Technique for making fiber composite object

Details Technique for making fiber composite object Technique for making fiber composite object

1999-08-06

2001-07-24

Weisberger, Richard (Department: 2164)

Adhesive bonding and miscellaneous chemical manufacture

Surface bonding means and/or assembly means therefor

Automatic and/or material-triggered control

C156S060000, C156S064000, C156S349000, C156S441000

Reexamination Certificate

active

06263936

ABSTRACT:

BACKGROUND ART
1. Field of the Invention
The present invention relates generally to the fabrication of objects using fiber composite materials, and more specifically a technique for forming an object, such as a portion of a rotor blade for an aircraft, having a cross-sectional shape which varies along its length.
2. Description of Prior Art
Because of considerations such as weight and strength, fiber composite materials are seeing increasing use in high-tech structures, such as aircraft parts. They are seeing increasing use in aircraft parts such as air foils, rotor blades, and similar parts.
The design of some parts is fairly complex, and results in structures which are not easily fabricated. An example of such a structure are blade components for a helicopter rotor or aircraft propeller. Such blades often have a primary load bearing structure, typically fabricated along the leading edge of the blade. Such a structure is referred to herein as a spar. For some aircraft types, in particular helicopter rotors and rotors for tilt-rotor aircraft, the shape of the spar is relatively complex.
For example, a spar for a tilt-rotor aircraft rotor blade may be on the order of fifteen to thirty feet in length. Along the length of the spar, the cross-sectional area changes, as well as the shape of each cross-section. In addition, the spar includes a twist for aerodynamic purposes.
Numerous techniques are available for fabricating spars using fiber composite materials, but prior art techniques are not always suitable to state-of-the-art objects. For example, one technique for fabricating a spar for a tilt-rotor aircraft blade involves formation of the object in two pieces. A top half and a bottom half are each separately formed on a shaped mold, and then coupled together on another shaped mold. Attaching the two pieces together typically involves deformation of the two originally molded halves. Such techniques tend to be expensive both in terms of assembly time and labor, and in tooling to make the product.
To enhance strength and stiffness of the product, it is desirable that as many fibers as possible be laid full length along the spar. Because of the complex nature of the spar shape, this can be difficult using prior art techniques.
It would be desirable to provide a technique, and the resulting product, for manufacturing complex shapes such as rotor spars for tilt-rotor aircraft rotor blades. It would be desirable for the technique to be relatively inexpensive in both manufacturing and tooling costs, and to provide an accurate reproduction of an intended complex shape.
BRIEF SUMMARY OF THE INVENTION
Therefore, in accordance with the present invention, a complex object, such as a spar for a tilt-rotor aircraft rotor blade, is manufactured from fiber composite materials. Unbroken fiber strips are laid along the length of the spar to maximize the number of full length fibers used in the spar. Cross-sectional areas along the length of the spar can change in both shape and area. The fibers are laid to accommodate and form these variable shapes. The locations for the fibers are determined by defining locations for the strips for each cross-section, then connecting corresponding points together to specify where the strips are to be laid down.


REFERENCES:
patent: 4123212 (1978-10-01), Piazza
patent: 4562033 (1985-12-01), Johnson et al.
patent: 4696707 (1987-09-01), Lewis et al.
patent: 4750965 (1988-06-01), Pippel et al.
patent: 5022952 (1991-06-01), Vaniglia
patent: 5841892 (1998-11-01), McGrath et al.
patent: 5871604 (1999-02-01), Hohman
“Design Automation of V-22 Grip”, by Robert A. Moore, Bell Helicopter Textron, Inc., presented at the American Helicopter Society 50thAnnual Forum, Washington, D.C., May 11-13, 1994.

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