Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
2001-10-09
2004-11-23
Crispino, Richard (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S307100
Reexamination Certificate
active
06821368
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to assembly of components using woven preforms and particularly relates to assembly of components into structural joints using Z-pins and woven preforms.
2. Description of the Prior Art
Typical methods known in the art for attaching a composite skin to a composite frame web include forming the web as an “I” or “C” shape, making them more complex and expensive to fabricate. The flanged sections are fastened to adjacent sections using methods similar to those used with metal components, for example, by using fasteners. However, use of the fasteners adds weight to the joints.
These joints also have difficulty withstanding out-of-plane loading. Typical remedies for this are thick laminate stack-ups using many layers of composite fabric and having large flange radii. While this reduces the tension forces between the layers of the flanged section, the result is a heavy joint, reducing the weight savings realized when using composites.
Z-pins have been used to join two composite, laminate components in the prior art. For example, U.S. Pat. No. 5,968,639 to Childress discloses inserting Z-pins into a first composite component to form a stubble at a bonding face, then curing the first component. An uncured second component is then bonded to the first component with the stubble extending into and among the fibers of the second component and through the bond line.
Several techniques have been developed for inserting the Z-pins into composites laminates. Many techniques, like that described in U.S. Pat. No. 5,919,413 to Avila, are based on using a compressible foam carrier to retain the Z-pins before insertion. The pins are held in an orientation that is generally perpendicular to the surface in which they are to be inserted and are located near the surface. A piston is used to drive the pins into the surface, compressing the foam carrier as the pins are inserted. Typically, one or more nylon peel plies are placed on the surface of the laminate prior to insertion to ensure a clean bond surface and to protect the pins before assembly. The peel plies are removed prior to assembly.
SUMMARY OF THE INVENTION
A method is provided for using a woven preform having a base and at least one leg extending from the base. The preform is used to assemble first and second composite laminate components formed from tape or fabric and a resin matrix. Z-pins are inserted into the first component prior to its being cured, forming a stubble extending above a surface of the first component. The uncured preform is placed on the surface of the first component, the stubble extending into the preform. The cured second component is attached to the preform. Over-wrap plies are optionally placed on the outer surfaces of preform. Adhesive is optionally placed between the preform and the first and second components. A vacuum bag and tooling are used while curing the preform to adhere the legs of the preform to the second component and the base of the preform to the first component.
REFERENCES:
patent: 4671470 (1987-06-01), Jonas
patent: 4729860 (1988-03-01), Leach
patent: 4808461 (1989-02-01), Boyce et al.
patent: 5589015 (1996-12-01), Fusco et al.
patent: 5667859 (1997-09-01), Boyce et al.
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patent: 5879492 (1999-03-01), Reis et al.
patent: 5919413 (1999-07-01), Avila
patent: 5935680 (1999-08-01), Childress
patent: 5968639 (1999-10-01), Childress
patent: 5980665 (1999-11-01), Childress
Tension Pull-off and Shear Test Methods to Characterize 3-D Textile Reinforced Bonded Composite Tee-Joints; Owens et al., published 2000 Composite Structures, Theory and Practice, Editors: Peter Grant and Carl Q. Rosseau.
Primary Sandwich Structure, A Unitized Approach; Sheahen et al.; copyright 2000 by Lockheed Martin; Published by the American Institute of Aeronautics and Astronauts, Inc.; pp. 1-8.
Robust Composite Sandwich Structures; Sheahen et al.; copyright 1998 by Lockheed Martin; Published by the American Institute of Aeronautics and Astronauts, Inc.; pp. 1-12.
Affordable Composite Structure for Next Generation Fighters; Bersuch et al.; copyright 1998 by Lockheed Martin; published by Society for the Advancement of Material and Process Engineering; pp. 1-11.
Interlaminar Reinforced Composites Development for Improved Damage Tolerance; Wanthal et al; copyright 200 by the Boeing Company, Lockheed Martin; Northrop Grunman; Society for the Advancement of Material and Process Engineering; 15 pages.
3-D Composites in Primary Aircraft Structure Joints;; Bersuch et al.; published Jan. 1997 AGARD Bolted/Bonded Joints in Polymeric Composites ; pp. 16-1-16-10.
Affordable 3-D Integrated Composite Structures; Sheahen et al.; copyright 2000 by Lockheed Martin; published by the Universal Technology Corporation; 20 pages.
Benson Ross A.
Bersuch Larry R.
Sheahen Patrick D.
Bracewell & Patterson L.L.P.
Crispino Richard
Lockheed Martin Corporation
Musser Barbara J
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