Fiber structure and fiber reinforcement composite material

Abstract

To provide a fiber structure and a fiber reinforcement composite material capable of suppressing fraying from a cut part even when the fiber structure is cut.SOLUTION: A plurality of fiber layers include a plurality of first yarn layers and second yarn layers located between the first yarn layers in a stacking direction Z. The first yarn layer has multiple first yarns extending in a first direction arranged in a second direction perpendicular to the first direction, and the second yarn layer has multiple second yarns extending in the second direction without being entangled with the first yarn arranged in the first direction X, and is located at both ends of the stacking direction Z of a fiber structure 11. An interlayer bonding yarn 17 is adjacent to the first yarn in the second direction Y, extends in the first direction, and is entangled with the second yarns of the second yarn layer located at both ends in the stacking direction Z, and the interlayer bonding yarn 17 is entangled with the second yarns of the second yarn layer located between the second yarn layers located at both ends in the stacking direction Z, and is entangled with the second yarns of the second yarn layer located between the second yarn layers located at both ends in the stacking direction Z in a cutting target area RA including a cutting part S.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] As a conventional technique for a fiber structure and a fiber-reinforced composite, for example, a fiber structure and a fiber-reinforced composite material disclosed in Patent Document 1 are known. In the fiber structure disclosed in Patent Document 1, the multiple fiber layers include a plurality of first yarn layers in which a plurality of first yarns, each having a main axis extending in a first direction, are arranged in a second direction, and a second yarn layer in which a plurality of second yarns, each having a main axis extending in the second direction and not intertwined with the first yarns, are arranged in the first direction. The second yarn layer has end second yarns, which are second yarns located at the ends of the central region. The multiple interlayer bonding yarns located in the end regions include two interlayer bonding yarns that intertwine with the first yarns through different paths in a cross section of the fiber structure perpendicular to the first direction. The pitch spacing in the first direction between the interlayer bonding yarns in the end regions is smaller than the pitch spacing in the first direction between the interlayer bonding yarns in the central region.

[0003] According to this fiber structure, fraying at the end of the fiber structure is suppressed while suppressing an increase in the number of steps required for manufacturing the fiber structure. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2023-160586 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the fiber structure disclosed in Patent Document 1, the interlayer bonding yarn is simply entangled with the first yarn at both ends in the stacking direction, and there is a problem that, for example, when the fiber structure is cut along the first yarn, the tension of the interlayer bonding yarn is lost near the cut portion, causing fraying. Note that it is also possible to reduce the pitch interval in the first direction between the interlayer bonding yarns near the cut portion, but reducing the pitch interval leads to an increase in the number of interlayer bonding yarns.

[0006] The present invention has been made in consideration of the above-mentioned problems, and an object of the present invention is to provide a fiber structure and a fiber-reinforced composite material that can suppress fraying from the cut portion even when the fiber structure is cut. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, the present invention provides a fiber structure comprising a plurality of fiber layers stacked in a stacking direction and an interlayer bonding yarn that bonds the plurality of fiber layers in the stacking direction, wherein the plurality of fiber layers comprise a plurality of first yarn layers and a second yarn layer located between the first yarn layers in the stacking direction, wherein the first yarn layer has a plurality of first yarns, each having a yarn main axis extending in a first direction, arranged in a second direction perpendicular to the first direction, and the second yarn layer has a plurality of second yarns, each having a yarn main axis extending in the second direction, arranged in the first direction without intertwining with the first yarns, and located at both ends of the fiber structure in the stacking direction, and the interlayer bonding yarn is adjacent to the first yarn in the second direction, has a yarn main axis extending in the first direction, and is entangled with the second yarn of the second yarn layer located between the second yarn layers located at both ends of the stacking direction, in a region to be cut that includes a cutting portion to be cut in a direction intersecting the first direction.

[0008] In the present invention, in the region to be cut that includes the cut portion, the interlayer bonding yarn is entangled with the second yarn of the second yarn layer located between the second yarn layers located at both ends in the stacking direction. Therefore, even if the fiber structure is cut in the region to be cut in a direction intersecting the first direction at the cut portion, tension remains in the interlayer bonding yarn at a position close to the cut portion. In other words, by increasing the number of second yarns entangled with the interlayer bonding yarn in the second yarn layer located between the second yarn layers located at both ends in the stacking direction, fraying due to the second yarns falling off from the cut portion can be suppressed.

[0009] In addition, the above-mentioned fiber structure may have a non-cut region in the first direction excluding the planned cut region, and the interlayer bonding yarn may be configured not to be entangled with the second yarn of the second yarn layer located between the second yarn layers located at both ends in the stacking direction in the non-cut region. In this case, in the non-cut regions where the interlayer bonding yarn is not cut, the interlayer bonding yarn is not entangled with the second yarn of the second yarn layer located between the second yarn layers located at both ends in the stacking direction, making it easier to produce the fiber structure.

[0010] In the above fiber structure, at least one of the first yarn and the second yarn may be a spun yarn, and the interlayer binding yarn may be a continuous yarn. In this case, since at least one of the first yarn and the second yarn is a spun yarn, the second yarn located at the cut portion is less likely to shift position relative to the first yarn and the interlayer bonding yarn. Furthermore, since the interlayer bonding yarn is a continuous yarn, it is possible to increase the tension and thereby strengthen the pressing force in the stacking direction of the second yarn layer. As a result, the second yarn at the cut portion is less likely to fall off.

[0011] The present invention also provides a fiber-reinforced composite obtained by impregnating a fiber structure with a matrix resin, wherein the fiber structure is the above-described fiber structure. In the present invention, fraying due to the second yarns falling off from the cut portions in the fiber structure can be suppressed, and therefore a decrease in strength of the fiber-reinforced composite due to the second yarns falling off from the cut portions can be suppressed. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a fiber structure and a fiber-reinforced composite material that can suppress fraying from the cut portion even when the fiber structure is cut. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a perspective view schematically showing a fiber-reinforced composite material according to an embodiment of the present invention. [Figure 2] FIG. 1 is a perspective view showing an outline of a fiber structure before cutting according to an embodiment of the present invention. [Figure 3] FIG. 2 is a perspective view of the fiber structure before cutting. [Figure 4] FIG. 2 is a plan view of the fiber structure before cutting. [Figure 5] FIG. 4 is a view taken along the line AA in FIG. [Figure 6] FIG. 4 is a view taken along the line BB in FIG. 3. [Figure 7] FIG. 10 is a side view of the fiber structure after cutting. [Figure 8] FIG. 10 is a side view of a fiber structure after cutting according to a comparative example. [Figure 9] FIG. 10 is a side view of a fiber structure according to Modified Example 1. [Figure 10] FIG. 10 is a side view of a fiber structure according to Modified Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0014] A fiber structure and a fiber-reinforced composite material according to an embodiment of the present invention will be described below with reference to the drawings. First, the fiber-reinforced composite material will be described, and in the following description, the fiber-reinforced composite material will be described as being placed horizontally. In the drawings, directions along a horizontal plane are indicated by the X-axis and Y-axis, and a direction perpendicular to the horizontal plane is indicated by the Z-axis. The X-axis, Y-axis, and Z-axis are perpendicular to one another. 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 stacking direction Z is a direction parallel to the Z-axis.

[0015] As shown in FIG. 1, a fiber-reinforced composite material 10 is formed by impregnating a fiber structure 11 with a matrix resin M as a matrix material. The fiber structure 11 is a reinforcing base material for the fiber-reinforced composite material 10. The matrix resin M is, for example, a thermosetting resin. Examples of thermosetting resins include epoxy resin, vinyl ester resin, unsaturated polyester resin, and phenolic resin. The fiber-reinforced composite material 10 is formed by impregnating the fiber structure 11 with the thermosetting resin using a resin transfer molding (RTM) method.

[0016] As shown in FIG. 2, the fiber structure 11 is a precursor before cutting and before being impregnated with a matrix resin M and sintered. As shown in FIG. 3, the fiber structure 11 includes a plurality of fiber layers 12. The plurality of fiber layers 12 includes a plurality of warp layers 13 as first yarn layers and a plurality of weft layers 14 as second yarn layers. The plurality of warp layers 13 and the plurality of weft layers 14 are stacked in a stacking direction Z. In the warp layer 13, a plurality of warp yarns 15 as first yarns are arranged in a second direction Y. The warp yarns 15 have their main axes extending in the first direction X. In the weft layer 14, a plurality of weft yarns 16 as second yarns are arranged in the first direction X. The weft yarns 16 have their main axes extending in the second direction Y.

[0017] The warp yarns 15 are continuous yarns formed by bundling a plurality of continuous reinforcing fibers. The weft yarns 16 are spun yarns composed of discontinuous fibers. The continuous and discontinuous 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 warp yarns 15 and weft yarns 16 of this embodiment are yarns made of carbon fibers.

[0018] The weft layers 14 are located at both ends of the textile structure 11 in the stacking direction Z. Of the multiple weft layers 14 arranged in the stacking direction Z, one weft layer 14 is located at an end 11A, which is one end of the textile structure 11 in the stacking direction Z, and one weft layer 14 is located at an end 11B, which is the other end of the textile structure 11 in the stacking direction Z. For convenience of explanation, the weft layer 14 located at the end 11A of the textile structure 11 is referred to as the first end layer 14A. Similarly, the weft layer 14 located at the end 11B of the textile structure 11 is referred to as the second end layer 14B. In this embodiment, three weft layers 14 are arranged between the first end layer 14A and the second end layer 14B. Therefore, to distinguish between them, the weft layers 14 closest to the first end layer 14A may be referred to as the second layer, the third layer, and the fourth layer. Furthermore, the first end layer 14A may be referred to as the first layer, and the second end layer 14B may be referred to as the fifth layer. In this embodiment, the number of weft layers 14 is five, but there is no limit to the number of weft layers 14.

[0019] The warp layers 13 are located between the weft layers 14 in the stacking direction Z. The first end layer 14A and the second end layer 14B are each adjacent to a warp layer 13 in the stacking direction Z. In this embodiment, the warp layers 13 are located between the weft layers 14 in the stacking direction Z. Between the first end layer 14A and the second end layer 14B, the warp layers 13 and the weft layers 14 are alternately stacked in this order in the stacking direction Z. By stacking multiple warp layers 13 and weft layers 14 in the stacking direction Z, multiple fiber layers 12 are stacked in the stacking direction Z.

[0020] The warp threads 15 extend linearly in the first direction X. The multiple warp layers 13 are stacked so that the warp threads 15 are aligned in the stacking direction Z. The multiple warp threads 15 aligned in the stacking direction Z are referred to as a warp thread group T. The multiple warp thread groups T are aligned in the second direction Y.

[0021] The weft yarns 16 are not entangled with the warp yarns 15. In the warp layer 13 and the weft layer 14 adjacent to each other in the stacking direction Z, the weft yarns 16 constituting the weft layer 14 extend in the second direction Y so as to form a straight line along the warp yarns 15 constituting the warp layer 13. The multiple weft yarns 16 aligned in the stacking direction Z are referred to as a weft yarn group W. Multiple weft yarn groups W are aligned in the first direction X.

[0022] The fiber structure 11 has a region to be cut RA and a non-cut region RB. The region to be cut RA is a region including the center of the fiber structure 11 in the first direction X. The region of the fiber structure 11 adjacent to the region to be cut RA in the first direction X is a non-cut region RB. The non-cut region RB includes ends 11C and 11D of the fiber structure 11 in the first direction X. The region to be cut RA is a region to be cut, and is a region where a cut portion S is formed by cutting in the region to be cut RA in a direction along the main axis of the weft yarn 16, i.e., a direction intersecting the first direction X. The non-cut region RB is a region of the fiber structure 11 that will not be cut. In this embodiment, the non-cut region RB is located on both sides of the region to be cut RA in the first direction X of the fiber structure 11. The cut portion S forms an end face of the fiber structure 11 after cutting.

[0023] As shown in Fig. 3, the textile structure 11 includes interlayer bonding yarns 17 that bond multiple fiber layers 12 together in the stacking direction Z. That is, the textile structure 11 includes multiple warp yarns 15, multiple weft yarns 16, and multiple interlayer bonding yarns 17. The interlayer bonding yarns 17 are, for example, continuous yarns formed by bundling multiple reinforcing fibers, which are continuous fibers. The interlayer bonding yarns 17 are provided in the textile structure 11 by bonding the multiple fiber layers 12 together with the interlayer bonding yarns 17 during the weaving process of weaving the textile structure 11.

[0024] As shown in FIG. 4 , the interlayer bonding yarn 17 is adjacent to the warp yarn 15 in the second direction Y. The interlayer bonding yarn 17 has a main axis extending in the first direction X. The interlayer bonding yarn 17 is entangled with the weft yarn 16 located in the first layer and the weft yarn 16 located in the fifth layer. That is, the interlayer bonding yarn 17 is entangled with the weft yarns 16 of the weft layer 14 located at both ends of the multiple fiber layers in the stacking direction Z. The multiple interlayer bonding yarns 17 are composed of multiple first interlayer bonding yarns 17A and multiple second interlayer bonding yarns 17B. The first interlayer bonding yarns 17A and the second interlayer bonding yarns 17B are positioned alternately in the second direction Y. "Intertwining" refers to a state in which the interlayer bonding yarn 17 is entangled around the outer periphery of the weft yarn 16.

[0025] 5 and 6, each of the first interlayer binding yarn 17A and the second interlayer binding yarn 17B is alternately entangled with the weft yarns 16 located in the first layer and the weft yarns 16 located in the fifth layer from one end to the other of the fiber structure 11 in the first direction X. A weft yarn group W including the weft yarn 16 entangled with the first interlayer binding yarn 17A in the first layer is adjacent to a weft yarn group W including the weft yarn 16 entangled with the first interlayer binding yarn 17A in the fifth layer in the first direction X. Similarly, a weft yarn group W including the weft yarn 16 engaged with the second interlayer binding yarn 17B in the first layer is adjacent to a weft yarn group W including the weft yarn 16 entangled with the second interlayer binding yarn 17B in the fifth layer in the first direction X. In this embodiment, there are four weft groups W in the region to be cut RA, and when distinguishing them, they may be referred to as weft groups W1, W2, W3, and W4.

[0026] Each of the first interlayer binding yarn 17A and the second interlayer binding yarn 17B extends in the first direction X, with the weft yarn 16 located in the first layer and the weft yarn 16 located in the fifth layer being changed for each weft yarn group W. Each of the first interlayer binding yarn 17A and the second interlayer binding yarn 17B extends in the stacking direction Z between adjacent warp yarn groups T in the second direction Y.

[0027] In this embodiment, the only wefts 16 that intertwine with the first interlayer binding yarn 17A and the second interlayer binding yarn 17B in the non-cut region RB are the wefts 16 located in the first layer and the wefts 16 located in the fifth layer. The first interlayer binding yarn 17A and the second interlayer binding yarn 17B in the non-cut region RB extend in the stacking direction Z between adjacent weft groups W, and therefore do not intertwine with wefts 16 other than those in the first and fifth layers.

[0028] On the other hand, in the region to be cut RA, the wefts 16 intertwined with the first interlayer binding yarn 17A and the second interlayer binding yarn 17B are not limited to the wefts 16 located in the first layer and the wefts 16 located in the fifth layer. As shown in Figure 5, in the region to be cut RA, the first interlayer binding yarn 17A is intertwined with the wefts 16 in the first layer of the weft group W1, and is also intertwined with the wefts 16 in the second weft layer 14 of the weft group W2 located adjacent to the weft group W1. Specifically, the first interlayer binding yarn 17A is passed between the wefts 16 in the first layer and the wefts 16 in the second layer of the weft group W2 adjacent to the intertwined weft 16 so as to be separated in the first direction X from the wefts 16 in the first layer of the weft group W1 with which it was intertwined. Furthermore, the first interlayer binding yarn 17A is passed between the weft yarn 16 of the second layer and the weft yarn 16 of the third layer in the weft yarn group W2 so as to approach the weft yarn 16 of the third layer in the weft yarn group W1 in the first direction X from the weft yarn 16 of the second layer in the weft yarn group W2. Therefore, the first interlayer binding yarn 17A is entangled with the weft yarn 16 of the second layer in the weft yarn group W2. The first interlayer binding yarn 17A is passed between the weft yarn 16 of the third layer and the weft yarn 16 of the fourth layer in the weft yarn group W2 so as to move away from the weft yarn 16 of the weft yarn group W1 in the first direction X. Therefore, the first interlayer binding yarn 17A is entangled with the weft yarn 16 of the third layer in the weft yarn group W2. Furthermore, the first interlayer binding yarn 17A is passed between the weft yarn 16 of the fourth layer and the weft yarn 16 of the fifth layer in the weft yarn group W2 so as to approach the weft yarn 16 of the fifth layer in the weft yarn group W1 in the first direction X from the weft yarn 16 of the fourth layer in the weft yarn group W2. Therefore, the first interlayer binding yarn 17A is entangled with the weft yarn 16 of the fourth layer in the weft yarn group W2. Therefore, the first interlayer binding yarn 17A is passed in a zigzag manner in the stacking direction Z relative to the weft yarn group W2, and is entangled with each of the weft yarns 16 of the second to fifth layers in the weft yarn group W2.

[0029] The first interlayer binding yarn 17A is entangled with the weft yarn 16 of the fifth layer in the weft yarn group W2. The first interlayer binding yarn 17A is passed between the weft yarn 16 of the fifth layer and the weft yarn 16 of the fourth layer in the weft yarn group W3 so as to move away in the first direction X from the entangled weft yarn 16 of the fifth layer in the weft yarn group W2. Furthermore, the first interlayer binding yarn 17A is passed between the weft yarn 16 of the fourth layer and the weft yarn 16 of the third layer in the weft yarn group W3 so as to move away from the weft yarn 16 of the fourth layer in the weft yarn group W3 and towards the weft yarn 16 of the third layer in the weft yarn group W2 in the first direction X. Therefore, the first interlayer binding yarn 17A is entangled with the weft yarn 16 of the fourth layer in the weft yarn group W3. The first interlayer binding yarn 17A is passed between the weft yarn 16 of the third layer and the weft yarn 16 of the second layer in the weft yarn group W3 so as to be away from the weft yarn 16 of the third layer in the weft yarn group W2 in the first direction X. Therefore, the first interlayer binding yarn 17A is entangled with the weft yarn 16 of the third layer in the weft yarn group W3. Furthermore, the first interlayer binding yarn 17A is passed between the weft yarn 16 of the second layer and the weft yarn 16 of the first layer in the weft yarn group W3 so as to be closer to the weft yarn 16 of the first layer in the weft yarn group W2 in the first direction X from the weft yarn 16 of the second layer in the weft yarn group W3. Therefore, the first interlayer binding yarn 17A is entangled with the weft yarn 16 of the second layer in the weft yarn group W3. Therefore, the first interlayer binding yarn 17A is threaded zigzag in the layering direction Z relative to the weft yarn group W3, and is entangled with each of the weft yarns 16 of the first to fourth layers in the weft yarn group W3.

[0030] The first interlayer binding yarn 17A is entangled with the wefts 16 of the first layer in the weft group W3. The first interlayer binding yarn 17A is entangled with the wefts 16 of the weft group W4, but the entanglement between the first interlayer binding yarn 17A and the wefts 16 of the weft group W4 is the same as the entanglement between the first interlayer binding yarn 17A and the wefts 16 of the weft group W2. Therefore, the first interlayer binding yarn 17A is threaded zigzag in the stacking direction Z relative to the weft group W4, and is entangled with the wefts 16 of the second to fifth layers in the weft group W4. The first interlayer binding yarn 17A is entangled with the fifth layer in the weft group W4, but extends linearly in the stacking direction Z between the weft group W4 and the weft group W of the non-cut region RB, and is not entangled with any wefts other than the wefts 16 of the first and fifth layers in the non-cut region RB.

[0031] 6, the second interlayer binding yarn 17B is entangled with the weft yarn 16 of the first layer in the weft group W in the non-cut region RB adjacent to the weft group W1, and is further entangled with the weft yarn 16 of the second weft layer 14 of the weft group W1 located adjacent to the weft group W in the non-cut region RB. Specifically, the second interlayer binding yarn 17B is passed between the weft yarn 16 of the first layer and the weft yarn 16 of the second layer in the weft group W1 in the region to be cut RA so as to move away in the first direction X from the entangled weft yarn 16 of the first layer in the weft group W in the non-cut region RB. Furthermore, the second interlayer binding yarn 17B is passed between the weft yarn 16 of the second layer and the weft yarn 16 of the third layer in the weft group W1 so as to move closer in the first direction X from the weft yarn 16 of the second layer in the weft group W1 to the weft yarn 16 of the third layer in the weft group W in the non-cut region RB. Therefore, the second interlayer binding yarn 17B is entangled with the weft yarn 16 of the second layer of the weft group W1. The second interlayer binding yarn 17B is passed between the weft yarn 16 of the third layer and the weft yarn 16 of the fourth layer of the weft group W1 so as to be separated in the first direction X from the weft yarn 16 of the weft group W in the non-cut region RB. Therefore, the second interlayer binding yarn 17B is entangled with the weft yarn 16 of the third layer of the weft group W1. Furthermore, the second interlayer binding yarn 17B is passed between the weft yarn 16 of the fourth layer of the weft group W1 so as to be separated in the first direction X from the weft yarn 16 of the fourth layer of the weft group W1 and approach the weft yarn 16 of the fifth layer of the weft group W in the non-cut region RB. Therefore, the second interlayer binding yarn 17B is entangled with the weft yarn 16 of the fourth layer of the weft group W1. Therefore, the second interlayer binding yarn 17B is threaded in a zigzag pattern in the lamination direction Z relative to the weft yarn group W1, and is entangled with the weft yarns 16 of the second to fifth layers in the weft yarn group W2.

[0032] The second interlayer binding yarn 17B is entangled with the weft yarn 16 of the fifth layer in the weft yarn group W1. The second interlayer binding yarn 17B is passed between the weft yarn 16 of the fifth layer and the weft yarn 16 of the fourth layer in the weft yarn group W2 so as to move away in the first direction X from the entangled weft yarn 16 of the fifth layer in the weft yarn group W1. Furthermore, the second interlayer binding yarn 17B is passed between the weft yarn 16 of the fourth layer and the weft yarn 16 of the third layer in the weft yarn group W2 so as to move away from the weft yarn 16 of the fourth layer in the weft yarn group W2 and towards the weft yarn 16 of the third layer in the weft yarn group W1 in the first direction X. Therefore, the second interlayer binding yarn 17B is entangled with the weft yarn 16 of the fourth layer in the weft yarn group W2. The second interlayer binding yarn 17B is passed between the third layer weft 16 and the second layer weft 16 in the weft group W2 so as to move away from the third layer weft 16 in the weft group W1 in the first direction X. Therefore, the second interlayer binding yarn 17B is entangled with the third layer weft 16 in the weft group W2. Furthermore, the second interlayer binding yarn 17B is passed between the second layer weft 16 and the first layer weft 16 in the weft group W2 so as to move away from the second layer weft 16 in the weft group W2 towards the first layer weft 16 in the weft group W1 in the first direction X. Therefore, the second interlayer binding yarn 17B is entangled with the second layer weft 16 in the weft group W2. Therefore, the second interlayer binding yarn 17B is passed in a zigzag pattern in the stacking direction Z relative to the weft group W2.

[0033] The second interlayer binding yarn 17B is entangled with the wefts 16 of the first layer in weft group W2. The second interlayer binding yarn 17B is entangled with the wefts 16 of weft group W3, but the entanglement between the second interlayer binding yarn 17B and the wefts 16 of weft group W3 is the same as the entanglement between the second interlayer binding yarn 17B and the wefts 16 of weft group W1. Therefore, the second interlayer binding yarn 17B is threaded in a zigzag pattern in the stacking direction Z with respect to the weft group W3. The second interlayer binding yarn 17B is entangled with the fifth layer in weft group W3, but extends linearly in the stacking direction Z between weft group W3 and weft group W4, and is not entangled with any wefts other than the wefts 16 of the first and fifth layers in weft group W4.

[0034] Incidentally, the fiber structure 11 of this embodiment is cut at the cutting portion S of the region to be cut RA. Specifically, in the region to be cut RA, the fiber structure 11 is cut in the first direction X along the second direction Y. The non-cut region RB having the end portion 11C of the fiber structure 11 remains as the fiber structure 11 after cutting, and the non-cut region RB having the end portion 11D is not used. The fiber structure 11 after cutting is impregnated with a matrix resin M, and the RTM method is used to impregnate the fiber structure 11 with the thermosetting matrix resin M, thereby forming a fiber-reinforced composite material 10.

[0035] As shown in Figure 7, when the warp yarn 15 and the interlayer bonding yarn 17 are cut at the cutting portion S in the region to be cut RA, the weft yarn 16 is also cut in this embodiment. When the interlayer bonding yarn 17 is cut, the tension of the interlayer bonding yarn 17 is zero at the cutting portion S, but the tension increases in the first direction X from the cutting portion S toward the region to be cut RA, and the initial tension is generated in the interlayer bonding yarn 17 in the non-cut region RB. Even when the interlayer bonding yarn 17 is cut, frictional force is generated between the interlayer bonding yarn 17 and the weft yarn 16 due to the entanglement between the interlayer bonding yarn 17 and the weft yarn 16, so the frictional force of the interlayer bonding yarn 17 increases with increasing distance from the cutting portion S.

[0036] 7 shows the tension F in a schematic manner, and for ease of explanation, the length in the stacking direction Z is taken as the magnitude of the tension F, and the magnitude of the tension F in the first direction X is shown. In this embodiment, in the region to be cut RA, there are more weft yarns 16 intertwined with the interlayer bonding yarns 17 than in the non-cut region RB. Therefore, the tension F of the interlayer bonding yarns 17 increases rapidly from the cut portion S toward the region to be cut RA in the first direction X, and remains constant in the region to be cut RA.

[0037] 8 shows a fiber structure 111 as a comparative example, in which only the weft yarns 16 of the weft layers 14 at both ends in the stacking direction Z are entangled with the interlayer bonding yarns 17 and are in a cut state. In the fiber structure 111, the tension F of the interlayer bonding yarns 17 increases in the first direction X from the cut portion S toward the planned cut region RA, but the increase in tension F is gradual and remains constant at a position far away from the cut portion S compared to this embodiment.

[0038] As described above, in this embodiment, the tension F of the interlayer bonding yarn 17 increases rapidly from the cut portion S toward the cut-prospective region RA in the first direction X. Therefore, compared to the fiber structure 111 of the comparative example, the weft yarn 16 near the cut portion S is less likely to fall off from the weft layer 14, and fraying of the cut portion S is suppressed.

[0039] The fiber structure 11 and the fiber reinforced composite material 10 according to this embodiment have the following advantages. (1) The fiber structure 11 has a predetermined region in the first direction X that includes a cut portion S that is to be cut along the second direction Y, referred to as a cut region RA, and a non-cut region RB that is a region of the fiber structure 11 in the first direction X excluding the cut region RA. The interlayer bonding yarn 17 is entangled with the weft yarn 16 of the weft layer 14 located between the weft layers 14 located at both ends in the stacking direction Z in the cut region RA. Because the weft yarn 16 entangled with the interlayer bonding yarn 17 exists in the cut region RA, even if the fiber structure 11 is cut in the direction intersecting the first direction X in the cut region RA, tension remains in the interlayer bonding yarn 17 at a position close to the cut portion S. In other words, by increasing the number of weft yarns 16 entangled with the interlayer bonding yarn 17 in the weft layers 14 located between the weft layers 14 located at both ends in the stacking direction Z, fraying due to the weft yarn 16 falling off from the cut portion S can be suppressed. In addition, in the non-cut region RB where the interlayer bonding yarn 17 is not cut, the interlayer bonding yarn 17 is not entangled with the weft yarn 16 of the weft layer 14 located between the weft layers 14 located at both ends in the stacking direction Z, making it easier to produce a fiber structure.

[0040] (2) Because the weft yarn 16 is a spun yarn, the frictional force of the weft yarn 16 located at the cut portion S against the warp yarn 15 and the interlayer bonding yarn 17 is increased, making it less likely to shift position. In addition, because the interlayer bonding yarn 17 is a continuous yarn, it is possible to increase the tension and strengthen the pressing force in the stacking direction Z of the weft layer 14. As a result, the weft yarn 16 at the cut portion S is more unlikely to fall off.

[0041] (3) The fiber-reinforced composite material 10 is formed by impregnating a fiber structure 11 with a matrix resin M. Since fraying of the fiber structure 11 due to the weft yarn 16 falling off from the cut portion S can be suppressed, a decrease in the strength of the fiber-reinforced composite material 10 caused by the weft yarn 16 falling off from the cut portion S can be suppressed.

[0042] Next, a fiber structure 21 according to Modified Example 1 shown in Fig. 9 will be described. In the region to be cut RA of the fiber structure 21, the first interlayer binding yarn 17A is entangled with the weft yarn 16 of the first layer in the weft yarn group W1, and is passed between the weft yarn 16 of the first layer and the weft yarn 16 of the second layer in the weft yarn group W2 adjacent to the entangled weft yarn 16 so as to move away from the weft yarn 16 of the first layer in the entangled weft yarn group W1 in the first direction X. Furthermore, the first interlayer binding yarn 17A is passed in the stacking direction Z from the weft yarn 16 of the second layer in the entangled weft yarn group W2, and is passed between the weft yarn 16 of the fourth layer and the weft yarn 16 of the fifth layer in the weft yarn group W2 so as to approach the weft yarn 16 of the fifth layer in the weft yarn group W1. Therefore, the first interlayer binding yarn 17A is entangled with the weft yarns 16 of the second and fourth layers in the weft yarn group W2. The first interlayer binding yarn 17A is entangled with the weft yarn 16 of the fifth layer of weft group W2. Therefore, the first interlayer binding yarn 17A is entangled with the weft yarns 16 of the second, fourth, and fifth layers of weft group W2. The first interlayer binding yarn 17A is also entangled with the wefts of the second and fourth layers of weft groups W3 and W4.

[0043] Similar to the first interlayer binding yarn 17A, the second interlayer binding yarn 17B is entangled with the wefts 16 of the second and fourth layers in the region to be cut RA. Specifically, in the weft groups W1 to W3 in the region to be cut RA of the fiber structure 21, the second interlayer binding yarn 17B is entangled with the wefts 16 of the second and fourth layers.

[0044] The fiber structure 21 according to Alternative Example 1 includes a third layer of unentangled weft yarns 16, as compared with the fiber structure 11 of the embodiment, but the number of weft yarns 16 entangled with the interlayer binding yarns 17 is increased in the weft layers 14 located between the weft layers 14 located at both ends in the stacking direction Z. This makes it possible to suppress fraying due to the weft yarns 16 falling off from the cut portions S.

[0045] Next, a fiber structure 31 according to Modified Example 2 shown in Fig. 10 will be described. In the region to be cut RA of the fiber structure 21, the first interlayer binding yarn 17A is entangled with the weft yarn 16 of the first layer in the weft group W1. The first interlayer binding yarn 17A is passed between the weft yarn 16 of the second layer and the weft yarn 16 of the third layer in the weft group W2 adjacent to the entangled weft yarn 16, so as to move away from the weft yarn 16 of the first layer in the entangled weft group W1 in the first direction X. The first interlayer binding yarn 17A is also passed between the weft yarn 16 of the third layer and the weft yarn 16 of the fourth layer in the weft group W2, so as to move away from the weft yarn 16 of the third layer in the entangled weft group W2. The first interlayer binding yarn 17A is passed in the stacking direction Z and is entangled with the weft yarn 16 of the fifth layer in the weft group W2. Therefore, the first interlayer binding yarn 17A is entangled with the weft yarns 16 of the third layer in the weft yarn group W2, and also with the weft yarns 16 of the second and fourth layers. The first interlayer binding yarn 17A is also entangled with the weft yarns 16 of the third layer in the weft yarn groups W3 and W4, and is also entangled with the weft yarns 16 of the second and fourth layers.

[0046] Similar to the first interlayer binding yarn 17A, the second interlayer binding yarn 17B is entangled with the weft yarn 16 of the third layer in the region to be cut RA, and is also entangled with the weft yarns 16 of the second and fourth layers. Specifically, in the weft yarn groups W1 to W3 in the region to be cut RA of the fiber structure 21, the second interlayer binding yarn 17B is entangled with the weft yarn 16 of the third layer, and is also entangled with the weft yarns 16 of the second and fourth layers.

[0047] The fiber structure 21 of Alternative Example 2 includes unentangled weft yarns 16 in a third layer, as compared with the fiber structure 11 of the embodiment. However, the number of weft yarns 16 entangled with the interlayer bonding yarns 17 in the weft layers 14 located between the weft layers 14 located at both ends in the stacking direction Z is increased compared with the non-cut region RB. In addition, the interlayer bonding yarns 17 are entangled with the weft yarns 16 in the second and fourth layers. This prevents fraying due to the weft yarns 16 falling off from the cut portion S.

[0048] The present invention is not limited to the above-described embodiment (including the alternative examples), and various modifications are possible within the scope of the spirit of the invention. For example, the following modifications may be made.

[0049] In the above embodiment (including the modified examples), the first yarn is the warp yarn and the second yarn is the weft yarn, but this is not limiting. For example, the first yarn may be the weft yarn and the second yarn may be the warp yarn. In the above-described embodiments (including alternative examples), the fiber structure has a region to be cut and a region not to be cut, but this is not limiting. For example, the interlayer bonding yarn may be adjacent to the first yarn in the second direction, have a main axis extending in the first direction, and be entangled with the second yarn of the second yarn layer located at both ends in the stacking direction, so that the entire fiber structure is the region to be cut. In this case, as long as the cut portion is in a direction intersecting the first direction of the fiber structure, even if the fiber structure is cut at any position, fraying due to the second yarn falling off from the cut portion can be suppressed by increasing the number of second yarns entangled with the interlayer bonding yarn in the second yarn layer located between the second yarn layers located at both ends in the stacking direction. In the above embodiment (including the alternatives), the weft yarn, which is the second yarn, is a spun yarn, and the interlayer binding yarn is a continuous yarn, but this is not limited to this. For example, the second yarn may be a continuous yarn, and the interlayer binding yarn may be a spun yarn. In the above embodiment (including other examples), a fiber structure in which non-cut regions are formed on both sides of the region to be cut in the first direction has been described as an example, but this is not limited thereto. For example, the fiber structure before cutting may be formed only on one side of the region to be cut in the first direction. Furthermore, the length of the region to be cut in the first direction and the number of first and second yarn layers in the stacking direction are not particularly limited. In the above embodiment (including the alternative examples), the weft yarn as the second yarn is cut along the second direction in the region to be cut, but this is not limited to this. The weft yarn may be cut between adjacent weft yarns in the region to be cut. Furthermore, the direction of the cut portion does not have to be the second direction, and may be a direction inclined toward the second direction and the stacking direction, as long as the cut portion is included in the region to be cut. [Explanation of symbols]

[0050] 10 Fiber-reinforced composites 11 Fiber structures 11A, 11B end 11C, 11D end 12 Fiber layer 13 Warp layer (first layer) 14 Weft layer (second layer) 14A 1st end layer 14B 2nd end layer 15 Warp thread (first thread) 15A Warp group 16 Weft thread (second thread) 17 Interlayer bonding thread 17A First interlayer bonding thread 17B Second interlayer bonding thread M matrix resin RA planned cleavage area RB uncut area T warp group S cutting section W, W1, W2, W3, W4 weft group X 1st direction Y Second direction Z stacking direction

Claims

1. A fiber structure comprising a plurality of fiber layers stacked in a stacking direction and an interlayer binding yarn that binds the plurality of fiber layers in the stacking direction, The plurality of fiber layers are a plurality of first yarn layers; a second yarn layer located between the first yarn layers in the stacking direction, The first yarn layer includes a plurality of first yarns, each having a main axis extending in a first direction, arranged in a second direction perpendicular to the first direction, the second yarn layer includes a plurality of second yarns arranged in the first direction, the second yarns having a main axis extending in the second direction without being entangled with the first yarns, and the second yarn layer is located at both ends of the fiber structure in the layering direction, A fiber structure characterized in that the interlayer bonding yarn is adjacent to the first yarn in the second direction, has a yarn main axis extending in the first direction, is entangled with the second yarn of the second yarn layer located at both ends in the stacking direction, and is entangled with the second yarn of the second yarn layer located between the second yarn layers located at both ends in the stacking direction in a planned cutting region including a cutting portion planned to be cut in a direction intersecting the first direction.

2. a non-cutting region excluding the planned cutting region in the first direction; The fiber structure according to claim 1, characterized in that the interlayer bonding yarn is not entangled with the second yarn of the second yarn layer located between the second yarn layers located at both ends in the stacking direction in the non-cut region.

3. 3. The fiber structure according to claim 1, wherein at least one of the first yarn and the second yarn is a spun yarn, and the interlayer bonding yarn is a continuous yarn.

4. A fiber reinforced composite material formed by impregnating a fiber structure with a matrix resin, A fiber-reinforced composite material, characterized in that the fiber structure is the fiber structure according to any one of claims 1 to 3.

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