Indian Industries, Inc.

Simula, Inc.

Christopher Karl DeLap

James R Allshouse

Jeffrey A Mears

Christopher Peter Petrole

Robert F Monks

Howard A Lindsay

Scott David Cokeing

Steven M Motoyama

Howard Alvin Lindsay

A method of fabricating complex hollow composite structures from laminates of fiber reinforced synthetic resins. The structures are fully monocoque tubes with no seams. The tubes are manufactured by wrapping a hollow semi-rigid inner mandrel made of thermoplastic material such as polystyrene or ABS (acrylonitrile-butadiene-styrene co-polymer) with layers of composite sheets. The sheets are made from high-strength fibers impregnated with thermosetting or thermoplastic resins. The laminated mandrel is placed in a mold, heated and inflated to a predetermined pressure. The pressure can range from 20-200 psig and even higher, while the curing temperature can range from 200.degree.-600.degree. F. The pressure generated by the expanding core produces a highly consolidated composite structure that has fewer voids, a more uniform thickness, and an increased fiber content compared to hollow composites made by other fabrication methods.

High pressure hollow process for manufacturing composite structures

An optimized composite bow limb is provided wherein the bow limb is composed mainly of thin sheets of resin impregnated laminates. In a method for making the composite bow limb, laminates are selectively distributed throughout the limb so as to aid in equalizing the stress throughout the working area of the limb and so as to increase the stiffness in the fork section of the limb. The laminates are layed up as part of a bundle in a mold such that some portions of the bundle have more fabric weaves than other portions of the bundle, and thus have increased thickness. The desired thickness of the limb is defined such that the fork portion has an increased thickness to provide increased stiffness for the tines. Additionally, the working area of the limb is designed so as to distribute stress substantially equally throughout that area such that the thinnest area of the limb is adjacent the fork section and whereas the thickness of the limb increases substantially proportional to the square of the distance from the axle hole near the tip of the limb. Heat and pressure are applied to the mold to cure the bundle. The resulting paddle is machined to form an optimized bow limb. In one embodiment of the present invention the laminates include fabric weaves including longitudinal fibers and off-axial fibers interwoven therewith.

Composite bow limb

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Phoenix, AZ, United States of America

Christopher Karl DeLap