Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Patent
1995-01-27
1999-04-27
Lorin, Francis J.
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
156382, 156292, B32B 3100
Patent
active
058977392
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to manufacturing honeycomb core composite articles, and more particularly, to an improved-method of manufacturing such composite articles wherein the honeycomb core thereof is accurately located and substantially distortion-free.
BACKGROUND OF THE INVENTION
Composite articles incorporating honeycomb cores are commonly utilized for fabricating aerospace structures due to their advantageous strength to weight ratio. Honeycomb core (HC) composite articles are typically comprised of upper and lower composite skins, i.e., fiber reinforced resin matrix laminates, that are separated and stabilized by the honeycomb core. Due to the high bending stiffness and compressive strength properties of HC composite articles, i.e., the honeycomb core functions as a shear web and spaces the composite skins from the bending neutral axis, HC composite articles have particular utility in aerospace applications such as aircraft fuselage panels and door structures. The high strength and low weight of such construction results in lower overall aircraft system weight.
HC composite articles may be fabricated utilizing various composite forming methods. The most commonly employed technique involves the use of a vacuum bag molding assembly wherein an impervious membrane or "vacuum bag" is employed for consolidating the composite skins and ensuring proper adhesion thereof to the centrally disposed honeycomb core. More specifically, the lower composite skin, honeycomb core, and upper composite skin are sequentially laid in a rigid mold member so that the honeycomb core is overlaid by the upper and lower composite skins. The upper and lower composite skins are formed from uncured "prepreg" or "B-stage" laminates comprised of a fiber reinforcement such as graphite, aramide or fiberglass fibers disposed in a binding matrix such as epoxy, phenolic or other similar organic resinous material. Film adhesive, which is applied to the honeycomb core prior to the lay-up, forms the bonds between the upper and lower composite laminates and the honeycomb core. The vacuum bag is disposed over the rigid mold member and sealed thereto so as to form a mold cavity which is occupied by the uncured composite lay-up. The mold cavity is then evacuated and additional pressure and temperature are applied via an autoclave oven to cure the lay-up. The combination of vacuum and external pressure functions to consolidate the composite skins, remove air and volatiles from the resin binder, and apply the necessary compaction pressure to ensure full and uniform adhesion of the lay-up.
Difficulties commonly encountered during the fabrication of HC composite articles relate to shifting and/or distortion of the honeycomb core under compaction pressure. While the honeycomb core is relatively stable in the direction of the individual cells, i.e., the cells provide significant buckling stability, it will be appreciated that pressure applied transversely of the cells may cause distortion and/or shifting, e.g., accordioning, of the honeycomb core due to the inadequate strength thereof in a lateral direction. This is more clearly understood by reference to FIG. 1a wherein a lay-up of upper and lower composite skins 100, 102, and a honeycomb core 104 is disposed in a vacuum bag molding assembly 108. The vacuum bag 110 is shown applying a lateral component of pressure P along the ramped edges of the honeycomb sore, which lateral pressure component causes the local collapse and distortion of the honeycomb core edges. FIG. 1b shows a top view of the cured HC composite article wherein the distortion, indicated by dashed lines 112, is exaggerated for illustrative purposes.
Attempts to overcome problems of distortion and shifting have included stabilization techniques wherein the edges of the honeycomb core, i.e., several rows of honeycomb cells about the entire periphery, are stabilized by the application of film adhesive or filled with a low density syntactic foam. Once cured, the film adhesive and/or the foamfilled cells serve to re
REFERENCES:
patent: 3912542 (1975-10-01), Hirano et al.
patent: 4816106 (1989-03-01), Turris et al.
patent: 4869770 (1989-09-01), Christensen et al.
patent: 4942013 (1990-07-01), Palmer et al.
patent: 5242651 (1993-09-01), Brayden et al.
patent: 5261993 (1993-11-01), Dahlgren
patent: 5281388 (1994-01-01), Palmer et al.
Forster William V.
Nowak Kenneth M.
Osiecki Larry J.
Collins Brian A.
Lorin Francis J.
Sikorsky Aircraft Corporation
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