plurality of fiber-reinforced composite materials. A knot is formed by tying the knots to form a knot, and an exposed portion of the fiber or the like containing the knot is filled with a filler to be solidified. 6. The fiber according to claim 5, wherein when knotting a plurality of fibers of the fiber-reinforced composite material, a knot is formed while inserting an inlaying material different from the filler to weaken the bending of the fibers. How to join reinforced composites. 7. The method for joining fiber-reinforced composite materials according to claim 6, wherein the insertion material is a fiber or a fiber strand. 8. The method according to claim 6, wherein a plurality of small cavities located around the knot are formed in the filler.