Airfoil with an integrally stiffened composite cover
An airfoil according to an exemplary aspect of the present disclosure includes, among other things, a main body extending between a leading edge and a trailing edge separated in a chordwise direction and extending between a tip and a root in a spanwise direction. The main body defines a suction side and a pressure side separated in a thickness direction and a plurality of channels extending inwardly from at least one of said suction and pressure sides. A composite cover is attached to the main body. The composite cover includes a plurality of stiffeners each received within one of the channels. A cover skin is adjacent the stiffeners, and an over-wrap surrounds the stiffeners and the cover skin.
1. An airfoil comprising:
a main body extending between a leading edge and a trailing edge in a chordwise direction and extending between a tip and a root in a spanwise direction, said main body defining a suction side and a pressure side separated in a thickness direction and a plurality of channels extending inwardly from at least one of said suction and pressure sides; and
a composite cover attached to said main body, wherein said composite cover includes a plurality of stiffeners each received within one of said channels, a cover skin adjacent said stiffeners, and an over-wrap surrounding said stiffeners and said cover skin.
2. The airfoil of claim 1 , wherein each of said stiffeners is formed from a stiffener wrap surrounding a stiffener body.
3. The airfoil of claim 2 , wherein said stiffener body is removable from said stiffener wrap to define a stiffener shell.
4. The airfoil of claim 2 , wherein said stiffener wrap includes a plurality of braided yarns.
5. The airfoil of claim 2 , wherein said stiffener is made of a first material and said main body is made of a second material different from the first material in density.
6. The airfoil of claim 1 , wherein said cover skin includes a braided fabric.
7. The airfoil of claim 6 , wherein said braided fabric includes a first fiber material extending in a braid axial direction and a second fiber material different from said first fiber material and extending in a braid bias direction.
8. The airfoil of claim 1 , wherein said composite cover is bonded to said channels.
9. The airfoil of claim 1 , wherein said composite cover defines a continuous surface with at least one of said suction and pressure sides.
10. The airfoil of claim 1 , wherein said composite cover includes a plurality of spacers each received between said over-wrap, one of said stiffeners and said cover skin.
11. The airfoil of claim 10 , wherein each of said spacers includes at least one of a plurality of braided yarns and a braided fabric.
12. The airfoil of claim 11 , wherein each of said spacers includes a foam material encapsulated by a spacer over-wrap.
13. A gas turbine engine comprising:
a turbine section; and
a fan section in communication said turbine section, said fan section including a plurality of fan blades, each fan blade including an airfoil and root, said airfoil including a main body and a composite cover attached to said main body;
wherein said main body defines a plurality of channels extending inwardly from at least one of a suction side and a pressure side defined by said main body; and
wherein said composite cover includes a cover skin, a plurality of stiffeners each received within one of said channels and an over-wrap surrounding said stiffeners and said cover skin.
14. The gas turbine engine of claim 13 , wherein the fan section is driven by a geared architecture mechanically coupled to said turbine section.
15. The gas turbine engine of claim 13 , wherein each of said stiffeners is formed from a stiffener wrap surrounding a stiffener body.
16. The gas turbine engine of claim 15 , wherein said stiffener wrap includes a plurality of braided yarns.
17. The gas turbine engine of claim 13 , wherein said cover skin includes at least one ply of a braided fabric.
18. A method of forming a composite cover for an airfoil, comprising:
forming a plurality of channels within at least one of a pressure side and a suction side of a main body;
fabricating a plurality of stiffeners each by braiding a plurality of fiber yarns over a stiffener body;
fabricating a cover skin from at least one ply of a braided fabric;
arranging each of said stiffeners adjacent to said cover skin;
surrounding said stiffeners and said cover skin with an over-wrap;
curing said stiffeners, said cover skin and said over-wrap within a resin to define a composite cover; and
bonding said composite cover to said channels.
19. The method as recited in claim 18 , comprising the step of curing said fiber yarns within a resin to define a stiffener shell prior to the step of encapsulating said stiffeners and said cover skin with said over-wrap.
20. The method as recited in claim 18 , wherein said composite cover defines a continuous surface with at least one of said suction and pressure sides.