Production method of composite material

A production method of a composite material includes placing a fiber base material on a mold. The fiber base material includes a first fiber base material portion and a second fiber base material portion. The method further includes disposing a mold release member in part of a region where the first fiber base material portion and the second fiber base material portion are in contact with each other, and curing a resin with which the first fiber base material portion and the second fiber base material portion are impregnated, so as to mold the composite material.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority from Japanese Patent Application No. 2019-012789 filed on Jan. 29, 2019, the entire contents of which are hereby incorporated by reference.

BACKGROUND

The disclosure relates to a production method of a composite material.

Japanese Unexamined Patent Application Publication No. 2018-172474 discloses molding a composite material by placing, on a mold, a fiber base material including a first fiber base material portion and a second fiber base material portion, and heating and curing a resin with which the first fiber base material portion and the second fiber base material portion are impregnated.

SUMMARY

An aspect of the disclosure provides a production method of a composite material. The method includes: placing, on a mold, including a first fiber base material portion and a second fiber base material portion; disposing a mold release member in part of a region where the first fiber base material portion and the second fiber base material portion are in contact with each other; and curing a resin with which the first fiber base material portion and the second fiber base material portion are impregnated, so as to mold the composite material.

DETAILED DESCRIPTION

When heated to cure, a resin sets and contracts. The heated and set resin undergoes thermal contraction on cooling. After molding a composite material, a first fiber base material portion is coupled to a second fiber base material portion with the resin. Consequently, when a contraction factor of the resin in the first fiber base material portion is different from a contraction factor of the resin in the second fiber base material portion, the composite material may unintentionally deform. In this respect, there is still room for improvement.

It is desirable to provide a production method of a composite material that makes it possible to prevent the composite material from deforming.

FIG. 1is a schematic perspective view of an aircraft1. As illustrated inFIG. 1, the aircraft1includes main wings3, horizontal stabilizers5, and a vertical stabilizer7. Hereinafter, the main wings3, the horizontal stabilizers5, and the vertical stabilizer7will be simply referred to as wings.FIG. 2is a schematic perspective view of part of a wing of the aircraft1. As illustrated inFIG. 2, the wing of the aircraft1includes a skin9, stringers11, a front wing spar13, a rear wing spar15, and ribs17.

The skin9is an outer shell of the wing of the aircraft1. The skin9has, for example, a flat plate shape. The skin9extends in a longitudinal direction of the wing. The stringers11are used as reinforcement materials that reinforce the skin9, and are attached to a region of the skin9inside the wing. The stringers11extend in the longitudinal direction of the wing. Each stringer11includes a coupling portion11acoupled to the skin9and a protrusion11bthat protrudes away from the skin9.

A hollow portion11cis formed between the protrusion11band the skin9. Examples of the stringer11include a hat stringer having a hat shape and a corrugated stringer having a corrugated shape.FIG. 2illustrates an example in which the stringers11are the corrugated stringers. The stringers11are not limited thereto. Alternatively, the stringers11may be the hat stringers.

The front wing spar13stands at a substantially right angle relative to the skin9. The front wing spar13is located inside the wing and supports a front edge of the wing. The front wing spar13has, for example, a flat plate shape. The front wing spar13extends in the longitudinal direction of the wing.

The rear wing spar15stands at a substantially right angle relative to the skin9. The rear wing spar15is located inside the wing and supports a rear edge of the wing. The rear wing spar15has, for example, a flat plate shape. The rear wing spar15extends in the longitudinal direction of the wing.

The ribs17stand at a substantially right angle relative to the skin9. The ribs17are located inside the wing and support the front wing spar13and the rear wing spar15. Each rib17has, for example, a flat plate shape. The ribs17are perpendicular to the longitudinal direction of the wing. Consequently, the ribs17are disposed perpendicularly to the direction in which the stringers11, the front wing spar13, and the rear wing spar15extend.

FIG. 3is a schematic sectional view of part of the wing of the aircraft1taken along a line III-III inFIG. 2. As illustrated inFIG. 3, plural notches17bare formed in a lower end17aof each rib17. The notches17bare opposed to the stringers11. The lower ends17aof the rib17are coupled to (in contact with) the skin9but not coupled to (in non-contact with) the stringers11. Side ends17cof the rib17are coupled to the front wing spar13and the rear wing spar15to join the front wing spar13and the rear wing spar15.

The skin9, the stringers11, the front wing spar13, the rear wing spar15, and the ribs17are made of a composite material. In the embodiment, examples of the composite material include glass fiber reinforced plastics (GFRP) and carbon fiber reinforced plastics (CFRP). The composite material is molded by a composite material molding device100described below.

FIG. 4is a diagram illustrating the composite material molding device100according to the embodiment. The composite material molding device100molds the composite material by a vacuum assisted resin transfer molding (VaRTM) technique. As illustrated inFIG. 4, the composite material molding device100includes a molding die101, a film material103, seal members105, a fiber base material107, jigs109, resin distribution media111, a resin supply unit113, and a resin discharge unit115. In one embodiment, the molding die101may serve as a “mold”.

A space S is formed between the molding die101and the film material103. The space S is sealed by the seal members105disposed between the molding die101and the film material103. The fiber base material107and the resin distribution media111are disposed in the space S.

The fiber base material107is placed on the molding die101. The fiber base material107is formed by stacking fiber materials such as glass fibers or carbon fibers. It is noted that the fiber base material107may be a prepreg including a fiber material impregnated with a resin.

The fiber base material107includes a fiber base material portion107acorresponding to the skin9(hereinafter referred to as skin material portion107a), fiber base material portions107bcorresponding to the stringers11(hereinafter referred to as stringer material portions107b), a fiber base material portion107ccorresponding to the front wing spar13(hereinafter referred to as front-wing-spar material portion107c), a fiber base material portion107dcorresponding to the rear wing spar15(hereinafter referred to as rear-wing-spar material portion107d), and fiber base material portions107ecorresponding to the ribs17(hereinafter referred to as rib material portions107e). In one embodiment, the rib material portions107emay serve as “first fiber base material portions”, and the skin material portion107a, the front-wing-spar material portion107c, and the rear-wing-spar material portion107dmay serve as a “second fiber base material portion”.

In the embodiment, the skin material portion107ais permanently affixed to the front-wing-spar material portion107c. The skin material portion107aand the front-wing-spar material portion107care placed on the molding die101. The stringer material portions107b, the rear-wing-spar material portion107d, and the rib material portions107eare placed on the skin material portion107a. However, the disclosure is not limited thereto. Alternatively, the skin material portion107amay be formed separately from the front-wing-spar material portion107c.

The jigs109are disposed between the skin material portion107aand the stringer material portions107b. The jigs109have an outer shape approximate to the outer shape of the hollow portions11c(seeFIG. 2) formed between the skin9and the protrusions11bof the stringers11. The jigs109retain the shape of the protrusions11b(seeFIG. 2) after the stringers11are molded. The outer shape of the jigs109is substantially identical with an inner surface shape of the protrusions11bof the stringers11.

The jigs109extend in a depth direction inFIG. 4(that is, a direction perpendicular to the plane of the paper ofFIG. 4). The jigs109are placed on the skin material portion107a, and the stringer material portions107bare placed on the jigs109. That is, the jigs109are disposed between the skin material portion107aand the stringer material portions107b.

The resin distribution media111is placed on the fiber base material107. For example, a polyethylene net is used as the resin distribution media111. Supplied resin is uniformly distributed in the space S via the resin distribution media111.

The resin supply unit113and the resin discharge unit115are coupled to the space S sealed by the seal members105. The resin supply unit113includes a resin supply tank113athat stores the resin. The resin supply unit113supplies the resin stored in the resin supply tank113ainto the space S.

The resin discharge unit115includes a vacuum pump115athat suctions air and evacuates the space S, and a resin discharge tank115bthat stores the resin. The vacuum pump115asuctions the air and resin in the space S. The resin discharge tank115bstores (collects) the resin (that is, surplus resin) suctioned from the space S.

In the embodiment, the resin is thermosetting resin. The disclosure is not limited thereto. Alternatively, the resin may be, for example, thermoplastic resin. When the resin is supplied into the space S, the resin flows from the resin supply unit113side (right side inFIG. 4) toward the resin discharge unit115side (left side inFIG. 4). The plural jigs109are arranged along a flowing direction of the resin (hereinafter referred to as resin flowing direction). A longitudinal direction (that is, an extending direction) of the jigs109intersects the resin flowing direction. The longitudinal direction of the jigs109may be orthogonal to the resin flowing direction. The disclosure is not limited thereto. Alternatively, the longitudinal direction of the jigs109may be parallel to the resin flowing direction.

Next, a production method of the composite material using the composite material molding device100will be described. First, a user places the fiber base material107and the jigs109on the molding die101.

Next, the user covers the fiber base material107with the resin distribution media111and the film material103, and disposes the seal members105between the film material103and the molding die101so as to enclose the fiber base material107. Accordingly, the sealed space S is formed between the film material103and the molding die101, and the resin distribution media111, the fiber base material107, and the jigs109are accommodated in the space S.

Thereafter, the user couples the resin supply unit113and the resin discharge unit115to the space S. When the resin supply unit113and the resin discharge unit115are coupled to the space S, the resin discharge unit115drives the vacuum pump115a. The vacuum pump115asuctions air in the space S to evacuate the space S. When the space S is in the vacuum state, the resin supply unit113supplies the resin stored in the resin supply tank113ainto the space S.

The resin supplied into the space S is distributed via the resin distribution media111throughout the fiber base material107. The fiber base material107is impregnated with the resin distributed via the resin distribution media111. A surplus of the resin with which the fiber base material107is impregnated is discharged into the resin discharge tank115bof the resin discharge unit115.

When the fiber base material107is impregnated with the resin, the composite material molding device100causes a heating device (not illustrated) to heat the resin. The resin is cured when heated by the heating device (not illustrated). Portions of the composite material (corresponding to the skin9, the stringers11, the front wing spar13, the rear wing spar15, and the ribs17) are integrally molded by curing the resin. That is, the molded composite material portions (the skin9, the stringers11, the front wing spar13, the rear wing spar15, and the ribs17) are permanently affixed to each other.

After the composite material is molded, the jigs109are pulled out from between the skin9and the stringers11. Accordingly, as illustrated inFIG. 2, the hollow portions11care formed between the skin9and the protrusions lib of the stringers11.

In this manner, the composite material is molded by heating and curing the resin. However, when heated to cure, the resin sets and contracts. The heated and set resin undergoes thermal contraction on cooling. After the composite material is molded, for example, the resin makes the rib material portions107ecoupled to the front-wing-spar material portion107cand the rear-wing-spar material portion107d. Consequently, when a contraction factor of the resin in the rib material portions107eis different from contraction factors of the resin in the front-wing-spar material portion107cand the rear-wing-spar material portion107d, the composite material may unintentionally deform. In this respect, there is still room for improvement.

FIGS. 5A and 5Bare diagrams illustrating unintentional deformation of a composite material in related art.FIG. 5Aillustrates the composite material in the related art before molding (that is, before the resin is cured), andFIG. 5Billustrates the composite material in the related art after molding (that is, after the resin is cured). As illustrated inFIG. 5B, as a result of curing contraction and thermal contraction of the resin, the ribs17contract (deform) in directions indicated with arrows inFIG. 5B. Thus, the front wing spar13and the rear wing spar15coupled to the side ends17cof the ribs17with the resin deform along with the ribs17in the directions indicated with the arrows inFIG. 5Bby contraction amounts (deformation amounts) of the ribs17.

In this case, initial stress is exerted on coupling portions between the front wing spar13(the rear wing spar15) and the ribs17, thereby decreasing the composite material in strength. In view of this, in the embodiment, the fiber base material107includes a mold release sheet19disposed in at least one of (i) a position between the rib material portions107eand the front-wing-spar material portion107cor (ii) a position between the rib material portions107eand the rear-wing-spar material portion107d. In one embodiment, the mold release sheet19may serve as a “mold release member”.

FIG. 6is a diagram illustrating the structure of the fiber base material107according to the embodiment. As illustrated inFIG. 6, the fiber base material107according to the embodiment includes the mold release sheet19. The mold release sheet19is disposed in part of a region where the rib material portions107eare in contact with the skin material portion107a, the front-wing-spar material portion107c, and the rear-wing-spar material portion107d. In the embodiment, the mold release sheet19is simply interposed between the rib material portions107eand the front-wing-spar material portion107c. Since the mold release sheet19is interposed between the rib material portions107eand the front-wing-spar material portion107c, the rib material portions107eare in non-contact with the front-wing-spar material portion107c. After disposing the mold release sheet19, the composite material molding device100(seeFIG. 4) is used in the above-described manner to impregnate the fiber base material107with the resin and cure the resin.

FIG. 7is a diagram illustrating the fiber base material107according to the embodiment after the resin is cured. As illustrated inFIG. 7, when the mold release sheet19is removed from the composite material after the resin is cured, a gap SS is formed between the ribs17and the front wing spar13. In one embodiment, the gap may serve as “space”. The reason is that the ribs17contract (deform) in a direction away from the front wing spar13owing to curing contraction and thermal contraction of the resin. As described above, the mold release sheet19causes the front-wing-spar material portion107cto be in non-contact with the rib material portions107e, so that the front-wing-spar material portion107ccan maintain the disposed position irrespective of deformation of the ribs17. Thus, the ribs17are not coupled to the front wing spar13. That is, the ribs17are apart from the front wing spar13.

Consequently, no initial stress is exerted between the ribs17and the front wing spar13. Since the ribs17are in non-contact with the front wing spar13, initial stress exerted between the ribs17and the rear wing spar15(exerted on portions where the ribs17and the rear wing spar15are coupled to each other) is decreased. In this manner, in the embodiment, the ribs17are not coupled to the front wing spar13to prevent deformation of the composite material.

In this case, however, the front wing spar13is not coupled to the ribs17and not supported by the ribs17in consequence. This may decrease the composite material in strength. Therefore, in the embodiment, a shim21is disposed in the gap SS between the front wing spar13and the ribs17. Furthermore, the front wing spar13and the ribs17are fastened by fastening members23, with the shim21interposed between the front wing spar13and the ribs17.

FIG. 8is a diagram illustrating the front wing spar13and the ribs17that are fastened by the fastening members23, with the shim21interposed between the front wing spar13and the ribs17. As illustrated inFIG. 8, the shim21is disposed in the gap SS (seeFIG. 7) between the front wing spar13and the ribs17. The shim21has substantially the same shape as the gap SS between the front wing spar13and the ribs17. The fastening members23fasten the front wing spar13and the ribs17to each other with the shim21disposed in between. Thus, the front wing spar13is fastened to the ribs17with the shim21interposed between the front wing spar13and the ribs17so as to reinforce the composite material in strength.

FIG. 9is a flowchart illustrating a production method of the composite material according to the embodiment. In the production method of the composite material according to the embodiment, as illustrated inFIG. 4, the fiber base material107is first placed on the molding die101(step S901).

Next, as illustrated inFIG. 6, the mold release sheet19is disposed between the rib material portions107eand the front-wing-spar material portion107c(step S903). Then, the fiber base material107provided with the mold release sheet19is impregnated with the resin (step S905).

Thereafter, the resin with which the fiber base material107is impregnated is cured to mold the composite material (step S907). After molding the composite material, as illustrated inFIG. 7, the mold release sheet19is removed from the composite material (step S909). For example, the mold release sheet19is removed from between the front wing spar13and the ribs17.

After removing the mold release sheet19, as illustrated inFIG. 8, the shim21is inserted into the gap between the ribs17and the front wing spar13, from which the mold release sheet19has been removed (step S911). After inserting the shim21, the composite material and the shim21are fastened by the fastening members23(step S913). For example, the front wing spar13and the ribs17are fastened by the fastening members23.

As described above, according to the embodiment, the mold release sheet19is disposed in part of the region where the rib material portions107eis in contact with the skin material portion107a, the front-wing-spar material portion107c, and the rear-wing-spar material portion107d. Thus, (i) the rib material portions107eand (ii) the skin material portion107a, the front-wing-spar material portion107c, and the rear-wing-spar material portion107dcan be permanently affixed to each other, and at the same time, the composite material can be prevented from deforming. The shim21is inserted in the gap from which the mold release sheet19has been removed, and the composite material and the shim21are fastened by the fastening members23so as to prevent the composite material from decreasing in strength.

The embodiment of the disclosure has been described above with reference to the accompanying drawings. It is needless to say that the present disclosure is not limited to such an embodiment. It will be apparent to those skilled in the art that various changes and modifications to the embodiment can be conceived within the scope of the appended claims, and it is to be understood that such changes and modifications also belong to the technical scope of the disclosure.

A possible example of the disclosure may also provide a program that causes a computer to implement the production method of the composite material illustrated inFIG. 9, and a storage medium such as a computer readable flexible disc, a magneto-optical disc, a ROM, a CD, a DVD, or a BD that stores the program. Here, the program refers to a data processing application described in any language or description method.

In the above embodiment, the mold release sheet19is interposed between the rib material portions107eand the front-wing-spar material portion107c. However, this is not to be construed in a limiting sense. The mold release sheet19may be interposed between the rib material portions107eand the rear-wing-spar material portion107d. Alternatively, the mold release sheet19may be interposed both between the rib material portions107eand the front-wing-spar material portion107cand between the rib material portions107eand the rear-wing-spar material portion107d. In any case, the mold release sheet19may be simply disposed in a region except for at least part of a region between the rib material portions107eand the skin material portion107aso as to permanently affix the ribs17and the skin9with the resin.

In the above embodiment, the shim21is inserted in the gap SS between the ribs17and the front wing spar13, and the ribs17and the front wing spar13are fastened by the fastening members23. However, this is not to be construed in a limiting sense. An additional fiber base material (hereinafter referred to as gap material portion) may be disposed in the gap SS between the ribs17and the front wing spar13, and the gap material portion may be impregnated with the resin to cure the resin and couple the ribs17and the front wing spar13to each other.

According to the embodiment of the disclosure, deformation of the composite material can be prevented.