Induction welding of composite structures
A composite structure and methods of forming composite structures are provided. A composite structure comprises 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 comprising doped fibers.
1 . A composite structure that comprises:
a first composite part that comprises a plurality of thermoplastic plies and a doped prepreg ply that comprises graphene grown on fibers within only a first surface on the first composite part, doped in a resin and configured to generate heat without metallic additives; and
a second composite part that comprises a second plurality of thermoplastic plies and a second doped prepreg ply that comprises a second graphene grown on second fibers within only a second surface on the second composite part, doped in a second resin and configured to generate heat without metallic additives, wherein the second composite part is induction welded to the first composite part where the doped prepreg ply contacts the second doped prepreg ply.
2 . The composite structure of claim 1 , wherein the resin and the second resin are identical.
3 . The composite structure of claim 1 , wherein the fibers comprise unidirectional fibers.
4 . The composite structure of claim 1 , wherein the fibers comprise woven fabric.
5 . The composite structure of claim 1 , wherein the graphene grown on the fibers is isolated within a joint.
6 . The composite structure of claim 1 , wherein the resin present in the doped prepreg ply is identical to a resin present in the plurality of thermoplastic plies in the first composite part.
7 . The composite structure of claim 1 , wherein the fibers are part of a structural ply of one of the first composite part.
8 . The composite structure of claim 1 , wherein the doped prepreg ply is structured independently of a structural design for the first composite part.
9 . A method of welding two composite parts to form a composite structure, the method comprising:
forming a first composite part comprising a plurality of thermoplastic plies and a first surface;
doubling a heat energy generation characteristic of only the first surface by growing vertical graphene from fibers existing in the first surface and then doping the fibers existing in the first surface with a resin and forming the first surface as a doped prepreg ply;
positioning a second composite part in contact with the first surface such that the doped prepreg ply contacts the second composite part; and
generating, from an induction welding coil receiving a current insufficient for welding the first surface before modifying the first surface into the doped prepreg ply, a current forming an electromagnetic field welding the first composite part to the second composite part using heat generated only by the fibers in the doped prepreg ply responding to the electromagnetic field.
10 . The method of claim 9 , further comprising:
applying the electromagnetic field to the doped prepreg ply at an intensity below an activation intensity for fibers in the second composite part beyond a set distance from the doped prepreg ply.
11 . The method of claim 9 , wherein forming the first composite part with the doped prepreg ply comprises forming the first composite part with the doped prepreg ply replacing a structural ply.
12 . The method of claim 9 further comprising:
forming the second composite part with a second doped prepreg ply comprising doped fibers at a second surface of the second composite part; and
wherein positioning the second composite part in contact with the first surface comprises positioning the second surface in contact with the first surface.
13 . The method of claim 9 further comprising:
isolating welding heat to plies within a set distance from the doped prepreg ply.
14 . A method comprising:
forming a first composite part comprising a plurality of thermoplastic plies and a first surface;
doubling a heat energy generation characteristic of only the first surface by growing vertical graphene from fibers existing in the first surface and then doping the fibers existing in the first surface with a resin, without metal additives, and;
positioning a second composite part relative to the first composite part such that the doped prepreg ply contacts the second composite part; and
generating, from an induction welding coil receiving a current insufficient for welding the first surface before modifying the first surface into the doped prepreg ply, a current forming an electromagnetic field welding only the first composite part and the second composite part together using heat generated by the doped prepreg ply responding to the electromagnetic field.
15 . The method of claim 14 , wherein doping the fibers comprises forming vertical graphene on the fibers to form doped fibers.
16 . The method of claim 15 , wherein forming vertical graphene on the fibers comprises applying plasma enhanced chemical vapor deposition to the fibers.
17 . The method of claim 14 , wherein forming the doped prepreg ply comprises infusing resin into a woven fabric.
18 . The method of claim 14 , wherein forming the doped prepreg ply comprises unidirectional fibers.
19 . The method of claim 14 , wherein the resin forming the doped prepreg ply is identical to resins forming the plurality of thermoplastic plies forming the first composite part.
20 . The method of claim 14 , wherein resin present in the doped prepreg ply does not include conductive metal additives.
21 . The method of claim 14 further comprising:
welding the first composite part and the second composite part while isolating welding heat to plies within a set distance from the doped prepreg ply by increased heat generation of the doped prepreg ply.