A reinforcing member for FRP, a method for manufacturing the same, an FRP molded body, and an FRP connecting structure

Abstract

The present technology provides an FRP reinforcing member for suppressing the generation and progression of cracks in a bolt fastening portion, a rivet joint portion, or a bending portion with an extremely small bending radius, and a manufacturing method thereof, in light of an increasing demand for lightweight and thin-walled FRP molded bodies. An FRP reinforcing member for use on an FRP molded body of the present technology is characterized by being an FRP reinforcing member in which a plurality of fiber layers are integrated using a resin, the plurality of fiber layers including two or more spiral fiber layers in which fibers are wound in a spiral shape and molded, and cloth-like fiber layers in which fibers are woven in a grid shape, and the plurality of fiber layers include spiral fiber layers in which fibers are wound in a spiral shape and molded, and cloth-like fiber layers in which fibers are woven in a grid shape, and at least two of the cloth-like fiber layers are laminated in a manner that sandwiches the spiral fiber layers, and the fibers are composed of glass fibers, carbon fibers, and aramid fibers.

Description

Technical Field

[0001] This invention relates to fiber-reinforced plastic (FRP) reinforcing components and their manufacturing methods, FRP molded articles, and FRP connecting structures. Background Technology

[0002] FRP (fiber-reinforced plastic) is a lightweight and high-strength material compared to metals, meaning it has a high specific strength. It can be reinforced with glass fiber, carbon fiber, or, depending on the application, aramid fiber. Methods for manufacturing FRP include uniformly coating finely chopped glass fibers and infiltrating resin into glass or carbon fibers. The matrix of fiber-reinforced plastics mostly uses thermosetting resins such as unsaturated polyesters.

[0003] As manufacturing methods for FRP, there are hand lay-up, spraying, SMC (Sheet Molding Compound) compression molding, RTM (Resin Transfer Molding) based on high-pressure resin injection technology, autoclave method, etc., which are at the stage of being able to produce high-quality products.

[0004] Recently, due to changes in public infrastructure and power generation methods such as wind power, there has been an increased demand for large, thin-walled, lightweight FRP (fiberglass reinforced plastic) systems to improve the size of equipment and the fuel efficiency of transportation equipment such as trams, automobiles, and airplanes. The consideration is to increase the thickness of FRP to achieve high strength to accommodate larger sizes, while also aiming for lighter weight. Therefore, it is desirable to minimize the increase in FRP thickness while simultaneously improving the strength of the FRP body and its connections.

[0005] The fibers that make up FRP have high strength, but the resin has low strength and is prone to cracking. There is particular concern about applying excessive stress around bolt holes or holes drilled for other purposes. In addition, even without holes, stress concentration is unavoidable in the structure due to small bending radii, which may lead to cracking in the worst case.

[0006] Analysis of Japanese patent documents published after 1974 reveals the existence of techniques for reinforcing the area around bolt holes by altering the fiber structure of the FRP (Fiber Reinforced Polymer) structure (Patent Document 1, Patent Document 2). Additionally, while there are no records of FRP, there are techniques for attaching resin reinforcing sheets to bolt holes in resin components (Patent Document 3). However, no techniques have been found for suppressing crack propagation by attaching inventive components several millimeters or more thick, of the same thickness as FRP, to bolt holes or areas prone to cracking.

[0007] In addition, Non-Patent Document 1 describes a method for attaching FRPs to each other and a bolt connection technique between FRPs and metal. Some stress analysis has been performed around the bolts, and Non-Patent Document 2 also reports an increase in compressive stress around the bolt hole.

[0008] In such situations, techniques to reduce stress or suppress crack propagation are needed.

[0009] [Existing Technical Documents]

[0010] [Patent Literature]

[0011] [Patent Document 1] Japanese Patent Application Publication No. 2002-307585

[0012] [Patent Document 2] Japanese Patent Application Publication No. 2003-225914

[0013] [Patent Document 3] Japanese Patent Application Publication No. 2017-19311

[0014] [Non-patent literature]

[0015] [Non-patent literature 1]

[0016] FRP Molding Skills Textbook (New Edition), published by the China Reinforced Plastics Association on October 31, 1997.

[0017] [Non-patent literature 2]

[0018] Cutting-edge technologies for joining FRP components and bonding steel to FRP were released on November 12, 2013. Summary of the Invention

[0019] With the increasing demand for lightweight and thin-walled FRP molded parts, there is a need for a technology that can suppress crack initiation and crack propagation in bolt fasteners, rivet joints, or bending sections with extremely small bending radii.

[0020] The purpose of this invention is to provide an FRP reinforcement component, a manufacturing method thereof, and an FRP connection structure capable of suppressing crack initiation and crack propagation in high-stress-load or low-strength portions of an FRP molded body, such as bolt fastening portions, rivet joint portions, or bending portions with extremely small bending radii.

[0021] The FRP reinforcing component of the present invention, which is applied to an FRP molded body, is an FRP reinforcing component formed by integrating multiple stacked fiber layers with resin (claim 1).

[0022] It should be noted that, preferably, the plurality of fiber layers have at least one spiral fiber layer formed by winding and shaping the fibers into a spiral (claim 2).

[0023] In addition, it is preferable that the above-mentioned plurality of fiber layers have two or more cloth-like fiber layers in which the fibers are woven into a mesh (claim 3).

[0024] In addition, preferably, the plurality of fiber layers have a spiral fiber layer in which fibers are wound into a spiral shape and formed, and a cloth fiber layer in which fibers are woven into a mesh shape, wherein at least two of the cloth fiber layers are stacked in such a way as to hold the spiral fiber layer (claim 4).

[0025] In addition, it is preferable that the above-mentioned fabric fiber layers are stacked in such a way that the fiber extension direction of the upper fabric fiber layer and the fiber extension direction of the lower fabric fiber layer intersect at a 45-degree angle when viewed from their stacking direction (claim 5).

[0026] In addition, it is preferable that the fibers constituting the fiber layer are composed of glass fibers, carbon fibers or aramid fibers (claim 6).

[0027] The FRP connection structure of the present invention, which is formed by connecting FRP molded bodies to each other or by connecting an FRP molded body to a component made of a blank material different from FRP using bolts or rivets, is an FRP connection structure in which the FRP reinforcing component of any one of claims 1 to 6 is attached to the FRP molded body in such a way as to cover the periphery of the bolt holes or rivet holes of the FRP molded body (claim 7).

[0028] It should be noted that, preferably, the component made of a blank material different from FRP is a component made of any one of the following metallic materials: ferritic materials, ferritic stainless steel materials, austenitic stainless steel materials, aluminum alloy materials, and magnesium alloy materials (claim 8).

[0029] The FRP molded body of the present invention is an FRP molded body with recesses or holes formed on its surface, and is an FRP molded body (claim 9) in which the FRP reinforcing member of any one of claims 1 to 6 is installed in such a way that the opening of the recesses or holes is covered.

[0030] The manufacturing method of the FRP reinforcement component of the present invention includes the following steps: a step of feeding a plurality of fiber layers composed of glass fiber, carbon fiber or aramid fiber and resin into a mold; a step of pressing the plurality of fiber layers and the resin at 300°C or below for 60 minutes or less; and a step of removing the load pressure and cooling after the pressing step and demolding (claim 10).

[0031] The FRP reinforcement component and its manufacturing method, FRP molded body and FRP connection structure according to the present invention can suppress the generation and propagation of cracks in parts with high stress loads or low strength, such as bolt fastening parts, rivet joints or bending parts with extremely small bending radii. Attached Figure Description

[0032] Figure 1 This is a crack model diagram of an FRP molded body with bolt holes.

[0033] Figure 2 Examples of constituent elements and composite patch structures of the FRP reinforcement component (hereinafter referred to as patch) of the present invention.

[0034] Figure 3 This is a design example that uses patch 12 to fasten the FRP molded body to the metal structural material 19 with bolts.

[0035] Figure 4 This is a design example in which the FRP molded body and the metal structural material 19 are fastened together by bolts using a patch 12, and the upper part of the bolt is housed in a recess on the surface of the FRP molded body.

[0036] Figure 5 This design example uses two patches 12 to fasten two FRP molded bodies together with bolts.

[0037] Figure 6 This is a design example of using patches 4, 5, and 12 to fasten a flat FRP molded body to an FRP molded body with a recess using bolts.

[0038] Figure 7 This is a design example of using patches 5 and 12 to fasten a flat FRP molded body to an FRP molded body with a recess using bolts. Figure 7 Example (a) shows a construction where the depression is filled with resin. Figure 7 (b) is an example of a structure in which patch 11 covers the recessed opening. The surface of the FRP molded body is designed to be smooth.

[0039] Figure 8 This is a design example of attaching patch 12 to the opening of a convex FRP molded body.

[0040] Figure 9 This is a design example of attaching patch 13 to a partial recess formed in an FRP molded body.

[0041] Figure 10 This is a design example of attaching patch 11 (without holes) to a partial crack on the surface of an FRP molded body.

[0042] Figure 11 This is a design example of using an integral irregular shape patch 120, which is a perforated disc-shaped patch with two layers overlapping, to improve the shear strength of the patch, and fastening two FRP molded bodies together with bolts.

[0043] Figure 12This is a design example in which two FRP molded bodies are fastened together by bolts using the aforementioned integral irregular shape patch 120, with the upper part of the bolts housed in a recess on the surface of the FRP molded body.

[0044] Figure 13 This is a design example in which the above-mentioned integral irregular shape patch 120 is arranged on both sides of the bolt side and the nut side, and the two FRP molded bodies are fastened together by bolts.

[0045] Figure 14 This is a design example of a bolt fastening structure connected to a metal structural material 19. In order to improve the shear strength of the patch, an integral irregular shape patch 130 with three overlapping perforated disc-shaped patches is used.

[0046] Figure 15 This is an explanatory diagram illustrating the manufacturing process of the patch. Figure 15 (a) in the text represents the pressing and molding process. Figure 15 (b) in the diagram represents the patch removal process.

[0047] Figure 16 The internal structure and appearance of patches W1-W3 in embodiments of the present invention are shown.

[0048] Figure 17 The internal structure and appearance of patches W4-W5 in embodiments of the present invention are shown.

[0049] Figure 18 The internal structure and appearance of patches W6-W7 in embodiments of the present invention are shown.

[0050] Figure 19 This is a top view showing an example of a perforated FRP board.

[0051] Figure 20 This represents an example of a perforated FRP board with artificial cracks. Figure 20 (a) in the image is a top view. Figure 20 (b) in the image is a magnified view of the crack. Figure 20 (c) in the figure is an explanatory diagram showing the depth of the artificial crack in the A1-C1-B1 section.

[0052] Figure 21 This is a diagram illustrating the composition of a test piece with a patch attached to a perforated FRP plate with artificial cracks, used for an accelerated crack propagation test.

[0053] Figure 22 This is a structural diagram showing the configuration of a crack propagation acceleration test device that utilizes bolt fastening.

[0054] Figure 23 This is a verification result of the effect of the patch in the embodiment of the present invention on preventing crack propagation.

[0055] Figure 24 This is an explanatory diagram showing radial cracks generated by an accelerated crack propagation test. Detailed Implementation

[0056] FRP molded parts are mostly used to connect FRP molded parts to each other or to other materials. In addition, the shapes are often complex depending on the application. For example, there are shapes used to apply stress by using complex structures such as bolts, nuts or rivets for tightening.

[0057] Figure 1 This is a model diagram of a crack on the surface of an FRP molded body with bolt holes. The surface cracks are expected to be radial cracks that propagate radially from the holes 3 in the FRP molded body 1 in the radial direction. To prevent crack propagation, it is conceivable to arrange the fibers perpendicular to the crack to resist cracking.

[0058] Figure 2 This illustrates a representative patch design example where the fiber composition is altered and impregnated with resin to prevent the propagation of radial cracks. The fiber material is glass, carbon fiber, or aramid fiber. The design pattern is as follows.

[0059] 4. Patch 4 (spiral, no holes)

[0060] 5 patch 5 (spiral, hole)

[0061] 7. Patch 7 (fiber cloth, non-porous)

[0062] 8. Patch 8 (fiber cloth, perforated)

[0063] 9. Patch 9 (fiber cloth, fiber cloth at 45 degrees, non-porous)

[0064] 10 Patches 10 (fiber cloth, 45-degree angle, perforated)

[0065] 11 Patch 11 (fiber cloth, spiral, fiber cloth 45 degrees, non-porous)

[0066] 12 Patch 12 (fiber cloth, spiral, fiber cloth 45 degrees, perforated)

[0067] 13 Patch 13 (half the material of Patch 11)

[0068] Here, the "45-degree angle of the fiber cloth" in the above-mentioned patches 9 to 12 refers to the fiber cloth rotated 45 degrees relative to the center of the patch. That is, the "45 degrees" in "45-degree angle of the fiber cloth" means that when the patch is viewed from the stacking direction of the fiber layers, the fiber extension direction of the "45-degree angle of the fiber cloth" intersects the fiber extension direction of the "fiber cloth" at a 45-degree angle.

[0069] The patch can be used by stacking one or more patches and connecting them to the FRP molded body 1 with an adhesive material or the like. Alternatively, as described later, an integral irregular-shaped patch can also be used, which is an overlap of two disc-shaped patches with improved performance, enhanced strength, and excellent shear strength.

[0070] In addition, in the crack propagation acceleration test described later, in order to observe the fibers inside the patch, a transparent resin can be used for the test, but it can also be colored white, black, or other colors.

[0071] In addition, when using the patch of the present invention, washers can be used or not used as needed, especially for bolt fastening.

[0072] The patch of this invention can also be manufactured using other manufacturing technologies such as 3D printing.

[0073] Figure 3 The structure using patch 12 is a composite three-layer perforated patch, consisting of a fiber cloth woven longitudinally and transversely, a fiber cloth with spiral glass fibers sandwiched between the fiber cloth and a fiber cloth rotated 45 degrees around the center of the holes, and impregnated with resin. Bolt fastening is performed together with nuts 17 provided in the metal structural material 19. It is a structure example where the bolts protrude from the top of the FRP molded body 1. The metal structural material 19 can be made of ferrous materials, ferritic stainless steel, austenitic stainless steel, aluminum alloys, or magnesium alloys. To prevent corrosion of the metal structural material 19, it can be sealed with resin 14 as designed.

[0074] Here, we will explain spiral glass fiber and glass fiber cloth. Spiral glass fiber refers to fibers composed of untwisted glass rovings with filaments combined into a spiral shape with a radius larger than the diameter of a bolt hole or rivet hole.

[0075] In addition, fiberglass cloth refers to plain weave yarn made by combining multiple twisted monofilaments. Both can be used as reinforcing materials for composite materials such as plastics.

[0076] As used in the embodiments described later, the glass roving material has a count of ER2310 as specified in JIS3410, and the glass fiber cloth has a count of 200 as specified in JISR3416.

[0077] Figure 4 This is an example of a structure where the bolts on the FRP molded body 1 using patch 12 do not protrude. Bolt tightening is performed together with the nut 17 provided in the metal structural material 19. By smoothing the surface of the FRP molded body, it is desirable to suppress turbulence in the liquid or gas phase. In the following design, surface smoothing technology is also easy to use from the viewpoint of preventing scratches.

[0078] Figure 5 This is a design example in which two patches 12 are used on the surface and back of the joint to join two FRP molded bodies 1. Bolt fastening is achieved by using bolts 15 and nuts 17.

[0079] Figure 6 This is a design example of combining two FRP molded bodies 1 of different shapes. It is a design example using patches 4, 5, and 12. It is a design using bolts 15 and nuts 17. The heads of the metal bolts are positioned within the FRP recesses.

[0080] Figure 7 This is an example of inserting and pasting (a) resin or (b) patch into the recess when bonding FRP with recesses.

[0081] Figure 7 (a) is a design example of combining two FRP molded bodies 1 of different shapes. It is an example of designing the surface of the FRP molded body to be smooth by placing resin 14 in the recess. It becomes a structure using patch 4, patch 5, and patch 12. It is joined by bolt 15 and nut 17.

[0082] Figure 7 (b) is a design example of combining two FRP molded bodies 1 with different shapes. It is an example of designing the surface of the FRP molded body to be smooth by arranging patches 11, 5, and 12 in the recess. It becomes a structure using patches 11, 5, and 12. It is connected with bolts 15 and nuts 17.

[0083] Figure 8 This is a design example of using patch 12 when the FRP molding 1 is convex in the design.

[0084] Figure 9 This is an example of a patch application in the case of FRP molding 1 having a partially recessed structure, and it is a design example of patch 13 as half of patch 11.

[0085] Figure 10 This is a design example using patch 11. It is a design example that uses a non-porous patch 11 to suppress radial cracks when there are partial cracks in the FRP molding 1.

[0086] Figure 11 This is an example of connecting two FRP molded bodies. Here, we present a design example of an integral first irregular-shaped patch 120, which uses two perforated disc-shaped patches overlapping each other to improve the patch's shear strength. Since a portion of the integral irregular-shaped patch is embedded in the body of the FRP molded body 1, it exhibits strong resistance to shear forces.

[0087] Figure 12This is an example of connecting two FRP molded bodies. In this case, it is a design example of an integral first irregular shape patch 120 with two perforated disc-shaped patches overlapping each other to improve the shear strength of the patch, and the structure is such that the bolts do not protrude from the surface.

[0088] Figure 13 This is an example of connecting two FRP molded bodies. Here, it is a design example of an integral first irregular shape patch 120, formed by overlapping two perforated disk-shaped patches to improve the shear strength of the patch. This is an example of arranging patches on both the surface and back side, creating a further reinforced structure.

[0089] Figure 14 This is a design example of a bolt-fastening structure connected to a metal structural material 19. Here, a design example uses an integral second irregular-shaped patch 130, which is formed by overlapping three perforated discs, to improve the shear strength of the patch. The integral irregular-shaped patch used here can be manufactured using the method described in this patent. The manufactured integral irregular-shaped patch can be used to manufacture reinforced FRP using the FRP vacuum forming manufacturing method (VPI method), utilizing a method pre-set inside the molding body. Although this is the method, since the structure is constrained around the holes, the patch does not have to be made of FRP; an integral second irregular-shaped patch, formed by overlapping three disc-shaped patches made of soft resins such as polypropylene or nylon, can be used.

[0090] It should be noted that, as Figures 11-14 The described method for manufacturing a patch structure involves attaching an FRP reinforcing member to an FRP molded body, then adjusting the shape by cutting through bolt holes, and finally attaching an FRP reinforcing member including the bolt portion to create a connecting structure.

[0091] The molded patches can also be bonded together to create a composite. Adhesive can be applied to each patch individually to create a composite patch assembly. Considering industrial applications, irregularly shaped patches formed by overlapping two disc-shaped patches are preferred as they are easier to use.

[0092] For strong bonding of these components, instant adhesives, epoxy-based adhesives, or acrylic-based adhesives can be used. Patch-to-patch bonding can also use instant adhesives, epoxy-based adhesives, or acrylic-based adhesives. Alternatively, strong-adhesive double-sided tape can also be used.

[0093] [Example]

[0094] In society, the industrial reliability of FRP products is of paramount importance. For high-stress-load or low-strength sections such as bolt fasteners, rivet joints, or bends with extremely small radii, a technique to prevent crack formation is desired, and thus the patch of this invention was developed. In the embodiments described later, the patch is flat and disc-shaped (with or without a central hole), but it can be flexibly designed into squares, rectangles, polygons with more than pentagons, irregular shapes, etc., as needed. Many methods for manufacturing the patch have been considered, but an easy-to-manufacture method is implemented here. The following describes the method of this implementation and examples of the manufactured patch. The following embodiments are designed with a resin-to-fiber weight ratio of 7:3.

[0095] Figure 15 Examples of pressing and removing the patch in the manufacturing method of the patch of the present invention are shown. Figure 15 In (a), 20 is an upper die for pressing material (fiber cloth made of resin and glass fiber or carbon fiber) 23, 21 is a lower die, and 22 is a shaft alignment hole. Figure 15 In (b), 12 is the patch removed from the mold after pressing.

[0096] The fabrication method of the patch will be explained next. First, polypropylene and glass fiber or carbon fiber are sequentially placed into the lower mold 21. At this point, the reinforcing material composed of polypropylene and glass fiber or carbon fiber is configured in a prescribed combination to form the designed structure, and subjected to a stress of 1.7 kgf / mm² at 230°C. 2 (Load 907kgf / 530mm) 2 After pressing and holding for 15 minutes, the load stress is removed, followed by cooling. The manufactured piece, approximately 5mm thick, such as patch 12, is then demolded.

[0097] The following examples illustrate the use of the patch of the present invention in FRP molded bodies or FRP connection structures.

[0098] Figure 16 The internal structure and appearance of a 5mm thick patch, which is an invention, are shown.

[0099] All patches W1 through W3 can be manufactured into usable patches without defects such as voids.

[0100] The patch W1 can be made of 8 sheets of fiberglass cloth (0°) (0°: fiberglass cloth rotation angle 0°) and polypropylene. The individual fiberglass cloths are not rotated.

[0101] The patch W2 consists of eight pieces of fiberglass cloth (0°) staggered by 45 degrees (45°: fiber cloth rotation angle of 45°), demonstrating a patch made of these fiberglass cloths and polypropylene.

[0102] Patch W3 demonstrates a patch composed of glass fiber cloth (0°), spiral glass fibers using glass roving, glass fiber cloth (0°), and polypropylene.

[0103] Figure 17 The internal structure and appearance of a 5mm thick patch, which is an invention, are shown.

[0104] Patches W4 through W5 can all be manufactured into usable patches without defects such as voids.

[0105] Patch W4 shows a patch composed of glass fiber cloth (0°), spiral glass fibers using glass roving, glass fiber cloth (45°), and polypropylene.

[0106] The patch W5 consists of 13 pieces of carbon fiber fabric (0°) offset by 45 degrees (45°: 45° rotation angle of the fiber fabric), demonstrating a patch made of these carbon fiber fabric fibers and polypropylene.

[0107] Figure 18 To analyze the effect of thickness, photographs of the internal structure and appearance of the 2mm thick W6 and 3mm thick W7 were produced using the same internal structure as the 5mm thick patch W4, which is the original invention. Patches W6 through W7 can all be manufactured into practical patches without defects such as voids.

[0108] Figures 19-22 The diagram illustrates a test performed under large bending strain conditions using a specimen with an artificial crack introduced into a fabricated patch. The diagram also explains the specimen shape prepared for performance evaluation and the testing machine used for the evaluation.

[0109] Figure 19 It is a 3mm thick perforated FRP board. The diameter of the central hole is 17mm.

[0110] Figure 20 This refers to the case of a perforated FRP board with artificial cracks introduced. Assuming that microcracks exist during hole machining, an inlet crack (1.5mm in length) is applied to the hole cut, and an accelerated cracking test is conducted. Figure 20 (a) is an overall view of the perforated FRP board with artificial cracks introduced. Figure 20 (b) in the middle is Figure 20 The enlarged view of the artificial crack portion in (a) is an enlarged view of the crack portion 24. Figure 20 (c) in the figure shows that in Figure 20The enlarged view of (b) shows the cross-section of the artificial crack when cut with section A1-C1-B1. The artificial crack is roughly triangular in shape. C1 is the front end of the artificial crack.

[0111] Figure 21 This is a diagram of a test piece consisting of patches attached to a perforated FRP board (artificial cracks are shown in the image). In all test pieces, a commercially available adhesive, "grasp-neo," was used to bond the patches to the FRP board.

[0112] Figure 22 This is a device structure used for accelerated crack initiation testing using bolt tightening, showing the fixtures and tightening conditions for bolt tightening evaluation testing.

[0113] The accelerated crack initiation test was conducted as follows: The hex bolts were slowly tightened, and a torque wrench was used to continuously apply a load until 10 N·m was reached. This load was kept constant throughout the test. Rotation speed: approximately 4 rpm.

[0114] Figure 23 This is a verification result of the crack-prevention effect of the invented patch. The evaluation results of the crack-prevention patch's effect in inhibiting crack propagation are summarized.

[0115] First, tests were conducted using a perforated FRP sheet with artificial cracks, without any patches. The results show that the patchless FRP molded body 1, presented as a comparison, is... Figure 24 As shown, radial cracks 23 are generated near the artificial cracks 24 around the FRP holes.

[0116] Next, crack acceleration tests were conducted using 5mm thick patches W1 to W5, the inventions, with artificially created cracks, and with comparison tests conducted without artificially created cracks. The results showed that no crack propagation was observed in any of the samples. Therefore, crack propagation was inhibited. Among the invented patches, patch W4 was considered easy to use due to economic and processability considerations. Furthermore, it was believed that thicker patches have higher strength and thinner patches have lower strength; therefore, crack acceleration tests were conducted using patches with the same structure as patch W4, with thicknesses of 3mm and 2mm. The results showed that even under the stringent thin-thickness condition, i.e., patches with thicknesses of 3mm and 2mm, no crack propagation was observed in the patches. These results confirm the effectiveness of the patches in preventing cracks.

[0117] [Industry availability]

[0118] The FRP reinforcement component and its manufacturing method, FRP molded body and FRP connecting structure of the present invention are applicable to components of light small aircraft, air conditioning equipment, industrial and nursing robots, truck, bus, tram components, wind power generation equipment, medical device housings, large drones, other FRP housings and FRP components.

[0119] Symbol Explanation

[0120] 1 FRP Molded Body

[0121] 2. Radial Crack Model

[0122] 3 holes

[0123] 4. Patch (spiral, non-porous)

[0124] 5 patches (spiral, with holes)

[0125] 6. Glass or carbon fiber

[0126] 7. Patch (fiber cloth, non-porous)

[0127] 8. Patch (fiber cloth, perforated)

[0128] 9. Patch (fiber cloth, 45-degree fiber cloth, non-porous)

[0129] 10. Patch (fiber cloth, 45-degree angled fiber cloth, perforated)

[0130] 11. Patch (fiber cloth, spiral, 45-degree fiber cloth, non-porous)

[0131] 12 Patches (fiber cloth, spiral, 45-degree fiber cloth, perforated)

[0132] 13 Patch (half the material of Patch 12)

[0133] 14 Resin

[0134] 15 bolts

[0135] 16 Washers

[0136] 17 Nuts

[0137] 18. Adhesive materials

[0138] 19. Metal structural materials

[0139] 20 upper mold

[0140] 21 Lower mold

[0141] 22-axis alignment with hole

[0142] 23. Resin and glass or carbon fiber fabric

[0143] 24 Artificial cracks

[0144] 25. Flat plate test fixture

[0145] 26. Cylindrical test fixture

[0146] 27. Radial cracks

[0147] 120 First irregular patch

[0148] 130 Second irregular patch

Claims

1. A fiber-reinforced plastic reinforcing component, characterized in that, It is a fiber-reinforced plastic reinforcing component that is applied to a fiber-reinforced plastic molded body. It is formed by integrating multiple fiber layers with resin. The multiple fiber layers include a spiral fiber layer in which fibers are wound into a spiral shape and shaped, and a cloth fiber layer in which fibers are woven into a mesh shape. At least two of the cloth fiber layers are stacked in a manner that clamps the spiral fiber layer.

2. The fiber-reinforced plastic reinforcing component according to claim 1, which is used to be attached to the surface of the fiber-reinforced plastic molded body.

3. The fiber-reinforced plastic reinforcing component according to claim 1, characterized in that, The fabric fiber layers are stacked such that the fiber extension direction of the upper fabric fiber layer and the fiber extension direction of the lower fabric fiber layer intersect at a 45-degree angle when viewed from their stacking direction.

4. The fiber-reinforced plastic reinforcing component according to claim 1, characterized in that, The fibers constituting the fiber layer are composed of glass fibers, carbon fibers, or aramid fibers.

5. A fiber-reinforced plastic connection structure, characterized in that it is a fiber-reinforced plastic molded body connected to each other or to a component made of a preform different from the fiber-reinforced plastic by bolts or rivets, wherein the fiber-reinforced plastic molded body is characterized in that, The fiber-reinforced plastic reinforcing component according to any one of claims 1 to 4 is attached to the fiber-reinforced plastic molded body in such a way as to cover the periphery of the bolt holes or rivet holes of the fiber-reinforced plastic molded body.

6. The fiber-reinforced plastic connecting structure according to claim 5, characterized in that, The component made of a preform different from fiber-reinforced plastic is a component made of any metal material selected from iron-based materials, aluminum alloy-based materials, and magnesium alloy-based materials.

7. A fiber-reinforced plastic molded article, characterized in that, It is a fiber-reinforced plastic molded body with recesses or holes formed on its surface, and the fiber-reinforced plastic reinforcing component according to any one of claims 1 to 4 is mounted on it in such a way that the opening of the recesses or holes is covered.

8. A method for manufacturing a fiber-reinforced plastic reinforcing component according to any one of claims 1 to 4, characterized in that, The device comprises the following steps: a step of feeding multiple fiber layers composed of glass fiber, carbon fiber or aramid fiber and resin into a mold; a step of pressing the multiple fiber layers and resin at a temperature below 300°C for a period of 60 minutes; and a step of removing the load pressure and cooling the material after the pressing step and then demolding it.

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