Composite structure and flying object

Abstract

SOLUTION: A composite structure 40A includes a first composite material 50 and a second composite material 60. The first composite material 50 includes a first conductive layer 54, and the second composite material 60 includes a second conductive layer 64. The first composite material 50 and the second composite material 60 are laminated on a substrate 42. The composite structure 40A further includes an overlapping portion 70 and a conductive portion 46. The overlapping portion 70 is formed by a first end portion 51 of the first composite material 50 being overlapped with a second end portion 61 of the second composite material 60. The conductive portion 46 electrically connects, in the overlapping portion 70, the first conductive layer 54 in the first end portion 51 and the second conductive layer 64 in the second end portion 61.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a composite structure including a base material and a conductive layer. The present invention also relates to an aircraft including the base material in the composite structure as a surface structure material and the conductive layer in the composite structure as a lightning protection structure.

Background Art

[0002] An aircraft may be struck by lightning during flight. For this countermeasure, the aircraft is provided with a lightning protection structure. The lightning protection structure is, for example, a conductor provided on a surface structure material (skin). The lightning current is quickly guided to a static discharger through the conductor and discharged into the air.

[0003] The surface structure material is, for example, a fiber-reinforced resin. The conductor is, for example, a metal mesh. In Patent Document 1, a laminated composite material in which a matrix resin is impregnated with a metal mesh is called an integrated surface protection system and is laminated on the surface structure material. Reinforcing fibers made of chopped fibers are dispersed in the matrix resin.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] When laminating a laminated composite material on a surface structure material, it is conceivable to cut a part of a roll body in which the laminated composite material is wound into a roll shape into a predetermined length to obtain a sheet-shaped body and join this sheet-shaped body to the surface structure material.

[0006] In the roll body, the height direction orthogonal to the winding direction is about 1 m. On the other hand, the length of the airframe of the flying object is, for example, several meters to several tens of meters. Therefore, in order to provide a lightning protection structure for the entire surface structural material of the airframe, it is necessary to join a plurality of sheet-shaped bodies to the surface structural material of the airframe.

[0007] When a gap is formed between two adjacent sheet-shaped bodies, there is a concern that rainwater or the like may penetrate into the gap, resulting in a decrease in the weather resistance and strength of the surface structural material. To avoid this, in two adjacent sheet-shaped bodies, it is conceivable to overlap the end of one sheet-shaped body with the end of the remaining one sheet-shaped body. However, in this configuration, it is assumed that the conductor included in the sheet-shaped body located below and the conductor included in the sheet-shaped body located above are electrically non-contact at the overlapped portion. In this case, it is not easy to maintain the lightning protection performance.

[0008] An object of the present invention is to solve the above-described problems.

Means for Solving the Problems

[0009] According to an embodiment of the present invention, there is provided a composite structure including a base material, and a first composite material and a second composite material disposed on the surface of the base material. The first composite material is a sheet-shaped body having a first fiber layer, a first conductive layer laminated on the first fiber layer, and a first matrix resin impregnated in the first fiber layer and the first conductive layer. The first composite material is laminated on the base material such that the first fiber layer is positioned between the base material and the first conductive layer. The second composite material is a sheet-shaped body having a second fiber layer, a second conductive layer laminated on the second fiber layer, and a second matrix resin impregnated in the second fiber layer and the second conductive layer. The second composite material is laminated on the base material such that the second fiber layer is positioned between the base material and the second conductive layer. The composite structure includes an overlapping portion formed by overlapping a first end portion of the first composite material with a second end portion of the second composite material, and a conduction portion that electrically connects the first conductive layer at the first end portion and the second conductive layer at the second end portion in the overlapping portion.

[0010] According to another embodiment of the present invention, there is provided an aircraft including the above-described base material as a surface structure material and including the above-described first conductive layer and the above-described second conductive layer as a lightning protection structure.

Advantages of the Invention

[0011] According to the present invention, the first conductive layer and the second conductive layer can be used as a lightning protection structure. In this case, since the first conductive layer and the second conductive layer are electrically connected by the conduction portion, it is possible to balance the potential of the first conductive layer and the potential of the second conductive layer. Thereby, the composite structure can maintain its lightning resistance. In addition, since the first composite material and the second composite material can be arranged side by side without a gap at the end face of the base material, the composite structure exhibits sufficient weather resistance and durability. Furthermore, the strength of the composite structure is maintained.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

MODE FOR CARRYING OUT THE INVENTION

[0013] Hereinafter, a case will be exemplified in which the second composite material 60 (see FIG. 2) is disposed closer to the static discharger 24 than the first composite material 50 on the surface of the airframe 12 (see FIG. 1), and a lightning current C flows from the first conductive layer 54 to the second conductive layer 64.

[0014] FIG. 1 is a schematic perspective view of the flying object 100. In the illustrated example, the flying object 100 is the multicopter 10. However, the flying object 100 is not limited to the multicopter 10.

[0015] The multicopter 10 includes an airframe 12. From the left front side portion and the right front side portion of the airframe 12, the left main wing 14L and the right main wing 14R project in the width direction, respectively. From the left rear side portion and the right rear side portion of the airframe 12, the left horizontal tail wing 16L and the right horizontal tail wing 16R project in the width direction, respectively. The left support bar 18L straddles the left main wing 14L and the left horizontal tail wing 16L. The right support bar 18R straddles the right main wing 14R and the right horizontal tail wing 16R.

[0016] On the right main wing 14R, the right support bar 18R, and the right horizontal tail 16R, props 20a, 20b, and 20c are respectively provided. On the left main wing 14L, the left support bar 18L, and the left horizontal tail 16L, props 22a, 22b, and 22c are respectively provided. The six props 20a - 20c, 22a - 22c are lift generating devices. The multicopter 10 takes off and flies in the air as the six props 20a - 20c, 22a - 22c rotate.

[0017] For example, a plurality of static dischargers 24 are provided on the left main wing 14L and the right main wing 14R. Since the static discharger 24 is well - known, a detailed description is omitted. The static discharger 24 may be provided other than on the left main wing 14L and the right main wing 14R.

[0018] FIG. 2 is a schematic cross - sectional view of a main part when the outer surface of the fuselage 12 is viewed along the thickness direction. The lower part of FIG. 2 is the direction towards the inside of the fuselage 12 (for example, the passenger cabin), and the upper part of FIG. 2 is the direction towards the outside of the fuselage 12. The left side of FIG. 2 is the direction towards the front (flight direction) of the fuselage 12, and the right side of FIG. 2 is the direction towards the rear (opposite to the flight direction) of the fuselage 12. The fuselage 12 has a surface structural material 30, a plurality of frames 32, and a plurality of stringers 34. As is well - known, each frame 32 is substantially ring - shaped, and each stringer 34 extends along the front - rear direction of the fuselage 12. The frames 32 and the stringers 34 function as reinforcing materials.

[0019] The surface structural material 30 is sometimes called a skin. In FIG. 2, the shape of the surface structural material 30 is simplified for easy understanding, but the actual surface structural material 30 is formed into an appropriate shape that fits the outer shape of the multicopter 10.

[0020] The fuselage 12 includes a composite material structure 40A. The composite material structure 40A includes the surface structural material 30 as a base material 42, and further includes a first composite material 50 and a second composite material 60 disposed on the surface of the surface structural material 30.

[0021] The surface structural material 30 (base material 42) is made of, for example, a fiber-reinforced resin containing carbon fiber as a reinforcing fiber. The carbon fiber has, for example, a laminated structure of a first cross layer, a first UD (Uni Direction) layer, a second UD layer, and a second cross layer. The cross layer which is the material of the first cross layer and the second cross layer, and the UD layer which is the material of the first UD layer and the second UD layer are well-known. Therefore, detailed description and illustration of the first cross layer, the first UD layer, the second UD layer, and the second cross layer are omitted. The first cross layer, the first UD layer, the second UD layer, and the second cross layer are impregnated with a matrix resin for the base material such as an epoxy resin. Alternatively, the surface structural material 30 (base material 42) may be a metal material such as aluminum.

[0022] As shown in FIGS. 2 and 3, the first composite material 50 has a first fiber layer 52, a first conductive layer 54 laminated on the first fiber layer 52, and a first matrix resin 56 impregnated in the first fiber layer 52 and the first conductive layer 54. The first fiber layer 52 is composed of, for example, a single layer of carbon fiber layer. The carbon fiber layer is preferably a cross layer.

[0023] The first conductive layer 54 is made of a layered conductor. When the first composite material 50 is laminated on the surface structural material 30, the first fiber layer 52 is located between the surface structural material 30 and the first conductive layer 54. The first conductive layer 54 constitutes a lightning protection structure 44 in the multicopter 10.

[0024] Specific examples of the conductor include the metal mesh 58 shown in FIG. 3. The metal mesh 58 is preferably made of a copper mesh or an aluminum mesh. The copper mesh or the aluminum mesh is a good electrical conductor and has excellent weather resistance. When using an aluminum mesh, it is desirable to perform a pretreatment on the aluminum mesh. This pretreatment is a pretreatment for preventing electrolytic corrosion from occurring between the aluminum and the fibers (for example, carbon fibers) contained in the first fiber layer 52.

[0025] In the first composite material 50, the first conductive layer 54 may be in direct contact with the first fiber layer 52. The first matrix resin 56 impregnates the mutually contacting first fiber layer 52 and first conductive layer 54. In other words, the first matrix resin 56 covers the first fiber layer 52 and the first conductive layer 54. When the conductor is the metal mesh 58, the first matrix resin 56 enters the meshes of the metal mesh 58. However, in FIG. 2, by sandwiching the first conductive layer 54 and the first fiber layer 52 between two layers of the first matrix resin 56, it schematically shows that the first matrix resin 56 covers the first conductive layer 54 and the first fiber layer 52.

[0026] Although not shown, a thin layer made of the first matrix resin 56 may be interposed between the first fiber layer 52 and the first conductive layer 54 throughout. In this case, the first conductive layer 54 does not contact the first fiber layer 52. Note that the thin layer is formed from the first matrix resin 56 that has unavoidably entered between the first fiber layer 52 and the first conductive layer 54.

[0027] Another specific example of the conductor is a non-woven fabric with a metal coating on its surface. The metal coated on the surface of the non-woven fabric is called the coating metal. Suitable examples of the coating metal include silver, copper, titanium, or aluminum. In this case, the first matrix resin 56 enters the pores of the non-woven fabric. When this structure is used as the lightning protection structure 44, the lightning current C flows toward the static discharger 24 (see FIG. 1) through the coating metal.

[0028] The non-woven fabric with the coating metal formed is a lighter conductor than the metal mesh 58. Therefore, in this case, the weight of the composite material structure 40A and the multicopter 10 can be reduced further.

[0029] A suitable example of the resin material forming the first matrix resin 56 is an epoxy resin, similar to the matrix resin for the base material. However, the resin material of the first matrix resin 56 is not limited to the epoxy resin.

[0030] As shown in FIG. 2, the second composite material 60 is disposed on the surface of the surface structure material 30 so as to be adjacent to the first composite material 50. The second composite material 60 includes a second fiber layer 62, a second conductive layer 64 laminated on the second fiber layer 62, and a second matrix resin 66 impregnated into the second fiber layer 62 and the second conductive layer 64. When the second composite material 60 is laminated on the surface structure material 30, the second fiber layer 62 is positioned between the surface structure material 30 and the second conductive layer 64. The second conductive layer 64 and the first conductive layer 54 constitute a lightning protection structure 44 in the multicopter 10.

[0031] The second fiber layer 62, the second conductive layer 64, and the second matrix resin 66 each have a configuration similar to that of the first fiber layer 52, the first conductive layer 54, and the first matrix resin 56, respectively. The second fiber layer 62 is composed of, for example, a single layer of carbon fiber layer in the same manner as the first fiber layer 52. In this case, the cross-section of the second composite material 60 has a structure similar to the structure shown in FIG. 3. The first composite material 50 and the second composite material 60 are, for example, sheet-shaped bodies cut out from the same roll body or separate roll bodies.

[0032] The configuration of the second composite material 60 may be different from the configuration of the first composite material 50. For example, when the first conductive layer 54 is a copper mesh, the second conductive layer 64 may be an aluminum mesh. The resin material of the second matrix resin 66 may be a different type from the resin material of the first matrix resin 56.

[0033] As shown in FIG. 2, the composite material structure 40A has an overlapping portion 70. The overlapping portion 70 is formed by overlapping the first end portion 51 of the first composite material 50 with the second end portion 61 of the second composite material 60. The overlapping portion 70 avoids the formation of a gap between the first composite material 50 and the second composite material 60 adjacent to each other.

[0034] A through-hole is formed in each of the first end portion 51, the second end portion 61, the surface structure member 30, and the stringer 34. By connecting the through-holes, one insertion hole 72 is formed. A fastening member 74, also called a fastener, is passed through the insertion hole 72. In the illustrated example, the fastening member 74 is a bolt 76. By screwing a nut 78 onto the bolt 76, the first end portion 51, the second end portion 61, the surface structure member 30, and the stringer 34 are fastened. The second end portion 61 is located between the first end portion 51 and the surface structure member 30. Note that the fastening member 74 is not limited to the bolt 76. As another example of the fastening member 74, a rivet can be mentioned. The fastening member 74 such as the bolt 76 and the rivet is a conductor made of a metal material.

[0035] The first end portion 51, the second end portion 61, the surface structure member 30, and the frame 32 may be fastened by the fastening member 74. An L-shaped connecting member (not shown) may be connected to the stringer 34 or the frame 32, and the fastening member 74 may be fastened to this connecting member.

[0036] The fastening member 74 is a member for fastening the surface structure member 30 and the stringer 34 or the frame 32. Therefore, in this case, the overlapping portion 70 can be joined to the surface structure member 30 by mechanical joining with the fastening member 74. Note that it is not essential to fasten the first end portion 51, the second end portion 61, and the surface structure member 30 to the stringer 34 or the frame 32.

[0037] As understood from FIG. 2, a sealant 80 is filled between the inner peripheral surface of the insertion hole 72 and the bolt 76. The sealant 80 may be conductive or insulating (non-conductive). When the sealant 80 is conductive, when the first conductive layer 54 and the bolt 76 are not in contact, the sealant 80 electrically connects the first conductive layer 54 and the bolt 76. Also, the conductive sealant 80 electrically connects the bolt 76 and the second conductive layer 64 when the bolt 76 and the second conductive layer 64 are not in contact. Also, the bolt 76 is a conductor made of a metal material. Therefore, the bolt 76 (fastening member 74) functions as a conduction portion 46 that electrically connects the first conductive layer 54 and the second conductive layer 64.

[0038] When the bolt 76 is in electrical contact with the first conductive layer 54 and the second conductive layer 64, an insulating filler or the like can be used as the sealant 80. Even in this case, the bolt 76 (fastening member 74) functions as the conduction part 46 that electrically connects the first conductive layer 54 and the second conductive layer 64.

[0039] The composite material structure 40A and the multicopter 10 (flying object 100) according to the first embodiment are basically configured as described above. Next, the effects of the composite material structure 40A and the flying object 100 will be described.

[0040] The composite material structure 40A includes a base material 42, and a first composite material 50 and a second composite material 60 disposed on the surface of the base material 42. The first composite material 50 is a sheet-shaped body having a first fiber layer 52, a first conductive layer 54 laminated on the first fiber layer 52, and a first matrix resin 56 impregnated in the first fiber layer 52 and the first conductive layer 54. The first composite material 50 is laminated on the base material 42 such that the first fiber layer 52 is positioned between the base material 42 and the first conductive layer 54. The second composite material 60 is a sheet-shaped body having a second fiber layer 62, a second conductive layer 64 laminated on the second fiber layer 62, and a second matrix resin 66 impregnated in the second fiber layer 62 and the second conductive layer 64. The second composite material 60 is laminated on the base material 42 such that the second fiber layer 62 is positioned between the base material 42 and the second conductive layer 64.

[0041] The composite material structure 40A includes an overlapping portion 70 formed by overlapping the first end portion 51 of the first composite material 50 with the second end portion 61 of the second composite material 60, and in the overlapping portion 70, a conduction part 46 that electrically connects the first conductive layer 54 at the first end portion 51 and the second conductive layer 64 at the second end portion 61.

[0042] Since the first conductive layer 54 and the second conductive layer 64 are electrically connected via the conduction part 46, for example, the first conductive layer 54 and the second conductive layer 64 can be used as the lightning protection structure 44. In this case, when lightning T strikes the first composite material 50 of the composite material structure 40A, for example, dielectric breakdown or the like occurs in the composite material structure 40A. As a result, the lightning current C flows through the first conductive layer 54 and the second conductive layer 64. Thereby, since the potential balance between the potential of the first conductive layer 54 and the potential of the second conductive layer 64 can be achieved, the lightning protection performance can be maintained.

[0043] Further, since the first end portion 51 of the first composite material 50 is overlapped with the second end portion 61 of the second composite material 60, the first composite material 50 and the second composite material 60 can be arranged side by side on the surface of the base material 42 without a gap. For this reason, the composite material structure 40A exhibits sufficient weather resistance and durability. Also, the strength of the composite material structure 40A is maintained.

[0044] The aircraft 100 includes the base material 42 as a surface structure material 30 and includes the first conductive layer 54 and the second conductive layer 64 as a lightning protection structure 44.

[0045] When the aircraft 100 is struck by lightning, the lightning current C flows along the first conductive layer 54 and the second conductive layer 64 that constitute the lightning protection structure 44. Therefore, it is easy to guide the lightning current C to the static discharger 24 and discharge it to the atmosphere.

[0046] The above effects can be obtained in the same manner in the second to fourth embodiments described later. According to the first embodiment, further, the following specific effects can be obtained.

[0047] The conduction part 46 is a fastening member 74 that fastens the base material 42, the first end portion 51, and the second end portion 61. That is, the fastening member 74 used for fastening the base material 42, the first end portion 51, and the second end portion 61 can be utilized as the conduction part 46. Therefore, the first conductive layer 54 and the second conductive layer 64 can be electrically connected without performing special processing on the composite material structure 40A.

[0048] An insertion hole 72 through which a fastening member 74 passes is formed in the base material 42, the first end portion 51, and the second end portion 61. A sealant 80 is filled between the inner peripheral surface of the insertion hole 72 and the fastening member 74.

[0049] The sealant 80 seals between the inner peripheral surface of the insertion hole 72 and the fastening member 74. Therefore, rainwater and the like are prevented from entering the insertion hole 72, so that the fastening member 74 is prevented from corroding. Thereby, the bonding strength between the base material 42, the first end portion 51, and the second end portion 61 is maintained. Further, when a gap is formed between the fastening member 74 and the first conductive layer 54 or the second conductive layer 64, a conductive sealant 80 may be filled in this gap. Thereby, the first conductive layer 54 and the second conductive layer 64 are surely electrically connected via the fastening member 74 and the conductive sealant 80.

[0050] Next, with reference to FIG. 4, a composite material structure 40B according to the second embodiment will be described. Note that the same components as those shown in FIGS. 1 to 3 are denoted by the same reference numerals, and detailed descriptions thereof are omitted.

[0051] The composite material structure 40B includes a base material 42, a first composite material 50, and a second composite material 60 disposed on the surface of the base material 42. The base material 42 is the surface structural material 30 of the multicopter 10.

[0052] Similar to the first embodiment, the first composite material 50 has a first fiber layer 52, a first conductive layer 54 laminated on the first fiber layer 52, and a first matrix resin 56 impregnated in the first fiber layer 52 and the first conductive layer 54. The second composite material 60 has a second fiber layer 62, a second conductive layer 64 laminated on the second fiber layer 62, and a second matrix resin 66 impregnated in the second fiber layer 62 and the second conductive layer 64. The first end portion 51 of the first composite material 50 is overlapped with the second end portion 61 of the second composite material 60. The composite material structure 40B includes an overlapping portion 70 formed by this overlap. Further, the composite material structure 40B includes a conduction portion 46 that electrically connects the first conductive layer 54 at the first end portion 51 and the second conductive layer 64 at the second end portion 61 in the overlapping portion 70.

[0053] In the second embodiment, the conduction part 46 is a conductive coating 82. The conductive coating 82 is formed so as to cover an end face 51a along the thickness direction of the first composite material 50 at the first end part 51. The conductive coating 82 can be formed, for example, by applying a paste containing silver, copper, titanium or aluminum to the end face 51a in the same manner as the above-described coating metal, and then solidifying the paste.

[0054] The conductive coating 82 is in contact with the second end part 61. It is not necessary for the conductive coating 82 to be in contact with the stringer 34 or the frame 32. In the illustrated example, the end face 51a is a vertical plane along the thickness direction, but it may be an inclined plane.

[0055] At the second end part 61, the second conductive layer 64 may be exposed from the second matrix resin 66. In this case, it is easy to bring the conductive coating 82 into contact with the second conductive layer 64.

[0056] The composite material structure 40B and the flying object 100 according to the second embodiment exhibit the following specific effects.

[0057] The conduction part 46 is a conductive coating 82 formed so as to cover an end face 51a along the thickness direction of the first composite material 50 at the first end part 51 of the first composite material 50. The conductive coating 82 is in contact with the second end part 61.

[0058] Even in a location where the fastening member 74 cannot be used in the first composite material 50 and the second composite material 60, or in the airframe 12, the first conductive layer 54 and the second conductive layer 64 can be electrically connected via the conductive coating 82. Therefore, the first conductive layer 54 and the second conductive layer 64 can be used as a lightning protection structure 44 for passing a lightning current C.

[0059] In addition, the paste for forming the conductive coating 82 is excellent in shape followability. Therefore, for example, even when there are irregularities or the like on the end face 51a, a conductive coating 82 that sufficiently covers the end face 51a can be formed on the end face 51a.

[0060] Next, with reference to FIG. 5, the composite material structure 40C according to the third embodiment will be described. Note that the same reference numerals are given to the same components as those shown in FIGS. 1 to 4, and detailed descriptions thereof are omitted.

[0061] The composite material structure 40C includes a base material 42, and a first composite material 50 and a second composite material 60 disposed on the surface of the base material 42. The base material 42 is the surface structural material 30 of the multicopter 10.

[0062] Similar to the first and second embodiments, the first composite material 50 has a first fiber layer 52, a first conductive layer 54 laminated on the first fiber layer 52, and a first matrix resin 56 impregnated in the first fiber layer 52 and the first conductive layer 54. The second composite material 60 has a second fiber layer 62, a second conductive layer 64 laminated on the second fiber layer 62, and a second matrix resin 66 impregnated in the second fiber layer 62 and the second conductive layer 64. The first end portion 51 of the first composite material 50 is overlapped with the second end portion 61 of the second composite material 60. The composite material structure 40C includes an overlapping portion 70 formed by this overlap. Further, the composite material structure 40C includes a conduction portion 46 that electrically connects the first conductive layer 54 at the first end portion 51 and the second conductive layer 64 at the second end portion 61 at the overlapping portion 70.

[0063] In the third embodiment, the conduction portion 46 is the edge portion 55 of the first conductive layer 54 at the first end portion 51. The edge portion 55 of the first conductive layer 54 is bent toward the second end portion 61 and contacts the surface of the second end portion 61. The edge portion 55 of the first conductive layer 54 does not need to contact the stringer 34 or the frame 32. In the illustrated example, the edge portion 55 is bent substantially vertically, but it may be bent so as to be inclined.

[0064] In the second end portion 61, the second conductive layer 64 may be exposed from the second matrix resin 66. In this case, it is easy to bring the edge portion 55 of the first conductive layer 54 into contact with the second conductive layer 64.

[0065] The composite material structure 40C and the aircraft 100 according to the third embodiment exhibit the following specific effects.

[0066] The conduction part 46 is the edge part 55 of the first conductive layer 54 at the first end part 51. The edge part 55 is bent toward the second end part 61 and contacts the second end part 61.

[0067] Even in a location where the fastening member 74 cannot be used in the first composite material 50 and the second composite material 60, or in the airframe 12, the first conductive layer 54 and the second conductive layer 64 can be electrically connected via the edge part 55 of the first conductive layer 54. Therefore, the first conductive layer 54 and the second conductive layer 64 can be used as a lightning protection structure 44 for passing a lightning current C. Also, operations such as applying a conductive coating 82 to the side surface of the first end part 51 of the first conductive layer 54 are unnecessary.

[0068] Thus, according to the third embodiment, the conduction part 46 can be easily provided.

[0069] Next, referring to FIG. 6, the composite material structure 40D according to the fourth embodiment will be described. Note that the same reference numerals are given to the same components as those shown in FIGS. 1 to 5, and detailed descriptions thereof are omitted.

[0070] The composite material structure 40D includes a base material 42 and a first composite material 50 and a second composite material 60 disposed on the surface of the base material 42. The base material 42 is the surface structural material 30 of the multicopter 10.

[0071] The first composite material 50 includes a first fiber layer 52, a first conductive layer 54, and a first matrix resin 56. The second composite material 60 includes a second fiber layer 62, a second conductive layer 64, and a second matrix resin 66. The composite material structure 40D includes an overlapping portion 70 formed by overlapping a first end portion 51 of the first composite material 50 with a second end portion 61 of the second composite material 60. The composite material structure 40D includes a conduction portion 46 that electrically connects the first conductive layer 54 at the first end portion 51 and the second conductive layer 64 at the second end portion 61 in the overlapping portion 70.

[0072] In the fourth embodiment, the conduction portion 46 is composed of a fastening member 74 shown in FIG. 2 and a conductive solid 90 other than the first conductive layer 54 (edge portion 55) shown in FIG. 5. Here, the "solid" refers to a corporeal substance that does not exhibit viscosity or fluidity from before being provided as the conduction portion 46 in the overlapping portion 70 to after being provided as the conduction portion 46 in the overlapping portion 70. According to this definition, the conductive coating 82 shown in FIG. 4 does not correspond to the "solid".

[0073] The conductive solid 90 is exposed outside the first end portion 51 and the second end portion 61 that constitute the overlapping portion 70. That is, unlike the fastening member 74 (see FIG. 2), the conductive solid 90 does not penetrate the overlapping portion 70. Specific examples of the conductive solid 90 (see FIG. 6) that can be joined to the first end portion 51 and the second end portion 61 outside the overlapping portion 70 include a stapler or a bonding wire.

[0074] The conductive solid 90 has a base portion 92, a first tongue piece portion 94 that bends and continues substantially perpendicular to one end of the base portion 92, and a second tongue piece portion 96 that bends and continues substantially perpendicular to the other end of the base portion 92. The extending direction of the first tongue piece portion 94 and the extending direction of the second tongue piece portion 96 are opposite to each other. The first tongue piece portion 94 and the second tongue piece portion 96 may be bent so as to be inclined with respect to the base portion 92. In FIG. 6, the lower surface of the first tongue piece portion 94 abuts on the upper surface 51b at the first end portion 51 of the first composite material 50. The lower surface of the second tongue piece portion 96 abuts on the upper surface 61b at the second end portion 61 of the second composite material 60.

[0075] At the first end portion 51, the first conductive layer 54 may be exposed from the first matrix resin 56. In this case, it is easy to bring the first conductive layer 54 into contact with the lower surface of the first tongue piece portion 94. Similarly, at the second end portion 61, the second conductive layer 64 may be exposed from the second matrix resin 66. In this case, it is easy to bring the second conductive layer 64 into contact with the lower surface of the second tongue piece portion 96. Note that in the illustrated example, the base portion 92 is in contact with the end face 51a at the first end portion 51 of the first composite material 50, but the base portion 92 may be spaced apart from the end face 51a.

[0076] The composite material structure 40D and the flying object 100 according to the fourth embodiment have the following specific effects in addition to the same operational effects as those of the third embodiment.

[0077] When providing the conductive solid 90 at the overlapping portion 70, the contact point between the first tongue piece portion 94 and the first composite material 50 and the contact point between the second tongue piece portion 96 and the second composite material 60 are joined. As can be understood from this, according to the conductive solid 90, the conduction portion 46 can be provided at the overlapping portion 70 by a partial joining operation. That is, the joining operation for providing the conduction portion 46 is simple.

[0078] Regarding the above disclosure, the following additional remarks are further disclosed.

[0079] (Additional Remark 1) The composite material structure (40A, 40B, 40C, 40D) includes a base material (42), a first composite material (50) and a second composite material (60) disposed on the surface of the base material. The first composite material is a sheet-shaped body having a first fiber layer (52), a first conductive layer (54) laminated on the first fiber layer, and a first matrix resin (56) impregnated in the first fiber layer and the first conductive layer, and is laminated on the base material so that the first fiber layer is positioned between the base material and the first conductive layer. The second composite material is a sheet-shaped body having a second fiber layer (62), a second conductive layer (64) laminated on the second fiber layer, and a second matrix resin (66) impregnated in the second fiber layer and the second conductive layer, and is laminated on the base material so that the second fiber layer is positioned between the base material and the second conductive layer.

[0080] The composite material structure includes an overlapping portion (70) formed by overlapping a first end portion (51) of the first composite material with a second end portion (61) of the second composite material, and in the overlapping portion, a conduction portion (46) that electrically connects the first conductive layer at the first end portion and the second conductive layer at the second end portion.

[0081] Since the first conductive layer and the second conductive layer are electrically connected via the conduction portion, for example, the first conductive layer and the second conductive layer can be used as a lightning protection structure. In this case, when the composite material structure is struck by lightning, the lightning current flows through the first conductive layer and the second conductive layer. Thereby, the potential balance between the potential of the first conductive layer and the potential of the second conductive layer can be achieved, so that damage to the lightning protection structure can be prevented and the lightning resistance can be maintained.

[0082] Furthermore, since the lightning current easily flows through the composite material structure through the first conductive layer and the second conductive layer, electromagnetic interference is unlikely to occur. Therefore, when the composite material structure is provided in the mobility of a flying object or the like, malfunction is unlikely to occur in the electronic components mounted on the mobility.

[0083] Also, since the first end portion of the first composite material is overlapped with the second end portion of the second composite material, the first composite material and the second composite material can be arranged side by side without a gap on the end face of the base material. Therefore, the composite material structure exhibits sufficient weather resistance and durability. Also, the strength of the composite material structure is maintained.

[0084] (Appendix 2) In the composite material structure according to Appendix 1, the conduction portion may be a fastening member (74) that fastens the base material, the first end portion, and the second end portion.

[0085] In this case, the fastening member used to fasten the base material, the first end portion, and the second end portion can be utilized as the conduction portion. Therefore, the first conductive layer and the second conductive layer can be electrically connected without performing special processing on the composite material structure.

[0086] (Appendix 3) In the composite material structure described in Supplementary Note 2, insertion holes (72) through which the fastening members pass may be formed in the base material, the first end portion, and the second end portion, and a sealant (80) may be filled between the inner peripheral surface of the insertion holes and the fastening members.

[0087] The sealant seals between the inner peripheral surface of the insertion hole and the fastening member. Therefore, intrusion of rainwater or the like into the insertion hole is prevented, so that corrosion of the fastening member is avoided. Thereby, the joining strength between the base material, the first end portion, and the second end portion is maintained.

[0088] (Supplementary Note 4) In the composite material structure described in Supplementary Note 3, the sealant may have conductivity.

[0089] According to this configuration, the fastening member can be reliably electrically connected to the first conductive layer and the second conductive layer via the conductive sealant.

[0090] (Supplementary Note 5) In the composite material structure described in Supplementary Note 1, the conduction portion may be a conductive coating (82) formed so as to cover the end face (51a) of the first end portion and contacting the second end portion.

[0091] Even in a location where a fastening member cannot be used, the first conductive layer and the second conductive layer can be electrically connected via the conductive coating.

[0092] (Supplementary Note 6) In the composite material structure described in Supplementary Note 1, the conduction portion may be an edge portion (55) of the first conductive layer at the first end portion, and the edge portion may be bent toward the second end portion and contact the second end portion.

[0093] Even in a location where a fastening member cannot be used, the first conductive layer and the second conductive layer can be electrically connected via the edge portion of the first conductive layer. Also, operations such as applying a conductive coating are unnecessary.

[0094] (Appendix 7) In the composite material structure described in Appendix 1, the conduction part may be a conductive solid (90) joined to the first end part and the second end part outside the overlapping part.

[0095] When the conduction part is composed of a conductive solid, the conduction part can be provided in the overlapping part by a simple joining operation.

[0096] (Appendix 8) The flying object (100) includes the base material described in Appendix 1 as a surface structural material (30), and includes the first conductive layer described in Appendix 1 and the second conductive layer described in Appendix 1 as a lightning protection structure (44).

[0097] When the flying object is struck by lightning, the lightning current flows along the first conductive layer and the second conductive layer that constitute the lightning protection structure. Therefore, it is easy to discharge the lightning current into the atmosphere.

[0098] (Appendix 9) In the flying object described in Appendix 8, the conduction part may be a fastening member (74) that fastens the frame (32) or stringer (34), the base material, the first end part, and the second end part.

[0099] A fastening member for fastening the frame or stringer and the composite material structure can be utilized as the conduction part. In this case, in the composite material structure, the fastening member fastens the base material, the first end part, and the second end part. Therefore, the first conductive layer and the second conductive layer can be electrically connected without performing special processing on the composite material structure.

[0100] (Appendix 10) In the flying object described in Appendix 8, the conduction part may be a conductive coating (82) formed so as to cover the end face (51a) of the first end part and contacting the second end part.

[0101] Even in a location where a fastening member cannot be used, the first conductive layer and the second conductive layer can be electrically connected through the edge part of the first conductive layer.

[0102] (Appendix 11) In the flying object described in Appendix 8, the conductive portion is an edge (55) of the first conductive layer exposed from the first end portion, and the edge portion may be bent toward the second end portion and contact the second end portion.

[0103] Even in a location where a fastening member cannot be used, the first conductive layer and the second conductive layer can be electrically connected via a conductive coating. Also, operations such as applying a conductive coating are unnecessary.

[0104] (Appendix 12) In the flying object described in Appendix 8, the conductive portion may be a conductive solid (90) joined to the first end portion and the second end portion outside the overlapping portion.

[0105] In this case, the conductive portion can be provided in the overlapping portion by a simple joining operation.

[0106] (Appendix 13) In the flying object according to any one of Appendices 8 to 12, the surface structural material may be composed of a fiber-reinforced resin containing carbon fiber as a reinforcing fiber.

[0107] According to this structure, weight reduction and thinning of the surface structural material can be achieved.

[0108] Note that the present invention is not limited to the above-described disclosure, and various configurations can be adopted without departing from the gist of the present invention.

Explanation of Signs

[0109] 10... Multi-copter 24... Static discharger 30... Surface structural material 32... Frame 34... Stringer 40A to 40D... Composite material structure 42... Base material 44... Lightning protection structure 46... Conductive portion 50... First composite material 51... First end portion 52... First fiber layer 54…First conductive layer 56…First matrix resin 60…Second composite material 61…Second end 62…Second fiber layer 64…Second conductive layer 66…Second matrix resin 70…Overlap portion 74…Fastening member 80…Sealant 82…Conductive coating 90…Conductive solid 100…Aircraft C…Lightning current

Claims

1. A composite material structure comprising a base material and a first composite material and a second composite material disposed on the surface of the base material, The first composite material is a sheet-shaped body having a first fiber layer, a first conductive layer laminated on the first fiber layer, and a first matrix resin impregnated in the first fiber layer and the first conductive layer, and the first fiber layer is laminated on the base material so as to be positioned between the base material and the first conductive layer, The second composite material is a sheet-shaped body having a second fiber layer, a second conductive layer laminated on the second fiber layer, and a second matrix resin impregnated in the second fiber layer and the second conductive layer, and the second fiber layer is laminated on the base material so as to be positioned between the base material and the second conductive layer, The composite material structure includes an overlapping portion formed by overlapping a first end portion of the first composite material with a second end portion of the second composite material, In the overlapping portion, a conduction portion that electrically connects the first conductive layer at the first end portion and the second conductive layer at the second end portion, A composite material structure comprising.

2. The composite material structure according to claim 1, wherein the conduction portion is a fastening member that fastens the base material, the first end portion, and the second end portion.

3. The composite material structure according to claim 2, wherein insertion holes through which the fastening member passes are formed in the base material, the first end portion, and the second end portion, and a sealant is filled between an inner peripheral surface of the insertion hole and the fastening member.

4. The composite material structure according to claim 3, wherein the sealant has conductivity.

5. The composite material structure according to claim 1, wherein the conduction portion is a conductive coating formed so as to cover an end surface of the first end portion and contact the second end portion.

6. The composite material structure according to claim 1, wherein the conduction portion is an edge portion of the first conductive layer at the first end portion, and the edge portion is bent toward the second end portion and contacts the second end portion.

7. The composite material structure according to claim 1, wherein the conduction portion is a conductive solid joined to the first end portion and the second end portion outside the overlapping portion.

8. An aircraft comprising the base material according to claim 1 as a surface structural material and comprising the first conductive layer and the second conductive layer as a lightning protection structure.

9. In the aircraft according to claim 8, the electrical connection portion is a fastening member that fastens the frame or stringer, the base material, the first end portion, and the second end portion. Aircraft.

10. In the aircraft according to claim 8, the electrical connection portion is a conductive coating formed so as to cover the end face of the first end portion and contact the second end portion. Aircraft.

11. In the aircraft according to claim 8, the electrical connection portion is an edge portion of the first conductive layer exposed from the first end portion, and the edge portion is bent toward the second end portion and contacts the second end portion. Aircraft.

12. In the aircraft according to claim 8, the electrical connection portion is a conductive solid joined to the first end portion and the second end portion outside the overlapping portion. Aircraft.

13. In the aircraft according to any one of claims 8 to 12, the surface structural material is composed of a fiber-reinforced resin containing carbon fiber as a reinforcing fiber. Aircraft.

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