Bearingless main rotor assembly torque tube
First Claim
1. A composite torque tube for a bearingless main rotor assembly that is optimally fabricated for minimal weight with respect to predetermined torsional stiffness, fatigue strength, and buckling strength design constraints of the bearingless main rotor assembly, comprising:
- a hollow, elongated, tapered structural member formed from a combination of continuous filament windings, wound filaments, fibrous wraps, and fibrous laminates, said structural member includingan inboard section configured for mechanically coupling said composite torque tube in combination with the bearingless main rotor assembly, said inboard section including a snubber subsection and an inboard transition subsection;
an outboard section, andan intermediate section continuous with said inboard and outboard sections and configured to accommodate pitch, flapwise, and edgewise loads acting on the bearingless main rotor assembly during operation thereof, said intermediate section being formed solely by said continuous filament windings, each of said continuous filament windings forming said intermediate section having a predetermined fiber orientation selected from a range of fiber orientations of about ±
18°
to about ±
40°
to provide a minimal, constant torque tube wall thickness for said intermediate section that accommodates the predetermined torsional stiffness, fatigue strength, and buckling strength design constraints of the bearingless main rotor assembly;
said inboard and outboard sections including each of said continuous filament windings forming said intermediate section, each of said continuous filament windings in said snubber subsection having a ±
45°
fiber orientation; and
whereineach of said continuous filament windings forming said intermediate section transitions from said predetermined fiber orientation of said intermediate section to said ±
45°
fiber orientation of said snubber subsection over said inboard transition subsection.
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Accused Products
Abstract
A composite torque tube for a bearingless main rotor (BMR) assembly that is optimally fabricated to meet torsional stiffness, fatigue strength, and buckling strength design constraints at minimal unit weight. The composite torque tube includes a strengthened inboard section for mechanically coupling the torque tube in combination with the hub structure of the BMR assembly, a strengthened outboard section for mechanically coupling the torque tube in combination with a corresponding main rotor blade, and an intermediate section that is operative to accommodate the pitch, flapwise, and/or edgewise loads acting on the BMR assembly during operation thereof. The intermediate section of the torque tube has a constant wall thickness and is formed from continuous filament windings having a predetermined fiber orientation within a broad range of about +/-18° to about +/-40° and/or a narrow range of about +/-26° to about +/-35°. The torque tube is preferably formed from continuous filament windings having an optimal fiber orientation of about +/-35° to provide an intermediate section having a minimal torque tube wall thickness.
32 Citations
9 Claims
-
1. A composite torque tube for a bearingless main rotor assembly that is optimally fabricated for minimal weight with respect to predetermined torsional stiffness, fatigue strength, and buckling strength design constraints of the bearingless main rotor assembly, comprising:
-
a hollow, elongated, tapered structural member formed from a combination of continuous filament windings, wound filaments, fibrous wraps, and fibrous laminates, said structural member including an inboard section configured for mechanically coupling said composite torque tube in combination with the bearingless main rotor assembly, said inboard section including a snubber subsection and an inboard transition subsection; an outboard section, and an intermediate section continuous with said inboard and outboard sections and configured to accommodate pitch, flapwise, and edgewise loads acting on the bearingless main rotor assembly during operation thereof, said intermediate section being formed solely by said continuous filament windings, each of said continuous filament windings forming said intermediate section having a predetermined fiber orientation selected from a range of fiber orientations of about ±
18°
to about ±
40°
to provide a minimal, constant torque tube wall thickness for said intermediate section that accommodates the predetermined torsional stiffness, fatigue strength, and buckling strength design constraints of the bearingless main rotor assembly;said inboard and outboard sections including each of said continuous filament windings forming said intermediate section, each of said continuous filament windings in said snubber subsection having a ±
45°
fiber orientation; and
whereineach of said continuous filament windings forming said intermediate section transitions from said predetermined fiber orientation of said intermediate section to said ±
45°
fiber orientation of said snubber subsection over said inboard transition subsection. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
-
Specification