WO2011021463A1

WO2011021463A1 - Three-dimensional braiding, fiber reinforced composite material, and method for producing fiber reinforced composite material

Info

Publication number: WO2011021463A1
Application number: PCT/JP2010/062193
Authority: WO
Inventors: 隆太神谷
Original assignee: 株式会社豊田自動織機
Priority date: 2009-08-19
Filing date: 2010-07-20
Publication date: 2011-02-24
Also published as: JP2011042887A; JP5381493B2

Abstract

Disclosed is cylindrical three-dimensional braiding. Core yarn layers of the braiding include a plurality of core yarns extending in the axial direction. Through yarns of the braiding extend so as to pass through the core yarn layers. The core yarn layers are provided by four layers or more. The through yarns include through yarns which pass through adjacent two core yarn layers and extend so as to be folded back. The strength of a selected core yarn layer among the core yarn layers provided between the outermost core yarn layer and the innermost core yarn layer is less than the strength of the other core yarn layers.

Description

Three-dimensional braiding, fiber reinforced composite material, and method for producing fiber reinforced composite material

The present invention relates to a three-dimensional braiding, a fiber reinforced composite material, and a method of manufacturing a fiber reinforced composite material, and more specifically, a tertiary suitable for application to an energy absorbing member provided around a bumper of an automobile, around an aircraft seat, and the like. The present invention relates to original braiding, a fiber-reinforced composite material, and a method for manufacturing a fiber-reinforced composite material.

A fiber-reinforced composite material is known as an energy absorbing member that absorbs impact energy by breaking itself when subjected to an excessive impact load. The fiber reinforced composite material has an excellent impact energy absorption capability. A fiber reinforced composite material is usually formed by laminating a plurality of sheet-like prepregs, but in recent years, it has been formed using a material that has improved impact energy absorption capability due to the presence of interlaminar thread, or using three-dimensional braiding. Have been proposed. When the energy absorbing member is used in, for example, a crash box disposed between a bumper and a body frame, the crash box usually has a mechanical strength sufficient to maintain its own shape, and is set in advance. When an impact load exceeding the value is applied, it is required to be deformed and destroyed while absorbing the impact energy.

An energy absorbing member formed by laminating prepregs requires a large amount of work for manufacturing and has a low raw material yield. Further, since the reinforcing fibers are not continuous between the laminated prepreg layers, it is necessary to laminate more prepregs than the number originally required as a crush box in order to obtain strength for maintaining the shape of the self. In order to solve this problem, in Patent Document 1, a fiber reinforced resin obtained by impregnating a resin into a reinforcing fiber braid formed by flattening a tubular body knitted by a braiding method is formed into a three-dimensional shape. A shock absorbing material (energy absorbing member) for a crash box is disclosed.

Further, Patent Document 2 discloses an energy absorbing member that causes local breakage or deformation starting from one end of itself and efficiently absorbs large impact energy using the local breakage or deformation. A cylindrical energy absorbing member 41 shown in FIG. 5A includes a plurality of reinforcing

fiber layers

42a, 42b, 42c, and 42d impregnated with a resin, and a resin layer disposed between the reinforcing fiber layers 42a to 42d. 43a, 43b, 43c. The reinforcing fiber layers 42a to 42d are formed of prepregs in which reinforcing fibers are impregnated with resin. The resin layers 43a to 43c are formed of a resin having a higher elongation than the resin impregnated in the reinforcing fiber layers 42a to 42d. In this energy absorbing member 41, the resin 43b disposed in the central portion in the thickness direction is not reinforced with the reinforcing fiber, so the strength of the resin 43b is smaller than the strength of the reinforcing

fiber layers

42b and 42c adjacent to the resin 43b. . Therefore, as shown in FIG. 5B, the resin 43b becomes a starting point of bending deformation or a breaking point from the center of the energy absorbing member 41 to both sides when receiving the compressive load P. Therefore, bending deformation and destruction of the energy absorbing member 41 are started smoothly.

JP 2009-107408 A JP-A-6-307478

When three-dimensional braiding is used for the crush material, depending on the strength of the fiber that penetrates between the layers, as shown in FIG. Bending and breaking in the middle in the axial direction, the impact energy absorption capacity is small, and the fracture mode is not stable.

On the other hand, the energy absorbing member of Patent Document 2 needs to be formed by interposing high-

strength resins

43a, 43b, 43c between a plurality of prepregs constituting the reinforcing fiber layers 42a to 42d. Accordingly, there is a problem of a general energy absorbing member formed by simply laminating a plurality of prepregs, and the amount of work when laminating the prepregs is increased.

An object of the present invention is to provide a three-dimensional braiding, a fiber reinforced composite material, and a method for producing a fiber reinforced composite material that are suitable for a crash member having a light weight and high energy absorption capability and having a stable failure mode. is there.

In order to achieve the above object, a cylindrical three-dimensional braiding is provided according to an aspect of the present invention. The three-dimensional braiding has a core yarn layer and a penetrating yarn. The core yarn layer is formed of a plurality of core yarns extending along the axial direction. The penetrating yarn extends so as to penetrate the core yarn layer. Four or more core yarn layers are provided. The penetrating thread includes a penetrating thread extending so as to be folded back through two adjacent core thread layers. The strength of the selected core yarn layer among the core yarn layers provided between the outermost core yarn layer and the innermost core yarn layer is smaller than the strength of the other core yarn layers. Alternatively, the peel strength between selected adjacent core yarn layers is smaller than the peel strength between other adjacent core yarn layers.

(A) is a schematic perspective view of the three-dimensional braiding of one Embodiment of this invention, (b) is the partial schematic diagram which looked at the three-dimensional braiding from the axial direction. (A) is a schematic diagram showing a state in which the energy absorbing member formed by the three-dimensional braiding of FIG. 1 (a) is broken, and (b) is a breakage of the penetrating yarn in the three-dimensional braiding of FIG. 1 (a). The schematic diagram which shows the part which is easy to do. The partial schematic diagram which shows the three-dimensional braiding of another embodiment. The partial schematic diagram which shows the three-dimensional braiding of another embodiment. (A) is a fragmentary sectional view of the conventional energy absorption member, (b) is a fragmentary sectional view which shows the state in which the energy absorption member of Fig.5 (a) is destroyed. The schematic diagram which shows the destruction state of another energy absorption member in the past.

Hereinafter, an embodiment embodying the present invention will be described with reference to FIGS. 1 and 2.
As shown in FIG. 1A, the three-dimensional braiding 11 of this embodiment is formed in a cylindrical shape. As shown in FIG. 1B, the three-dimensional braiding 11 penetrates the core yarn layer 13 and the core yarn layer 13 formed of a plurality of core yarns 12 extending in the axial direction (direction orthogonal to the paper surface). Penetrating

threads

14a and 14b extending in this manner. In the present embodiment, five core yarn layers 13 are provided concentrically. The first penetrating thread 14a extends through the two adjacent core thread layers 13 so as to be folded back. The second penetrating thread 14b is disposed only in the core thread layer 13 (hereinafter referred to as the outermost layer, which corresponds to the first layer in this embodiment) disposed on the outermost side in the radial direction and on the innermost side in the radial direction. Only the core yarn layer 13 (hereinafter referred to as the innermost layer, which corresponds to the fifth layer in this embodiment) extends so as to be folded back. And between the selected core yarn layers 13 among the three core yarn layers 13 provided between the outermost layer (first layer in this embodiment) and the innermost layer (fifth layer in this embodiment) ( In this embodiment, peeling between the second core yarn layer 13 and the third core yarn layer 13 and between the third core yarn layer 13 and the fourth core yarn layer 13) is performed. The strength is formed so as to be smaller than the peel strength between the other core yarn layers 13. That is, the strength of the three-dimensional braiding 11 is formed such that the central portion in the thickness direction is smaller than the other portions. The axial direction of the three-dimensional braiding 11 is the direction of the axis of the cylinder in FIG. Further, the thickness direction of the three-dimensional braiding 11 is a direction orthogonal to the central axis of the three-dimensional braiding 11 in FIG. 1A, and is a vertical direction in FIG.

More specifically, the core yarn 12 and the

penetrating yarns

14a and 14b are all composed of untwisted fiber bundles made of the same kind of material. By reducing the number of fibers (filaments) constituting the fiber bundle and reducing the thickness of the fiber bundle, a fiber bundle with low strength is formed. In this embodiment, the core yarn 12 and the

penetrating yarns

14a and 14b are formed by untwisted fiber bundles made of carbon fibers. One carbon fiber bundle is formed by bundling hundreds to tens of thousands of thin carbon fibers, and the number of carbon fibers is determined according to the required performance. The first penetrating thread 14a extending so as to fold through the second core thread layer 13 and the third core thread layer 13 or the third core thread layer 13 and the fourth core thread layer 13 The penetrating yarn 14a extending so as to penetrate and bend back is formed of a fiber bundle that is thinner than the other

penetrating yarns

14a and 14b, that is, a fiber bundle having a low strength. Further, a fiber bundle having the same thickness as that of the second penetrating yarn 14b is used for the core yarn 12.

In FIG. 1B, for the sake of illustration, the penetrating

yarns

14a and 14b are drawn so as to be arranged in the same plane, but they are not actually arranged in the same plane and penetrate the paper surface. They are arranged in a misaligned direction. Moreover, the fiber bundle which comprises the core yarn 12 and the

penetration yarns

14a and 14b comprises the three-dimensional braiding 11 in the state expanded so that the cross section may become a flat state. For example, the fiber bundle is organized in a state where the width is expanded to about 10 mm.

The three-dimensional braiding 11 is used as a reinforcing fiber of a fiber reinforced composite material using a thermosetting resin as a matrix resin. For example, an epoxy resin is used as the thermosetting resin.

The three-dimensional braiding 11 is organized using a three-dimensional braiding device (three-dimensional braider). For example, the three-dimensional braiding apparatus has a mandrel that has a shape corresponding to the hollow portion of the three-dimensional braiding 11 to be formed and can be divided into a plurality of parts. The three-dimensional braiding 11 is formed around the mandrel by winding the core yarn 12 and the penetrating

yarns

14a and 14b around the outer surface of the mandrel to form a braided structure (three-dimensional braiding forming step). After the three-dimensional braiding 11 is formed to a predetermined length, the three-dimensional braiding 11 is removed from the three-dimensional braiding apparatus together with the mandrel. And a mandrel is removed from the three-dimensional braiding 11 (mandrel removal process). As a result, the three-dimensional braiding 11 is completed.

The fiber reinforced composite material that becomes the energy absorbing member is formed by impregnating and curing the thermosetting resin in the resin impregnation and curing step on the formed three-dimensional braiding 11. The resin is impregnated and cured by, for example, an RTM (resin transfer molding) method.

Now, the fiber-reinforced composite material configured as described above is used as a crash member 20 that absorbs the impact energy by being broken when subjected to an impact load (compression load) along the axial direction. When three-dimensional braiding is formed without positively making a difference in the strength of the core yarn layer and the peel strength between adjacent core yarn layers, the crush member formed by such three-dimensional braiding is excessive. When subjected to an impact load, as shown in FIG. 6, the crash member is bent and broken in the middle in the axial direction. As a result, the absorbed energy is reduced and the fracture mode is not stable.

However, the three-dimensional braiding 11 of this embodiment includes a second core yarn layer 13 and a third core yarn layer 13, and a third core yarn layer 13 and a fourth core yarn layer 13. The first penetrating yarn 14a extending so as to pass through each of the two penetrating yarns is composed of a fiber bundle having a smaller strength than the other penetrating

yarns

14a and 14b. The peel strength between the adjacent core yarn layers 13 depends on the strength of the first penetrating yarn 14a extending so as to fold through the adjacent core yarn layers 13. When a compressive load acts on the crash member 20, the compressive load acts as a tensile force on the first penetrating thread 14a. Then, the second core yarn layer 13 and the third core yarn layer 13, and the third core yarn layer 13 and the fourth core yarn layer 13 extend through the respective core layers. 1 penetration thread 14a becomes easy to fracture in the portion shown by arrow Y in Drawing 2 (b). As a result, the peel strength between the core yarn layer 13 of the second layer and the core yarn layer 13 of the third layer, and between the core yarn layer 13 of the third layer and the core yarn layer 13 of the fourth layer The peel strength is relatively smaller than the peel strength between the other core yarn layers 13.

As shown in FIG. 2 (a), when an excessive impact load F is applied to the crash member 20, the crash member 20 cracks at one end of the portion where the peel strength between the core yarn layers 13 is small. . The crush member 20 is torn at the central portion in the thickness direction from the one end portion, and is bent substantially symmetrically on both sides of the central portion to be sequentially deformed and broken. The isolation strength between the second core yarn layer 13 and the third core yarn layer 13 and the peel strength between the third core yarn layer 13 and the fourth core yarn layer 13 are: It is not completely the same, and the site between the core yarn layers 13 having the smaller peel strength is the starting point of the fracture. Therefore, the crush member 20 has a portion between the second core yarn layer 13 and the third core yarn layer 13 or the third core yarn layer 13 and the fourth core yarn layer 13. The destruction is started from a portion between the two and the destruction proceeds. As a result, the crash member 20 does not bend and break in the middle in the axial direction, but sequentially undergoes deformation and breakage so as to tear along the thickness direction from its end, so that the impact energy is efficiently absorbed. The amount of energy absorption increases.

This embodiment has the following advantages.
(1) The three-dimensional braiding 11 includes five core yarn layers 13 formed of a plurality of core yarns 12 extending in the axial direction, and penetrating

yarns

14a and 14b extending through the core yarn layer 13 so as to be folded back. Is formed in a cylindrical shape. The penetrating

threads

14a and 14b pass through the adjacent core thread layers 13 and extend through the first penetrating thread 14a, and the second penetrating threads extend through only the outermost and innermost core thread layers 13 respectively. The peel strength between the selected core yarn layers 13 of the core yarn layers 13 provided between the outermost layer and the innermost layer is higher than the peel strength between the other core yarn layers 13. small. The three-dimensional braiding 11 is used as a reinforcing fiber of a fiber-reinforced composite material that is used as an energy absorbing member (crash member 20) that is broken and absorbs impact energy when an excessive impact load (compression load) F is applied. . The three-dimensional braiding 11 is used in a state where an excessive impact load is applied from the axial direction. Since the crush member 20 is subjected to a sequential deformation and fracture so that the end portion of the crush member 20 is torn along the thickness direction from a portion where the peel strength between the core yarn layers 13 is small when an excessive impact load F is applied. Energy can be absorbed efficiently. Therefore, the three-dimensional braiding 11 is suitable for the crash member 20 that is lightweight, can absorb high energy, and has a stable failure mode.

(2) The three-dimensional braiding 11 has the strength of the first penetrating thread 14a extending so as to fold through the selected core thread layer 13 (second layer, third layer, and fourth layer). By forming it smaller than the strength of 14a, 14b, the peel strength between the selected core yarn layers 13 (between the second layer and the third layer, and between the third layer and the fourth layer) can be changed. It is formed smaller than the peel strength between the core yarn layers 13. Therefore, the three-dimensional braiding 11 having the target breaking mode can be formed simply by changing the fiber bundle of the predetermined first penetrating yarn 14a to a fiber bundle having a lower strength than the other penetrating

yarns

14a and 14b.

(3) In the three-dimensional braiding 11, the core yarn 12 and the penetrating

yarns

14a and 14b are all made of the same kind of material. The first penetrating thread 14a extending so as to fold through the selected core thread layer 13 is formed smaller than the other penetrating

threads

14a, 14b. Therefore, as compared with the case where the core yarn 12 and the penetrating

yarns

14a and 14b are all formed of the same thickness yarn (fiber bundle), if the number of yarns is the same, the three-dimensional braiding 11 is reduced in weight and thickness. Can be achieved.

(4) The fiber-reinforced composite material constituting the crash member 20 uses the three-dimensional braiding 11 having the advantages described in the above (1) to (3) as the reinforcing fiber. Therefore, the fiber-reinforced composite material of this embodiment obtains the advantages described in the above (1) to (3).

(5) The fiber-reinforced composite material of the present embodiment is formed using a three-dimensional braiding apparatus. The manufacturing method includes a three-dimensional braiding forming step of forming a three-dimensional braiding 11 around a mandrel of a three-dimensional braiding device, a mandrel removing step of removing a mandrel from the formed three-dimensional braiding 11, and a mandrel And a resin impregnating and curing step of impregnating and curing the resin in the three-dimensional braiding 11 from which is removed. Therefore, the three-dimensional braiding 11 is formed in a shape corresponding to the shape of the mandrel to be used, and the cylindrical three-dimensional braiding 11 can be easily formed. The three-dimensional braiding 11 can be formed into a fiber-reinforced composite material having a shape corresponding to the shape of the mold used for the impregnation and curing in the resin impregnation and curing step.

(6) Since carbon fiber is used as the core yarn 12 and the penetrating

yarns

14a and 14b constituting the three-dimensional braiding 11, the crash member 20 uses fibers other than carbon fiber as long as they have the same impact strength. It is possible to reduce the weight compared to that of a material, and if the weight is the same, it is possible to improve the impact strength compared to a material using fibers other than carbon fibers.

The said embodiment is not limited to the above, For example, you may change as follows.
The three-dimensional braiding 11 only needs to have four or more core yarn layers 13, and the number of the core yarn layers 13 is not limited to an odd number and may be an even number. For example, as shown in FIG. 3, the three-dimensional braiding 11 may have four core yarn layers 13. When the number of the core yarn layers 13 is an even number, the center in the thickness direction of the three-dimensional braiding 11 is the two layers (the second layer and the third layer in FIG. 3) of the core yarn layers 13 in the center in the thickness direction. Between. The strength of the first penetrating thread 14a extending so as to fold through the two core thread layers 13 in the central portion in the thickness direction is determined with respect to the other core thread layers 13 (the first layer and the fourth layer in FIG. 3). When it is made smaller than the first penetrating thread 14 a extending so as to penetrate and bend back, the peel strength between the two core yarn layers 13 in the central portion in the thickness direction is smaller than the peel strength between the other core yarn layers 13. In this case, the crash member 20 formed of a fiber-reinforced composite material using the three-dimensional braiding 11 as a reinforcing fiber is always the second core yarn layer at the center in the thickness direction when an excessive impact load is applied. The crush member 20 can absorb the impact energy efficiently because it is successively deformed and broken so as to tear along the thickness direction from the corresponding end between the core layer 13 and the third core yarn layer 13. On the other hand, when the number of core yarn layers 13 is an odd number, the center in the thickness direction of the three-dimensional braiding 11 is the core yarn layer 13 in the center in the thickness direction of the crash member 20 (when the core yarn layers 13 are five layers). Is between the third core yarn layer 13) and the two adjacent core yarn layers 13 (if the core yarn layer 13 is five layers, the second core yarn layer 13). 13 and the third core yarn layer 13 and between the third core yarn layer 13 and the fourth core yarn layer 13). When the number of the core yarn layers 13 is an odd number, 2 corresponding to a portion between the core yarn layer 13 in the center portion in the thickness direction and the two core yarn layers 13 adjacent to the central core yarn layer 13. Since the location is easier to destroy than other locations, the destruction proceeds at one or two locations. For this reason, when the number of the core yarn layers 13 is an odd number, the breakage can proceed stably.

The three-dimensional braiding 11 may not have the second penetrating thread 14b.
When the number of the core yarn layers 13 of the three-dimensional braiding 11 is an odd number, the same strength yarn (fiber bundle) is used for all the penetrating

yarns

14a and 14b, and the core yarn layer 13 at the central portion in the thickness direction is attached to another core yarn layer 13 You may form smaller than the intensity | strength of the core yarn layer 13. FIG. For example, as shown in FIG. 4, the core yarn 12 constituting the core yarn layer 13 (third core yarn layer 13) at the center in the thickness direction is thinner than the core yarn 12 constituting the other core yarn layer 13. It is formed of yarn (fiber bundle). In this case, when an excessive impact load is applied to the crash member 20, the tension of the first penetrating thread 14a extending so as to fold through the core thread layer 13 in the center portion in the thickness direction is caused by the tension of the concentric thread layer 13. The core yarn 12 is cut. Therefore, even if the number of the core yarn layers 13 is an odd number, the crush member 20 can be removed from the end corresponding to the core yarn layer 13 at the center in the thickness direction of the crush member 20 when an excessive impact load is applied. Sequentially deform and break so as to tear in the thickness direction.

The fiber bundles constituting the core yarn 12 and the penetrating

yarns

14a and 14b are not limited to carbon fibers. For example, inorganic fibers such as glass fibers and ceramic fibers, or high-strength organic fibers such as aramid fibers, poly-p-phenylenebenzobisoxazole fibers, and ultrahigh molecular weight polyethylene fibers may be used. It is selected as appropriate. For example, when the required performance of rigidity and strength for the crash member 20 is high, carbon fiber is preferable. If an inexpensive glass fiber is used for the fiber material, the cost is low.

The yarn constituting the core yarn 12 and the penetrating

yarns

14a and 14b is not limited to a non-twisted fiber bundle, and may be a yarn in which fibers are twisted.
The configuration in which the strength of the fiber bundle constituting the first penetration yarn 14a penetrating the core yarn 12 and the adjacent core yarn layer 13 is made smaller than that of the other core yarn 12 and the

penetration yarns

14a and 14b is a method for making the fiber bundle thinner. Not limited to this, a method of changing the material and type (non-twisted yarn, twisted yarn, filament yarn, staple yarn) of the fiber bundle may be used.

As a configuration for making the peel strength between the selected core yarn layers 13 smaller than the peel strength between the other core yarn layers 13, the first extending extending through the selected adjacent core yarn layers 13. The number of penetrating threads 14a may be reduced. In this case, it is possible to reduce the weight and cost of the three-dimensional braiding 11 and thus the fiber-reinforced composite material by simply reducing the number of penetrating yarns 14a set in the three-dimensional braiding device when the three-dimensional braiding 11 is manufactured. .

The configuration for making the peel strength between the selected core yarn layers 13 smaller than the peel strength between the other core yarn layers 13 uses the same yarn as the core yarn 12 and the penetrating

yarns

14a and 14b. The configuration is not limited to a configuration in which the number of first penetrating yarns 14a extending so as to penetrate through the selected adjacent core yarn layers 13 is reduced. For example, the first penetrating thread 14a extending so as to fold through the selected core thread layer 13 is thinner and less in number than the other penetrating

threads

14a and 14b, or is made of a material having a low strength and the number There may be a configuration with less.

The three-dimensional braiding 11 is not limited to a configuration formed so that the strength of the central portion in the thickness direction is smaller than other portions. That is, when the number of the core yarn layers 13 is an even number, the strength of the first penetrating yarn 14a at the center in the thickness direction is smaller than the penetrating

yarns

14a and 14b in other portions, and the number of the core yarn layers 13 is an odd number. It is not restricted to the structure by which the intensity | strength of the core yarn layer 13 of the thickness direction center is formed smaller than the intensity | strength of the other core yarn layer 13. FIG. In the case of the three-dimensional braiding 11 having a large number of core yarn layers 13, it may be formed so as to reduce the strength of portions other than the center in the thickness direction. However, when the crash member 20 receives an excessive impact load, the impact energy is efficiently used in a stable fracture mode when the sequential deformation fracture progresses from the end in a symmetric state with respect to the thickness direction from the central portion in the thickness direction. Since it can absorb well, it is preferable that the strength of the portion near the center in the thickness direction is small.

The three-dimensional braiding 11 may be formed so that the peel strength gradually increases from the center in the thickness direction toward the outermost layer and the innermost layer. When a fiber reinforced composite material using the three-dimensional braiding 11 as a reinforcing fiber is used as the crash member 20, by setting an appropriate change in peel strength, when an excessive impact load acts on the crash member 20, The crash member 20 can be sequentially and stably deformed and destroyed from its end.

The three-dimensional braiding 11 is not limited to a cylindrical shape and may be a cylindrical shape. For example, the cross-sectional area in a polygonal cylinder shape such as a square cylinder shape or a hexagonal cylinder shape or an elliptical cylinder shape, a cylindrical shape (conical truncated cone shape) whose diameter changes in the axial direction, or a cross section perpendicular to the axial direction is from one end to the other. Alternatively, it may be a polygonal frustum shape that gradually decreases toward.

The thermosetting resin used as the matrix resin of the fiber reinforced composite material is not limited to an epoxy resin, and a thermosetting resin such as a vinyl ester resin, an unsaturated polyester resin, a phenol resin, or a polyimide resin may be used. The matrix resin is not limited to a thermosetting resin, and a thermoplastic resin such as polyamide, polybutylene terephthalate, polycarbonate, polyethylene, polypropylene, or ABS resin may be used. However, thermosetting resins are preferred because they are generally excellent in moldability and excellent in chemical resistance and weather resistance.

When forming a fiber-reinforced composite material using the three-dimensional braiding 11 as a reinforcing fiber, the resin may be impregnated and cured after changing the shape of the three-dimensional braiding 11.

11 ... 3D braiding, 12 ... core yarn, 13 ... core yarn layer, 14a, 14b ... penetrating yarn.

Claims

A cylindrical three-dimensional braiding having a core yarn layer formed of a plurality of core yarns extending along the axial direction and a penetrating yarn extending so as to penetrate the core yarn layer,
Four or more core yarn layers are provided,
The penetrating yarn includes a penetrating yarn extending so as to fold through two adjacent core yarn layers,
The strength of the selected core yarn layer among the core yarn layers provided between the outermost core yarn layer and the innermost core yarn layer is smaller than or selected from the strength of the other core yarn layers Three-dimensional braiding in which the peel strength between adjacent core yarn layers is smaller than the peel strength between other adjacent core yarn layers.
The three-dimensional braiding according to claim 1, wherein the three-dimensional braiding is formed so that the strength of the central portion in the thickness direction is smaller than other portions.
The three-dimensional braiding according to claim 1 or 2, wherein the three-dimensional braiding is formed so that the strength of the penetrating thread that penetrates the selected adjacent core yarn layer is smaller than the strength of the other penetrating thread.
The core yarn and the penetrating yarn are all formed of the same kind of material,
The thickness of the core yarn constituting the selected core yarn layer is smaller than the thickness of the core yarn constituting the other core yarn layer, or the thickness of the penetrating yarn penetrating the selected adjacent core yarn layer. The three-dimensional braiding according to any one of claims 1 to 3, wherein the thickness is smaller than the thickness of the other penetrating thread.
The number of core yarns constituting the selected core yarn layer is less than the number of core yarns constituting the other core yarn layer, or the number of penetrating yarns penetrating the selected adjacent core yarn layers is the other penetration. The three-dimensional braiding according to claim 1 or 2, wherein the three-dimensional braiding is less than the number of yarns.
A fiber-reinforced composite material using the three-dimensional braiding according to any one of claims 1 to 5 as a reinforcing fiber.
In a method of manufacturing a fiber reinforced composite material using a three-dimensional braiding device having a mandrel,
Forming the three-dimensional braiding according to any one of claims 1 to 5 around the mandrel;
Removing the mandrel from the formed three-dimensional braiding;
And impregnating and curing the resin in the three-dimensional braiding from which the mandrels have been removed.