JP5503481B2 - Wing-like structure using fiber-reinforced composite material and manufacturing method thereof - Google Patents

Description

  The present invention relates to a wing-like structure using a fiber-reinforced composite material and a method for manufacturing the same, and more particularly to a wing-like structure suitably used as, for example, a blade included in a helicopter and a method for manufacturing the same.

  Wing-like structures are widely used not only for aircraft but also as parts for various industrial machines. As a material of this wing-like structure, a metal material has been used before, but recently a fiber reinforced composite material has also been used.

  When a rotor blade included in a helicopter is taken as an example of a typical wing-like structure, the rotor blade is required to be lighter in addition to high strength. Therefore, in recent years, it is often manufactured using a fiber reinforced composite material. As a typical fiber reinforced composite material, carbon fiber reinforced plastic (CFRP) using a carbon fiber as a fiber material and a thermosetting resin composition containing an epoxy resin or the like as a matrix material is known.

  As a method for molding CFRP, a method is generally used in which prepregs are laminated in a desired shape and then heated and pressurized with an autoclave (pressure cooker). The prepreg is a fiber material that is impregnated with a thermosetting resin composition, which is a matrix material, in a semi-cured state. However, if the matrix material is in a semi-cured state, the prepreg is sticky and difficult to handle. . Therefore, as a rule, the prepreg lamination operation is performed manually.

  However, since the prepreg is more expensive than a general resin material, a rotor blade manufactured using the prepreg is also expensive. Furthermore, manual prepreg lamination not only causes a decrease in manufacturing efficiency, but also increases a manufacturing cost. Accordingly, various techniques for manufacturing a rotor blade without using a prepreg have been proposed.

  For example, RTM (Resin Transfer Molding) or VaRTM (Vacuum Assisted RTM) manufactures a preform with a desired shape from a fiber material, places it in the cavity of the mold, vacuums the inside of the cavity, and then fills the injection gate. This is a method in which a resin composition is further injected (in VaRTM, the resin is sucked only by a vacuum pressure) and cured. As a technique for manufacturing the wing-like structure using this method, specifically, for example, a technique disclosed in Patent Document 1 or Patent Document 2 is cited.

  Further, from the viewpoint of improving moldability without using an autoclave, a technique using a thermoplastic resin composition instead of a thermosetting resin composition as a matrix material has been proposed. As a technique for manufacturing the wing-like structure using this method, specifically, for example, a technique disclosed in Patent Document 3 or 4 can be cited.

  By the way, in the field of a general fiber reinforced composite material, the technique which uses a fiber material as a braiding (braid or braid) is also known. Braiding is produced by mechanically weaving a tow of fiber material into a cylinder (or other shape) in two or three directions. As a result, the fiber material can be automatically manufactured in a desired shape, so that the production efficiency of the fiber-reinforced composite material can be improved. For example, Patent Document 5 discloses a technique related to manufacturing of a rotor blade by braiding.

Japanese Patent No. 2948434 Japanese Patent No. 2948435 JP-A-6-219392 JP-A-6-219393 Japanese Patent No. 4504374

  If braiding is used for the production of the wing-like structure, the type or composition of the resin composition does not need to be greatly changed without using any prepreg, and can be combined with a known RTM or VaRTM. There are advantages. However, since the following problems occur in reality, in the field of manufacturing a wing-like structure, a technique using the braiding as a fiber material is a spar (blade girder) like the technique disclosed in Patent Document 5. It is limited to a specific part.

  Braiding is one in which the bending of the fiber material is relatively large compared to the prepreg. Therefore, (1) since the extensibility of the fiber material is reduced inside the cured matrix material (thermosetting resin composition), the contribution of the fiber material to the strength improvement of the composite material is reduced. Further, (2) the increase in the bending of the fiber material means that the fiber material is relatively bulky, and therefore the fiber content contained in the composite material is reduced when compared with the same volume. Furthermore, (3) if the fiber content is lowered, there is a possibility that a portion where the resin composition is unevenly distributed inside the composite material, so that the contribution of the fiber material to the improvement of the strength of the composite material is further reduced. .

  As described above, even when braiding is used for manufacturing a wing-like structure, the problems (1) to (3) occur, and therefore, even if the same amount of fiber material as that in the case of using a prepreg is included. There is a possibility that the strength of can not be realized. That is, when trying to achieve the same strength as the prepreg, the conventional braiding technique requires a larger amount of fiber lamination. For example, in the technique disclosed in Patent Document 5, the braiding technique is applied to the blade spar. However, since the braiding itself is the same as the conventional method, a larger amount of fiber lamination is required than the prepreg. This leads to an increase in weight.

  Furthermore, when applying molding by RTM or VaRTM to a preform formed by braiding, a resin composition having a low viscosity must be used in consideration of the impregnation property of fibers. However, a resin composition having low viscosity tends to have low fracture toughness due to the characteristics of the material. Since the reduction in fracture toughness leads to a decrease in interlaminar shear strength and CAI (compression strength after impact), there is a risk of reducing the strength characteristics of the blade.

  The present invention has been made to solve such problems, and in addition to improving manufacturing efficiency and suppressing manufacturing cost in a wing-like structure manufactured by RTM or VaRTM without using a prepreg. An object of the present invention is to provide a technique capable of realizing good strength.

As a result of intensive studies in view of the above problems, the inventors of the wing-like structure, for the skin (wing outer skin), as a fiber material, by using a braid made of spread yarn, For spar (blade girder), the braiding with a reduced ratio of braiding to the central yarn is used to effectively solve the above-mentioned problems related to braiding. Further, a thermoplastic resin is used for the fiber material used for braiding. By uniquely combining the compositions, it was found that fracture toughness can be improved, and the present invention has been completed.

That is, the wing-like structure according to the present invention has a skeletal structure composed of a fiber-reinforced composite material in order to solve the above-described problem, and the spar structure that constitutes the leading edge of the wing-like structure is included in the skeleton structure. A wing-like structure including an outer surface of the wing-like structure, and the fiber material included in the fiber-reinforced composite material serving as the spar and the skin is configured as a braiding. The braiding contained in the fiber reinforced composite material to be the spar is composed of a plurality of center yarns arranged in parallel in the same direction, and a braid yarn knitted crossing the center yarn, as the braids, a structure in which yarns having a smaller diameter than the central thread is used.

  In the above configuration, the braiding included in the fiber-reinforced composite material serving as the skin may be manufactured using a spread yarn.

  In the said structure, the structure by which the bale opening yarn by which the thermoplastic nonwoven fabric is affixed on the one or both surfaces of the said opening yarn may be used as the said opening yarn.

  In the above configuration, a thermoplastic fiber or a twisted yarn of an inorganic fiber and a thermoplastic fiber may be used as the braid.

  The specific type of the wing-like structure is not particularly limited, and can be applied to any known wing-like structure using a fiber-reinforced composite material. As a representative example, a helicopter Rotor blades.

  The present invention also includes a method for producing the wing-like structure. That is, the method for producing a wing-like structure according to the present invention has a skeleton structure made of a fiber-reinforced composite material, and the skeleton structure includes a spar that forms a leading edge of the wing-like structure, and the wing-like structure. A wing-like structure manufacturing method including a skin constituting the outer surface of the skeleton structure, the step of manufacturing a braiding as a preform of the skeleton structure, and the braiding installed in a cavity of a mold A step of injecting a thermosetting resin composition into the cavity, and a step of curing the thermosetting resin composition in the cavity, wherein the spar and the skin of the preform are included. In this configuration, the fiber material is manufactured as the braiding.

  As described above, in the present invention, in the wing-like structure manufactured by RTM or VaRTM without using a prepreg, it is possible to realize good strength in addition to improving manufacturing efficiency and suppressing manufacturing cost. , Has the effect.

(A) is a perspective view which shows the structural example of the rotor blade of a helicopter which is an example of the wing-like structure which concerns on Embodiment 1 of this invention, (b) is I of the rotor blade shown to (a). FIG. It is typical sectional drawing which shows an example of the process of shape | molding the rotor blade shown to Fig.1 (a), (b) with a shaping | molding die. (A) is a perspective view which shows the typical structural example of the two-way braiding manufactured using the opened yarn as a braid, (b) is general 2 manufactured using the tow | toe It is a perspective view which shows the typical structural example of direction braiding. (A) is a typical perspective view which shows the structural example of the spread yarn used for the blade preform of the rotor blade shown to Fig.3 (a). (B) is a schematic perspective view showing a configuration example of a backing spread yarn used for the two-way braiding yarn shown in FIG. (A) is a perspective view which shows the typical structural example of the three-way braiding manufactured using the thin braid with respect to the center yarn, (b) is the thickness of the center yarn and the braid. It is a perspective view which shows the typical structural example of the general three-way braiding manufactured by making it substantially equivalent. (A) is a fragmentary sectional view which shows the structural example when the braiding shown to Fig.5 (a) is used as a blade spar preform, (b) is a blade preform in the spar shown to (a). FIG. 2 is a partial cross-sectional view showing an example of a state in which the central threads are densely arranged. It is a typical perspective view which shows the structural example of the twisted yarn used for the braiding yarn of the three-way braiding shown to Fig.5 (a).

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the following description, the same or corresponding elements are denoted by the same reference symbols throughout the drawings, and redundant description thereof is omitted.

[Rotor blade]
First, a basic configuration and the like of a rotor blade that is an example of a wing-like structure according to the present embodiment will be described with reference to FIGS.

  As shown in FIG. 1 (a), the rotor blade 10 according to the present embodiment is in the form of an elongated plate, one end is a blade tip 10a that is the tip side, and the other end is a rotor hub (not shown). It is the root 10b couple | bonded. Further, the front side in the rotational direction of the rotor blade 10 is referred to as a front end 10c, and the rear side is referred to as a rear end 10d. An attachment hole 10e for attaching the rotor blade 10 to the rotor hub is formed in the root 10b. FIG. 1B is a cross-sectional view taken along the line I-I indicated by a two-dot chain line in the rotor blade 10 shown in FIG. 1A. As shown in this cross-sectional view, the rotor blade 10 is It has a spar 11, a skin 12, a leading edge balance weight 13, and a foam core 14.

  The spar 11 is a skeletal structure that is usually unevenly distributed in front of the rotor blade 10 and extends over the entire length of the rotor blade 10. The skin 12 constitutes the outer surface of the rotor blade 10 and is also a part of the skeleton structure. The front edge balance weight 13 is provided inside the front edge 10c so that the center of gravity of the rotor blade 10 is closer to the front edge 10c. The foam core 14 is a core material that occupies most of the interior of the rotor blade 10, and is provided to maintain the shape of the rotor blade 10.

  As will be described later, the spar 11 and the skin 12 are made of a fiber-reinforced composite material. The leading edge balance weight 13 is made of a known metal material or the like. The foamed core 14 may be a known foamed resin material, may be a honeycomb-structured aluminum material or an aramid material, and the shape of the rotor blade 10 can be maintained only by a skeleton structure. It may be a cavity. The specific configuration of the rotor blade 10 according to the present embodiment is not limited to the configuration shown in FIGS. 1A and 1B, and various known configurations can be employed. Therefore, the rotor blade 10 may include a skeleton structure other than the spar 11 and the skin 12, and may include members other than the leading edge balance weight 13 and the foam core 14.

  The rotor blade 10 according to the present embodiment is manufactured by RTM or VaRTM as shown in FIG. The mold 20 of the rotor blade 10 includes an upper mold 21 and a lower mold 22, and a resin supply pipe 24 and a resin discharge pipe 25 are connected to a cavity 20 a in the mold 20. A resin pot 23 is connected to the resin supply pipe 24, and the thermosetting resin composition accumulated in the resin pot 23 is supplied to the cavity 20 a through the resin supply pipe 24. In addition, a resin discharge tank and a suction pump (not shown) are connected to the discharge pipe 25 via a valve 26. By opening the valve 26 and sucking the cavity 20a, the air originally present in the cavity 20a is sucked. Then, the inside of the cavity 20a can be evacuated, or the supplied thermosetting resin composition can be sucked to discharge the excess to the resin discharge tank.

  The manufacturing process of the rotor blade 10 will be described by taking RTM as an example. First, a blade preform 15 which is a core material of the spar 11 and the skin 12 of the rotor blade 10 is manufactured using a fiber material. The blade preform 15 includes a preform 15a corresponding to the spar 11 and a preform 15b corresponding to the skin 12, and these preforms 15a and 15b are braided as will be described later. Then, the upper mold 21 and the lower mold 22 are opened, and the blade preform 15 is disposed inside. At this time, the leading edge balance weight 13, the foam core 14, or an inflatable mandrel if the inside is hollow are also arranged in accordance with the blade preform 15. Thereafter, the upper mold 21 and the lower mold 22 are closed by a press or the like, so that the blade preform 15 and the like are installed in the cavity 20 a of the mold 20.

  Next, the inside of the resin pot 23 is pressurized while the mold 20 is heated, and the valve 26 is opened and the cavity 20a is sucked by a suction pump (not shown). Thereby, the thermosetting resin composition in the resin pot 23 is injected into the cavity 20 a through the resin supply pipe 24. The suction of the cavity 20a and the injection of the thermosetting resin composition are continued until the cavity 20a is sufficiently filled with the thermosetting resin composition, and the cavity 20a is filled with the thermosetting resin composition. The thermosetting resin composition is cured by heating the mold 20. Thereafter, the upper die 21 and the lower die 22 are separated, the cured product is taken out, and predetermined post-processing (trimming or the like) is performed, whereby the rotor blade 10 is manufactured.

  The manufacturing process described above is basic, and other processes are added within a known range, some processes are omitted or simplified, and some processes are replaced with other processes. can do. Further, the molding technique used for manufacturing the rotor blade 10 is not limited to RTM or VaRTM, and any other method that does not use a prepreg can be adopted.

  In the obtained rotor blade 10, a spar 11 and a skin 12 made of a fiber-reinforced composite material are formed by impregnating and curing the blade preform 15, which is braiding, with a thermosetting resin composition. That is, the blade preform 15 is a fiber material in a fiber reinforced composite material. If the skeleton structure includes a part other than the spar 11 and the skin 12, a braid including the part may be manufactured in advance as the blade preform 15.

  Moreover, the thermosetting resin composition supplied from the resin pot 23 is a matrix material of a fiber reinforced composite material, and its specific configuration is not particularly limited. For example, examples of the thermosetting resin used in the resin composition include an epoxy resin, a bismaleimide resin, a vinyl ester resin, an unsaturated polyester resin, a phenol resin, and a silicone resin. These resins may be used alone or in combination of a plurality of types as appropriate. Further, the more specific chemical structure of these thermosetting resins is not particularly limited, and may be a polymer in which various known monomers are polymerized or a copolymer in which a plurality of monomers are polymerized. . Further, the average molecular weight, the structure of the main chain and the side chain, etc. are not particularly limited.

  In addition to the thermosetting resin, the thermosetting resin composition may include a known curing agent, a curing accelerator, a reinforcing material other than the fiber base material, a filler, and other known additives. The specific types and compositions of these additives such as curing agents and curing accelerators are not particularly limited, and those of known types or compositions can be suitably used. Furthermore, from the viewpoint of improving the fracture toughness of the obtained rotor blade 10, a known thermoplastic resin may be included in a known composition.

[Skin Braiding]
Next, the braiding manufactured as the blade preform 15 will be specifically described. First, of the fiber material constituting the blade preform 15, the braiding as a skin will be specifically described with reference to FIGS. 3 (a) and 3 (b) and FIGS. 4 (a) and 4 (b). In the following description, for convenience of explanation, a fiber reinforced composite material using prepreg is referred to as “prepreg composite material”, and a fiber reinforced composite material using braiding is referred to as “brading composite material”.

  Braiding (braids, braids or braids) is made by mechanically weaving a tow of fiber material in two or three directions and mechanically weaving it into a cylinder (or other shape). As an example of a general configuration for skin braiding, as shown in FIG. 3 (b), a braided yarn 152 arranged in a state of crossing each other around the mandrel 60 is knitted. One example is a two-way braiding 150A. In the example shown in FIG. 3B, two kinds of braids 152, 152 intersect at an angle of about 45 °.

  Here, when the braiding composite material is configured by using the braiding 150A having the above-described configuration as the skin braiding, the fiber material is used to improve the strength of the rotor blade 10 compared to the prepreg composite material for the following reason. (Blading 150A) cannot sufficiently contribute.

  First, as shown in FIG. 3B, in the braiding 150A, when the two braiding yarns 152 and 152 are knitted so as to intersect, the crimping (bending) of the braiding yarn 152 becomes large. That is, in the braiding 150A, the fiber material constituting the braided yarn 152 is not stretched but is in a tortuous state. In this case, in the braided composite material, the rigidity is locally lowered inside the braided composite material, and the load transmission efficiency of the composite material as a whole is lowered. Therefore, the braiding composite material generally cannot sufficiently improve its tensile strength as compared with the prepreg composite material.

  Further, when the fiber material is crimped by the manufactured braiding, a gap is inevitably generated between the yarns. In the braided composite material, this gap is an area of only the matrix material (thermosetting resin composition) that is not reinforced with the fiber material. That is, in the braided composite material, the fiber material cannot be present substantially uniformly in the matrix material, and the matrix material is unevenly distributed. If this is evaluated as the fiber content Vf in the fiber reinforced composite material, the Vf of the braiding composite material is clearly lower than the Vf of the prepreg composite material. The decrease in the fiber content Vf, that is, the occurrence of uneven distribution of the matrix material leads to the occurrence of microcracks due to external forces at the uneven distribution portion of the matrix material, which causes a decrease in the strength of the entire composite material. Cannot sufficiently improve the strength as compared with the prepreg composite material.

  For these reasons, it has been considered that the use of the braiding 150A as shown in FIG. 3 (b) for the skin constituting the blade preform 15 is not practical in the manufacture of the rotor blade 10. .

  On the other hand, in the present invention, for example, a braiding 50A as shown in FIG. 3 (a) is manufactured and used as the blade preform 15. This braiding 50A has the same configuration as the braiding 150A shown in FIG. 3B except that the spread yarn 31 shown in FIG. The resulting braiding composite material can achieve strength equal to or higher than that of the prepreg composite material.

  As shown in FIG. 4A, the opened yarn 31 (shown on the right side) is a tow composed of, for example, carbon fiber 301, like the raw yarn 30 (shown on the left side). Unlike the raw yarn 30 having a substantially circular cross section, it has a wide shape like a tape. In general, the spread yarn 31 is obtained by thinly opening the raw yarn 30 so as to have a desired width by a spreader. When the spread yarn 31 is used as the fiber material of the fiber reinforced composite material, the matrix material (resin composition) can be more uniformly impregnated compared to the case where the raw yarn 30 is used. And the strength of the fiber-reinforced composite material can be improved. However, it has hardly been known to produce braiding using the spread yarn 31.

  As shown in FIG. 3A, if the braiding 50A is manufactured using the spread yarn 31 as the braid 52 and used as the skin fiber material, the crimp of the fiber material can be effectively suppressed. Therefore, when a wing-like structure is manufactured by RTM or VaRTM, if a preform made of braiding 50A is used, it is possible to ensure good straightness of the fiber material in the composite material and to reduce the content of the fiber material. Can also be avoided. As a result, the contribution of the fiber material to the strength improvement of the composite material can be improved, the strength of the obtained wing-like structure can be improved, and the wing-like structure can be produced with RTM or VaRTM. The manufacturing cost can be reduced.

  Further, in the present embodiment, it is preferable that the spread yarn 31 that is the braided yarn 52A of the braiding 50A includes a thermoplastic resin because fracture toughness and workability can be further improved.

  Although the specific structure of the spread yarn 31 containing a thermoplastic resin is not specifically limited, As a preferable example, the bale spread yarn 32 shown in FIG.4 (b) can be mentioned. The bale opening yarn 32 is obtained by, for example, attaching a bale 33 made of a thermoplastic nonwoven fabric to one surface of the opening yarn 31 made of carbon fiber 301. Although the method for attaching the bale 33 to the spread yarn 31 is not particularly limited, a method of fusing the bale 33 to the spread yarn 31 by heating can be given because the bale 33 is a thermoplastic nonwoven fabric. In addition, although the bale opening yarn 32 shown in FIG.4 (b) becomes a structure by which the bale 33 was affixed only to one side of the opening yarn 31, the bale 33 was affixed on both surfaces. It may be a configuration.

  In this way, if the tow itself constituting the braiding 50B contains a thermoplastic resin, when the thermosetting resin composition is impregnated, the thermoplastic resin melts and mixes with the thermosetting resin composition. Therefore, compared to the case where a thermoplastic resin is blended in advance, the impregnation property of the thermosetting resin composition is not impaired, and the fracture toughness of the fiber-reinforced composite material can be improved.

  In addition, the dimension (width or thickness) of the spread yarn 31 may change or fray during braiding. On the other hand, if the bale 33 is used, the fibers of the spread yarn can be bonded together by fusing the thermoplastic resin, and the change in dimensions, fraying, and the like can be effectively suppressed.

  Here, the specific type of the thermoplastic resin is not particularly limited, and any type of thermoplastic resin can be used as long as it is a known resin that can improve the fracture toughness after curing of the thermosetting resin composition. Can do. For example, polyethylene resin, polyamide resin, polyphenylene sulfide resin, polyether ether ketone resin, and the like can be used. Only one of these thermoplastic resins may be used, or two or more of them may be used in appropriate combination.

  In addition to the bale, it has been confirmed that a sizing agent is also effective as a means for preventing the size and fraying of the spread yarn 31, and the bale and the sizing agent may be used in combination.

  In the present embodiment, the spread yarn 31 is made of carbon fiber 301. However, the material of the spread yarn 31 is not limited to this, and in the field of fiber-reinforced composite materials, a fiber material is used. Various materials used as can be suitably used. Specifically, for example, organic fibers such as polyester fiber, nylon fiber, aramid fiber, PBO (polyparaphenylene benzobisoxazole) fiber; boron fiber, glass fiber, silica fiber (quartz fiber), silicon carbide (SiC) Examples thereof include inorganic fibers such as fibers. These materials may be used alone, or may be used by appropriately combining a plurality of types of materials including carbon fibers.

  Further, the width and thickness of the spread yarn 31 are not particularly limited, and preferable numerical values may be set according to the shape and dimensions of the blade preform 15 to be manufactured, the type of matrix material, and the like. Further, the braiding 50 </ b> A may be one in which tows other than the spread yarn 31 are knitted in an auxiliary manner.

  Further, the skin braiding may be composed of only one braiding 50A, but a multilayer braiding composed of a plurality of braidings 50A may be used. The number of laminations of the braiding 50A in this multilayer braiding is not particularly limited, and is appropriately set according to various conditions required for the skin.

[Spar Braiding]
Next, of the fiber material constituting the blade preform 15, the braiding that becomes a spar is specifically described with reference to FIGS. 5 (a), 5 (b), 6 (a), 6 (b), and FIG. Explained.

  As described above, the braiding is manufactured by assembling the tows of fiber material in two or three directions and mechanically weaving them into a cylindrical shape or the like. As an example of a general configuration for spar braiding, as shown in FIG. 5 (b), a plurality of center threads 151 arranged in parallel in the same direction around the mandrel 60, and the center threads For example, a three-way braiding 150B manufactured by weaving braided yarns 153 arranged in a state of crossing 151 can be given. In the example shown in FIG. 5B, two types of braiding yarns 153 and 153 intersect at an angle of about 45 ° with respect to one type of central yarn 151.

  Here, if the braiding composite material is configured by using the braiding 150B having the above-described configuration as skin braiding, the fiber material can improve the strength of the rotor blade 10 compared with the prepreg composite material for the following reason. (Braiding 150B) cannot sufficiently contribute.

  As shown in FIG. 5B, in the braiding 150B, when the central yarn 151 and the braided yarn 153 are knitted with tows having substantially the same thickness, the fibers in the blade axial direction (central yarn 151) necessary as a spar are formed. The amount is relatively reduced. Since the fiber in the axial direction of the spar is a member that supports the centrifugal force and bending moment acting on the rotor blade 10, when its amount is reduced, its tensile strength is reduced compared to a prepreg composite material having the same spar cross-sectional area. It cannot be improved sufficiently. In other words, if an attempt is made to achieve the same strength as that of the prepreg composite material, a larger amount of fiber is required, resulting in an increase in weight.

  Here, in the technique disclosed in Patent Document 5 described above, three-way braiding including an oblique direction other than the axial direction is applied to the spar, and twisting of the rotor blade is performed with the fibers of the braided yarn in the oblique direction. It becomes the structure which supports. However, when the center yarn and the braid are knitted with tows having substantially the same thickness in such a configuration, the axial strength is relatively insufficient. As a result, compared with the prepreg composite material, an overall larger amount of fiber lamination is required, resulting in an increase in weight.

  For this reason, in the manufacture of the rotor blade 10, using the braiding 150B as shown in FIG. 5 (b) for the spar constituting the blade preform 15 is less efficient in terms of strength. Conceivable.

  On the other hand, in the present invention, as shown in FIG. 5A, the amount of fibers in the axial direction is relatively reduced by combining the small-diameter fine braid 53 with the large-diameter central yarn 51. Increasing. In the braiding 50B, a plurality of central yarns 51 having a large diameter are connected so as to maintain a parallel state with each other by a braided yarn 53 having a small diameter. This state is substantially a barred lattice, and the central threads 51 can be arranged with high density in a substantially straightened state. Furthermore, a gap for impregnating the resin composition can be formed between the central yarns 51 by appropriately setting the thickness of the fine braided yarn 53 without causing a decrease in the fiber content. Therefore, it is possible to ensure good extensibility of the fiber material inside the braided composite material and to avoid a decrease in the content of the fiber material, so that the strength of the obtained wing-like structure is improved. It can be.

  Here, the size of the diameter of the fine braided yarn 53 is not particularly limited, but is preferably as small as possible than the diameter of the central yarn 51. By appropriately setting the diameter of the fine braided yarn 53, the impregnation efficiency of the matrix material into the blade preform 15 can be improved.

  Specifically, for example, at the portion corresponding to the spar 11 in the blade preform 15, the central yarns 51 are arranged in parallel in a straightened state in order to achieve good strength. At this time, if there is no fine braid 53 or if the diameter is negligible compared to the size of the central yarn 51, the central yarns 51 are closely packed as shown in FIG. Contact. Here, at the time of molding the rotor blade 10 (see FIG. 2), the thermosetting resin composition is impregnated from a direction substantially perpendicular to the outer surface of the spar 11 as indicated by an arrow R in the figure. However, if the central threads 51 are closely arranged, the impregnation property of the thermosetting resin composition is lowered, and there is a possibility that voids or resin defects occur.

  On the other hand, as shown in FIG. 6A, by appropriately setting the diameter of the fine braided yarn 53, a gap serving as a passage for the thermosetting resin composition is formed between the central yarns 51. Can do. Thereby, the thermosetting resin composition can flow into the gap and be satisfactorily impregnated into the blade preform 15. Therefore, if the braiding 50B is used as the blade preform 15, a gap for impregnating the resin composition can be formed between the opened yarns 31 without causing a decrease in the fiber content Vf. Therefore, the strength of the obtained wing-like structure can be improved.

  Here, the size of the diameter of the central thread 51 is not particularly limited, and a preferable numerical value may be set according to various conditions. Further, the size of the diameter of the fine braided yarn 53 is not particularly limited as long as it is at least a yarn having a diameter smaller than the diameter of the central yarn 51, and preferably a gap enough to keep the impregnation property of the central yarn 51 good. As long as the yarn can be formed, it is sufficient if the yarn has a diameter as small as possible.

  Further, the material used for the fine braided yarn 53 is not particularly limited, and any material can be used as long as it can exert the tension for holding the braiding 50B even if the diameter is smaller than that of the central yarn. . Typically, inorganic fibers such as glass fibers and carbon fibers can be used, but resin fibers made of a resin composition may be used.

  Furthermore, in the present embodiment, it is preferable that the braided yarn 53 constituting the braiding 50B includes a thermoplastic resin because fracture toughness can be further improved.

  Although the specific structure of the braided yarn 53 containing a thermoplastic resin is not specifically limited, As a preferable example, the twisted yarn 34 shown in FIG. 7 can be mentioned. The twisted yarn 34 is obtained by twisting, for example, a glass fiber yarn 34a made of glass fiber 302 and a thermoplastic fiber yarn 34b made of thermoplastic fiber 303, and is used as a braided yarn of the braiding 50B. In the case where only 303 is used, it can be particularly preferably used when the material breaks due to tension. Of course, if the thermoplastic fiber 303 has sufficient strength against tension, the thermoplastic fiber 303 can be used alone as a braid.

  In this way, if the tow itself constituting the braiding 50B contains a thermoplastic resin, when the thermosetting resin composition is impregnated, the thermoplastic resin melts and mixes with the thermosetting resin composition. Therefore, an effect equivalent to that of adding a thermoplastic resin to the thermosetting resin composition that is a matrix material can be brought about. In addition, the viscosity of the thermosetting resin composition is increased and the impregnation of the fiber material is not reduced as compared with the case where the thermoplastic resin is previously blended with the thermosetting resin composition injected from the outside. It is possible to improve the fracture toughness of the fiber-reinforced composite material. Moreover, by using the twisted yarn 34, the center yarns 51 can be appropriately connected by the fine braided yarn 53, and the thermosetting resin composition can be satisfactorily impregnated between the center yarns 51. it can.

  Here, the specific type of the thermoplastic resin is not particularly limited, and any type of thermoplastic resin can be used as long as it is a known resin that can improve the fracture toughness after curing of the thermosetting resin composition. Can do. For example, polyethylene resin, polyamide resin, polyphenylene sulfide resin, polyether ether ketone resin, and the like can be used. Only one of these thermoplastic resins may be used, or two or more of them may be used in appropriate combination.

  Further, the spar braiding may be composed of only one braiding 50B, but multi-layer braiding composed of a plurality of braidings 50B may be used. The number of layers of the braiding 50B in this multi-layer braiding is not particularly limited, and is appropriately set according to various conditions required for the spar.

  In the present embodiment, the rotor blade 10 is exemplified as the wing-like structure 50. However, the present invention is not limited to this, and for example, a propeller blade, a turbofan blade, and a general industry used in an aircraft other than a helicopter. Well-known wing-like structures, such as a rotary blade for machines and a blade for wind power generation, can be mentioned.

  Further, the present invention is not limited to the description of the above-described embodiment, and various modifications can be made within the scope shown in the scope of the claims, and technologies disclosed in different aspects and a plurality of modifications, respectively. Embodiments obtained by appropriately combining technical means are also included in the technical scope of the present invention.

  The present invention can be suitably used in the field of various wing-like structures such as propeller blades, turbofan blades, rotary blades for general industrial machinery, blades for wind power generation, etc. used for aircraft other than helicopters.

10 Rotor blade (wing structure)
11 Spar 12 Skin 15 Blade preform (skeleton structure)
15a preform (compatible with spars)
15b Preform (corresponds to skin)
20 Mold 20a Cavity 31 Opening yarn 32 Bale opening yarn 34 Twisting yarn 50A, 50B Braiding 51 Central yarn 52 Braiding yarn 53 Fine braiding yarn (braiding yarn)

Claims (6)

A wing structure having a skeleton structure made of a fiber-reinforced composite material, the skeleton structure including a spar that forms an inner girder of the wing structure and a skin that forms an outer surface of the wing structure A structure,
The fiber material contained in the fiber reinforced composite material to be the spar and the skin is configured as braiding ,
The braiding contained in the fiber-reinforced composite material to be the spar is composed of a plurality of center yarns arranged in parallel in the same direction, and braided yarns that are knitted crossing the center yarns, A wing-like structure characterized in that a yarn having a diameter smaller than that of the central yarn is used as the braid.   The wing-like structure according to claim 1, wherein the braiding contained in the fiber-reinforced composite material serving as the skin is manufactured using a spread yarn.   The wing-like structure according to claim 2, wherein a bale-opening yarn obtained by attaching a thermoplastic nonwoven fabric to one or both surfaces of the opening yarn is used as the opening yarn. . The wing-like structure according to any one of claims 1 to 3, wherein a thermoplastic fiber or a twisted yarn of an inorganic fiber and a thermoplastic fiber is used as the braid. The wing-like structure according to any one of claims 1 to 4 , wherein the wing-like structure is a helicopter rotor blade. A wing structure having a skeleton structure made of a fiber reinforced composite material, the skeleton structure including a spar that forms a leading edge of the wing structure and a skin that forms an outer surface of the wing structure. A structure manufacturing method comprising:
Producing a braiding as a preform of the skeleton structure;
Injecting a thermosetting resin composition into the cavity with the braiding installed in the cavity of the mold,
Curing the thermosetting resin composition in the cavity, and
A method for producing a wing-like structure, wherein a fiber material that becomes the spar and the skin of the preform is produced as the braiding.

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