Fiber structure and fiber-reinforced composite material

Abstract

To provide a fiber structure capable of suppressing fraying from an end of the fiber structure while suppressing an increase in man-hours for manufacturing the fiber structure.SOLUTION: In a fiber structure 11 composed of a plurality of fiber layers 20, the plurality of fiber layers 20 comprises a plurality of first yarn layers 21 in which a plurality of first yarns 31 having a yarn main axis extending in a first direction X are arranged in a second direction Y, and a plurality of second yarn layer 22 in which a plurality of second yarns 32 having a yarn main axis extending in the second direction Y are arranged in the first direction X without being entangled with the first yarns 31. The second yarn layer 22 has a terminal second yarn 32a which is a second yarn 32 located at an end portion Rc of a central region Ra. A plurality of interlayer binding yarns 35 located in a terminal region Rb include two interlayer binding yarns 35 which are entangled with the first yarns 31 via different paths in a cross section of the fiber structure orthogonal to the first direction X. The pitch interval in the first direction X between the interlayer binding yarns 35 in the terminal region Rb is smaller than that in the first direction X between the interlayer binding yarns 35 in the central region Ra.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a fiber structure and a fiber-reinforced composite material.

Background Art

[0002] For example, the fiber structure described in Patent Document 1 includes a first yarn whose yarn axis extends in a first direction, and a second yarn whose yarn axis extends in a second direction orthogonal to the first direction. A plurality of the first yarns are arranged in the second direction. A plurality of the second yarns are arranged in the first direction. Further, the fiber structure described in Patent Document 1 includes a heat-sealing yarn containing heat-sealing fibers. By welding the heat-sealing yarn at a position where the first yarn and the second yarn intersect, displacement of the first yarn and the second yarn in the fiber structure is suppressed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the fiber structure, it is desired to suppress the fraying of the second yarn from the end of the fiber structure in the first direction. For example, if the heat-sealing yarn described in Patent Document 1 is provided at the end of the fiber structure in the first direction and this heat-sealing yarn is welded to the first yarn and the second yarn, the fraying of the second yarn can be suppressed. However, in this case, a step of welding the heat-sealing yarn to the first yarn and the second yarn is required separately from the weaving step of weaving the fiber structure, so the man-hours related to the production of the fiber structure increase. It has been desired to suppress the fraying from the end of the fiber structure while suppressing an increase in the man-hours related to the production of the fiber structure.

Means for Solving the Problems

[0005] The fibrous structure for solving the above problems is a fibrous structure including a plurality of fiber layers laminated in the lamination direction and interlayer binding yarns that bind the plurality of fiber layers in the lamination direction. The plurality of fiber layers include a plurality of first yarn layers and a second yarn layer positioned between the first yarn layers in the lamination direction. In the first yarn layer, a plurality of first yarns whose yarn main axes extend in a first direction are arranged in a second direction orthogonal to the first direction, and are positioned at both ends of the fibrous structure in the lamination direction. In the second yarn layer, a plurality of second yarns whose yarn main axes extend in the second direction without being entangled with the first yarns are arranged in the first direction. The interlayer binding yarns are adjacent to the second yarns in the first direction, have yarn main axes extending in the second direction, and engage with the first yarns of the first yarn layers positioned at both ends of the fibrous structure in the lamination direction. Taking the region of the fibrous structure including the center of the fibrous structure in the first direction as the central region, and the region of the fibrous structure adjacent to the central region in the first direction and including the end of the fibrous structure in the first direction as the end region, the second yarn layer has end second yarns that are the second yarns positioned at the end of the central region in the first direction. The interlayer binding yarns are located in plural numbers in both the central region and the end region. The plurality of interlayer binding yarns located in the end region include the interlayer binding yarn positioned at the outermost end in the first direction among the interlayer binding yarns provided in the fibrous structure, and include two interlayer binding yarns that are entangled with the first yarns through different paths from each other in the cross section of the fibrous structure orthogonal to the first direction. The pitch interval in the first direction between the interlayer binding yarns in the end region is smaller than the pitch interval in the first direction between the interlayer binding yarns in the central region.

[0006] According to the above configuration, the pitch interval between the interlayer bonding yarns in the end region in the first direction is smaller than the pitch interval between the interlayer bonding yarns in the central region in the first direction. Therefore, the interlayer bonding yarns can bond the multiple fiber layers more firmly in the end region than in the central region. The interlayer bonding yarns in the end region make the end second yarns, which are second yarns located at the end of the central region in the first direction, less likely to fray from the end of the fiber structure in the first direction. Furthermore, since this fraying prevention can be achieved by bonding the multiple fiber layers with the interlayer bonding yarns in the weaving process, there is no need to add a process separate from the weaving process to prevent the fraying. Therefore, it is possible to prevent fraying from the end of the fiber structure while suppressing an increase in the number of steps required for manufacturing the fiber structure.

[0007] In the fiber structure, the multiple interlayer bonding yarns located in the central region include a first interlayer bonding yarn and a second interlayer bonding yarn, and the first interlayer bonding yarn and the second interlayer bonding yarn are entangled with the first yarn through different paths in a cross section of the fiber structure perpendicular to the first direction, and among the multiple interlayer bonding yarns located in the end region, some of the interlayer bonding yarns are entangled with the first yarn through the same path as the first interlayer bonding yarn in a cross section of the fiber structure perpendicular to the first direction, and other interlayer bonding yarns are entangled with the first yarn through the same path as the second interlayer bonding yarn in a cross section of the fiber structure perpendicular to the first direction.

[0008] According to the above configuration, the interlayer bonding yarn located in the central region and the interlayer bonding yarn located in the end region can share a common path in the cross section of the fiber structure perpendicular to the first direction, making it easier to manufacture the fiber structure.

[0009] In the fiber structure, the plurality of interlayer binding yarns located in the end region may have a smaller thickness than the second yarns. According to the above configuration, compared with the case where the thickness of the plurality of interlayer binding yarns located in the end region is equal to or greater than the thickness of the second yarn, the meandering of the first yarn due to the engagement of the interlayer binding yarns is less likely to occur. Therefore, it is possible to suppress a decrease in the strength of the fiber structure caused by the meandering of the first yarn.

[0010] In the fiber structure, the plurality of interlayer binding yarns located in the end region may be melted by impregnating the fiber structure with a thermosetting resin using the RTM method. According to the above configuration, even if the first yarn is meandering due to the engagement of the interlayer binding yarns in the end region, the plurality of interlayer binding yarns located in the end region are melted by impregnating the fiber structure with a thermosetting resin using the RTM method, so that the meandering of the first yarn can be eliminated. Therefore, it is possible to suppress a decrease in the strength of the fiber structure caused by the meandering of the first yarn.

[0011] The fiber-reinforced composite material that solves the above problems is a fiber-reinforced composite material formed by impregnating a fiber structure with a matrix material, wherein the fiber structure is the above fiber structure.

Effect of the Invention

[0012] According to the present invention, it is possible to suppress an increase in the number of man-hours related to the production of the fiber structure and suppress fraying from the end of the fiber structure.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0014] Hereinafter, an embodiment in which the fiber structure and the fiber-reinforced composite material are embodied will be described with reference to FIGS. 1 to 6. <Fiber-reinforced composite material> As shown in FIG. 1, the fiber-reinforced composite material 10 is configured by impregnating a fiber structure 11 with a matrix resin Ma as a matrix material. The fiber structure 11 is a reinforcing base material of the fiber-reinforced composite material 10. The matrix resin Ma is, for example, a thermosetting resin. Examples of the thermosetting resin include epoxy resin, vinyl ester resin, unsaturated polyester resin, and phenolic resin. For example, by impregnating the fiber structure 11 with a thermosetting resin using the RTM (Resin Transfer Molding) method, the fiber-reinforced composite material 10 is formed.

[0015] <Fiber structure>[[ID=ID=19]] As shown in FIG. 2, the fiber structure 11 includes a plurality of fiber layers 20. The plurality of fiber layers 20 are laminated in the lamination direction Z. The fiber structure 11 of the present embodiment does not change in configuration before and after the thermosetting of the matrix material.

[0016] In the following description, it is assumed that the fiber structure 11 is placed in a horizontal plane. In the drawings, the direction along the horizontal plane is indicated by the X-axis and the Y-axis, and the direction perpendicular to the horizontal plane is indicated by the Z-axis. The X-axis, the Y-axis, and the Z-axis are perpendicular to each other. The direction parallel to the X-axis is also referred to as the first direction X. The direction parallel to the Y-axis is also referred to as the second direction Y. The second direction Y is a direction perpendicular to the first direction X. The lamination direction Z is a direction parallel to the Z-axis.

[0017] The plurality of fiber layers 20 includes a plurality of first yarn layers 21 and a plurality of second yarn layers 22. Each of the plurality of first yarn layers 21 and the plurality of second yarn layers 22 is laminated in a lamination direction Z. In the first yarn layer 21, a plurality of first yarns 31 are arranged in a second direction Y. The first yarns 31 have a main axis extending in the first direction X. In the second yarn layer 22, a plurality of second yarns 32 are arranged in the first direction X. The second yarns 32 have a main axis extending in the second direction Y.

[0018] The first yarn 31 and the second yarn 32 are fiber bundles formed by bundling a plurality of reinforcing fibers, for example, continuous fibers. The reinforcing fibers may be organic or inorganic fibers, or different types of organic fibers, different types of inorganic fibers, or mixed fibers of organic and inorganic fibers. Examples of organic fibers include acrylic fibers, nylon fibers, polyester fibers, aramid fibers, poly-p-phenylene benzobisoxazole fibers, and ultra-high molecular weight polyethylene fibers. Examples of inorganic fibers include carbon fibers, glass fibers, and ceramic fibers. The first yarn 31 and the second yarn 32 of this embodiment are yarns made of carbon fibers.

[0019] The first yarn layers 21 are located at both ends of the fiber structure 11 in the stacking direction Z. Specifically, of the multiple first yarn layers 21, one first yarn layer 21 is located at an end 11a, which is one end of the fiber structure 11 in the stacking direction Z, and one first yarn layer 21 is located at an end 11b, which is the other end of the fiber structure 11 in the stacking direction Z. The first yarn layer 21 located at the end 11a of the fiber structure 11 is also referred to as a first end layer 21a. The first yarn layer 21 located at the end 11b of the fiber structure 11 is also referred to as a second end layer 21b.

[0020] The second yarn layer 22 is located between the first yarn layers 21 in the stacking direction Z. Each of the first end layer 21a and the second end layer 21b is adjacent to a second yarn layer 22 in the stacking direction Z. In this embodiment, two first yarn layers 21 are located between the second yarn layers 22 in the stacking direction Z. Between the first end layer 21a and the second end layer 21b, one second yarn layer 22 and two first yarn layers 21 are alternately stacked in this order in the stacking direction Z. By stacking a plurality of first yarn layers 21 and a plurality of second yarn layers 22 in the stacking direction Z in this way, a plurality of fiber layers 20 are stacked in the stacking direction Z.

[0021] The first yarns 31 extend linearly in the first direction X. The multiple first yarn layers 21 are stacked such that the first yarns 31 are aligned in the stacking direction Z. The multiple first yarns 31 aligned in the stacking direction Z are referred to as a first yarn group 31a. The multiple first yarn groups 31a are aligned in the second direction Y.

[0022] The second yarns 32 are not entangled with the first yarns 31. In the first yarn layer 21 and the second yarn layer 22 that are adjacent to each other in the stacking direction Z, the second yarns 32 that constitute the second yarn layer 22 extend in the second direction Y so as to form a straight line along the first yarns 31 that constitute the first yarn layer 21.

[0023] A region of the fiber structure 11 including the center of the fiber structure 11 in the first direction X is referred to as a central region Ra. A region of the fiber structure 11 adjacent to the central region Ra in the first direction X is referred to as an end region Rb. The end region Rb includes end portions 11c and 11d of the fiber structure 11 in the first direction X.

[0024] Each of the plurality of second yarn layers 22 has a terminal second yarn 32a. The terminal second yarn 32a is a second yarn 32 located at an end Rc of a central region Ra in the first direction X. In the present embodiment, among the plurality of second yarns 32 in each of the plurality of second yarn layers 22, the second yarn 32 located at one end in the first direction X and the second yarn 32 located at the other end correspond to the terminal second yarn 32a. The terminal second yarn 32a is located at both ends of the central region Ra in the first direction X. The central region Ra includes the terminal second yarns 32a located at both ends in the first direction X and a plurality of second yarns 32 located between the terminal second yarn 32a at one end and the terminal second yarn 32a at the other end in the first direction X.

[0025] The end region Rb is a region of the fiber structure 11 located outside in the first direction X with respect to the terminal second yarn 32a. In each of the plurality of first yarn layers 21, both end portions of the plurality of first yarns 31 protrude from the terminal second yarn 32a toward the outside of the fiber structure 11. The end region Rb includes the end portions of the plurality of first yarns 31 protruding from the terminal second yarn 32a in this way. Portions of the plurality of first yarns 31 other than those located in the end region Rb are located in the central region Ra.

[0026] <Interlayer binding yarn> As shown in FIGS. 2 and 3, the fiber structure 11 includes an interlayer binding yarn 35 that binds a plurality of fiber layers 20 in the stacking direction Z. The interlayer binding yarn 35 is, for example, a fiber bundle formed by bundling a plurality of reinforcing fibers that are continuous fibers. The interlayer binding yarn 35 is provided in the fiber structure 11 by binding the plurality of fiber layers 20 with the interlayer binding yarn 35 in a weaving process of weaving the fiber structure 11.

[0027] The interlayer binding yarn 35 is adjacent to the second yarn 32 in the first direction X. The main axis of the interlayer binding yarn 35 extends in the second direction Y. The interlayer binding yarn 35 engages with the first yarn 31 located in the first end layer 21a and the first yarn 31 located in the second end layer 21b. That is, the interlayer binding yarn 35 engages with the first yarns 31 of the first yarn layer 21 located at both ends in the stacking direction Z of the plurality of fiber layers 20.

[0028] The interlayer binding threads 35 are located in plural numbers in the central region Ra and the end regions Rb. The plurality of interlayer binding threads 35 located in the central region Ra are composed of a plurality of first interlayer binding threads 36a and a plurality of second interlayer binding threads 36b. The first interlayer binding threads 36a and the second interlayer binding threads 36b are alternately positioned in the first direction X.

[0029] As shown in FIGS. 4 and 5, each of the first interlayer binding threads 36a and the second interlayer binding threads 36b alternately engages with a first thread 31 located in the first end layer 21a and a first thread 31 located in the second end layer 21b from one end to the other end of the fiber structure 11 in the second direction Y. The first threads 31 with which the first interlayer binding thread 36a engages in the first end layer 21a and the first threads 31 with which the first interlayer binding thread 36a engages in the second end layer 21b are located in first thread groups 31a adjacent to each other in the second direction Y. Similarly, the first threads 31 with which the second interlayer binding thread 36b engages in the first end layer 21a and the first threads 31 with which the second interlayer binding thread 36b engages in the second end layer 21b are located in first thread groups 31a adjacent to each other in the second direction Y. Each of the first interlayer binding threads 36a and the second interlayer binding threads 36b extends in the second direction Y while changing the first thread 31 with which it engages for each first thread group 31a between the first thread 31 located in the first end layer 21a and the first thread 31 located in the second end layer 21b. Each of the first interlayer binding threads 36a and the second interlayer binding threads 36b extends in the stacking direction Z between adjacent first thread groups 31a in the second direction Y.

[0030] The first interlayer binding yarn 36a and the second interlayer binding yarn 36b are entangled with the first yarn 31 through different paths from each other in the cross-section of the fiber structure 11 orthogonal to the first direction X. The first interlayer binding yarn 36a engages with the first yarn 31 located in the first end layer 21a and then the first yarn 31 located in the second end layer 21b in order from one end to the other end of the fiber structure 11 in the second direction Y. The second interlayer binding yarn 36b engages with the first yarn 31 located in the second end layer 21b and then the first yarn 31 located in the first end layer 21a in order from one end to the other end of the fiber structure 11 in the second direction Y. In the first yarn group 31a in which the first interlayer binding yarn 36a engages with the first yarn 31 located in the first end layer 21a, the second interlayer binding yarn 36b engages with the first yarn 31 located in the second end layer 21b. In the first yarn group 31a in which the first interlayer binding yarn 36a engages with the first yarn 31 located in the second end layer 21b, the second interlayer binding yarn 36b engages with the first yarn 31 located in the first end layer 21a.

[0031] As shown in FIG. 3, the interlayer binding yarn 35 located in the end region Rb is composed of a first end interlayer binding yarn 37a and a second end interlayer binding yarn 37b. The first end interlayer binding yarn 37a and the second end interlayer binding yarn 37b are adjacent to each other in the first direction X. In the present embodiment, one first end interlayer binding yarn 37a is located in the end region Rb of the end portion 11c of the fiber structure 11 and one in the end region Rb of the end portion 11d of the fiber structure 11. One second end interlayer binding yarn 37b is located in the end region Rb of the end portion 11c of the fiber structure 11 and one in the end region Rb of the end portion 11d of the fiber structure 11.

[0032] The first end interlayer binding yarn 37a and the second end interlayer binding yarn 37b are thinner than the second yarn 32. In other words, the plurality of interlayer binding yarns 35 located in the end region Rb are thinner than the second yarn 32. In the present embodiment, all the interlayer binding yarns 35 provided in the fiber structure 11 have the same thickness. Therefore, the first interlayer binding yarn 36a and the second interlayer binding yarn 36b, which are the interlayer binding yarns 35 located in the central region Ra, are also thinner than the second yarn 32.

[0033] The second end interlayer binding thread 37b is the interlayer binding thread 35 located at the outermost end in the first direction X among the interlayer binding threads 35 provided in the fiber structure 11. That is, the plurality of interlayer binding threads 35 located in the end region Rb include the interlayer binding thread 35 located at the outermost end in the first direction X among the interlayer binding threads 35 provided in the fiber structure 11.

[0034] As shown in FIG. 6, each of the first end interlayer binding thread 37a and the second end interlayer binding thread 37b alternately engages with the first thread 31 located in the first end layer 21a and the first thread 31 located in the second end layer 21b from one end to the other end of the fiber structure 11 in the second direction Y. The first thread 31 with which the first end interlayer binding thread 37a engages in the first end layer 21a and the first thread 31 with which the first end interlayer binding thread 37a engages in the second end layer 21b are located in the first thread group 31a adjacent to each other in the second direction Y. Similarly, the first thread 31 with which the second end interlayer binding thread 37b engages in the first end layer 21a and the first thread 31 with which the second end interlayer binding thread 37b engages in the second end layer 21b are located in the first thread group 31a adjacent to each other in the second direction Y. Each of the first end interlayer binding thread 37a and the second end interlayer binding thread 37b extends in the second direction Y while changing the first thread 31 with which it engages for each first thread group 31a between the first thread 31 located in the first end layer 21a and the first thread 31 located in the second end layer 21b. Each of the first end interlayer binding thread 37a and the second end interlayer binding thread 37b extends in the stacking direction Z between the adjacent first thread groups 31a in the second direction Y.

[0035] The first end interlayer binding thread 37a and the second end interlayer binding thread 37b are intertwined with respect to the first thread 31 through different paths in the cross-section of the fiber structure 11 orthogonal to the first direction X. The first end interlayer binding thread 37a engages the first thread 31 located in the first end layer 21a and then the first thread 31 located in the second end layer 21b in sequence from one end to the other end of the fiber structure 11 in the second direction Y. The second end interlayer binding thread 37b engages the first thread 31 located in the second end layer 21b and then the first thread 31 located in the first end layer 21a in sequence from one end to the other end of the fiber structure 11 in the second direction Y. In the first thread group 31a where the first end interlayer binding thread 37a engages the first thread 31 located in the first end layer 21a, the second end interlayer binding thread 37b engages the first thread 31 located in the second end layer 21b. In the first thread group 31a where the first end interlayer binding thread 37a engages the first thread 31 located in the second end layer 21b, the second end interlayer binding thread 37b engages the first thread 31 located in the first end layer 21a.

[0036] FIG. 6 schematically shows the path through which the first interlayer binding thread 36a passes as a two-dot chain line first path R1, and the path through which the second interlayer binding thread 36b passes as a one-dot chain line second path R2. In the cross-section of the fiber structure 11 orthogonal to the first direction X, the first end interlayer binding thread 37a passes through the first path R1, and the second end interlayer binding thread 37b passes through the second path R2. Therefore, among the plurality of interlayer binding threads 35 located in the end region Rb, the first end interlayer binding thread 37a, which is a part of the interlayer binding threads 35, is intertwined with respect to the first thread 31 through the same first path R1 as the first interlayer binding thread 36a in the cross-section of the fiber structure 11 orthogonal to the first direction X. The second end interlayer binding thread 37b, which is the other interlayer binding thread 35, is intertwined with respect to the first thread 31 through the same second path R2 as the second interlayer binding thread 36b in the cross-section of the fiber structure 11 orthogonal to the first direction X.

[0037] <Pitch interval> As shown in FIG. 3, the pitch interval between the first interlayer binding yarn 36a and the second interlayer binding yarn 36b adjacent to each other in the first direction X is the first pitch interval L1. In the central region Ra, the interlayer binding yarns 35 are separated from each other in the first direction X.

[0038] The pitch interval between the first end interlayer binding yarn 37a and the second end interlayer binding yarn 37b adjacent to each other in the first direction X is the second pitch interval L2. In the present embodiment, the first end interlayer binding yarn 37a and the second end interlayer binding yarn 37b adjacent to each other in the first direction X are in contact with each other in the first direction X. Therefore, the second pitch interval L2, which is the pitch interval in the first direction X between the interlayer binding yarns 35 in the end region Rb, is smaller than the first pitch interval L1, which is the pitch interval in the first direction X between the interlayer binding yarns 35 in the central region Ra.

[0039] [Function] Next, the function in the present embodiment will be described. The first interlayer binding yarn 36a and the second interlayer binding yarn 36b located in the central region Ra are entangled with the first yarn 31 through different paths from each other in the cross section of the fiber structure 11 orthogonal to the first direction X. Therefore, the portions of the plurality of first yarns 31 located in the central region Ra are engaged from both sides in the stacking direction Z by the first interlayer binding yarn 36a and the second interlayer binding yarn 36b. By such engagement of the interlayer binding yarns 35 in the central region Ra, the second yarn 32 located in the central region Ra in the first direction X is supported so as to be sandwiched from both sides in the stacking direction Z by the first yarns 31 adjacent to each other in the stacking direction Z in each of the second yarns 32. Thereby, the portion located in the central region Ra among the plurality of fiber layers 20 is joined by the first interlayer binding yarn 36a and the second interlayer binding yarn 36b.

[0040] The first end interlayer binding yarn 37a and the second end interlayer binding yarn 37b located in the end region Rb are intertwined with the first yarn 31 through different paths in the cross-section of the fiber structure 11 orthogonal to the first direction X. Therefore, portions of the plurality of first yarns 31 located in the end region Rb are engaged from both sides in the stacking direction Z by the first end interlayer binding yarn 37a and the second end interlayer binding yarn 37b. By such engagement of the interlayer binding yarn 35 in the end region Rb, the end second yarn 32a adjacent to the end region Rb in the first direction X is supported so as to be sandwiched from both sides in the stacking direction Z by the first yarn 31 adjacent to the end second yarn 32a in the stacking direction Z. Thereby, the portion located in the end region Rb among the plurality of fiber layers 20 is joined by the first end interlayer binding yarn 37a and the second end interlayer binding yarn 37b.

[0041] The second pitch interval L2, which is the pitch interval between the first end interlayer binding yarn 37a and the second end interlayer binding yarn 37b in the end region Rb, is smaller than the first pitch interval L1, which is the pitch interval between the first interlayer binding yarn 36a and the second interlayer binding yarn 36b in the central region Ra. Therefore, in the end region Rb, the plurality of fiber layers 20 can be joined more firmly by the interlayer binding yarn 35 than in the central region Ra. By such engagement of the interlayer binding yarn 35 in the end region Rb, the end second yarn 32a is more strongly sandwiched from both sides in the stacking direction Z by the first yarn 31 adjacent thereto in the stacking direction Z than the other second yarns 32 located in the central region Ra.

[0042] [Effect] According to the above embodiment, the following effects can be obtained. (1-1) In the end region Rb, the pitch interval in the first direction X between the interlayer binding yarns 35 is smaller than the pitch interval in the first direction X between the interlayer binding yarns 35 in the central region Ra. Therefore, in the end region Rb, the plurality of fiber layers 20 can be more firmly joined by the interlayer binding yarns 35 than in the central region Ra. The end second yarn 32a, which is the second yarn 32 located at the end Rc of the central region Ra in the first direction X, is less likely to fray from the ends 11c, 11d of the fiber structure 11 in the first direction X due to the interlayer binding yarns 35 in the end region Rb. Furthermore, since such suppression of fraying can be achieved by joining the plurality of fiber layers 20 with the interlayer binding yarns 35 in the weaving process, there is no need to add a process separate from the weaving process for suppressing the above fraying. Therefore, it is possible to suppress fraying from the ends 11c, 11d of the fiber structure 11 while suppressing an increase in the man-hours related to the production of the fiber structure 11.

[0043] (1-2) Among the plurality of interlayer binding yarns 35 located in the end region Rb, some of the interlayer binding yarns 35 cross the first yarn 31 through the same first path R1 as the first interlayer binding yarn 36a in the cross-section of the fiber structure 11 orthogonal to the first direction X. The other interlayer binding yarns 35 cross the first yarn 31 through the same second path R2 as the second interlayer binding yarn 36b in the cross-section of the fiber structure 11 orthogonal to the first direction X. Therefore, the paths passing through in the cross-section of the fiber structure 11 orthogonal to the first direction X can be made common between the interlayer binding yarns 35 located in the central region Ra and the interlayer binding yarns 35 located in the end region Rb, so that the fiber structure 11 can be manufactured more easily.

[0044] (1-3) The plurality of interlayer binding yarns 35 located in the end region Rb are thinner than the second yarn 32. Therefore, compared with the case where the thickness of the plurality of interlayer binding yarns 35 located in the end region Rb is equal to or greater than the thickness of the second yarn 32, meandering of the first yarn 31 due to the engagement of the interlayer binding yarns 35 is less likely to occur. Therefore, it is possible to suppress a decrease in the strength of the fiber structure 11 caused by the meandering of the first yarn 31.

[0045] (1-4) By forming entanglement yarns at the end portions 11c and 11d of the fiber structure 11 in the first direction X, it is possible to suppress the fraying from the end portions 11c and 11d of the fiber structure 11. However, in this case, a tool for forming the entanglement yarns is required separately. According to the above embodiment, the path passing through the cross-section of the fiber structure 11 orthogonal to the first direction X can be shared by the interlayer binding yarns 35 located in the central region Ra and the interlayer binding yarns 35 located in the end region Rb. Therefore, it is not necessary to increase the number of tools for the interlayer binding yarns 35 provided in the end region Rb. Thus, it is possible to suppress the fraying from the end portions 11c and 11d of the fiber structure 11 while suppressing an increase in the number of tools used in the weaving process.

[0046] [Modification Example] Note that the above embodiment can be implemented with the following modifications. The above embodiment and the following modification examples can be implemented in combination with each other within a technically non-conflicting range.

[0047] [[ID= 10]]○ As shown in FIG. 7, the plurality of interlayer binding yarns 35 located in the end region Rb may be melted by impregnating the fiber structure 11 with a matrix resin Ma as a thermosetting resin using the RTM method. In this case, as the material of the plurality of interlayer binding yarns 35 located in the end region Rb, for example, a resin having a property of melting at the curing temperature of the matrix resin Ma can be adopted. When an epoxy resin is adopted as the matrix resin Ma, for example, a phenoxy resin, a methyl methacrylate resin, or the like can be adopted as the material of the plurality of interlayer binding yarns 35 located in the end region Rb. When the fiber structure 11 is heated by the RTM method, the matrix resin Ma impregnated in the fiber structure 11 is thermoset. At the same time, in the fiber structure 11, the plurality of interlayer binding yarns 35 located in the end region Rb disappear from the fiber structure 11. Thus, by the disappearance of the plurality of interlayer binding yarns 35 in the end region Rb from the fiber structure 11, as shown in FIG. 7, a fiber structure 11e in which the interlayer binding yarns 35 are not located in the end region Rb is obtained. In this modification example, the fiber structure 11e serves as the reinforcing base material of the fiber reinforced composite material 10.

[0048] According to this modification example, the following effects can be obtained. (2-1) The plurality of interlayer binding yarns 35 located in the end region Rb melt by impregnating the fiber structure 11 with a thermosetting resin using the RTM method. Even if the first yarn 31 has meandered due to the engagement of the interlayer binding yarns 35 in the end region Rb, since the plurality of interlayer binding yarns 35 located in the end region Rb melt by impregnating the fiber structure 11 with a thermosetting resin using the RTM method, the meandering of the first yarn 31 can be eliminated. Therefore, a decrease in the strength of the fiber structure 11 caused by the meandering of the first yarn 31 can be suppressed.

[0049] ○ As shown in FIG. 8, the fiber structure 11 may be manufactured by cutting the fiber body 11f as a precursor of the fiber structure 11. In this case, the fiber body 11f has the same first yarn 31, second yarn 32, and interlayer binding yarns 35 as the fiber structure 11. In the fiber body 11f, the central regions Ra and the end regions Rb are arranged in plurality in the first direction X. Between the central regions Ra in the first direction X, two end regions Rb are adjacent to each other in the first direction X. A plurality of first yarns 31 are connected between the adjacent end regions Rb in the first direction X. The plurality of first yarns 31 extend in the first direction X between both ends of the fiber body 11f in the first direction X. After manufacturing such a fiber body 11f, the fiber body 11f is cut along the cutting position C shown by the dashed-dotted line in FIG. 8. Thereby, since the fiber body 11f is cut between the adjacent end regions Rb in the first direction X, the fiber structure 11 can be manufactured from the fiber body 11f.

[0050] ○ In the fiber structure 11, the number of layers of the first yarn layer 21 located between the second yarn layers 22 in the stacking direction Z may be 1 layer or 3 or more layers. ○ The second yarn 32 may be located in the end region Rb. Also in this case, the fraying of the end second yarn 32a from the ends 11c, 11d of the fiber structure 11 in the first direction X can be suppressed by the interlayer binding yarns 35 in the end region Rb.

[0051] In a cross section of the fiber structure 11 perpendicular to the first direction X, the first interlayer bonding yarn 36a may follow a path different from the first path R1. In a cross section of the fiber structure 11 perpendicular to the first direction X, the second interlayer bonding yarn 36b may follow a path different from the second path R2. In short, it is sufficient that the first interlayer bonding yarn 36a and the second interlayer bonding yarn 36b are entangled with the first yarn 31 by following different paths in the cross section of the fiber structure 11 perpendicular to the first direction X.

[0052] In a cross section of the fiber structure 11 perpendicular to the first direction X, the first end interlayer bonding yarn 37a may follow a path different from the first path R1. In a cross section of the fiber structure 11 perpendicular to the first direction X, the second end interlayer bonding yarn 37b may follow a path different from the second path R2. In other words, in a cross section of the fiber structure 11 perpendicular to the first direction X, the multiple interlayer bonding yarns 35 located in the end region Rb may follow a path different from the interlayer bonding yarns 35 located in the central region Ra.

[0053] The number of interlayer binding yarns 35 located in the end region Rb may be three or more. For example, two or more first end interlayer binding yarns 37a may be located in the end region Rb. Two or more second end interlayer binding yarns 37b may be located in the end region Rb.

[0054] Interlayer bonding yarns 35 of different thicknesses may be provided in the fiber structure 11. For example, the thickness of the interlayer bonding yarns 35 located in the central region Ra may be different from that of the interlayer bonding yarns 35 located in the end regions Rb.

[0055] The thickness of the interlayer binding yarn 35 located in the central region Ra may be equal to or greater than the thickness of the second yarn 32 . The thickness of the interlayer binding yarns 35 located in the end regions Rb may be equal to or greater than the thickness of the second yarns 32 .

[0056] ○ In the end region Rb, the interlayer binding threads 35 may be separated from each other in the first direction X. Also in this case, the second pitch interval L2, which is the pitch interval in the first direction X between the interlayer binding threads 35 in the end region Rb, is smaller than the first pitch interval L1, which is the pitch interval in the first direction X between the interlayer binding threads 35 in the central region Ra.

[0057] ○ The fiber structure 11 may be manufactured using the first thread 31 and the second thread 32 impregnated with the matrix resin Ma. ○ At least one of the first thread 31, the second thread 32, and the interlayer binding thread 35 may be a fiber bundle formed by bundling a plurality of non-reinforcing fibers. Note that the expression "at least one" used in this specification means "one or more" of the desired options. As an example, the expression "at least one" used in this specification means "only one option" or "both of the two options" if the number of options is two. As another example, the expression "at least one" used in this specification means "only one option" or "any combination of two or more options" if the number of options is three or more.

Explanation of Reference Numerals

[0058] L1... First pitch interval, L2... Second pitch interval, Ma... Matrix resin, Ra... Central region, Rb... End region, Rc... End of (central region), X... First direction, Y... Second direction, Z... Laminating direction, 10... Fiber-reinforced composite material, 11, 11e... Fiber structure, 11a, 11b, 11c, 11d... Ends of (fiber structure), 20... Fiber layer, 21... First thread layer, 22... Second thread layer, 31... First thread, 32... Second thread, 32a... End second thread, 35... Interlayer binding thread, 36a... First interlayer binding thread, 36b... Second interlayer binding thread, 37a... First end interlayer binding thread, 37b... Second end interlayer binding thread.

Claims

1. A fiber structure comprising a plurality of fiber layers laminated in a stacking direction and interlayer binding yarns that bind the plurality of fiber layers in the stacking direction, wherein the plurality of fiber layers include a plurality of first yarn layers and a second yarn layer positioned between the first yarn layers in the stacking direction, the first yarn layer has a plurality of first yarns whose yarn main axes extend in a first direction arranged in a second direction orthogonal to the first direction and is positioned at both ends of the fiber structure in the stacking direction, the second yarn layer has a plurality of second yarns whose yarn main axes extend in the second direction without being entangled with the first yarn arranged in the first direction, the interlayer binding yarn is adjacent to the second yarn in the first direction, has a yarn main axis extending in the second direction, and engages with the first yarn of the first yarn layer positioned at both ends of the fiber structure in the stacking direction, when a region of the fiber structure including the center of the fiber structure in the first direction is defined as a central region, and a region of the fiber structure adjacent to the central region in the first direction and including the end of the fiber structure in the first direction is defined as an end region, the second yarn layer has end second yarns that are second yarns positioned at the ends of the central region in the first direction, the interlayer binding yarns are respectively positioned in plural numbers in the central region and the end region, the plurality of interlayer binding yarns positioned in the end region include the interlayer binding yarn positioned at the outermost end in the first direction among the interlayer binding yarns provided in the fiber structure and two interlayer binding yarns that are entangled with the first yarn through different paths from each other in a cross section of the fiber structure orthogonal to the first direction, and a pitch interval in the first direction between the interlayer binding yarns in the end region is smaller than a pitch interval in the first direction between the interlayer binding yarns in the central region. A fiber structure characterized by this.

2. The plurality of interlayer binding yarns positioned in the central region include a first interlayer binding yarn and a second interlayer binding yarn, and the first interlayer binding yarn and the second interlayer binding yarn are entangled with the first yarn through different paths from each other in a cross section of the fiber structure orthogonal to the first direction. Among the plurality of the interlayer binding yarns positioned in the end region, some of the interlayer binding yarns are entangled with the first yarn through the same path as the first interlayer binding yarn in a cross-section of the fibrous structure orthogonal to the first direction, and the other interlayer binding yarns are entangled with the first yarn through the same path as the second interlayer binding yarn in a cross-section of the fibrous structure orthogonal to the first direction. The fibrous structure according to claim 1.

3. The fibrous structure according to claim 1 or claim 2, wherein the plurality of the interlayer binding yarns positioned in the end region are smaller in thickness than the second yarn.

4. The fibrous structure according to claim 1 or claim 2, wherein the plurality of the interlayer binding yarns positioned in the end region are melted by impregnating the fibrous structure with a thermosetting resin using the RTM method.

5. A fiber-reinforced composite material formed by impregnating a fibrous structure with a matrix material, wherein the fibrous structure is the fibrous structure according to claim 1 or claim 2.

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