5549370 : Fiber-reinforced plastic springs with helical fiber wind

ABSTRACT:   Fiber-reinforced composite springs having a unidirectional fiber wind. The present invention is a cylindrical torsion bar, or a helical tension or

compression spring having a core that is either unreinforced or axial-fiber reinforced, and a continuous-fiber-reinforced composite cladding having most or

all of its fibers helically arrayed around the core. The core may be solid or hollow. The sense of the helical winding is that which places the fibers in tension

when the spring is used as intended. A fiber winding helix angle of approximately 55° is used with a weak and unreinforced core, while larger or smaller

helix angles are used only with a cores having sufficient stiffness to resist axial-normal stress. By carefully selecting the materials for the core and cladding,

as well as utilizing a fiber winding helix angle appropriate to the application, significant advantages over prior art springs are realized in energy per-unit-

volume, energy per-unit-weight, and spring velocity.

U.S. REFERENCES:

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15 CLAIMS: First Claim Shown (Show all claims)

I claim:

• 1. A fiber-reinforced composite spring comprising:
• • a core having moderate working shear strain and stiff elastic response to bulk compression;
  • a fiber-reinforced composite cladding formed of reinforcing fibers, said fibers being substantially wound in one direction only helically and concentrically about said core at a prescribed winding angle, said cladding compressing said core when the spring is subjected to one of any and all of compression, tension or torsion; and
  • a resin matrix for intimately bonding said fibers of said cladding together and to said core.

RELATED U.S. APPLICATIONS: none

FOREIGN REFERENCES:

OTHER REFERENCES: none
PRIMARY/ASSISTANT EXAMINERS: Graham; Matthew C.;