Induction welding of composite structures

Abstract

The invention relates to induction welding of composite structures. A composite structure and a method of forming a composite structure are provided. The composite structure comprises a first composite part; a second composite part welded to the first composite part at the joint; and the joint between the first composite part and the second composite part comprises doped fibers.

Description

Technical Field

[0001] The present disclosure relates generally to composite manufacturing and, more particularly, to induction welding of composite structures. Background Art

[0002] Thermoplastic polymer composites are suitable for structural aircraft applications due to their mechanical property capabilities. Thermoplastic polymer composites are capable of rapid processing and are capable of remelting and reshaping. The ability to remelt and reshape enables induction welding. Induction welding is a process that can join composite structures together without the use of chemical adhesive bonds or mechanical fasteners. Induction welding can be performed without external heaters in direct contact with the structure.

[0003] In induction welding, an alternating current is induced in the carbon fibers, which melts the surrounding polymer. Two thermoplastic structures can be joined together by melting and recrystallizing them together.

[0004] Induction welding can be difficult to control because specific fiber contacts are required in order to induce current in the structure. Induction welding can be difficult to control because the induced current can melt the entire structure, resulting in desoldering and poor surface quality without precise machining.

[0005] It would therefore be desirable to have methods and apparatus that take into account at least some of the issues discussed above, as well as other possible issues. Summary of the invention

[0006] Embodiments of the present invention provide a composite structure. The composite structure includes a first composite part, a second composite part welded to the first composite part at a joint, and the joint between the first composite part and the second composite part includes doped fibers.

[0007] Another embodiment of the present disclosure provides a method of welding two composite parts to form a composite structure. A first composite part is formed with a doped prepreg ply, the doped prepreg ply including doped fibers at a first surface of the first composite part. A second composite part is positioned in contact with the first surface such that the doped prepreg ply is positioned at a joint between the first composite part and the second composite part. The first composite part and the second composite part are welded at the joint using heat generated by the doped fibers in response to an electromagnetic field.

[0008] Yet another embodiment of the present disclosure provides a method. Doping fibers to form doped fibers having increased electrical conductivity. Forming a doped prepreg ply including the doped fibers. Applying the doped prepreg ply to a first composite part. Positioning a second composite part relative to the composite part such that the doped prepreg ply is positioned between the second composite part and the first composite part.

[0009] The features and functions can be achieved independently in various embodiments of the present disclosure or may be combined in yet other embodiments, in which further details can be seen with reference to the following description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The novel features which are believed to be characteristic of the illustrative embodiments are set forth in the appended claims. However, the illustrative embodiments and their preferred modes of use, further objects and features will be best understood by reference to the following detailed description of illustrative embodiments of the present disclosure when read in conjunction with the accompanying drawings, in which:

[0011] Figure 1 is a diagram of an aircraft according to an illustrative embodiment;

[0012] Figure 2 is an illustration of a block diagram of a manufacturing environment according to an illustrative embodiment;

[0013] Figure 3 is an illustration of an isometric view of induction welding a composite structure having doped plies at a joint in accordance with an illustrative embodiment;

[0014] Figure 4 is a flow chart of a method of welding two composite parts to form a composite structure according to an illustrative embodiment;

[0015] Figure 5 is a flow chart of a method of placing a dopant fiber between a first composite part and a second composite part according to an illustrative embodiment;

[0016] Figure 6 is an illustration of an aircraft manufacturing and service methodology in block diagram form in accordance with an illustrative embodiment; and

[0017] Figure 7 is an illustration of an aircraft in block diagram form in which illustrative embodiments may be implemented. DETAILED DESCRIPTION

[0018] The illustrative examples recognize and take into account several considerations. The illustrative examples recognize and take into account that some challenges of induction welding can be overcome by isolating current generation to only the surfaces of the structures to be joined at the joint interface.

[0019] Illustrative examples isolate current generation at a joint interface by using at least one surface ply having functionalized fibers and increased conductivity.

[0020] The fibers can be functionalized using plasma enhanced chemical vapor deposition (PECVD), which causes vertical graphene to grow from existing fibers, increasing the conductivity of the fibers. The increased conductivity increases the current that can be induced in the fibers at the joint interface, which increases the heat energy that can be generated there by a theoretical power of 2.

[0021] Now turn to Figure 1 , an illustration of an aircraft is depicted in accordance with an illustrative embodiment. Aircraft 100 has wing 102 and wing 104 attached to fuselage 106. Aircraft 100 includes engine 108 attached to wing 102 and engine 110 attached to wing 104.

[0022] Fuselage 106 has a tail section 112 . Horizontal stabilizer 114 , horizontal stabilizer 116 , and vertical stabilizer 118 are attached to tail section 112 of fuselage 106 .

[0023] Aircraft 100 is an example of an aircraft that may have a composite structure induction welded using illustrative examples. In some illustrative examples, the induction welded composite structure may be present in at least one of wing 102 , wing 104 , or fuselage 106 of aircraft 100 .

[0024] Now turn to Figure 2 , an illustration of a block diagram of a manufacturing environment is depicted in accordance with an illustrative embodiment. Composite structure 202 may be induction welded in manufacturing environment 200. Composite structure 202 may be a composite part of aircraft 100.

[0025] Composite structure 202 includes first composite part 204 , second composite part 206 welded to first composite part 204 at joint 208 , and joint 208 between first composite part 204 and second composite part 206 that includes doped fiber 210 .

[0026] In some illustrative examples, doped fiber 210 includes fiber 211 doped with vertical graphene 212. In some illustrative examples, fiber 211 includes a carbon-based fiber. Vertical graphene 212 may be deposited on fiber 211 using plasma enhanced chemical vapor deposition 214.

[0027] In some illustrative examples, doped fibers 210 include unidirectional fibers 216. In some illustrative examples, doped fibers 210 include woven fabric 218. After vertical graphene 212 is formed on fibers 211, resin 220 is applied to fibers 211 to form doped prepreg plies 224. In some illustrative examples, resin 220 present in joint 208 is the same as resin 222 present in first composite part 204. In some illustrative examples, resin 220 present in doped prepreg plies 224 does not include a conductive metal additive.

[0028] After applying resin 220 to doped fibers 210, doped prepreg plies 224 may be applied to one of first composite part 204 or second composite part 206. As depicted, doped prepreg plies 224 are part of first composite part 204. In other illustrative examples, doped prepreg plies 224 are not present in first composite part 204. In some illustrative examples, doped prepreg plies 224 are present in second composite part 206.

[0029] When present in first composite part 204 , doped prepreg plies 224 form first surface 226 . First surface 226 of first composite part 204 contacts second surface 228 of second composite part 206 in joint 208 .

[0030] First composite part 204 is formed from plurality of composite plies 230. Plurality of composite plies 230 is formed from fibers and resin 222. Plurality of composite plies 230 includes structural composite plies 232. Structural composite plies 232 are present in first composite part 204 to contribute to the material and structural features of first composite part 204. Structural composite plies 232 are part of the design of first composite part 204.

[0031] Plurality of composite plies 230 includes surface composite plies 234 that form first surface 226 . Surface composite plies 234 are not present to meet design specifications for strength or other properties of first composite part 204 .

[0032] In some illustrative examples, doped prepreg ply 224 is one of surface composite plies 234. In some illustrative examples, doped prepreg ply 224 is applied after structural composite plies 232 sufficient to satisfy the structural properties of first composite part 204.

[0033] In some illustrative examples, doped prepreg ply 224 is one of structural composite plies 232. In these illustrative examples, doped prepreg ply 224 is manufactured according to a manufacturing method for a corresponding structural ply after being doped using plasma enhanced chemical vapor deposition 214.

[0034] As shown, doped fibers 236 are also present at joint 208. In some illustrative examples, doped fibers 236 include fibers 238 doped with vertical graphene 240. Vertical graphene 240 may be deposited on fibers 238 using plasma enhanced chemical vapor deposition 214.

[0035] In some illustrative examples, doped fibers 236 include unidirectional fibers 242. In some illustrative examples, doped fibers 236 include woven fabric 244. After vertical graphene 240 is formed on fibers 238, resin 246 is applied to fibers 238 to form doped prepreg plies 248. In some illustrative examples, resin 246 present in joint 208 is the same as resin 251 present in second composite part 206. In some illustrative examples, resin 246 present in doped prepreg plies 248 does not include a conductive metal additive.

[0036] Second composite part 206 is formed from second plurality of composite plies 250. Second plurality of composite plies 250 is formed from fibers and resin 251. Second plurality of composite plies 250 includes second structural composite plies 252. Second structural composite plies 252 are present in second composite part 206 to contribute to the material and structural features of second composite part 206. Second structural composite plies 252 are part of the design of second composite part 206.

[0037] Second plurality of composite plies 250 includes second surface composite plies 254 that form second surface 228. Second surface composite plies 254 are not present to meet design specifications for strength or other properties of second composite part 206.

[0038] In some illustrative examples, doped prepreg ply 248 is one of second surface composite plies 254. In some illustrative examples, doped prepreg ply 248 is applied after second structural composite plies 252 sufficient to satisfy the structural properties of second composite part 206.

[0039] In some illustrative examples, doped prepreg ply 248 is one of second structural composite plies 252. In these illustrative examples, doped prepreg ply 248 is manufactured according to a manufacturing method for a corresponding structural ply after being doped using plasma enhanced chemical vapor deposition 214.

[0040] As depicted, doped prepreg plies 224 form first surface 226 of first composite part 204. As depicted, doped prepreg plies 248 form second surface 228 of second composite part 206. Doped prepreg plies 224 and doped prepreg plies 248 are present in joint 208.

[0041] In some illustrative examples, doped fiber 210 is isolated within joint 208 .

[0042] In some illustrative examples, doped fiber 210 is part of a structural ply of one of first composite part 204 or second composite part 206. In some illustrative examples, doped fiber 210 is part of an additional ply used to connect first composite part 204 and second composite part 206, independent of the structural design of first composite part 204 and the second structural design of second composite part 206.

[0043] The doped fibers 210 in the doped prepreg plies 224 are more conductive than conventional prepreg plies. The increase in conductivity may increase heat generation in the doped prepreg plies 224. By positioning the doped prepreg plies 224 in the joint 208, heat during induction welding may be localized within the joint 208.

[0044] Doped fibers, such as doped fibers 210 or doped fibers 236, in joint 208 enable induction welding without undesirably affecting the resulting composite structure 202. Doped fibers in joint 208 enable induction welding without part deconsolidation and without degradation of surface quality, and without the need for high precision tooling.

[0045] The doped fiber 210 isolates the welding heat 262 to the plies within the set distance 256 from the doped fiber 210 through the increased heat generation of the doped fiber 210. The doped fiber 236 isolates the welding heat 262 to the plies within the set distance 256 from the doped fiber 236 through the increased heat generation of the doped fiber 236. By applying the doped fiber 210 and the doped fiber 236 only within the joint 208, the welding heat 262 is isolated at or near the joint 208.

[0046] The increased heat generation of doped fibers 210 and doped fibers 236 enables induction welding coil 258 to operate at current 260. Current 260 is a lower operating current than conventional induction welding. By utilizing a reduced current, current 260, induction welding coil 258 reduces or eliminates heat generation in the remainder of first composite part 204 and second composite part 206.

[0047] Joint 208 is formed between first composite part 204 and second composite part 206 by welding heat 262 generated in response to electromagnetic field 261 generated by induction welding coil 258. Induction welding coil 258 generates electromagnetic field 261 having current 260. At least one of doped fiber 210 or doped fiber 236 is present in joint 208 and generates welding heat 262 in response to electromagnetic field 261.

[0048] First composite part 204 and second composite part 206 may be processed in a conventional manner and then joined together without additional materials or joining aids by heating joint 208 using at least one of doped prepreg plies 224 with doped fibers 210 or doped prepreg plies 248 with doped fibers 236. The plasma enhanced chemical vapor deposition 214 process of doped fibers 211 and the prepreg of doped fibers 210 results in doped prepreg plies 224 having increased electrical conductivity without any changes to the part design, joint 208 interface, or processing methods.

[0049] Figure 2 The illustration of manufacturing environment 200 in FIG. 1 is not meant to imply physical or architectural limitations on the manner in which the illustrative embodiments may be implemented. Other components may be used in addition to or in place of the components shown. Some components may be unnecessary. Moreover, the blocks are presented to illustrate some functional components. When implemented in the illustrative embodiments, one or more of these blocks may be combined, divided, or combined and divided into different blocks.

[0050] For example, more than one doped ply may be present in at least one of first composite part 204 or second composite part 206. As another example, only one of doped prepreg plies 224 or doped prepreg plies 248 may be present in composite structure 202. Although resin 222 and resin 251 are discussed separately, resin 222 may be the same as resin 251. In some illustrative examples, resin 222, resin 251, resin 220, and resin 246 may be the same.

[0051] In some illustrative examples, doped fibers 210 and doped fibers 236 are the same. In some illustrative examples, doped fibers 210 and doped fibers 236 are unidirectional fibers 216 and unidirectional fibers 242. In some illustrative examples, doped fibers 210 and doped fibers 236 are woven fabric 218 and woven fabric 244.

[0052] Now turn to Figure 3 , depicts an isometric view of a composite structure having doped plies being induction welded at a joint in accordance with an illustrative embodiment. The composite structure 302 in view 300 is Figure 2 Physical realization of the composite structure 202.

[0053] Composite structure 302 includes first composite part 304, second composite part 306, and joint 308 between first composite part 304 and second composite part 306. Joint 308 includes doped fibers.

[0054] As shown, first composite part 304 includes first surface 310. First surface 310 includes doped prepreg plies 312. Doped prepreg plies 312 include doped fibers.

[0055] Doped prepreg plies 312 are in contact with second composite part 306. In some illustrative examples, second composite part 306 includes doped composite plies instead of or in addition to doped prepreg plies 312 of first composite part 304.

[0056] To induction weld first composite part 304 to second composite part 306, induction welding coil 314 is positioned relative to first composite part 304 and second composite part 306. Due to the doped fibers in doped prepreg plies 312, induction welding coil 314 may have a reduced current when welding first composite part 304 and second composite part 306.

[0057] As the current of induction welding coil 314 is reduced, heat affected zones 316 of first composite part 304 and second composite part 306 are reduced. Doped prepreg plies 312 isolate welding heat to plies within a set distance 318 of the doped fibers through increased heat generation of the doped fibers.

[0058] Now turn to Figure 4 , a flow chart of a method of welding two composite parts to form a composite structure is depicted according to an illustrative embodiment. The method 400 may be used to weld two composite parts to form a composite structure. Figure 2 The method 400 may be used to weld the first composite part 204 and the second composite part 206 together. Figure 3 First composite part 304 and second composite part 306 are welded together.

[0059] A first composite part is formed using doped prepreg plies that include doped fibers at a first surface of the first composite part (operation 402). A second composite part is positioned in contact with the first surface such that the doped prepreg plies are positioned at a joint between the first composite part and the second composite part (operation 404). The first composite part and the second composite part are welded at the joint using heat generated by the doped fibers in response to the electromagnetic field (operation 406). Thereafter, method 400 terminates.

[0060] In some illustrative examples, method 400 applies an electromagnetic field with a reduced current to the joint (operation 414). The reduced current causes heat generation in the doped fiber. The reduced current does not generate undesirable heat in the non-doped fiber.

[0061] In some illustrative examples, forming the first composite part with the doped prepreg plies includes replacing the structural plies with the doped prepreg plies to form the first composite part (operation 408). In some illustrative examples, when the doped prepreg plies replace the structural plies, the doped prepreg plies have the same fiber orientation as the structural plies.

[0062] In some illustrative examples, method 400 forms a second composite part with a second doped prepreg ply that includes doped fibers at a second surface of the second composite part (operation 410). In some illustrative examples, positioning the second composite part in contact with the first surface includes positioning the second surface in contact with the first surface (operation 412).

[0063] In some illustrative examples, method 400 isolates welding heat to plies within a set distance from the doped fibers through increased heat generation of the doped fibers (operation 416). Isolating heat to plies within a set distance from the doped fibers limits heat applied to the first composite part and the second composite part outside the joint. Isolating heat to plies within a set distance from the doped fibers may result in a higher quality composite structure than conventional induction welding.

[0064] Now turn to Figure 5 , depicts a flow chart of a method for placing a doped fiber between a first composite part and a second composite part according to an illustrative embodiment. The method 500 may be used to place a doped fiber between a first composite part and a second composite part. Figure 2 The method 500 may be used to weld the first composite part 204 and the second composite part 206 together. Figure 3 First composite part 304 and second composite part 306 are welded together.

[0065] Method 500 dopes fibers to form doped fibers having increased conductivity (operation 502). Method 500 forms a doped prepreg ply including the doped fibers (operation 504). Method 500 applies the doped prepreg ply to a first composite part (operation 506). Method 500 positions a second composite part relative to the composite part such that the doped prepreg ply is positioned between the second composite part and the first composite part (operation 508). Thereafter, method 500 terminates.

[0066] In some illustrative examples, doping the fiber includes forming vertical graphene on the fiber to form the doped fiber (operation 510). In some illustrative examples, forming the vertical graphene on the fiber includes applying plasma enhanced chemical vapor deposition to the fiber (operation 512).

[0067] In some illustrative examples, forming the doped prepreg plies includes infusing a resin into a woven fabric including doped fibers (operation 514). In some illustrative examples, forming the doped prepreg plies includes mixing unidirectional fibers including doped fibers with the resin (operation 516). In some illustrative examples, forming the doped prepreg plies includes applying the same resin as included in the first composite part to the doped fibers (operation 518). In some illustrative examples, the resin present in the doped prepreg plies does not include a conductive metal additive (operation 520).

[0068] In some illustrative examples, method 500 welds the first composite part and the second composite part while isolating welding heat to plies within a set distance from the doped prepreg plies through increased heat generation of the doped prepreg plies (operation 522). The increased heat generation of doped fibers in the doped prepreg plies may allow the induction welding coil to operate at a reduced current.

[0069] As used herein, the phrase "at least one," when used with a list of items, means that different combinations of one or more of the listed items may be used, and only one of each item in the list may be required. For example, "at least one of item A, item B, or item C" may include, but is not limited to, item A, item A and item B, or item B. This example may also include item A, item B, and item C, or item B and item C. Of course, any combination of these items may exist. In other examples, "at least one" may be, for example, but not limited to, two of item A; one of item B; and ten of item C; four of item B and seven of item C; or other suitable combinations. Items may be specific objects, things, or categories. In other words, it means that at least one of any combination of items and number of items may be used from the list, but all items in the list are not required.

[0070] As used herein, "plurality" when used with reference to items means one or more items.

[0071] The flowcharts and block diagrams in the depicted different embodiments illustrate the architecture, functionality and operation of some possible implementations of the devices and methods in the illustrative embodiments. In this regard, each box in the flowchart or block diagram can represent at least one of a module, a segment, a function or a part of an operation or a step.

[0072] In some alternative embodiments of the illustrative embodiments, one or more functions indicated in the blocks may not occur in the order indicated in the drawings. For example, in some cases, two blocks shown in succession may be performed substantially simultaneously, or the blocks may sometimes be performed in reverse order, depending on the functions involved. In addition, in addition to the blocks shown in the flow chart or block diagram, other blocks may be added. Some blocks may be optional. For example, operations 408 to 416 may be optional. For example, operations 510 to 522 may be optional.

[0073] You can Figure 6 Aircraft manufacturing and service method 600 and the like are shown in Figure 7 Illustrative embodiments of the present disclosure are described in the context of aircraft 700 as shown. Figure 6 , an illustration of an aircraft manufacturing and service method in block diagram form is depicted in accordance with an illustrative embodiment. During pre-production, aircraft manufacturing and service method 600 may include Figure 7 Specification and design 602 of aircraft 700 and material procurement 604 .

[0074] During production, component and subassembly manufacturing 606 and system integration 608 of aircraft 700 occurs. Thereafter, aircraft 700 may undergo certification and delivery 610 for entry into service 612. While in service 612 by a customer, aircraft 700 is scheduled for routine maintenance and service 614, which may include modification, reconfiguration, refurbishment, or other maintenance and service.

[0075] Each of the processes of aircraft manufacturing and service method 600 may be performed or carried out by a system integrator, a third party, and / or an operator. In these examples, the operator may be a customer. For purposes of this description, a system integrator may include, but is not limited to, any number of aircraft manufacturers and major system subcontractors; a third party may include, but is not limited to, any number of suppliers, subcontractors, and vendors; and an operator may be an airline, leasing company, military entity, service organization, etc.

[0076] Reference now Figure 7 , depicts an illustration of an aircraft in block diagram form in which an illustrative embodiment may be implemented. In this example, aircraft 700 is Figure 6 Aircraft manufacturing and service method 600 is produced and may include airframe 702 having plurality of systems 704 and interior 706. Examples of systems 704 include one or more of propulsion system 708, electrical system 710, hydraulic system 712, and environmental system 714. Any number of other systems may be included.

[0077] Apparatus and methods embodied herein may be employed during at least one of the stages of aircraft manufacturing and service method 600. One or more illustrative embodiments may be employed in Figure 6 The components and subassemblies are manufactured or used during at least one of manufacturing 606 , system integration 608 , service 612 , or maintenance and service 614 .

[0078] The illustrative examples enable induction welding without undesirable effects on part quality or surface quality and without the use of high precision tooling. The illustrative examples provide improved induction welding using doped fibers to increase localized heat generation in a joint between two composite parts.

[0079] Illustrative examples include fibers doped with vertical graphene. In some illustrative examples, the fibers may take the form of unidirectional carbon fibers. In other illustrative examples, the fibers take the form of woven fibers. The fibers are doped with vertical graphene and prepregged with material using a pre-preparation method. The doped prepreg plies are then laid down at the joining surfaces of the component laminate. In the illustrative examples, the composite parts can be processed in the same manner and then joined together without additional materials or joining aids.

[0080] The illustrative examples provide targeted applications of doped fiber prepregs at the joining surfaces of component laminates. By isolating the doped fiber prepregs at the joint, heat generation during induction heating is isolated at the joint interface.

[0081] The illustrative examples enable the use of low melting point polymer composites with less impact on the quality of the structure. The illustrative examples increase the efficiency of the joining process in terms of energy consumption, processing rate, and requirements for tools and equipment.

[0082] This application involves the following terms:

[0083] Clause 1. A composite structure, comprising:

[0084] A first composite part;

[0085] a second composite part welded to the first composite part at a joint; and

[0086] The joint between the first composite part and the second composite part, the joint comprising doped fibers.

[0087] Clause 2. The composite structure of Clause 1, wherein the doped fibers comprise fibers doped with vertical graphene.

[0088] Clause 3. The composite structure of Clause 1, wherein the doped fibers comprise unidirectional fibers.

[0089] Clause 4. The composite structure of Clause 1, wherein the doped fibers comprise a woven fabric.

[0090] Clause 5. The composite structure of Clause 1, wherein the doped fibers are isolated within the joint.

[0091] Clause 6. The composite structure of Clause 1, wherein the resin present in the joint is the same as the resin present in the first composite part.

[0092] Clause 7. The composite structure of Clause 1, wherein the doped fiber is part of a structural ply of one of the first composite part and the second composite part.

[0093] Clause 8. The composite structure of Clause 1, wherein the doped fiber is part of an additional ply used to join the first composite part and the second composite part that exists independently of the structural design of the first composite part and the second structural design of the second composite part.

[0094] Clause 9. A method of welding two composite parts to form a composite structure, the method comprising:

[0095] forming a first composite part with a doped prepreg ply, the doped prepreg ply comprising doped fibers at a first surface of the first composite part;

[0096] positioning a second composite part in contact with the first surface such that the doped prepreg ply is positioned at a joint between the first composite part and the second composite part; and

[0097] The first composite part and the second composite part are welded at the joint using heat generated by the doped fiber in response to an electromagnetic field.

[0098] Clause 10. The method according to clause 9, further comprising:

[0099] An electromagnetic field having a reduced current is applied to the joint.

[0100] Clause 11. The method of Clause 9, wherein forming the first composite part with the doped prepreg plies comprises forming the first composite part with the doped prepreg plies replacing structural plies.

[0101] Clause 12. The method according to clause 9, further comprising:

[0102] forming the second composite part with a second doped prepreg ply, the second doped prepreg ply comprising doped fibers at a second surface of the second composite part; and

[0103] Wherein, positioning the second composite part to contact the first surface includes: positioning the second surface to contact the first surface.

[0104] Clause 13. The method according to clause 9, further comprising:

[0105] By means of the increased heat generation of the doping fibers, the welding heat is isolated to the plies within a set distance from the doping fibers.

[0106] Clause 14. A method comprising:

[0107] doping the fibers to form doped fibers having increased conductivity;

[0108] forming a doped prepreg ply including the doped fibers;

[0109] applying the doped prepreg plies to a first composite part; and

[0110] A second composite part is positioned relative to the first composite part such that the doped prepreg plies are positioned between the second composite part and the first composite part.

[0111] Clause 15. The method of Clause 14, wherein doping the fiber comprises forming vertical graphene on the fiber to form a doped fiber.

[0112] Clause 16. The method of Clause 15, wherein forming vertical graphene on the fiber comprises applying plasma enhanced chemical vapor deposition to the fiber.

[0113] Clause 17. The method of Clause 14, wherein forming the doped prepreg plies comprises infusing a resin into a woven fabric comprising the doped fibers.

[0114] Clause 18. The method of Clause 14, wherein forming the doped prepreg ply comprises mixing unidirectional fibers including the doped fibers with a resin.

[0115] Clause 19. The method of Clause 14, wherein forming the doped prepreg plies comprises applying the same resin to the doped fibers as is contained in the first composite part.

[0116] Clause 20. The method of Clause 14, wherein the resin present in the doped prepreg plies does not include conductive metal additives.

[0117] Clause 21. The method according to clause 14, further comprising:

[0118] The first composite part and the second composite part are welded while isolating welding heat to plies within a set distance from the doped prepreg plies through increased heat generation of the doped prepreg plies.

[0119] The descriptions of different illustrative embodiments have been presented for purposes of illustration and description, and are not intended to be exhaustive or limited to the embodiments in the disclosed form. Many modifications and variations will be apparent to those of ordinary skill in the art. In addition, different illustrative embodiments may provide different features compared to other illustrative embodiments. The selected one or more embodiments are selected and described in order to best explain the principles of the embodiments, the practical application, and to enable those of ordinary skill in the art to understand the disclosure of various embodiments with various modifications suitable for the intended specific use.

Claims

1. A composite structure, comprising: A first composite part; a second composite part, the second composite part being welded to the first composite part at a joint; as well as The joint between the first composite part and the second composite part, the joint comprising doped fibers.

2. The composite structure according to claim 1, wherein: The doped fibers include fibers doped with vertical graphene.

3. The composite structure according to claim 1, wherein: The doped fibers include unidirectional fibers.

4. The composite structure according to claim 1, wherein: The doped fibers include a woven fabric.

5. The composite structure according to claim 1, wherein: The doped fibers are isolated within the joint.

6. The composite structure of claim 1, wherein: The resin present in the joint is the same as the resin present in the first composite part.

7. The composite structure of claim 1, wherein: The doped fiber is part of a structural ply of one of the first composite part and the second composite part.

8. The composite structure of claim 1, wherein: The doping fiber is part of an additional ply for joining the first composite part and the second composite part that exists independently of the structural design of the first composite part and the second structural design of the second composite part.

9. A method of welding two composite parts to form a composite structure, the method comprising: forming a first composite part with a doped prepreg ply, the doped prepreg ply comprising doped fibers at a first surface of the first composite part; positioning a second composite part in contact with the first surface such that the doped prepreg ply is positioned at a joint between the first composite part and the second composite part; as well as The first composite part and the second composite part are welded at the joint using heat generated by the doped fiber in response to an electromagnetic field.

10. A method comprising: doping the fibers to form doped fibers having increased conductivity; forming a doped prepreg ply including the doped fibers; applying the doped prepreg ply to a first composite part; as well as A second composite part is positioned relative to the first composite part such that the doped prepreg plies are positioned between the second composite part and the first composite part.

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