Reinforced stiffeners and method for making the same
AssigneeThe Boeing Company
InventorsLyle R. Deobald, John D. Morris, Karl B. Lee, Jeffery L. Marcoe, Mark C. Iden, Christopher G. Harris
Life of this patent
Estimating the term…
Abstract
A composite stiffener is fabricated using preforms of laminated, unidirectional composite tape. The stiffener includes a void that is reinforced by a filler wrapped with a structural adhesive. The surfaces of the preforms surrounding the void include a layer of composite fabric which is bonded to the filler by the adhesive, thereby increasing the toughness of stiffeners around the void and improving pull-off strength of the stiffener.
Claims15
A method of fabricating a composite stiffener, comprising:
- forming a pair of composite channels each having a flange and a radius portion using composite fiber tape having only unidirectional reinforcing fibers, the composite fiber tape placed over a tool;
- placing a layer of composite fiber fabric on the radius portion of each of the channels, said composite fiber fabric comprising fibers transversely oriented with respect to one another and with respect to said unidirectional reinforcing fibers comprising said channels;
- forming a base using additional composite fiber tape;
- placing a layer of said composite fiber fabric on at least a portion of the base;
- placing a layer of adhesive on and around an outer surface of a filler while said outer surface is not in contact with the channels and the base, said adhesive only on said outer surface and not within said filler;
- assembling the channels and the base following placing said layer of adhesive;
- placing the filler and the layer of adhesive in a radius filler zone between the radius portions of the channels and the base;
- and,
- curing the assembly to form the composite stiffener.
A method of fabricating a reinforced composite stiffener, comprising:
- forming a composite structure having a web and a pair of flanges extending in opposite directions from the web, including forming multi-ply lay-ups of only unidirectional fiber composite tape on a tool and placing a layer of composite fiber fabric on a radius portion between one of the flanges and one of the webs, said composite fiber fabric comprising fibers transversely oriented with respect to one another and with respect to said unidirectional reinforcing fibers comprising said channels,
- placing an adhesive around and on an outer surface of the filler for joining the reinforcing filler to the composite fabric layers on the composite structure and a cap, said adhesive only on said outer surface and not within said filler, said placing an adhesive following formation of said filler while said outer surface is not in contact with the web and the cap and prior to assembling said cap;
- placing the reinforcing filler in a radius filler zone;
- applying a second layer of said composite fabric on a surface of the cap;
- and
- joining the surface of the cap to the flanges.
A method of fabricating a reinforced composite stiffener for aircraft applications, comprising:
- forming multi-ply lay-ups of unidirectional fiber composite tape on a tool;
- forming the lay-ups into first and second C-channels, a cap and a base;
- assembling the C-channels, the cap and the base into an I-section structure having a web and a pair of flanges on each end of the web;
- applying composite fabric on outer surfaces of the C-channels, the cap and the base in areas forming radius filler zones at the intersection of the web with the cap and with the cap and with the base, said composite fabric comprising fibers transversely oriented with respect to one another and with respect to fibers comprising said C-channels;
- wrapping a structural adhesive around and on an outer surface of a reinforcing filler following formation of said filler while said outer surface is not in contact with the web and the base and prior to assembling said cap and said base, said adhesive only on said outer surface and not within said filler;
- placing the reinforcing filler and the adhesive in the radius filler zone following assembling said cap and said base;
- and
- curing the assembly to form the composite stiffener.
Dependencies are inferred from the claim text.