High performance composite tubular structures

Abstract

This invention relates generally to the design and manufacture of high performance, composite, tubular structures. More specifically, the invention relates to a high performance, composite, tubular structure that utilizes an integral pattern of ribs on the internal diameter (“ID”) or outer diameter (“OD”) surface of the tube. The present invention provides high performance, composite, tubular structures that are both lighter and stiffer than conventional tubes. In general, the present invention incorporates unconventional features into the design of tubular structures, to greatly enhance performance. For example, in accordance with one preferred embodiment of the present invention, tubular structures are enhanced by incorporating small, stabilizing, raised ribs on the ID of the tubes.

Description

CROSS-REFERENCES TO RELATED APPLICATIONS [0001] This application claims priority to to U.S. patent application Ser. No. 09 / 881,591 entitled “High Performance Composite Tubular Structures.”BACKGROUND OF THE INVENTION [0002] 1. Technical Field of the Invention [0003] This invention relates generally to the design and manufacture of high performance, composite, tubular structures. More specifically, the invention relates to high performance, composite, tubular structures that utilize an integral pattern of reinforcing ribs on the inner diameter (“ID”) or outer diameter (“OD”) surface of the tube. [0004] 2. Background of the Prior Art [0005] Thin-walled, high performance, tubular structures have a wide variety of practical uses, such as for graphite composite golf shafts, arrows, bats, ski poles, hockey sticks, bicycle parts and many other applications. Current state of the art, high performance, tubular structures are constructed by various methods and from various materials. Designers...

AI Technical Summary

Benefits of technology

[0012] The present invention satisfies the needs described above by providing high performance, composite, tubular structures that are lighter and / or more resistant to buckling-related stress than conventional tubes. In general, the present invention incorporates features into the design of tubular structures to enhance performance.

[0013] For example, in accordance with one preferred embodiment of the present invention, tubular structures are enhanced by incorporating small, stabilizing, raised ribs on the ID or OD of the tubes. These ribs enable designers to optimize the tubes' inertial properties (area mass moments of inertia) to achieve lighter weight, greater stiffness, increased strength or some combination of all three. The ribs may be configured in a variety of shapes and sizes, but are typically helical or circular, parallel or non-parallel, and / or may travel in opposite directions and cross over one another. In accordance with various aspects of the present invention, the ribs may also be hollow. Hollow ribs optionally allow specific materials that are different from the rest of the tubular structure to be included within the ribs. Thus, it will be readily apparent to one skilled in the art that countless combinations and variations of ribs according to one embodiment of the present invention are possible. Like I-beams used in construction, the integral ribs allow designers of tubular structures to use lesser amounts of material, thus optimizing wall thinness, while simultaneously maintaining wall stability and, therefore, strength.

Problems solved by technology

The standard flag wrapping and filament wound processes for manufacturing high performance tubes have several drawbacks due to the fact that, during consolidation / curing, the diameter of the tube is reduced.

This reduction in diameter typically makes the final OD surface rough and irregular, thus requiring secondary finishing by centerless grinding and sanding.

However, the grinding / sanding process also typically cuts and abrades the outermost fibers of a tubular structure.

Because these outermost fibers are the most highly stressed due to their location (i.e., a max=MC / I, where “C” is the distance to the outside layer), the grinding / sanding process usually reduces the structural integrity of a tubular structure.

Though the net molding technique may be an improvement over the shrink wrapping techniques, prior art methods for producing high performance, composite, tubular structures are still limited.

One problem, aside from the wall irregularities discussed above, is the inability of prior art tubular structures to attain optimal wall thinness while retaining sufficient tubular strength.

For example, as the wall of a tubular structure is made thinner, its overall stiffness and strength usually decrease.

A fundamental failure mode, such as buckling, of a tubular structure may result if the wall of the structure is too thin.

A tube that buckles (typically from compression) cannot achieve its maximum strength.

Buckling, in turn, usually leads to further structural failures, such as local fiber breaking and premature catastrophic structure failure.

If deflection 310 reaches a certain point, a situation of exponential decay is reached, wherein the stresses present at the wall section increase exponentially until the wall eventually buckles catastrophically.

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