United Technologies Corporation

George J Wehnert

Francis E Byrnes

Peter C Ogle

Edward S Hibyan

Thomas J Toner

Stanley J Richter

This invention is directed toward a fiber reinforced resin matrix composite article having fiber reinforced resin matrix bushings. These bushings are formed by tightly wrapping the fibers to form a plug having the fiber orientation from about .+-.20.degree. to about .+-.60.degree. to the central axis around which the fibers are wrapped. The plug is then snugly inserted into a hole which has been cut in the composite article such that the central axis of the plug is perpendicular to the fibers in the composite article. The entire composite article containing the plug is then cured and the plug is then drilled out forming the bushing.

Molded-in composite bushings

A composite helicopter rotor hub is described having a composite retention plate, yokes and torque tubes. The retention plate is made up of graphite and glass fiber reinforced epoxy resin. The graphite fiber reinforcement is in-plane isotropically laid continuous graphite fibers and the glass fiber reinforcement comprises segments of fiberglass continuously and circumferentially wound around the areas of retention. The yoke is made up of glass fibers unidirectionally oriented in the direction of principle stress, i.e., along the length of the yoke. The yoke also has clevis sections on either end and the clevis sections additionally contain multiaxially oriented multiple plies of unidirectionally oriented continuous graphite fibers interleaved with the unidirectionally oriented continuous glass fibers. The torque tube contains upper and lower load bearing surfaces connected by two sidewall portions. Both the sidewall and load bearing portions contain filament wound glass fiber reinforced epoxy resin such fibers having a .+-.45.degree. orientation. The upper and lower load bearing portions additionally contain multiaxially oriented multiple plies of unidirectionally oriented continuous graphite fibers interleaved with the glass fibers. The particular materials selected combined in the unique manner described provide the individual components as well as the entire hub assembly with crack resistance, damage tolerance, light weight, strength and integrity inspectability.

Composite helicopter rotor hub

A helicopter hub main retention plate is described made up of graphite and glass fiber reinforced epoxy resin. The graphite fiber reinforcement is in-plane isotropically laid continuous graphite fibers and the glass fiber reinforcement comprises segments of fiberglass continuously and circumferentially wound around the areas of retention. Such materials and configuration provide crack resistance, damage tolerance, and integrity inspectability to the retention plate.

Fiber reinforced/epoxy matrix composite helicopter rotor main hub plate

A composite torque tube for a helicopter rotor hub is described. The torque tube contains upper and lower load bearing surfaces connected by two sidewall portions. Both the sidewall and load bearing portions contain filament wound glass fiber reinforced epoxy resin such fibers having a .+-.45.degree. orientation. The upper and lower load bearing portions additionally contain a plurality of multiaxially oriented plies of continuous unidirectionally oriented graphite fibers interleaved with the glass fibers so as to produce a torque tube with crack resistance, damage tolerance, light weight, strength and integrity inspectability.

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Madison, CT, United States of America

George J Wehnert