Fiber-reinforced plastic member and method for producing fiber-reinforced plastic member

Abstract

A fiber-reinforced plastic member (33) has: a fiber-reinforced plastic part (1) comprising a plurality of fiber-reinforced plastic layers (2) and having a corner part (12); and a core (11) disposed on the corner part (12) and provided between two fiber-reinforced plastic layers (2) of the plurality of fiber-reinforced plastic layers (2). The core (11) has a core inner surface part (inner curved surface part (14)) located inside the corner part (12), a core outer surface part (outer curved surface part (15)) located outside the corner part (12), and a core flat surface part (17) disposed between an end of the core inner surface part (inner curved surface part (14)) and an end of the core outer surface part (outer curved surface part (15)).

Description

Fiber-reinforced plastic member and method for manufacturing the same

[0001] The present disclosure relates to a fiber-reinforced plastic member in which a corner portion is formed, and a core to be placed inside the corner portion of the fiber-reinforced plastic member.

[0002] Fiber-reinforced plastics are used in the structural components of artificial satellites, and adhesive structures are used to connect the components. The corners of the structural components are provided with curved surfaces to prevent excessive stress concentration (Patent Document 1). Another example is known in which reinforcing materials are provided inside the structural components to eliminate gaps that occur at the corners when the fiber-reinforced plastics are stacked (Patent Document 2).

[0003] Japanese Patent Application Laid-Open No. 2014-12403 International Publication No. 2018 / 037766 Pamphlet

[0004] The technology of Patent Document 1 uses a corner filler with a triangular cross section to increase the adhesive area, thereby improving adhesive strength. Patent Document 2 uses a crescent-shaped reinforcing material inside the corner to eliminate gaps that occur at the corners when fiber-reinforced plastics are laminated.

[0005] The corner filler used in Patent Document 1 is designed only for hat-shaped structures and cannot fill gaps that occur in L-shaped or V-shaped corners. The reinforcing material in Patent Document 2 is crescent-shaped, so it can only be placed on the curved surface of the corner. Furthermore, when placing the reinforcing material in the corner, it is difficult to accurately place the reinforcing material on the curved surface of the corner.

[0006] An object of the present disclosure is to obtain a fiber-reinforced plastic member having improved strength at corner portions.

[0007] The fiber-reinforced plastic member of the present disclosure comprises a fiber-reinforced plastic portion made of a plurality of fiber-reinforced plastic layers and having a corner portion; and a core disposed at the corner portion and provided between two of the plurality of fiber-reinforced plastic layers, wherein the core has a core inner surface portion located inside the corner portion, a core outer surface portion located outside the corner portion, and a core flat surface portion located between an end of the core inner surface portion and an end of the core outer surface portion.

[0008] According to the present disclosure, the flat core surface of the core allows the core to be placed accurately in a corner without being displaced, thereby making it possible to obtain a fiber-reinforced plastic component with no gaps between the fiber-reinforced plastic layers.

[0009] 1 is a perspective view showing a fiber-reinforced plastic member 33 molded into an L-shape according to embodiment 1; FIG. 2 is a side view showing a fiber-reinforced plastic member 33 molded into an L-shape according to embodiment 1; FIG. 3 is a view showing a core 11 according to embodiment 1; (A) is a side view of the core 11, (B) is a perspective view of the core from the inside, and (C) is a perspective view of the core 11 from the outside. FIG. 4 is a side view showing that only the outer curved surface portion 15 of the core 11 arranged in the corner portion 12 of the fiber-reinforced plastic member 33 according to embodiment 1 is an arc; FIG. 5 is a side view showing that only the inner curved surface portion 14 of the core 11 arranged in the corner portion 12 of the fiber-reinforced plastic member 33 according to embodiment 1 is an arc; FIG. 6 is a side view showing that both the outer curved surface portion 15 and the inner curved surface portion 14 of the core 11 arranged in the corner portion 12 of the fiber-reinforced plastic member 33 according to embodiment 1 are arcs; and FIG. 7 is a side view showing a case where a plurality of cores 11 are arranged in the corner portion 12 of the fiber-reinforced plastic member 33 according to embodiment 1. 1 is a side view showing a case where a core 11 is arranged symmetrically with respect to a thickness centerline 26 at a corner portion 12 of a fiber-reinforced plastic member 33 according to embodiment 1. FIG. 2 is a perspective view schematically showing a fiber-reinforced plastic member 34 molded into a V-shape according to embodiment 1. FIG. 3 is a side view schematically showing a fiber-reinforced plastic member 34 molded into a V-shape according to embodiment 1. FIG. 4 is a schematic diagram for explaining an example of a manufacturing method for a fiber-reinforced plastic member 33 molded into an L-shape according to embodiment 2. FIG. 5A is a view showing a state in which an L-shaped mold is prepared, FIG. 5B is a view showing a state in which a fiber-reinforced plastic sheet 13 is layered on the L-shaped mold, FIG. 5C is a view showing the core 11 placed at a corner portion 12 of the fiber-reinforced sheet 13, and FIG. 5D and FIG. 5E are views showing a state in which the fiber-reinforced plastic sheet 13 is layered one layer at a time. FIG. 6 is a perspective view schematically showing a fiber-reinforced plastic member 35 molded into a hat shape according to embodiment 3. FIG. 7 is a side view schematically showing a fiber-reinforced plastic member 35 molded into a hat shape according to embodiment 3. 10 is a perspective view schematically showing a fiber-reinforced plastic member 36 molded into a U-shape according to embodiment 4. FIG. 11 is a side view schematically showing a fiber-reinforced plastic member 36 molded into a U-shape according to embodiment 4.10A and 10B are schematic diagrams illustrating an example of a manufacturing method for a fiber-reinforced plastic member 36 molded into a U-shape according to embodiment 4. (A) is a diagram illustrating a state in which a mold is prepared, (B) is a diagram illustrating a state in which a fiber-reinforced sheet 13 is layered on the mold, and (C) is a diagram illustrating a state in which a core 11 is placed at a corner portion of the fiber-reinforced sheet 13.

[0033] FIGS. 10A and 10B are schematic diagrams illustrating an example of a manufacturing method for a fiber-reinforced plastic member 36 molded into a U-shape according to embodiment 4. (D) and (E) are diagrams illustrating a state in which the fiber-reinforced plastic sheets 13 are layered one by one.

[0034] FIGS. 10A and 10B are schematic diagrams illustrating a fiber-reinforced plastic member 37 according to embodiment 5.

[0035] FIGS. 10A and 10B are schematic diagrams illustrating a fiber-reinforced plastic member 38 according to embodiment 5.

[0036] FIGS. 10A and 10B are schematic diagrams illustrating a fiber-reinforced plastic member 39 according to embodiment 6.

[0037] FIGS. 10A and 10B are schematic diagrams illustrating a fiber-reinforced plastic member 40 according to embodiment 7.

[0038] FIGS. 10A and 10B are schematic diagrams illustrating a fiber-reinforced plastic member 41 according to embodiment 7.

[0039] FIGS. 11A and 11B are schematic diagrams illustrating a fiber-reinforced plastic member 42 according to embodiment 8.

[0039] FIGS. 11A and 11B are schematic diagrams illustrating a fiber-reinforced plastic member 43 according to embodiment 8.

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the present disclosure is not limited to these embodiments. Furthermore, the components described below can be combined as appropriate. Furthermore, when there are multiple embodiments, the respective embodiments can also be combined.

[0011] The terms used in the following explanation have the following meanings. Fiber-reinforced plastic member: A composite member made from fiber-reinforced plastic. Specifically, a structural member used in artificial satellites and aircraft. Fiber-reinforced plastic part: A laminate in which multiple fiber-reinforced plastic layers are stacked. A fiber-reinforced plastic part has at least two fiber-reinforced plastic layers. Fiber-reinforced plastic layer: Each layer (one layer) stacked in a fiber-reinforced plastic part. A fiber-reinforced plastic part is made up of multiple fiber-reinforced plastic layers stacked together. Fiber-reinforced sheet: A fiber-reinforced plastic sheet before molding. A sheet that is molded in a molding die to become a fiber-reinforced plastic layer. One fiber-reinforced plastic layer is molded from one fiber-reinforced sheet. Core: A member placed at the corner of two fiber-reinforced plastic layers. A member filled in the gap at the corner of two fiber-reinforced plastic layers.

[0012] Embodiment 1 Fig. 1 is a perspective view of a fiber-reinforced plastic member 33 formed by molding fiber-reinforced plastic into an L-shape. The fiber-reinforced plastic member 33 is bent into an L-shape at a corner portion 12 shown in Fig. 1. The radius of curvature R of the corner portion 12 is arbitrary.

[0013] 1, the longitudinal direction of the fiber-reinforced plastic member 33 is defined as the X direction. Directions perpendicular to the longitudinal direction are defined as the Y direction and the Z direction. The X direction, the Y direction, and the Z direction are perpendicular to each other.

[0014] In FIG. 1, the inner side 21 of the L-shape (the inner diameter side of the corner portion 12) has an inner angle K of 90 degrees.

[0015] Figure 2 is a side view showing the portion indicated by the dashed line of the fiber-reinforced plastic member 33 in Figure 1. The shape of each cross section (cross section along the YZ plane) perpendicular to the longitudinal direction of the fiber-reinforced plastic member 33 is the same as that shown in the side view of Figure 2. Points P and Q marked with black circles in Figure 2 are points shown for the sake of convenience of explanation and do not actually exist.

[0016] The fiber-reinforced plastic member 33 has a fiber-reinforced plastic portion 1 and a core 11. The fiber-reinforced plastic portion 1 is a molded product in which a plurality of fiber-reinforced plastic layers 2 are laminated. A fiber-reinforced sheet 13 is used to mold the fiber-reinforced plastic layers 2.

[0017] The fiber-reinforced sheet 13 can be a shapable material such as woven fiber that is not impregnated with resin, or a prepreg material that is already impregnated with resin. Here, prepreg refers to a fiber-reinforced sheet that is pre-impregnated with resin. The fibers used in the fiber-reinforced plastic portion 1 preferably include carbon fiber or glass fiber. The fibers may also include high-strength fibers such as aramid fiber, cellulose nanofiber, or other suitable reinforcing materials. The resin used in the fiber-reinforced plastic portion 1 is preferably an epoxy resin, polyester, or vinyl ester resin. Other thermosetting resins may also be used. Instead of a thermosetting resin, polyetheretherketone (PEEK), polyetherketoneketone (PEKK), or other thermoplastic resins may also be used.

[0018] Although FIG. 2 shows a case where four fiber-reinforced plastic layers 2 are laminated, the number of fiber-reinforced plastic layers 2 is not particularly limited as long as it is plural.

[0019] The fiber-reinforced plastic member 33 has two flat portions 22 and a curved corner portion 12 connecting the two flat portions 22. Hereinafter, the flat portion 22 refers to the portion where all of the fiber-reinforced plastic layers 2 are flat. In FIG. 2 , the flat portion 22 is the rectangular portion surrounded by a dashed line (the portion outside point P) where all four fiber-reinforced plastic layers 2 are flat. The corner portion 12 refers to the portion of the fiber-reinforced plastic portion 1 excluding the two flat portions 22. In FIG. 2 , the corner portion 12 is the fan-shaped portion surrounded by a dashed line (the portion inside point P). Not all of the fiber-reinforced plastic layers 2 in the corner portion 12 are curved. In FIG. 2 , a flat surface exists between points P and Q on the inner and outer surfaces of the first fiber-reinforced plastic layer 2 from the outer side 20 of the corner portion 12. The inner and outer surfaces of the second, third, and fourth fiber-reinforced plastic layers 2 from the outer side 20 of the corner portion 12 are all curved.

[0020] Each fiber-reinforced plastic layer 2 is formed in an L-shape at the corner portion 12. The fiber-reinforced plastic layers 2 are laminated so that the fiber-reinforced plastic portion 1 has an L-shape in any cross section in the X direction on the YZ plane. The core 11 is provided between at least two layers of the plurality of fiber-reinforced sheets 13 that constitute the fiber-reinforced plastic portion 1.

[0021] 3 is a diagram showing the shape of the core 11 according to the first embodiment. The core 11 has the following four surfaces: 1. A core inner surface portion 4 (an inner curved surface portion 14 in FIG. 2 ) 2. A core outer surface portion 5 (an outer curved surface portion 15 in FIG. 2 ) 3. Two core flat surfaces 17

[0022] The core inner surface portion 4 (inner curved surface portion 14) is located on the inside 21 of the corner portion 12. The core inner surface portion 4 (inner curved surface portion 14) is a curved surface that convexly faces the outside 20. The core inner surface portion 4 (inner curved surface portion 14) is a curved surface surrounded by four points P. The core inner surface portion 4 (inner curved surface portion 14) has two straight sides (two straight lines PP) and two curved sides (two curved lines PP). The two straight sides (two straight lines PP) are end sides 7, which are the end portions of the core inner surface portion 4 (inner curved surface portion 14).

[0023] The core outer surface portion 5 (outer curved surface portion 15) is located on the outside 20 of the corner portion 12. The core outer surface portion 5 (outer curved surface portion 15) is a curved surface that convexly faces the outside 20. The core outer surface portion 5 (outer curved surface portion 15) is a curved surface surrounded by four points Q. The core outer surface portion 5 (outer curved surface portion 15) has two straight sides (two straight lines QQ) and two curved sides (two curved lines QQ) as end sides 6. The two straight sides (two straight lines QQ) are end sides 6 and are end portions of the core outer surface portion 5 (outer curved surface portion 15).

[0024] The core flat surface 17 is a rectangular plane bounded by two points P and two points Q. The core flat surface 17 exists on both sides of the core outer surface 5 (outer curved surface 15). The core flat surface 17 is a rectangular plane that exists between an edge 7 (straight line PP) at the end of the core inner surface 4 (inner curved surface 14) and an edge 6 (straight line QQ) at the end of the core outer surface 5 (outer curved surface 15). The core flat surface 17 and the core inner surface 4 (inner curved surface 14) are connected by the edge 7 (straight line PP). The core flat surface 17 and the core outer surface 5 (outer curved surface 15) are connected by the edge 6 (straight line QQ).

[0025] The core 11 is preferably made of a lightweight foamed resin material or the same material as the fiber-reinforced plastic portion 1. The material of the core 11 is preferably a fiber-reinforced composite material. Specifically, the material of the core 11 is preferably a fiber-reinforced plastic (FRP) such as carbon fiber-reinforced plastic (CFRP) or glass fiber-reinforced plastic (GFRP). Alternatively, the material may be a ceramic matrix composite (CMC). Another appropriate fiber-reinforced plastic or a heterogeneous composite material may also be used.

[0026] The core inner surface portion 4 does not have to be a curved surface. The inner curved surface portion 14 is a suitable example of the core inner surface portion 4, and the following description will be given using the inner curved surface portion 14. The core outer surface portion 5 does not have to be a curved surface. The outer curved surface portion 15 is a suitable example of the core outer surface portion 5, and the following description will be given using the outer curved surface portion 15.

[0027] The arrangement of the core 11 will be described with reference to Figure 2. In Figure 2, the core flat surface 17 is connected to the inner curved surface 14 and the outer curved surface 15 at points P and Q. The inner curved surface 14 is located on the inside 21 of the corner portion 12 of the fiber-reinforced plastic portion 1. The outer curved surface 15 is located on the outside 20 of the corner portion 12 of the fiber-reinforced plastic portion 1. The two core flat surfaces 17 are surfaces that connect the inner curved surface 14 and the outer curved surface 15. The planes of the two core flat surfaces 17 are parallel to the planes of the two flat surfaces 22 of the fiber-reinforced plastic portion 1, respectively.

[0028] Of the layers adjacent to the core 11, the layer on the outer side 20 of the fiber-reinforced plastic part 1 is defined as the reference layer 19. The reference layer 19 is an outer layer on the outer side of the core. The core 11 has a shape that follows the inner surface of the corner portion 12 of the fiber-reinforced plastic layer 2 that serves as the reference layer 19 and part of the inner surface of the flat portion 22 of the fiber-reinforced plastic layer 2 that serves as the reference layer 19.

[0029] The inner surface 21 of the reference layer 19 has the following three surfaces: 1. Reference flat surface portion 18 2. Reference curved surface portion 58 3. Reference flat surface portion 18 The reference flat surface portion 18 and the reference curved surface portion 58 are in contact with each other at point Q.

[0030] Of the layers adjacent to the core 11, the layer on the inside 21 is referred to as the inner layer 59. The inner layer 59 is the layer that is one layer inward from the reference layer 19. The outer surface 20 of the inner layer 59 has the following three surfaces: 1. Inner layer flat surface portion 28 2. Inner layer curved surface portion 55 3. Inner layer flat surface portion 28 The inner layer flat surface portion 28 and the inner layer curved surface portion 55 are in contact at point P.

[0031] The end of the inner curved surface portion 14 and the end of the outer curved surface portion 15 contact the reference flat surface portion 18. The outer curved surface portion 15 of the core 11 contacts the reference curved surface portion 58 of the reference layer 19 over its entire surface without any gaps. The inner curved surface portion 14 of the core 11 contacts the inner layer curved surface portion 55 of the inner layer 59 over its entire surface without any gaps. The core flat surface portion 17 of the core 11 contacts the reference flat surface portion 18 of the reference layer 19 over its entire surface without any gaps.

[0032] Points P and Q exist on the reference flat surface portion 18. Point P is the intersection of the inner flat surface portion 28 and the inner curved surface portion 55. Point Q is the intersection of the reference flat surface portion 18 and the reference curved surface portion 58. In FIG. 2, the relationship of lengths is as follows: Length of core flat surface portion 17 = Length of reference flat surface portion 18 - Length of inner flat surface portion 28

[0033] It is desirable that at least one of the inner curved surface portion 14 and the outer curved surface portion 15 of the core 11 has a cross-sectional shape that is an arc.

[0034] The curved surface of the outer curved surface portion 15 in Fig. 4 is a part of the curved surface of a cylinder that is tangent to the reference flat surface portion 18 of the reference layer 19. The cross-sectional shape of the outer curved surface portion 15 in Fig. 4 is an arc with an interior angle of 90 degrees. The cross-sectional shape of the outer curved surface portion 15 is an arc of an inscribed circle 24 that is tangent to the reference flat surface portion 18 of the reference layer 19. The cross-sectional shape of the inner curved surface portion 14 may be a part of an elliptical arc or a part of a parabola, or may be a part of a hyperbola as long as the corner angle is 90 degrees or more.

[0035] The curved surface of the inner curved surface portion 14 of the core 11 in Figure 5 is part of the curved surface of a cylinder that is tangent to the reference flat surface portion 18 of the reference layer 19. The cross-sectional shape of the inner curved surface portion 14 in Figure 5 is an arc with an interior angle of 90 degrees. The cross-sectional shape of the inner curved surface portion 14 is the arc of an inscribed circle 24 that is tangent to the inner layer flat surface portion 28 of the inner layer 59. The cross-sectional shape of the inner curved surface portion 14 may be part of an elliptical arc or part of a parabola, or may be part of a hyperbola as long as the corner angle is 90 degrees or more.

[0036] As shown in FIGS. 4 and 5, at least one of the inner curved surface portion 14 and the outer curved surface portion 15 may be a part of the curved surface of a cylinder that is in contact with the reference flat surface portion 18 of the reference layer 19 .

[0037] The inner curved surface portion 14 and the outer curved surface portion 15 of the core 11 in Figure 6 are part of the curved surfaces of a cylinder of different diameters that are tangent to the reference flat surface portion 18. In the core 11 in Figure 6, the cross-sectional shapes of the outer curved surface portion 15 and the inner curved surface portion 14 are both arcs with an interior angle of 90 degrees. In Figure 6, the radius R1 of the inscribed circle 24 that constitutes the inner curved surface portion 14 is larger than the radius R2 of the inscribed circle 25 that constitutes the outer curved surface portion 15. Furthermore, the radius R2 of the inscribed circle 25 that constitutes the outer curved surface portion 15 is larger than the thickness W of one layer of the fiber-reinforced plastic layer 2. In particular, the radius R2 of the inscribed circle 25 that constitutes the outer curved surface portion 15 is larger than the thickness W of the reference layer 19 and the inner layer 59. By making the radius of curvature of the inner curved surface portion 14 larger than the thickness W of one layer, stress concentration can be prevented.

[0038] 7 is a diagram showing a plurality of cores 11 arranged in a corner portion 12. In FIG. 7, one core 11 is located between the first and second layers and between the second and third layers from the outer side 20 of the fiber-reinforced plastic layers 2, which consist of a total of three layers. Although not shown, one core 11 may be located between the first and second layers, between the second and third layers, between the fifth and sixth layers, and between the sixth and seventh layers of the fiber-reinforced plastic layers 2, which consist of a total of seven layers. Furthermore, one core 11 may be located between the first and second layers, between the third and fourth layers, between the fourth and fifth layers, and between the sixth and seventh layers of the fiber-reinforced plastic layers 2, which consist of a total of seven layers. The number of cores 11 may be one or more. When stacking the fiber-reinforced sheets 13, gaps are likely to form between the first and second layers from the outside 20 of the corner portion 12, so it is preferable that at least one of the multiple cores 11 be positioned between the first and second layers.

[0039] 8 is a diagram showing the cores 11 arranged symmetrically with respect to the thickness center line 26 of the fiber-reinforced plastic layer 2. In Fig. 8, the thickness center line 26 of the fiber-reinforced plastic layer 2, which consists of a total of three layers, is present in the second layer, so one core 11 is arranged from the outside 20 between the first and second layers and between the second and third layers.

[0040] Although not shown, the thickness center line 26 of the fiber-reinforced plastic layers 2, which consist of a total of six layers, exists between the third and fourth layers, so when the core 11 is placed between the first and second layers, the core 11 is placed between the fifth and sixth layers. When the core 11 is placed between the second and third layers, the core 11 is placed between the fourth and fifth layers.

[0041] When multiple cores 11 are present between the fiber-reinforced plastic layers 2, at least one of the cores 11 has a core flat surface 17. The other cores 11 do not have to have a core flat surface 17. Also, there may be a core 11 that has only one core flat surface 17, rather than two core flat surfaces 17. Alternatively, all of the cores 11 may have two core flat surfaces 17.

[0042] ***Features of First Embodiment*** The features of the first embodiment are described below.

[0043] The fiber-reinforced plastic member 33 has a fiber-reinforced plastic portion 1 having two flat portions 22 and a curved corner portion 12 connecting the two flat portions 22. The fiber-reinforced plastic portion 1 has a plurality of fiber-reinforced plastic layers 2. The fiber-reinforced plastic layers 2 are made of a fiber-reinforced sheet 13. The fiber-reinforced plastic member 33 has at least one core 11 disposed between at least two of the plurality of fiber-reinforced plastic layers 2. The core 11 has an inner curved surface portion 14 located on the inside 21 of the corner portion 12, an outer curved surface portion 15 located on the outside 20 of the corner portion 12, and two core flat portions 17 connecting the inner curved surface portion 14 and the outer curved surface portion 15. The surfaces of the two core flat portions 17 are arranged parallel to the surfaces of the two flat portions 22, respectively.

[0044] Of the two layers adjacent to the core 11, the layer on the outside of the corner portion 12 is defined as the reference layer 19. The end edge 7 of the inner curved surface portion 14 and the end edge 6 of the outer curved surface portion 15 of the core 11 are in straight line contact with the reference flat portion 18 of the reference layer 19.

[0045] The cross-sectional shape of at least one or both of the inner curved surface portion 14 and the outer curved surface portion 15 of the core 11 is an arc of an inscribed circle that is tangent to the reference flat surface portion 18 of the reference layer 19 .

[0046] The cross-sectional shapes of the inner curved surface portion 14 and the outer curved surface portion 15 of the core 11 are arcs of inscribed circles of different radii that are tangent to the reference flat surface portion 18 of the reference layer 19 .

[0047] The radius R2 of the inscribed circle that forms the inner curved surface portion 14 is larger than the thickness of one layer of the fiber reinforced plastic layer 2.

[0048] At least two cores 11 are provided, and at least one fiber-reinforced plastic layer 2 is provided between the cores 11 .

[0049] At least one core 11 is disposed between the first and second fiber-reinforced plastic layers 2 .

[0050] At least two cores 11 are positioned between layers symmetrical with respect to the center of thickness of the fiber-reinforced plastic portion 1. By positioning the multiple cores 11 symmetrically with respect to the center of thickness, stress concentration in the corner portion 12 in the thickness direction can be suppressed.

[0051] The core 11 is made of a foamed resin material or a fiber-reinforced plastic. If it is made of a foamed resin material, it can be made lighter. If it is made of a fiber-reinforced plastic, it can be made of the same material as the fiber-reinforced plastic layer 2, so the material properties can be unified.

[0052] ***Effects of embodiment 1*** The entire surface of the outer curved surface portion 15 of the core 11 and the entire surfaces of the two core flat surfaces 17 contact the reference curved surface portion 58 and the reference flat surface portion 18 of the reference layer 19, thereby preventing stress from concentrating on the end portion (edge ​​7 and its vicinity) of the core 11.

[0053] In particular, since the flat portion 17 of the core 11 is in flat contact with the flat portion 18 of the reference layer 19, stress is not concentrated at the end of the core 11, and strength can be maintained.

[0054] If the core 11 does not have a core flat surface 17 and the outer curved surface 15 of the core 11 has a shape that follows only the reference curved surface 58 of the reference layer 19, it is difficult to stack the cores 11 without gaps, as the gaps extend to the reference flat surface 18 of the reference layer 19.

[0055] According to this embodiment, the end edge 7 of the inner curved surface portion 14 and the end edge 6 of the outer curved surface portion 15 of the core 11 are in contact with the reference flat portion 18 of the reference layer 19, so that the stress is dispersed to the end edge 7 and the end edge 6, preventing the stress from concentrating at the end of the core 11 and causing a decrease in the stress of the core 11.

[0056] If the length of the core flat portion 17 in the cross section is longer than the length of the reference flat portion 18, stress may be concentrated at the end of the fiber-reinforced plastic portion 1, and this may cause peeling of the fiber-reinforced plastic layer 2. Therefore, it is desirable that the length of the core flat portion 17 is shorter than the length of the reference flat portion 18.

[0057] ***Modification of First Embodiment*** Fig. 9 is a perspective view of a fiber-reinforced plastic member 34 formed by molding fiber-reinforced plastic into a V-shape. The fiber-reinforced plastic member 34 is bent into a V-shape at the corner portion 12.

[0058] As shown in Fig. 10, the fiber-reinforced plastic layer 2 may be laminated by bending it into a V-shape, in which the inner angle K of the corner portion 12 is smaller than when it is bent into an L-shape. The inner angle K of the corner portion 12 may be an acute angle or an obtuse angle. The inner angle of the corner portion 12 is not limited.

[0059] In FIG. 10, one core 11 is located between the first and second layers and one core 11 is located between the second and third layers from the outside 20 of the fiber reinforced plastic layers 2, which are made up of a total of three layers.

[0060] Embodiment 2 Next, a method for manufacturing a fiber-reinforced plastic member 33 according to embodiment 1 will be described with reference to Figure 11. Here, a method for manufacturing a fiber-reinforced plastic part 1 having one corner portion 12 by bending a fiber-reinforced sheet 13 into an L shape will be described. The fiber-reinforced sheet 13 is a fiber-reinforced plastic sheet.

[0061] In the following, a case where fiber reinforced plastic is bent and molded will be described as an example, but the manufacturing method is not limited to this.

[0062] [Preparation Step] In the preparation step, as shown in Fig. 11 (A), a molding die 23 having an L-shaped side surface in the YZ plane is prepared. The molding die 23 is a jig used when laminating the fiber reinforced sheet 13. A release treatment is performed on the lamination surface of the molding die 23 on which the fiber reinforced sheet 13 is to be laminated. As a method of release treatment, it is desirable to apply a release agent to the lamination surface, or to lay a release sheet on the lamination surface and fix the release sheet to the molding die 23 with Kapton tape.

[0063] [Molding process] In the molding process, a shapable fiber-reinforced sheet 13 is placed on the surface of an L-shaped mold 23 that has been subjected to a release treatment. Then, pressure is applied to the fiber-reinforced sheet 13 with a roller (not shown) to mold the fiber-reinforced sheet 13 into an L-shape ( FIG. 11(B) ). As a result, the fiber-reinforced plastic layer 2 is molded from the fiber-reinforced sheet 13. When molding the second and subsequent layers, each layer is pressed together to eliminate gaps between the fiber-reinforced sheets 13.

[0064] It is preferable to use a roller for pressing the fiber reinforced sheet 13. Any method for pressing the fiber reinforced sheet 13 can be used as long as it can remove voids between the fiber reinforced sheets 13 and improve adhesion.

[0065] Next, the core 11 is placed in the corner portion 12 of the fiber-reinforced sheet 13 (FIG. 11(C)). The core 11 is preferably made of a foamed resin material or fiber-reinforced plastic. If it is a foamed resin material, it can be made lighter. If it is a fiber-reinforced plastic, it can be made of the same material as the fiber-reinforced sheet 13, so the material properties can be unified. The core 11 is created in advance so that the shape of the outside 20 matches the shape of the inside 21 of the reference layer 19. In other words, the outer curved surface portion 15 of the core 11 is created so as to be in close contact with the reference curved surface portion 53, and the two core flat surfaces 17 are created so as to be in close contact with the two reference flat surfaces 18.

[0066] When placing the core 11, the fiber-reinforced sheet 13 on the outer side 20 of the core 11 becomes the reference layer 19. When placing the core 11, the outer curved surface 15 of the core 11 is brought into close contact with the reference curved surface 53, and the two flat surfaces 17 of the core are brought into close contact with the two reference flat surfaces 18. Next, the core 11 is pressed onto the fiber-reinforced sheet 13. When pressing the core 11, it is desirable to lay a release film (not shown) on the fiber-reinforced sheet 13 and the core 11, and then press the core 11 onto the fiber-reinforced sheet 13 from above the release film. Instead of the release film, a mat such as a sheet that can be easily peeled off after pressing may be laid. After pressing the core 11 onto the fiber-reinforced sheet 13, the release film or mat is removed. Then, at least one layer of fiber-reinforced sheet 13 is laminated onto the fiber-reinforced sheet 13 and the core 11, and pressed together (FIGS. 11(D) and 11(E)).

[0067] [Resin Impregnation Step] When a dry fiber reinforced sheet 13 that is not impregnated with resin is used as the fiber reinforced sheet 13, the fiber reinforced sheet 13 is impregnated with resin after molding of the fiber reinforced sheet 13. When a wet fiber reinforced sheet 13 that is impregnated with resin is used as the fiber reinforced sheet 13, there is no need to impregnate the fiber reinforced sheet 13 with resin.

[0068] If the corner portion 12 needs to be further compressed, a sealant may be applied to the center of the corner portion 12 to enhance adhesion. The sealant is preferably applied so that it extends in the longitudinal direction (X direction) of the corner portion 12. Furthermore, rather than applying the sealant directly onto the fiber-reinforced sheet 13, it is preferable to apply it after sandwiching a release film between them. This makes it easy to remove the sealant from the fiber-reinforced plastic portion 1 after curing, and prevents the generation of a peel load.

[0069] [Curing step] When a dry, shapable fiber-reinforced sheet 13 is used, the fiber-reinforced sheet 13 is cured after the resin impregnation step. When a prepreg is used as the fiber-reinforced sheet 13, the fiber-reinforced sheet 13 is cured after the molding step without the resin impregnation step. The curing is carried out in an oven or autoclave while evacuating. The molding profile is set under molding conditions suitable for the prepreg sheet. After molding in the oven or autoclave, the laminated fiber-reinforced sheet 13 is removed from the lamination surface of the mold 23.

[0070] ***Features of Second Embodiment*** A method for manufacturing a fiber-reinforced plastic member 33 having a core 11 disposed in a corner portion 12 is as follows: a preparation step of preparing a molding die having a release-treated surface on which the fiber-reinforced plastic (fiber-reinforced sheet 13) is to be laminated; a molding step of, after the preparation step, laminating the fiber-reinforced plastic (fiber-reinforced sheet 13) on the molding die, disposing the core 11 in the corner portion 12 of the fiber-reinforced plastic (fiber-reinforced sheet 13), and laminating the fiber-reinforced plastic (fiber-reinforced sheet 13) on the molding die, thereby molding a fiber-reinforced plastic part 1 having the fiber-reinforced plastic (fiber-reinforced sheet 13) laminated thereon; a resin impregnation step of, after the molding step, impregnating the fiber-reinforced sheet 13 with resin if a fiber-reinforced sheet 13 that was not impregnated with resin in the molding step is laminated; and a curing step of curing the fiber-reinforced plastic part 1 after the molding step or the resin impregnation step.

[0071] ***Effects of Embodiment 2*** Embodiment 2 has the following effects: The core 11 is placed in the reference layer with the outer curved surface 15 and the two core flat surfaces 17 of the core 11 aligned with the reference curved surface 53 and the two reference flat surfaces 18 of the reference layer, respectively. This allows the core 11 to be placed in the desired position, and the fiber-reinforced plastic can be stacked without gaps.

[0072] Furthermore, according to this embodiment, since the core 11 has the core flat surface 17, it is possible to stack the fiber reinforced sheet 13 without any gaps, even in gaps that extend to the reference flat surface 18 of the reference layer 19.

[0073] Furthermore, according to this embodiment, the shape of the outside 20 of the core 11 matches the shape of the inside 21 of the reference layer 19, so the core 11 can be accurately positioned in the corner portion 12 of the reference layer 19. In particular, the presence of the core flat portion 17 on the core 11 makes it possible to place the core 11 in the desired position without the core 11 being displaced from the corner portion 12.

[0074] If core 11 is crescent-shaped and formed only by curved surfaces, it has a shape with no flat surfaces, so core 11 moves along the arc of reference curved surface portion 58, making it difficult to place core 11 in the desired position. With core 11 having outer curved surface portion 15 and core flat surface portion 17 that intersects with outer curved surface portion 15, as in the case of core 11 of the present embodiment, the risk of core 11 shifting when placing core 11 relative to reference layer 19 can be eliminated.

[0075] ***Modification of Embodiment 2*** In this embodiment, the case where the fiber-reinforced plastic (fiber-reinforced sheet 13) is bent into an L shape in the molding process has been described as an example, but the bending method is not limited to this. As shown in Fig. 10, instead of bending the fiber-reinforced plastic (fiber-reinforced sheet 13) into an L shape, it may be bent into a V shape so that the interior angle K of the corner portion 12 is an acute angle, and then laminated and molded. Furthermore, it may be possible to fold the fiber-reinforced plastic (fiber-reinforced sheet 13) in the opposite direction to the L-shape, so as to be bent into a Z shape, and then laminated and molded.

[0076] Third Embodiment Next, a hat-shaped fiber-reinforced plastic member 35 according to a third embodiment and a method for manufacturing the same will be described. In the third embodiment, in order to avoid redundant description, only parts that differ from the above-described embodiments will be described, and parts that have the same configuration as the above-described embodiments will be denoted by the same reference numerals.

[0077] Fig. 12 is a diagram showing a hat-shaped fiber-reinforced plastic member 35 having a plurality of corner portions 12. Fig. 13 is a side view of the fiber-reinforced plastic member 35 according to embodiment 3. The fiber-reinforced plastic member 35 has four corner portions 12. Here, a case will be described in which no core 11 is placed in the upper corner portions 12a and 12b, and a core 11 is placed in the lower corner portions 12c and 12d.

[0078] The hat-shaped forming die (not shown) is convex and has four corner portions 12. As the hat-shaped forming die, a die in which the four corner portions 12 are each bent at 90 degrees is used.

[0079] [Preparation Step] In the preparation step, a hat-shaped mold is prepared. The subsequent preparation steps are the same as those in the second embodiment, and therefore, a description thereof will be omitted.

[0080] [Molding process] In the molding process, each layer of fiber-reinforced sheet 13 is pressed onto the surface of a hat-shaped mold that has been subjected to a mold release treatment, eliminating gaps between the fiber-reinforced sheets 13. Because the hat-shaped mold has a total of four corner portions 12, when the fiber-reinforced sheet 13 is laminated onto the hat-shaped mold 23, the fiber-reinforced sheet 13 is folded at four locations.

[0081] Cores 11 are placed in the corners 12c and 12d at the same time. Here, the upper corners 12a and 12b are only required to be shaped into a convex shape, so they do not need a core 11. At least one core 11 is placed in at least one of the lower corners 12c and 12d.

[0082] In FIG. 13, one core 11 is disposed at each of different corner portions 12 (corner portion 12c and corner portion 12d) between the first and second layers of the fiber reinforced plastic layer 2.

[0083] The subsequent step of laminating the fiber-reinforced sheets 13 is the same as that of the second embodiment except for folding the sheets at four locations, and therefore the description thereof will be omitted. The subsequent resin impregnation step and curing step are the same as those of the second embodiment, and therefore the description thereof will be omitted.

[0084] Although the hat-shaped molding die 23 is described as having four corners 12 bent at 90 degrees, the interior angles of the corners 12 may be less than 90 degrees or greater than 90 degrees. The interior angles of the four corners 12 may also be different.

[0085] ***Effects of Embodiment 3*** According to embodiment 3, the following effects are achieved: The corner portions 12c and 12d at the bottom of the hat shape can be simultaneously reinforced with the core 11. This eliminates the need to reinforce each corner portion 12 individually.

[0086] Fourth Embodiment Next, a U-shaped fiber-reinforced plastic member 36 according to a fourth embodiment and a method for manufacturing the same will be described. In the fourth embodiment, in order to avoid redundant description, only parts that differ from the above-described embodiments will be described, and parts that have the same configuration as the above-described embodiments will be denoted by the same reference numerals.

[0087] FIG. 14 shows a U-shaped fiber-reinforced plastic member 36 having a plurality of corner portions 12.

[0088] 15 is a side view of a fiber-reinforced plastic member 36 according to embodiment 3. The fiber-reinforced plastic member 36 has two corner portions 12. Here, a case where a core 11 is disposed in the corner portions 12 e and 12 f will be described.

[0089] The U-shaped forming die 23 is a concave shape with two corner portions 12. As the U-shaped forming die 23, a die in which the two corner portions 12 are each bent at 90 degrees is used.

[0090] A method for manufacturing the fiber-reinforced plastic member 36 will be described with reference to Figures 16 and 17. Figures 16 and 17 show a case where the fiber-reinforced sheet 13 is bent into a U-shape.

[0091] [Preparation Step] In the preparation step, a U-shaped forming die 23 is prepared (FIG. 16A). The subsequent preparation steps are the same as those in the first embodiment, and therefore, a description thereof will be omitted.

[0092] [Molding process] In the molding process, each layer of fiber-reinforced sheet 13 is pressed onto the surface of a U-shaped mold 23 that has been subjected to a mold release treatment, eliminating gaps between the fiber-reinforced sheets 13 (FIG. 16(B)). Because mold 23 has two corners 12e and 12f, fiber-reinforced sheet 13 is folded at these two locations when being laminated onto U-shaped mold 23.

[0093] The cores 11 are simultaneously placed in the corners 12e and 12f (FIG. 16C). The subsequent process of stacking the fiber-reinforced sheets 13 (FIGS. 17D and 17E) is the same as that in the second embodiment except for the two folding positions, and therefore a description thereof will be omitted.

[0094] There are two corner portions 12e and 12f, and at least one core 11 is disposed in at least one corner portion 12.

[0095] In FIG. 16, one core 11 is disposed at each of different corner portions 12 (corner portion 12 e and corner portion 12 f ) between the first and second layers of the fiber reinforced plastic layer 2 .

[0096] The subsequent resin impregnation and curing steps are the same as those in the second embodiment, and therefore the explanation will be omitted.

[0097] Although the U-shaped molding die 23 is described as having two corners 12 bent at 90 degrees, the interior angles of the corners 12 may be less than 90 degrees or greater than 90 degrees. The interior angles of the two corners 12 may also be different.

[0098] ***Effects of Embodiment 4*** According to Embodiment 4, the following effects are achieved: The corner portions 12e, 12f at the bottom of the U-shape can be simultaneously reinforced with the core 11. This eliminates the need to reinforce each corner portion 12 individually.

[0099] ***Variant of embodiment 4*** The cross-sectional shape of the fiber reinforced plastic member does not have to be U-shaped, but may be concave, stepped, C-shaped, H-shaped, F-shaped, M-shaped, N-shaped, W-shaped, Z-shaped, or any other shape.

[0100] Fifth Embodiment Figure 18 is a side view that schematically shows a fiber-reinforced plastic member 37 according to a fifth embodiment. The fiber-reinforced plastic member 37 in Figure 18 is obtained by removing one flat portion 22 from the fiber-reinforced plastic part 1 according to the first embodiment shown in Figure 2. In Figure 18, one flat portion 22 is missing, so the inner layer flat portion 28 is absent on one side of the inner layer 59. A reduced reference flat portion 18 remains on one side of the reference layer 19, and in a cross section along the YZ plane, one core flat portion 17 and one reference flat portion 18 have the same length.

[0101] Figure 19 is a side view that schematically shows a fiber-reinforced plastic member 38 according to embodiment 5. The fiber-reinforced plastic member 38 in Figure 19 is obtained by removing two flat portions 22 from the fiber-reinforced plastic part 1 according to embodiment 1 shown in Figure 2. In Figure 19, both flat portions 22 are missing, so there are no inner layer flat portions 28 in either of the inner layers 59. Smaller reference flat portions 18 remain in both of the reference layers 19, and in a cross section along the YZ plane, both core flat portions 17 and both reference flat portions 18 have the same length.

[0102] ***Effects of embodiment 5*** Even if one or both of the fiber-reinforced plastic parts 1 do not have a flat portion 22, the shape of the outside 20 of the core 11 matches the shape of the inside 21 of the reference layer 19, so the same effect as in embodiment 1 can be achieved.

[0103] Sixth Embodiment Figure 20 is a side view schematically showing a fiber-reinforced plastic member 39 according to a sixth embodiment. The fiber-reinforced plastic member 39 of Figure 20 is a member in which the shape of the inner curved surface portion 14 of the core 11 according to the first embodiment shown in Figure 4 has been changed. The core 11 shown in Figure 20 has an inner curved surface portion 14, an outer curved surface portion 15, and one core flat surface portion 17. In Figure 20, point P and point Q on one side coincide. Because point P and point Q on one side coincide, there is no core flat surface 17 on one side of the core 11.

[0104] ***Effects of Embodiment 6*** Even if one of the core flat surfaces 17 is missing, the outer curved surface 15 of the core 11 and the remaining core flat surface 17 can be aligned with the reference curved surface 53 and one reference flat surface 18 of the reference layer, respectively, and the core 11 can be placed in the reference layer. If there is at least one core flat surface 17, the same effect as in Embodiment 1 can be achieved.

[0105] Seventh Embodiment Fig. 21 is a side view schematically showing a fiber-reinforced plastic member 40 according to a seventh embodiment. The fiber-reinforced plastic member 40 in Fig. 21 is obtained by replacing the inner curved surface portion 14 of the core 11 according to the first embodiment shown in Fig. 4 with an inner flat surface portion 44.

[0106] The core 11 in FIG. 21 has the following four surfaces: 1. An inner flat surface 44 as the core inner surface 4; 2. An outer curved surface 15 as the core outer surface 5; and 3. Two flat core surfaces 17.

[0107] Fig. 22 is a side view schematically showing a fiber-reinforced plastic member 41 according to embodiment 7. The fiber-reinforced plastic member 41 in Fig. 22 is obtained by replacing the inner curved surface portion 14 of the core 11 according to embodiment 6 shown in Fig. 20 with an inner flat surface portion 44.

[0108] The core 11 in FIG. 22 has the following three surfaces: 1. an inner flat surface 44 as the core inner surface 4; 2. an outer curved surface 15 as the core outer surface 5; and 3. one core flat surface 17.

[0109] The core 11 shown in Figures 21 and 22 has an inner flat surface 44, an outer curved surface 15, and at least one core flat surface 17. As shown in Figures 21 and 22, the core inner surface 4 does not have to be curved and can be flat. The outside of the corner portion 12 of the inner layer 59 does not have to be curved and can be flat. The shapes of the outer surface of the corner portion 12 of the inner layer 59 and the inner surface of the corner portion 12 of the core 11 (core inner surface 4) can be any shape as long as there is no gap between them.

[0110] ***Effects of Embodiment 7*** Even with a core 11 in which the inner curved surface portion 14 has been changed to the inner flat surface portion 44, the core 11 can be positioned in the reference layer 19 by the outer curved surface portion 15 and the core flat surface portion 17, and the same effect as in Embodiment 1 can be achieved. By changing the inner curved surface portion 14 to the inner flat surface portion 44, the core 11 becomes thicker, and the strength of the corner portion 12 can be improved by the core 11.

[0111] Embodiment 8 Fig. 23 is a side view schematically showing a fiber-reinforced plastic member 42 according to embodiment 8. The fiber-reinforced plastic member 42 in Fig. 23 is obtained by replacing the outer curved surface portion 15 of the core 11 according to embodiment 7 shown in Fig. 21 with an outer flat surface portion 45.

[0112] The core 11 in FIG. 23 has the following four surfaces: 1. an inner flat surface 44 as the core inner surface 4; 2. an outer flat surface 45 as the core outer surface 5; and 3. two core flat surfaces 17.

[0113] Fig. 24 is a side view schematically showing a fiber-reinforced plastic member 43 according to embodiment 8. The fiber-reinforced plastic member 41 in Fig. 24 is obtained by replacing the outer curved surface portion 15 of the core 11 according to embodiment 7 shown in Fig. 22 with an outer flat surface portion 45.

[0114] The core 11 in FIG. 24 has the following three surfaces: 1. an inner flat surface 44 as the core inner surface 4; 2. an outer flat surface 45 as the core outer surface 5; and 3. one core flat surface 17.

[0115] The core 11 shown in Figures 23 and 24 has an inner flat surface 44, an outer flat surface 45, and at least one core flat surface 17. As shown in Figures 23 and 24, the core outer surface 5 does not have to be curved and can be flat. The inside of the corner 12 of the reference layer 19 does not have to be curved and can be flat. The shapes of the inner surface of the corner 12 of the reference layer 19 and the outer surface of the corner 12 of the core 11 (core outer surface 5) can be any shape as long as there is no gap between them.

[0116] ***Effects of Embodiment 8*** Even with core 11 in which outer curved surface portion 15 has been changed to outer flat surface portion 45, the shapes of outer flat surface portion 45 and core flat surface portion 17 match the shapes of reference layer 19, so core 11 can be placed in reference layer 19, achieving the same effect as in embodiment 1. By changing the inside of corner portion 12 of reference layer 19 from a curved surface to a flat surface, corner portion 12 of reference layer 19 becomes thicker, and the strength of corner portion 12 can be improved.

[0117] Various aspects of the present disclosure are described below as appendices. (Appendix 1) A fiber-reinforced plastic component comprising: a fiber-reinforced plastic component made of a plurality of fiber-reinforced plastic layers and having a corner portion; and a core disposed at the corner portion and provided between two of the plurality of fiber-reinforced plastic layers, wherein the core has: a core inner surface portion located inside the corner portion; a core outer surface portion located outside the corner portion; and a core flat surface portion disposed between an end of the core inner surface portion and an end of the core outer surface portion and in surface contact with the flat surface portion. (Appendix 2) The fiber-reinforced plastic component according to Appendix 1, wherein the core inner surface portion is an inner curved surface portion, and the core outer surface portion is an outer curved surface portion, and the outer fiber-reinforced plastic layer of the two fiber-reinforced plastic layers is a reference layer having a reference flat surface portion and a reference curved surface portion, and the ends of the inner curved surface portion and the outer curved surface portion contact the reference flat surface portion. (Appendix 3) The fiber-reinforced plastic component according to Appendix 2, wherein at least one of the inner curved surface portion and the outer curved surface portion is part of the curved surface of a cylinder that is in contact with the reference flat surface portion of the reference layer. (Appendix 4) The fiber-reinforced plastic component according to Appendix 2 or 3, wherein the inner curved surface portion and the outer curved surface portion are part of the curved surfaces of cylinders of different diameters that are in contact with the reference flat surface portion. (Appendix 5) The fiber-reinforced plastic component according to any one of Appendixes 2 to 4, wherein the radius of curvature of the inner curved surface portion is larger than the thickness of each of the plurality of fiber-reinforced plastic layers. (Appendix 6) The fiber-reinforced plastic component according to any one of Appendixes 1 to 5, which has two of the cores and at least one fiber-reinforced plastic layer between the two cores. (Appendix 7) The fiber-reinforced plastic component according to any one of Appendixes 1 to 6, wherein the core is arranged between a first fiber-reinforced plastic layer and a second fiber-reinforced plastic layer from the outside of the corner portion. (Appendix 8) A fiber-reinforced plastic member according to any one of Appendices 1 to 6, which has two cores, and the two cores are arranged between the same layer and the next layer from the center of the plate thickness of the fiber-reinforced plastic part toward the inside and outside.(Supplementary Note 9) The fiber-reinforced plastic member according to any one of Supplementary Notes 1 to 8, wherein the core is made using a foamed resin material or fiber-reinforced plastic. (Supplementary Note 10) A method for manufacturing a fiber-reinforced plastic member, comprising: a preparation step of preparing a mold for molding a corner portion, and a molding step of, after the preparation step, placing a fiber-reinforced sheet in the mold and molding a corner portion in the fiber-reinforced sheet to form an outer fiber-reinforced plastic layer, placing a core inside the corner portion, and further placing another fiber-reinforced sheet in the mold so as to cover the outer fiber-reinforced plastic layer and the core, and molding a corner portion in the other fiber-reinforced sheet while covering the outer fiber-reinforced plastic layer and the core with the other fiber-reinforced sheet, to form an inner fiber-reinforced plastic layer.

[0118] 1 Fiber reinforced plastic portion, 2 Fiber reinforced plastic layer, 4 Core inner surface portion, 5 Core outer surface portion, 6 Edge, 7 Edge, 11 Core, 12 Corner portion, 13 Fiber reinforced sheet, 14 Inner curved surface portion, 15 Outer curved surface portion, 17 Core flat surface portion, 18 Reference flat surface portion, 19 Reference layer, 20 Outer side, 21 Inner side, 22 Flat surface portion, 23 Molding mold, 24 Inscribed circle, 25 Inscribed circle, 26 Plate thickness center line, 28 Inner layer flat surface portion, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43 Fiber reinforced plastic member, 44 Inner flat surface portion, 45 Outer flat surface portion, 55 Inner layer curved surface portion, 58 Reference curved surface portion, 59 Inner layer.

Claims

1. A fiber-reinforced plastic component comprising: a fiber-reinforced plastic portion made of a plurality of fiber-reinforced plastic layers and having a corner portion; and a core disposed at the corner portion and provided between two of the plurality of fiber-reinforced plastic layers, wherein the core has a core inner surface portion located inside the corner portion, a core outer surface portion located outside the corner portion, and a core flat surface portion located between an end of the core inner surface portion and an end of the core outer surface portion.

2. A fiber-reinforced plastic component according to claim 1, wherein the inner surface of the core is an inner curved surface, the outer surface of the core is an outer curved surface, the outer fiber-reinforced plastic layer of the two fiber-reinforced plastic layers is a reference layer having a reference flat surface and a reference curved surface, and the ends of the inner curved surface and the outer curved surface are in contact with the reference flat surface.

3. A fiber-reinforced plastic member according to claim 2, wherein at least one of the inner curved surface portion and the outer curved surface portion is part of the curved surface of a cylinder that is in contact with the reference plane portion of the reference layer.

4. A fiber-reinforced plastic member according to claim 2 or 3, wherein the inner curved surface portion and the outer curved surface portion are part of the curved surfaces of cylinders of different diameters that are in contact with the reference flat surface portion.

5. A fiber-reinforced plastic member according to any one of claims 2 to 4, characterized in that the radius of curvature of the inner curved surface portion is greater than the thickness of each of the plurality of fiber-reinforced plastic layers.

6. A fiber-reinforced plastic member according to any one of claims 1 to 5, which has two of the cores and at least one fiber-reinforced plastic layer between the two cores.

7. A fiber-reinforced plastic component according to any one of claims 1 to 6, wherein the core is positioned between the first fiber-reinforced plastic layer and the second fiber-reinforced plastic layer from the outside of the corner portion.

8. A fiber-reinforced plastic member according to any one of claims 1 to 6, which has two cores, and the two cores are arranged between the same layer and the next layer from the center of the thickness of the fiber-reinforced plastic portion toward the inside and outside.

9. A fiber-reinforced plastic member according to any one of claims 1 to 8, wherein the core is manufactured using a foamed resin material or fiber-reinforced plastic.

10. A method for manufacturing a fiber-reinforced plastic member, comprising: a preparation step of preparing a mold for molding a corner portion; and a molding step of, after the preparation step, placing a fiber-reinforced sheet in the mold, molding a corner portion in the fiber-reinforced sheet to form an outer fiber-reinforced plastic layer, placing a core inside the corner portion, and further placing another fiber-reinforced sheet in the mold so as to cover the outer fiber-reinforced plastic layer and the core, and molding a corner portion in the other fiber-reinforced sheet while covering the outer fiber-reinforced plastic layer and the core with the other fiber-reinforced sheet to form an inner fiber-reinforced plastic layer.

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