US 5,549,947 A · Composite shaft structure and manufacture

Abstract

The invention provides improvements to a composite member that has a plurality of plies. The improved composite member has (1) an interior ply which functions to dampen or resist sudden forces exerted on the composite member, (2) an intermediate load-carrying ply, and (3) an exterior abrasion-resistant ply. These plies have multiple, often intertwined fiber components disposed or imbedded with a matrix material, preferably Nylon-6 thermoplastic, to inhibit sharp edges during breakage. One or more of the plies typically has "bi-axial" or "tri-axially" braided fiber geometries wherein one or more fibers are helically wound about the circumference of the member. The helically oriented fibers are oriented at a selectively variable angle which influences the overall bending strength of the composite material. In one aspect, the angles of the fiber components and other factors are used to maintain substantially uniform cross-sectional area over the length of the tubular member while simultaneously varying the bending stiffness. In another aspect, the intermediate ply is constructed with two or more sub-plies. Such sub-plies can include tri-axially extending plies, and circumferentially-wound plies. The circumferentially-wound plies are often wound more tightly at the ends of the composite member to increase resistance to stresses caused by objects within the tubular shaft. A composite member constructed according to the invention resists sudden or impact forces and has high, selectively variable bending strength, high impact resistance, and safe failure modes.

Claims25

Dependent claims

In an axially extending composite member having a plurality of plies and having primary bending stiffness along a longitudinal axis, the improvement comprising

at least one interior ply having a first fiber component with a matrix material, said interior ply providing a first fraction of the bending stiffness of said composite member and being structured to provide impact resistance,
at least one intermediate ply having a second fiber component disposed with said matrix material, said intermediate ply being exterior to said interior ply and being structured to provide primary load-carrying strength and providing a second fraction of the bending stiffness such that said second fraction is greater than said first fraction, and
at least one exterior ply having a third fiber component disposed with said matrix material, said exterior ply being exterior to said intermediate ply and being structured to provide abrasion resistance and providing a third fraction of the bending stiffness such that said second fraction is greater than said third fraction, and
wherein said intermediate ply comprises at least one sub-ply having at least one circumferentially-wound fiber component oriented relative to said axis at a selected angle variable along the length of said member, said angle being greater at at least one end of said member for providing selective structural reinforcement at said end.

1 more element

An axially extending composite member having at least one ply, said member comprising

a first tensile fiber component that is clockwise helically oriented to the axis of said composite member such that said first tensile fiber component has a first angle selectively varying along the length of said composite member, said first tensile fiber component having a first tensile modulus,
a second tensile fiber component that is counter-clockwise helically oriented to said axis at said first angle wherein said angles of said first and second tensile fiber components are substantially equal along the length of said composite member, said second tensile fiber component having said first tensile modulus,
a third tensile fiber component that is clockwise helically oriented to said axis such that said third tensile fiber component has a second angle selectively varying along the length of said composite member, said third tensile fiber component having a second tensile modulus that is different from said first tensile modulus, and
a fourth tensile fiber component that is counter-clockwise helically oriented to said axis at said second angle wherein said angles of said third and fourth tensile fibers are substantially equal along the length of said composite member, said fourth tensile fiber component having said second tensile modulus.

1 more element

In a method for manufacturing a composite member axially extending along an axis and having a plurality of plies, the improvement comprising the steps of

(A) forming a first ply having first and second fiber components wherein said first fiber component is clockwise helically oriented to said axis of said composite member and said second fiber component is counter-clockwise helically oriented to said axis, said step of forming a first ply including the step of arranging said first and second fiber components at a first common variable angle, .alpha..sub.1, along the length of said composite member, said first and second fiber components being selected with a first tensile modulus, E.sub.f1,
(B) forming a second ply having third and fourth fiber components wherein said third fiber component is clockwise helically oriented to said axis and said fourth fiber component is counter-clockwise helically oriented to said axis, said step of forming a second ply including the step of arranging said first and second fiber components at a second common variable angle, .alpha..sub.2, along the length of said composite member, said third and fourth fiber components being selected with a second tensile modulus, E.sub.f2, that is different from said first tensile modulus, and
(C) altering said first and second common variable angles at least one axial location along the length of said composite member such that the stiffness of said composite member along said axis changes at said at least one axial location.

In a method for manufacturing an axially extending composite member having a first axis and a first dimension and a plurality of plies, the improvement comprising the steps of

(A) applying about the circumference of an elongate mandrel a first fiber component, having a first tensile modulus, that is clockwise helically oriented to said first axis, said step of applying a first fiber component including the step of arranging said first fiber component at a first angle selectively varying relative to, and along said first dimension of, said composite member,
(B) applying about the circumference of said elongate mandrel a second fiber component, having said first tensile modulus, that is counter-clockwise helically oriented to said first axis, said step of applying a second fiber component including the step of arranging said second fiber component at said first angle relative to, and along said first dimension of, said composite member,
(C) applying about the circumference of said elongate mandrel a third fiber component, having a second tensile modulus, that is clockwise helically oriented to said first axis, said step of applying a third fiber component including the step of arranging said third fiber component at a second angle selectively varying relative to, and along said first dimension of, said composite member, and
(D) applying about the circumference of said elongate mandrel a fourth fiber component, having said second tensile modulus, that is counter-clockwise helically oriented to said longitudinal axis, said step of applying a fourth fiber component including the step of arranging said fourth fiber component at said second angle relative to, and along said first dimension of, said composite member.

1 more element

Dependencies are inferred from the claim text.

Composite shaft structure and manufacture

Life of this patent

Composite shaft structure and manufacture

Life of this patent

Abstract

Claims25