Braided spar for a rotor blade and method of manufacture thereof

• US 20050042109A1
• Filed: 08/22/2003
• Published: 02/24/2005
• Est. Priority Date: 08/22/2003
• Status: Active Grant

• Current Assignee: Sikorsky Aircraft Corporation (Martin Marietta Corporation)
• Original Assignee: Sikorsky Aircraft Corporation (Martin Marietta Corporation)
• Inventors: Kovalsky, David A., Viola, Kevin
• Granted Patent: US 7,165,945 B2
• Time in Patent Office: Days
• US Class Current: 416/230
• CPC Class Codes: B29C 70/222 the structure being shaped to form a three dimensional configuration
• CPC Class Codes: B29C 70/48 and impregnating the reinforcements in the closed mould, e.g. resin transfer moulding [RTM] , e.g. by vacuum
• CPC Class Codes: B29L 2031/082 Blades, e.g. for helicopters
• CPC Class Codes: B64C 2027/4736 from composite materials
• CPC Class Codes: B64C 27/008 Rotors tracking or balancing devices
• CPC Class Codes: B64C 27/463 Blade tips
• CPC Class Codes: B64C 27/473 Constructional features
• CPC Class Codes: D04C 1/02 made from particular materials
• CPC Class Codes: D04H 3/07 otherwise than in a plane, e.g. in a tubular way
• CPC Class Codes: D10B 2403/02411 with a single array of unbent yarn, e.g. unidirectional reinforcement fabrics
• CPC Class Codes: D10B 2505/02 Reinforcing materials; Prepregs

Abstract

A braided rotor blade spar includes a tri-axle braid in which braided bias angled fibers are located non-parallel to a longitudinal axis of the spar. Zero degree fibers are located parallel to the axis and are positioned to be on the upper and lower surfaces of the spar. The bias angle fibers are braided around the zero degree fibers. In a method of manufacture of the braided spar, a braided sleeve is formed dry over a mandrel by a multi-axial braiding machine. Once the braided sleeve is formed upon the mandrel, the mandrel is located within a matched metal mold, resin impregnated, and cured. The mandrel is then removed from the finished braided spar.

Claims

1. A hollow composite article, comprising:

a multiple of braided bias angled fibers, said braided bias angled fibers oriented non-parallel to a longitudinal axis; and

a multiple of zero degree fibers interwoven with said multiple of braided bias angled fibers, said zero degree fibers substantially parallel to said longitudinal axis.

2. The hollow composite article as recited in claim 1, wherein said braided bias angled fibers are offset approximately 40 degrees relative said longitudinal axis.

3. The hollow composite article as recited in claim 1, wherein said braided bias angled fibers are offset approximately 45 degrees relative said longitudinal axis.

4. The hollow composite article as recited in claim 1, wherein said braided bias angled fibers follow a spiral path around said longitudinal axis.

5. The hollow composite article as recited in claim 1, wherein a leading edge and a trailing edge conic of said hollow composite article comprise said braided bias angle fibers.

6. The hollow composite article as recited in claim 1, wherein said braided bias angled fibers are oriented to accommodate a twist along said longitudinal axis.

7. The hollow composite article as recited in claim 1, wherein said zero degree fibers are positioned upon an upper and lower surface of said hollow composite article.

8. The hollow composite article as recited in claim 1, further comprising a separate composite sheet interwoven with said multiple of braided bias angled fibers and said multiple of zero degree fibers.

9. A composite rotor blade spar, comprising:

a multiple of braided bias angled fibers, said braided bias angled fibers oriented non-parallel to a longitudinal axis; and

a multiple of zero degree fibers interwoven with said multiple of braided bias angled fibers, said zero degree fibers substantially parallel to said longitudinal axis.

10. The composite rotor blade spar as recited in claim 9, wherein said longitudinal axis is a faying axis.

11. The composite rotor blade spar as recited in claim 9, wherein said braided bias angled fibers follow a spiral path around said longitudinal axis.

12. The composite rotor blade spar as recited in claim 9, wherein a leading edge and a trailing edge conic of said spar comprise only said braided bias angle fibers.

13. The composite rotor blade spar as recited in claim 9, wherein said zero degree fibers are positioned upon an upper and lower surface of said spar.

14. The hollow composite article as recited in claim 9, further comprising a separate composite sheet interwoven with said multiple of braided bias angled fibers and said multiple of zero degree fibers.

15. The composite rotor blade spar as recited in claim 9, wherein said mandrel is non-linear.

17. A method as recited in claim 14, wherein said step (1) further comprises

braiding a multiple of bias angled fibers non-parallel to a longitudinal axis;

and

interweaving a multiple of zero degree fibers with the multiple of braided bias angled fibers, the zero degree fibers substantially parallel to the longitudinal axis.

16. A method of forming a hollow composite article comprising the steps of:

(1) braiding a multiple of composite fibers to form a braided sleeve over a mandrel;

(2) locating the braided sleeve and the mandrel within a mold; and

(3) impregnating the braided sleeve with a resin;

(4) curing the resin; and

(5) removing the mandrel.

18. A method as recited in claim 16, wherein said step (1) further comprises locating the zero degree fibers upon an upper and lower surface of the article.

19. A method as recited in claim 16, wherein said step (1) further comprises passing the mandrel through a multi-axial braiding machine.

20. A method as recited in claim 16, wherein said step (1) further comprises passing the mandrel through a multi-axial braiding machine.

21. A method as recited in claim 16, wherein said step (1) further comprises locating a separate composite sheet within the braided sleeve.