Preform for fiber-reinforced plastic molded body, fiber-reinforced plastic molded body, and method for manufacturing preform for fiber-reinforced plastic molded body

Abstract

The preform (1) for a fiber-reinforced plastic molding has a substrate (11), a continuous fiber bundle (12) arranged on the substrate, an optical fiber (13) arranged in at least a portion of the continuous fiber bundle (12) along the extension direction of the continuous fiber bundle (12), and a fixing thread (14) sewn to the substrate (11) to fix the continuous fiber bundle (12) and the optical fiber (13).

Description

[Technical field]

[0001] The present disclosure relates to a preform for a fiber-reinforced plastic molded body having a continuous fiber bundle and an optical fiber, and also to a fiber-reinforced plastic molded body and a method for manufacturing a preform for a fiber-reinforced plastic molded body. [Background technology]

[0002] For example, there is a movement to increase the functionality of fiber reinforced plastics (FRP) used in artificial satellites by mounting sensors such as optical fibers inside the FRP. On the other hand, in recent years, a preform has been devised in which reinforcing fibers are oriented in a desired direction, not in a plane but in a line, by sewing a flexible continuous fiber bundle to a base material such as a fiber fabric with thread to integrate it. In addition, a method for realizing FRP using such a preform (e.g. TFP: Tailored Fiber Placement) has been devised. Patent Document 1 discloses a method for manufacturing an integrally molded product of a flexible structure, flexible electrical wiring, and resin. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2023-79743 A Summary of the Invention [Problem to be solved by the invention]

[0004] The technology disclosed in Patent Document 1 makes it possible to realize a fiber-reinforced plastic molded article including electrical wiring by using continuous fiber bundles as a flexible structure. However, in Patent Document 1, it is not possible to stably measure the stress and strain states occurring in the continuous fiber bundle.

[0005] An object of this disclosure is to provide a fiber-reinforced plastic molded body that enables stable measurement of the stress and strain states occurring in a continuous fiber bundle, and a preform for a fiber-reinforced plastic molded body used in the production of the same. [Means for solving the problem]

[0006] The preform for a fiber-reinforced plastic molding according to the present disclosure is A substrate; A continuous fiber bundle disposed on a substrate; an optical fiber arranged in at least a portion of the continuous fiber bundle along the extending direction of the continuous fiber bundle; A fixing thread that is sewn to the base material to fix the continuous fiber bundle and the optical fiber; has. Effect of the Invention

[0007] According to the present disclosure, an optical fiber is arranged along the extending direction of the continuous fiber bundle on at least a portion of the substrate, so that the stress and strain generated in the continuous fiber bundle are easily transmitted to the optical fiber, thereby realizing stable measurement of the stress and strain by the optical fiber. [Brief description of the drawings]

[0008] [Figure 1] 1 is a plan view showing an example of the configuration of a preform for a fiber-reinforced plastic molded body according to a first embodiment. [Diagram 2] 1 is a cross-sectional view showing an example of the configuration of a preform for a fiber-reinforced plastic molding according to a first embodiment. [Diagram 3] FIG. 2 is an explanatory diagram showing an example of a manufacturing process of the preform for a fiber-reinforced plastic molding according to the first embodiment. [Figure 4] 1 is a perspective view showing an example of the configuration of a preform for a fiber-reinforced plastic molding according to a first embodiment. [Diagram 5] FIG. 11 is a plan view showing a configuration example of a preform for a fiber-reinforced plastic molding according to a second embodiment. [Figure 6]FIG. 6 is a cross-sectional view showing a configuration example of a preform for a fiber-reinforced plastic molding according to a second embodiment. [Figure 7] FIG. 11 is a plan view showing a configuration example of a preform for a fiber-reinforced plastic molding according to a third embodiment. [Figure 8] FIG. 11 is a cross-sectional view showing a configuration example of a preform for a fiber-reinforced plastic molding according to a third embodiment. [Figure 9] 10A to 10C are explanatory views showing a part of a manufacturing process of a fiber-reinforced plastic molded body according to a fourth embodiment, in which (a) is a view before lamination, (b) is a view after lamination, and (c) is a view of the fiber-reinforced plastic molded body. [Figure 10] 11 is an explanatory diagram showing a manufacturing process of a preform for a fiber-reinforced plastic molding according to embodiment 5. (a) is a diagram of an optical fiber sewing step, (b) is a diagram after the optical fiber sewing step, (c) is a diagram of a continuous fiber bundle sewing step, and (d) is a diagram after the continuous fiber bundle sewing step. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, a preform 1 for a fiber-reinforced plastic molded body, a fiber-reinforced plastic molded body 2 using the preform 1 for a fiber-reinforced plastic molded body, and a manufacturing method of the preform 1 for a fiber-reinforced plastic molded body for implementing the present disclosure will be described with reference to the drawings. In the description of the drawings, the same or corresponding parts are given the same reference numerals, and duplicate descriptions are omitted as appropriate.

[0010] Embodiment 1 Hereinafter, the present embodiment will be described in detail with reference to the drawings. FIG. 1 is a plan view showing an example of the configuration of a preform 1 for a fiber-reinforced plastic molding according to the first embodiment.

[0011] The preform 1 for a fiber-reinforced plastic molding comprises a substrate 11, a continuous fiber bundle 12 arranged on the substrate 11, an optical fiber 13, and a fixing thread 14. The optical fiber 13 is arranged along the stretching direction S of the continuous fiber bundle 12 in at least a part of the continuous fiber bundle 12. The continuous fiber bundle 12 has a curved portion on the surface of the substrate 11. The optical fiber 13 is arranged so as to follow the entire curved portion or at least a part of the curved portion.

[0012] 1, as the optical fibers 13 arranged along the stretching direction S of the continuous fiber bundle 12, an optical fiber formed in a position contained in the continuous fiber bundle 12 and an optical fiber formed in a position in contact with the continuous fiber bundle 12 are illustrated. The optical fibers 13 may include both an optical fiber formed in a position contained in the continuous fiber bundle 12 and an optical fiber formed in a position in contact with the continuous fiber bundle 12, or may include only one of them.

[0013] Here, "contained" means that continuous fibers are present around the optical fiber 13. In the case of "contained", when the continuous fiber bundle 12 is viewed from the outside, the optical fiber 13 cannot be seen with the naked eye. Moreover, "contact" means that a part of the optical fiber 13 is in contact with the continuous fiber bundle 12. In the case of "contact," when the continuous fiber bundle 12 is viewed from the outside, at least a part of the optical fiber 13 can be seen with the naked eye.

[0014] The continuous fiber bundle 12 and the optical fiber 13 are sewn and fixed to the base material 11 by a fixing thread 14 .

[0015] The configuration of the preform 1 for a fiber-reinforced plastic molding will be described in detail below by giving a specific example. FIG. 2 is a cross-sectional view showing an example of the configuration of the preform 1 for a fiber-reinforced plastic molding according to the first embodiment.

[0016] The continuous fiber bundle 12 and the optical fiber 13 are disposed on the substrate 11, and are fixed to the substrate 11 by the fixing thread 14. In FIG. 2, the optical fiber 13 contained in the continuous fiber bundle 12 and the optical fiber 13 disposed so as to be in contact with the continuous fiber bundle 12 and the substrate 11 are both shown, but there is no limit to the number of optical fibers. As shown in FIG. 1, in a part of the substrate 11, the optical fiber 13 is disposed so as to coincide with the extending direction of the continuous fiber bundle 12. The substrate 11 can be made of glass cloth, the continuous fiber bundle 12 can be made of carbon fiber (T700SC, 12K, manufactured by Toray Industries, Inc.), and the fixing thread 14 can be made of nylon fiber. The fixing thread 14 can include an upper thread and a lower thread.

[0017] As a method for manufacturing the preform 1 for a fiber-reinforced plastic molding, for example, a TFP (Tailored Fiber Placement) method can be used. The TFP method is a fiber preform production technology that applies textile technology to orient continuous fiber bundles 12. In the TFP method, an industrial embroidery machine (not shown) is used to sew the continuous fiber bundles 12. Based on preset path (route) data, the continuous fiber bundles 12 are arranged on the substrate 11 and sewn with a fixed thread 14. This makes it possible to produce a preform 1 for a fiber-reinforced plastic molding in which the continuous fiber bundles 12 are sewn to the substrate 11. In the TFP method, optimal fiber orientation can be achieved by setting an appropriate path based on stress analysis, etc. For example, when sewing the continuous fiber bundles 12 to the substrate 11, the fiber orientation angle can be continuously changed. A fiber-reinforced plastic (composite material) in which the fiber orientation angle is continuously changed is called a steering composite material. Figure 1 shows an example of a preform 1 for a fiber-reinforced plastic molding in which the fiber orientation angle is continuously changed, and a steering composite material can be realized by impregnating this preform 1 for a fiber-reinforced plastic molding with resin and curing it.

[0018] FIG. 3 is an explanatory diagram showing an example of a manufacturing process in the TFP method for the preform 1 for a fiber-reinforced plastic molding according to the first embodiment. With the optical fiber 13 disposed inside or on the side of the continuous fiber bundle 12 before sewing, an assembly 15 of the continuous fiber bundle 12 and the optical fiber 13 is supplied from a supply port 21 of an embroidery machine (not shown) and fixed to the substrate 11 by the fixing thread 14 by the up and down movement of a sewing needle 22. This makes it possible to realize a preform 1 for a fiber-reinforced plastic molding in which the optical fiber 13 is disposed in a position that is contained within or in contact with the continuous fiber bundle 12.

[0019] As a method for determining the strain based on the response of the optical fiber 13, a method of continuously measuring the strain of the optical fiber by the frequency shift of Rayleigh scattered light can be used.

[0020] Although the case where a glass cloth base material is used as the base material 11 has been described, any material may be used as long as the continuous fiber bundle 12 and the optical fiber 13 can be sewn together with the fixing thread 14 and the material can be impregnated with resin. Specifically, the base material 11 can be a carbon fiber base material, a nylon fiber base material, a polyester fiber base material, or the like. Fiber substrates, cotton fiber substrates, nonwoven fabrics, etc. can be used. It is also possible to use a thermosetting resin film or a thermoplastic resin film as the substrate 11. By using a thermosetting resin film or a thermoplastic resin film as the substrate 11, the substrate 11 can be integrated without remaining when the fiber-reinforced plastic molded body 2 is molded. In particular, by using the same material as the base resin of the fiber-reinforced plastic molded body 2 for the base material 11, the amount of the base material 11 remaining can be minimized.

[0021] In addition, although the above description concerns the use of carbon fiber as the continuous fiber bundle 12, fibers such as glass fiber, aramid fiber (Kevlar (registered trademark) fiber), polyethylene fiber (Dyneema (registered trademark) fiber), Zylon (registered trademark) fiber, boron fiber, alumina fiber, silicon carbide fiber, and flax fiber can be used instead of carbon fiber.

[0022] Although the above description has been given of the case where nylon fiber is used as the fixing thread 14, organic fibers such as glass fiber, carbon fiber, para-aramid fiber, and polyester fiber, as well as combinations of these, can also be used. Furthermore, a water-soluble material such as vinylon or a thermoplastic material can be used as the material for the fixing thread 14. Furthermore, the same material as the matrix resin used in making the fiber-reinforced plastic molded body 2 may be used as the material for all or a part of the fixing thread 14.

[0023] Moreover, the optical fiber 13 does not need to be arranged along the extension direction of the continuous fiber bundle 12 over the entire length of the continuous fiber bundle 12 constituting the preform 1 for a fiber-reinforced plastic molding. The optical fiber 13 only needs to have the same extension direction as the continuous fiber bundle 12 in at least a portion of the substrate 11. In particular, when a location where stress and strain are concentrated is specified, the optical fiber 13 may be arranged partially along the continuous fiber bundle 12 depending on the design.

[0024] Also, while the case has been described where Rayleigh scattered light is used as a measurement method for the optical fiber 13 to continuously measure the strain on the optical fiber 13, a measurement method using Raman scattered light or Brillouin scattered light can be used instead of Rayleigh scattered light. Furthermore, an FBG (Fiber Bragg Grating) sensor having a grating section in which the refractive index is periodically changed in part of the core of the optical fiber 13 may be used. The FBG sensor may have multiple grating sections.

[0025] In addition, the radius of curvature when the fiber orientation angle is continuously changed can be continuously and appropriately selected from, for example, 1 mm, 5 mm, 10 mm, 50 mm, 100 mm, 200 mm, values ​​therebetween, or other values ​​along a required path. Although the method for fixing the continuous fiber bundle 12 and the optical fiber 13 on the substrate 11 has been described using the TFP method, a method other than the TFP method may be used. For example, a method may be used in which, after only the continuous fiber bundle 12 is fixed on the substrate 11 by the TFP method, the optical fiber 13 is manually inserted between the fixing threads 14 used for fixing the continuous fiber bundle 12 to the substrate 11, and integrated with the optical fiber 13.

[0026] In addition, the method of arranging the optical fiber 13 has been described as being arranged so as to be in contact with the continuous fiber bundle 12 and the base material 11, but the optical fiber 13 need only be in contact with or contained within the continuous fiber bundle 12, and does not need to be in contact with the base material 11.

[0027] FIG. 4 is a perspective view of the continuous fiber bundle 12 according to the first embodiment. As a method of arranging the optical fiber 13, the optical fiber 13 may be wound in a spiral shape around the continuous fiber bundle 12 as shown in FIG. The continuous fiber bundle 12 and the optical fiber 13 are difficult to separate. When using the TFP method, a preform 1 for a fiber-reinforced plastic molding can be realized by using an assembly 15 in which the optical fiber 13 is wound around the continuous fiber bundle 12 in advance.

[0028] The optical fiber 13 may be arranged in the continuous fiber bundle in one or more of the following states: a state in which it is arranged at a position contained in the continuous fiber bundle 12, a state in which it is arranged at a position in contact with the continuous fiber bundle 12, or a state in which it is spirally wound around the continuous fiber bundle 12. In addition to the continuous fiber bundle 12 and the optical fiber 13, a fibrous device or the like may be disposed and sewn to the substrate 11. For example, a thermocouple, a strain gauge, a heating wire, or the like may be added as the fibrous device.

[0029] ***Explanation of the Effects of the First Embodiment*** According to this embodiment, the optical fiber 13 is arranged along the stretching direction of the continuous fiber bundle 12 in at least a part of the continuous fiber bundle 12, and the continuous fiber bundle 12 and the optical fiber 13 are fixed to the substrate 11 by a fixing thread 14. Therefore, in the fiber-reinforced plastic molding 2 using the preform 1 for a fiber-reinforced plastic molding, the stress and strain changes along the continuous fiber bundle 12 can be stably measured by the optical fiber 13.

[0030] According to this embodiment, a preform 1 for a fiber-reinforced plastic molding can be obtained to realize a fiber-reinforced plastic molding 2 in which strain changes along the continuous fiber bundle 12 can be stably measured using the optical fiber 13.

[0031] According to this embodiment, it is only necessary that the continuous fiber bundle 12 and the optical fiber 13 are fixed at a portion in the extension direction, so that the path of the continuous fiber bundle 12 according to the design can be realized.

[0032] Furthermore, if the fixing threads 14 are made of the same material as the base resin of the fiber-reinforced plastic molded body 2, the fiber-reinforced plastic molded body 2 can be realized without leaving any fixing threads 14 remaining.

[0033] Furthermore, if the base material 11 is made of the same material as the base resin of the fiber-reinforced plastic molded body 2, the fiber-reinforced plastic molded body 2 can be realized without leaving any of the base material 11 remaining.

[0034] If the optical fiber is arranged after manufacturing a preform for a fiber-reinforced plastic molding in which the continuous fiber bundle 12 is arranged, the optical fiber may be misaligned during the process of stacking or arranging the optical fiber, which may prevent the desired stress and strain from being measured. By arranging the optical fiber 13 along the extension direction of the continuous fiber bundle 12 and fixing the optical fiber 13 with the fixing thread 14 as in this embodiment, it is possible to prevent the optical fiber 13 from being misaligned and to achieve highly accurate measurement of stress and strain.

[0035] When the continuous fiber bundle 12 and the optical fiber 13 are disposed on separate substrates 11 and fixed with a fixing thread 14, even if the extending directions of the continuous fiber bundle 12 and the optical fiber 13 are the same, the stress and strain state of the continuous fiber bundle 12 cannot be measured directly and the measurement accuracy is reduced because the layers in which the continuous fiber bundle 12 and the optical fiber 13 are formed are different. By holding the optical fiber 13 in a state where it is contained within or in contact with the continuous fiber bundle 12 as in this embodiment, the stress and strain state of the continuous fiber bundle 12 can be measured directly and highly accurate measurement can be achieved.

[0036] Even when the continuous fiber bundle 12 and the optical fiber 13 are disposed on the same substrate, if the continuous fiber bundle 12 and the optical fiber 13 are fixed with separate fixing threads 14, the fixing threads 14 for fixing the optical fiber 13 act as a constraint, and it is not possible to stably measure the stress and strain state of the continuous fiber bundle 12. By fixing the continuous fiber bundle 12 and the optical fiber 13 with the same fixing thread 14 as in this embodiment, the stress and strain states of the continuous fiber bundle 12 and the optical fiber 13 become the same, and high-precision measurement is possible. This allows for accurate measurements.

[0037] Embodiment 2 The following mainly describes the differences from the above-described embodiment with reference to the drawings. FIG. 5 is a plan view showing a configuration example of the preform 1 for a fiber-reinforced plastic molding according to the second embodiment.

[0038] The preform 1 for fiber-reinforced plastic moldings is composed of a substrate 11, a continuous fiber bundle 12 arranged on the substrate 11, an optical fiber 13, a first fixing thread 16, and a second fixing thread 17. The optical fiber 13 is formed at a position in contact with the continuous fiber bundle 12 along the extension direction of the continuous fiber bundle 12 in at least a part of the continuous fiber bundle 12. The first fixing thread 16 is sewn to the substrate 11 so as to straddle only the optical fiber, and fixes the optical fiber 13 to the substrate 11. On the other hand, the second fixing thread 17 is sewn to the substrate 11 so as to straddle the continuous fiber bundle 12 and the optical fiber 13 in at least a part of a portion where the extension directions of the continuous fiber bundle 12 and the optical fiber 13 are aligned, and fixes both the continuous fiber bundle 12 and the optical fiber 13 to the substrate 11.

[0039] The configuration of the preform 1 for a fiber-reinforced plastic molding will be described in detail below by giving a specific example. FIG. 6 is a cross-sectional view showing an example of the configuration of a preform 1 for a fiber-reinforced plastic molding according to the second embodiment.

[0040] The continuous fiber bundle 12 and the optical fiber 13 are disposed on the substrate 11. The width of the continuous fiber bundle 12 in the cross section (the maximum width in the cross section in the direction parallel to the surface of the substrate 11) is L. The optical fiber 13 is disposed at a position where the center of the optical fiber 13 is shifted from the center of the continuous fiber bundle 12 by L / 2 (distance D=L / 2) in a plan view. The optical fiber 13 is disposed in a state of contact with the continuous fiber bundle 12 and the substrate 11, and is fixed to the substrate 11 by a first fixing thread 16. For example, a thread using a thermoplastic material can be used as the first fixing thread 16. The second fixing thread 17 is disposed so as to cover the continuous fiber bundle 12 and the optical fiber 13 at least in a part of the area where the continuous fiber bundle 12 and the optical fiber 13 are aligned in the extension direction, and fixes the continuous fiber bundle 12 and the optical fiber 13 to the substrate 11. Nylon fiber can be used as the second fixing thread 17.

[0041] By using the first fixing thread 16, the optical fiber 13 can be fixed to the substrate 11 independently of the continuous fiber bundle 12. This eliminates the need for the integration work of the continuous fiber bundle 12 and the optical fiber 13 before fixing them to the substrate 11, which is required in the above-mentioned first embodiment, and improves workability. Furthermore, when molding the fiber-reinforced plastic molding 2, by using the same material as the first fixing thread 16 as the base resin to be impregnated, the first fixing thread 16 can be melted in the base resin and integrated with it. Therefore, the optical fiber 13 is no longer restrained by the first fixing thread 16, and the strain occurring in the continuous fiber bundle 12 can be measured more stably.

[0042] Although the case where a thermoplastic material is used as the material of the first fixing thread 16 has been described, a water-soluble material or a soluble material may be used. As the material of the first fixing thread 16, organic fibers such as nylon fiber, glass fiber, carbon fiber, para-aramid fiber, and polyester fiber may be used. Furthermore, by using a material that dissolves or melts due to an external stimulus such as heat or moisture, such as a thermoplastic material, the fiber-reinforced plastic molded body 2 can be realized without leaving the first fixing thread 16. As a soluble or meltable material, in addition to a thermoplastic resin, a water-soluble material such as vinylon may be used. When a soluble resin such as a water-soluble material is used, the preform 1 for a fiber-reinforced plastic molded body similar to that of the first embodiment can be realized by dissolving the first fixing thread 16.

[0043] Furthermore, the material of the first fixing thread 16 or the second fixing thread 17, or both of them, may be the same as the matrix resin used when the fiber reinforced plastic molded body 2 is produced.

[0044] Also, although the case has been described where the center of the optical fiber 13 is disposed at a position shifted by L / 2 from the center of the continuous fiber bundle 12, it is sufficient that the optical fiber 13 is disposed at a position where it comes into contact with the continuous fiber bundle 12 and the substrate 11 and where the strain of the continuous fiber bundle 12 can be measured from the response of the optical fiber 13. Specifically, it is sufficient that the distance D between the center of the optical fiber 13 and the center of the continuous fiber bundle 12 is equal to or less than L / 2.

[0045] ***Explanation of the Effects of the Second Embodiment*** According to this embodiment, there is a first fixing thread 16 that fixes only the optical fiber 13, and a second fixing thread 17 that fixes the optical fiber 13 and the continuous fiber bundle 12. Therefore, the optical fiber 13 can be fixed to the substrate 11 independently of the continuous fiber bundle 12, improving the workability of preform manufacturing.

[0046] Furthermore, by using a material that dissolves or melts in response to an external stimulus as the first fixing thread 16, it is possible to realize the fiber-reinforced plastic molding 2 without leaving the first fixing thread 16. As a result, the optical fiber 13 is no longer constrained by the first fixing thread 16, and the stress and strain generated in the continuous fiber bundle 12 can be measured more stably.

[0047] Embodiment 3 The following mainly describes the differences from the above-described embodiment with reference to the drawings. FIG. 7 is a plan view showing a configuration example of the preform 1 for a fiber-reinforced plastic molding according to the third embodiment.

[0048] The first fixing thread 16 is sewn to the base material 11 so as to straddle only the optical fiber, and fixes the optical fiber 13 to the base material 11. On the other hand, the second fixing thread 17 is sewn to the base material 11 so as to straddle only the continuous fiber bundle 12, and fixes the continuous fiber bundle 12 and the optical fiber 13 to the base material 11.

[0049] The configuration of the preform 1 for a fiber-reinforced plastic molding will be described in detail below by giving a specific example. FIG. 8 is a cross-sectional view showing an example of the configuration of a preform 1 for a fiber-reinforced plastic molding according to the third embodiment.

[0050] The continuous fiber bundle 12 and the optical fiber 13 are disposed on the substrate 11. A thread using a thermoplastic material can be used as the first fixing thread 16. The second fixing thread 17 is disposed so as to cover only the continuous fiber bundle 12, and fixes the continuous fiber bundle 12 to the substrate 11. The second fixing thread 17 can be made of nylon fiber.

[0051] By using the first fixing thread 16, the optical fiber 13 can be fixed to the substrate 11 independently of the continuous fiber bundle 12. This eliminates the need to integrate the continuous fiber bundle 12 and the optical fiber 13 before fixing them to the substrate 11, as in the second embodiment, improving workability.

[0052] Furthermore, in this embodiment, there is no need to cover the optical fiber 13 with the second fixing thread 17, and the setting regarding sewing of the second fixing thread 17 is easy. On the other hand, the first fixing thread 16 made of a thermoplastic resin can become a constraint when the fiber-reinforced plastic molding 2 is formed. Therefore, the first fixing thread 16 is melted and solidified again in the state of the preform 1 for the fiber-reinforced plastic molding, and the optical fiber 13 is integrated with the continuous fiber bundle 12. .

[0053] As a method for treating the first fixing thread 16, a case has been described in which the first fixing thread 16 is melted in the state of the preform 1 for a fiber-reinforced plastic molding and the optical fiber 13 is integrated with the continuous fiber bundle 12, but the first fixing thread 16 can also be integrated with the base resin by impregnating the preform 1 for a fiber-reinforced plastic molding with resin and using the same thermoplastic resin as the first fixing thread 16 as the base resin when forming the fiber-reinforced plastic molding 2. Furthermore, the first fixing thread 16 can also be melted in the base resin by using a thermosetting resin with a higher molding temperature or a thermoplastic resin with a higher melting temperature than the first fixing thread 16 as the base resin.

[0054] ***Explanation of the Effects of the Third Embodiment*** According to this embodiment, there is a first fixing thread 16 that fixes only the optical fiber 13, and a second fixing thread 17 that fixes only the continuous fiber bundle 12. Therefore, the optical fiber 13 can be fixed to the substrate 11 independently of the continuous fiber bundle 12, improving the workability of preform manufacturing. Also, there is no need to cover the optical fiber 13 with the second fixing thread 17, and sewing of the second fixing thread 17 can be easily set.

[0055] According to this embodiment, the optical fiber 13 is fixed by a first fixing thread 16 made of a thermoplastic resin, and by melting the first fixing thread 16 after producing the preform 1 for a fiber-reinforced plastic molding, the continuous fiber bundle 12 and the optical fiber 13 can be integrated, and a preform 1 for a fiber-reinforced plastic molding that has the same effect as in embodiment 1 can be obtained.

[0056] According to this embodiment, there is no need to prepare an integrated body of the optical fiber 13 and the continuous fiber bundle 12 in advance, and they can be arranged separately on the substrate. This reduces the cost of producing the preform 1 for a fiber-reinforced plastic molding, while preventing misalignment of the optical fiber 13, and enables the stress and strain state of the continuous fiber bundle 12 to be measured with high accuracy.

[0057] Embodiment 4 The following mainly describes the differences from the above-described embodiment with reference to the drawings. FIG. 9 is an explanatory diagram showing a part of the manufacturing process of the fiber-reinforced plastic molded body 2 according to the fourth embodiment.

[0058] FIG. 9 shows an example in which the preform 1 for a fiber-reinforced plastic molded body of any of the above-mentioned embodiments is used, and a plain-woven preform 23 that does not include an optical fiber. The fiber-reinforced plastic molded body 2 has at least one layer made of the preform 1 for a fiber-reinforced plastic molded body. In the fiber-reinforced plastic molded body 2, the preform 1 for a fiber-reinforced plastic molded body is impregnated with a matrix resin, and when the fiber-reinforced plastic molded body 2 is composed of a plurality of layers as shown in FIG. 9, the layers are integrated by the matrix resin. Among the layers constituting the fiber-reinforced plastic molded body 2, the layer made of the preform 1 for a fiber-reinforced plastic molded body is equipped with an optical fiber 13, and the stress and strain occurring in the fiber-reinforced plastic molded body 2 can be measured from the response of this optical fiber 13.

[0059] An example of a method for impregnating a preform 1 for a fiber-reinforced plastic molding with a resin and producing a fiber-reinforced plastic molding 2 will be described. First, as shown in FIG. 9(a), a plain weave preform 23 is formed on a molding die 24, and then a preform 1 for a fiber-reinforced plastic molding is formed on the plain weave preform 23. Next, another plain woven preform 23 is formed on top of it to obtain a preform laminate 25 (FIG. 9(b)). In this state, the preform laminate 25 can be impregnated with a resin and cured to obtain a fiber reinforced plastic molded body 2. Examples of methods for impregnating and curing resin include VaRTM (Vacuum Assis VaRTM (VaRTM) can be used. To perform VaRTM, peel ply and flow media are laminated on the preform laminate 25, the whole is covered with a bagging film, and the periphery is fixed with a sealant tape. At this time, a vacuum tube connected to a vacuum pump and a resin injection tube are arranged so as to penetrate the bagging film. In this state, the vacuum tube and vacuum pump are connected, and the vacuum pump is started to create a vacuum inside the bagging film, and then resin is poured in from the resin injection tube. After the resin is impregnated into the preform laminate 25, the vacuum pump is stopped and the preform laminate is left to stand until the resin hardens. After the resin hardens, it is post-cured in an oven or the like as necessary to obtain a fiber-reinforced plastic molded body 2 (FIG. 9(c)).

[0060] The preforms may be temporarily fixed in the preform laminate 25 before impregnation. Tape, adhesive, or the like may be used for the temporary fixing. When a thermoplastic resin is used as the base material 11 of the preform 1 for a fiber-reinforced plastic molding and the plain weave preform 23, the preforms can be temporarily fixed by melting a part of the resin.

[0061] In addition, although the above description concerns the case where a plain weave preform 23 is used as a layer other than the preform 1 for a fiber-reinforced plastic molding, a satin weave preform, a twill weave preform, a non-crimp fabric, and a TFP (Tailored Fiber Placement) preform that does not include an optical fiber, as well as combinations thereof, may be used in place of the plain weave preform 23.

[0062] Although the preform 1 for a fiber-reinforced plastic molding is described as being one layer, two or more layers may be used. When two or more layers of preforms 1 for a fiber-reinforced plastic molding are used, the arrangement of the continuous fiber bundles 12 and the optical fibers 13 may be different in each preform 1 for a fiber-reinforced plastic molding.

[0063] In addition, although molding by VaRTM has been described, as long as the preform is impregnated with resin, methods such as RTM (Resin Transfer Molding), press molding, hand layup, etc. may also be used. Furthermore, when a base resin is used as the base material of the preform, there is no need to impregnate it with resin separately.

[0064] ***Explanation of the effect of the fourth embodiment*** According to this embodiment, the fiber-reinforced plastic molding 2 includes at least one layer of the preform for a fiber-reinforced plastic molding 1. Since the preform for a fiber-reinforced plastic molding 1 includes the optical fiber 13, the stress and strain of the fiber-reinforced plastic molding 2 can be measured from the response of the optical fiber 13.

[0065] Embodiment 5. The following mainly describes the differences from the above-described embodiment with reference to the drawings. FIG. 10 is an explanatory diagram showing a manufacturing process of the preform 1 for a fiber-reinforced plastic molding according to the fifth embodiment.

[0066] The manufacturing process of the preform 1 for a fiber-reinforced plastic molding disclosed in this embodiment includes an optical fiber sewing process for sewing the optical fiber 13 to the base material 11, and a continuous fiber bundle sewing process for sewing the continuous fiber bundle 12 to the base material 11.

[0067] The manufacturing process of the preform 1 for a fiber-reinforced plastic molding will be described in detail below with reference to a specific example. FIG. 10(a) shows an optical fiber 13 sewn onto a substrate 11 with a first fixing thread 16. 1 shows the fiber sewing process. 10(a) shows an example in which a continuous fiber bundle 12 without an optical fiber 13 nearby is already sewn onto a substrate 11. The optical fiber 13 is supplied from a supply port 21 of an embroidery machine (not shown), and is sewn onto the substrate 11 by a first fixed thread 16 caused by the up and down movement of a sewing needle 22. The supply port 21 of the embroidery machine and the sewing needle 22 move along route data set in advance, while sewing the optical fiber 13 onto the substrate 11. FIG. 10(b) shows a state in which the optical fiber 13 has been sewn along the entire predetermined path.

[0068] FIG. 10(c) shows a continuous fiber bundle sewing step in which the continuous fiber bundle 12 is sewn onto the substrate 11 with the second fixing thread 17. In the continuous fiber bundle sewing step, the material supplied from the supply port 21 of the embroidery machine is changed from the optical fiber 13 to the continuous fiber bundle 12. The continuous fiber bundle 12 is supplied from the supply port 21 of the embroidery machine so that it contacts the optical fiber 13 at least in a part on the substrate 11 and its stretching direction coincides with that of the optical fiber 13, and is sewn onto the substrate 11 with the second fixing thread 17 by the up and down movement of the sewing needle 22. The second fixing thread 17 is sewn so as to straddle the continuous fiber bundle 12 and the optical fiber 13 in a part on the substrate 11. In this way, the preform 1 for a fiber-reinforced plastic molding shown in the second embodiment can be obtained.

[0069] Although the above description concerns a case in which the material supplied from the supply port 21 of the embroidery machine during the continuous fiber bundle sewing process is changed from the optical fiber 13 to the continuous fiber bundle 12, different supply ports 21 may be used for the optical fiber 13 and the continuous fiber bundle 12.

[0070] Also, a soluble material may be used as the first fixing thread 16, and a first fixing thread removal step of removing the first fixing thread 16 may be added after the optical fiber sewing step and the continuous fiber bundle sewing step. By removing the first fixing thread 16, the preform 1 for fiber-reinforced plastic molding shown in the first embodiment is obtained. The method of removing the first fixing thread 16 depends on the material, but for example, removal by heating, adding water, or using a solvent can be used.

[0071] Also, the case where the second fixing thread 17 is sewn so as to straddle the continuous fiber bundle 12 and the optical fiber 13 on a part of the base material 11 has been described, but it is sufficient that the continuous fiber bundle 12 is in contact with the optical fiber 13 on at least a part of the base material 11 and is arranged so that the stretching directions are aligned, and the second fixing thread 17 may be sewn so as to straddle only the continuous fiber bundle 12. In this way, the preform 1 for fiber-reinforced plastic molding shown in the third embodiment is obtained. In this case, the optical fiber sewing step may be performed after the continuous fiber bundle sewing step.

[0072] ***Explanation of the effect of the fifth embodiment*** According to this embodiment, the manufacturing process of the preform 1 for fiber-reinforced plastic molding includes an optical fiber sewing step and a continuous fiber bundle sewing step. This makes it possible to manufacture the preform 1 for fiber-reinforced plastic molding in which the continuous fiber bundle 12 is in contact with the optical fiber 13 at least in a part of the substrate 11 and is arranged so that the stretching directions are aligned.

[0073] Various aspects of the present disclosure are summarized below as appendices. (Appendix 1) A substrate; A continuous fiber bundle disposed on the substrate; an optical fiber arranged in at least a portion of the continuous fiber bundle along the extending direction of the continuous fiber bundle; a fixing thread sewn to the base material to fix the continuous fiber bundle and the optical fiber; A preform for a fiber-reinforced plastic molding comprising:

[0074] (Appendix 2) The fixing thread is a first fixing thread sewn to the substrate to fix the optical fiber to the substrate; A second fixing thread that is sewn to the substrate and fixes at least the continuous fiber bundle to the substrate; The preform for a fiber-reinforced plastic molding according to claim 1,

[0075] (Appendix 3) 3. A preform for fiber-reinforced plastic moldings according to claim 2, wherein the second fixing thread fixes both the optical fiber and the continuous fiber bundle in at least a portion of an area where the extension direction of the continuous fiber bundle and the extension direction of the optical fiber coincide with each other.

[0076] (Appendix 4) 3. The preform for a fiber-reinforced plastic molding according to claim 2, wherein the second fixing thread fixes only the continuous fiber bundle to the substrate.

[0077] (Appendix 5) 5. A preform for fiber-reinforced plastic molding according to claim 1, wherein the fiber orientation angle changes continuously in at least a portion of the area where the extension direction of the continuous fiber bundle and the extension direction of the optical fiber coincide with each other.

[0078] (Appendix 6) 5. The preform for a fiber-reinforced plastic molding according to any one of claims 2 to 4, wherein the first fixing thread is made of a thermoplastic material, a water-soluble material, or a soluble material.

[0079] (Appendix 7) 7. A preform for a fiber-reinforced plastic molding according to any one of claims 1 to 6, wherein a distance between a center of the optical fiber in a cross section of the optical fiber and a center of the continuous fiber bundle in a cross section of the continuous fiber bundle is equal to or less than half a width of the continuous fiber bundle in a cross section of the continuous fiber bundle.

[0080] (Appendix 8) 6. The preform for a fiber-reinforced plastic molding according to any one of claims 1 to 5, wherein the optical fiber is disposed in the continuous fiber bundle in one or more of the following states: a state in which the optical fiber is disposed at a position contained in the continuous fiber bundle, a state in which the optical fiber is disposed at a position in contact with the continuous fiber bundle, and a state in which the optical fiber is spirally wound around the continuous fiber bundle.

[0081] (Appendix 9) In a fiber-reinforced plastic molding having a plurality of layers, At least one layer made of a preform for a fiber-reinforced plastic molding according to any one of claims 1 to 8, A fiber-reinforced plastic molded body in which the plurality of layers are impregnated with a matrix resin and hardened, and the plurality of layers are integrated together.

[0082] (Appendix 10) A fiber-reinforced plastic molded body according to appended claim 9, wherein a part or all of the fixing yarns of the preform for the fiber-reinforced plastic molded body are made of the same material as the base resin of the fiber-reinforced plastic molded body.

[0083] (Appendix 11) The substrate of the preform for a fiber-reinforced plastic molding is 11. The fiber-reinforced plastic molding according to claim 9 or 10, wherein the material is the same as the base resin of the fiber-reinforced plastic molding.

[0084] (Appendix 12) A method for manufacturing a preform for a fiber-reinforced plastic molding, comprising: supplying an assembly of a continuous fiber bundle and an optical fiber from a supply port of an embroidery machine to a substrate with an optical fiber arranged in the continuous fiber bundle; and sewing the assembly to the substrate with a fixed thread by the up and down movement of a sewing needle.

[0085] (Appendix 13) The first fixing thread sews the fiber to the substrate; A method for producing a preform for a fiber-reinforced plastic molding, comprising sewing a continuous fiber bundle to the base material.

[0086] (Appendix 14) 14. The method for producing a preform for a fiber-reinforced plastic molding according to claim 13, wherein a first fixing thread is removed after the optical fiber and the continuous fiber bundle are sewn together. [Explanation of symbols]

[0087] 1 Preform for fiber-reinforced plastic molding, 2 Fiber-reinforced plastic molding, 11 Substrate, 12 Continuous fiber bundle, 13 Optical fiber, 14 Fixing thread, 15 Aggregate, 16 First fixed thread, 17 second fixed thread, 21 supply port, 22 sewing machine needle, 23 plain woven preform, 24 molding die, 25 preform laminate.

Claims

1. Substrate and A continuous fiber bundle arranged on the substrate, In at least a portion of the continuous fiber bundle, optical fibers are arranged along the stretching direction of the continuous fiber bundle, A fixing thread is sewn to the substrate to fix the continuous fiber bundle and the optical fiber. It has, The continuous fiber bundle and the optical fiber are fixed in contact with the substrate in a preform for a fiber-reinforced plastic molded body.

2. The aforementioned fixing thread is A first fixing thread that is sewn to the substrate to fix the optical fiber to the substrate, A second fixing thread that is sewn to the substrate and fixes at least the continuous fiber bundle to the substrate, A preform for a fiber-reinforced plastic molded article according to claim 1, having the following characteristics:

3. The preform for a fiber-reinforced plastic molded body according to claim 2, wherein the second fixing thread fixes both the optical fiber and the continuous fiber bundle in at least a portion of the area where the stretching direction of the continuous fiber bundle and the stretching direction of the optical fiber coincide.

4. The preform for a fiber-reinforced plastic molded article according to claim 2, wherein the second fixing thread fixes only the continuous fiber bundle to the substrate.

5. The fiber orientation angle is continuously changed in at least a portion of the area where the stretching direction of the continuous fiber bundle and the stretching direction of the optical fiber coincide, according to any one of claims 1 to 4.

6. The preform for a fiber-reinforced plastic molded article according to any one of claims 2 to 4, wherein the first fixing thread is made of a thermoplastic material, a water-soluble material, or a soluble material.

7. The preform for a fiber-reinforced plastic molded article according to any one of claims 1 to 4, wherein the distance between the center of the optical fiber in the cross-section of the optical fiber and the center of the continuous fiber bundle in the cross-section of the continuous fiber bundle is less than or equal to half the width of the continuous fiber bundle in the cross-section of the continuous fiber bundle.

8. The optical fiber is arranged in the continuous fiber bundle in one or more of the following states: in a state in which it is in contact with the continuous fiber bundle, and in a state in which it is spirally wound around the continuous fiber bundle, as a preform for a fiber-reinforced plastic molded article according to any one of claims 1 to 4.

9. In a fiber-reinforced plastic molded article having multiple layers, The present invention comprises at least one layer made of a fiber-reinforced plastic molded article preform according to any one of claims 1 to 4, A fiber-reinforced plastic molded body in which the multiple layers are integrated by impregnating and curing the base resin in the multiple layers.

10. The fiber-reinforced plastic molded article according to claim 9, wherein some or all of the fixing threads of the fiber-reinforced plastic molded article preform are made of the same material as the base resin of the fiber-reinforced plastic molded article.

11. The fiber-reinforced plastic molded article according to claim 9, wherein the base material of the fiber-reinforced plastic molded article preform is the same material as the base resin of the fiber-reinforced plastic molded article.

12. A method for manufacturing a preform for a fiber-reinforced plastic molded body, comprising supplying an assembly of a continuous fiber bundle and optical fibers to a substrate from the supply port of an embroidery machine with optical fibers arranged in a continuous fiber bundle, and then sewing the assembly to the substrate by fixing the continuous fiber bundle and optical fibers to the substrate with fixing thread using the up-and-down movement of a sewing machine needle while the continuous fiber bundle and optical fibers are in contact with the substrate.

13. The optical fiber is sewn to the base material with the first fixing thread. A method for manufacturing a fiber-reinforced plastic molded preform, comprising sewing a continuous fiber bundle to a substrate such that it contacts the optical fiber in at least a portion of the substrate.

14. The method for manufacturing a fiber-reinforced plastic molded body preform according to claim 13, wherein the first fixing thread is removed after sewing the optical fiber and the continuous fiber bundle together.

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