Strained capable conductive/resistive composite hybrid heater for thermal anti-ice device

1. A rotor blade of a helicopter comprising:

a body; and

a heating mat arranged in said body and configured to supply heat to said body, said heating mat including a first plurality of fibers and a second plurality of fibers electrically connected to said first plurality of fibers, said second plurality of fibers being distinct from said first plurality of fibers;

wherein said first plurality of fibers define a positive angle smaller than about +45° relative to a first direction perpendicular to a longitudinal direction of said body,

wherein said second plurality of fibers define a negative angle greater than about −45° relative to said first direction, and

wherein when said heating mat is laid substantially in a plane, said first plurality of fibers extend in a first direction and said second plurality of fibers extend in a second direction different from the first direction.

2. The rotor blade of claim 1 , wherein said heating mat is configured to withstand strain values up to 10,000 μinch/inch along said longitudinal direction.

3. The rotor blade of claim 1 , wherein said heating mat is arranged along a leading edge of said body.

4. The rotor blade of claim 1 , wherein said first plurality of fibers and said second plurality of fibers define a plurality of trapezoids, said plurality of trapezoids being configured to scissor open or close when subject to strain.

5. The rotor blade of claim 4 , wherein when a surface of the body is in compression, the plurality of trapezoids shrink along a direction of the strain and expand along a direction perpendicular to the direction of the strain, and when the surface of the body is in tension, the plurality of trapezoids expand along the direction of the strain and shrink along the direction perpendicular to the direction of the strain.

6. The rotor blade of claim 1 , wherein said positive angle is between about +5° and +20° and wherein said negative angle is between about −20° and −5°.

7. The rotor blade of claim 1 , wherein said heating mat is configured to dissipate heat at a power density in the range from about 12 to about 30 W/inch 2 .

8. The rotor blade of claim 1 , wherein said first plurality of fibers include separate bundles of fibers.

9. The rotor blade of claim 8 , wherein said bundles of fibers include between 50 and 12,000 fibers.

10. The rotor blade of claim 1 , wherein said first and said second plurality of fibers are coated with metal.

11. The rotor blade of claim 10 , wherein said metal includes nickel or nickel-cadmium.

12. The rotor blade of claim 1 , wherein said first and said second plurality of fibers include carbon, boron or aluminum.

13. The rotor blade of claim 1 , wherein said first plurality and said second plurality of fibers are arranged to form a woven fabric.

14. The rotor blade of claim 13 , wherein said woven fabric includes bundles of fibers that each go over and under a neighboring bundle.

15. The rotor blade of claim 13 , wherein said woven fabric includes bundles of fibers that each go over one and under four neighboring bundles.

16. The rotor blade of claim 1 , wherein said first plurality of fibers and said second plurality of fibers have substantially a same number of fibers.

17. The rotor blade of claim 1 , wherein said heating mat includes continuous plies of a unidirectional fiber tape.

18. The rotor blade of claim 1 , wherein fibers in said first plurality of fibers are substantially parallel to each other.

19. The rotor blade of claim 1 , wherein said heating mat is encapsulated in a epoxy fiber glass matrix.

20. The rotor blade of claim 1 , wherein said rotor blade is a tiltrotor blade.

21. A heating device for supplying heat to a rotor blade of a helicopter, said heating device comprising a heating mat arranged in said rotor blade, said heating mat comprising:

a first plurality of fibers and a second plurality of fibers electrically connected to said first plurality of fibers, said second plurality of fibers being distinct from said first plurality of fibers;

wherein said first plurality of fibers define a positive angle smaller than about +45° relative to a first direction perpendicular to a longitudinal direction of said rotor blade,

wherein said second plurality of fibers define a negative angle greater than about −45° relative to said first direction, and

wherein when said heating mat is laid substantially in a plane, said first plurality of fibers extend in a first direction and said second plurality of fibers extend in a second direction different from the first direction.

22. A rotor blade of a helicopter comprising:

a body; and

a heating mat arranged in said body and configured to supply heat to said body, said heating mat including a woven fabric formed with bundles of conductive fibers oriented in a first direction and bundles of conductive fibers oriented in a second direction different from the first direction when said heating mat is laid substantially in a plane,

wherein said first direction defines a positive angle smaller than about +45° relative to a direction perpendicular to a longitudinal direction of said body, and

wherein said second plurality of fibers defines a negative angle greater than about −45° relative to a direction perpendicular to a longitudinal direction of said body.

23. A structure subject to high strain comprising:

a body; and

a heating mat arranged in said body and configured to supply heat to said body, said heating mat including a first plurality of fibers and a second plurality of fibers electrically connected to said first plurality of fibers, said second plurality of fibers being distinct from said first plurality of fibers;

wherein said first plurality of fibers define a positive angle smaller than about +45° relative to a first direction perpendicular to a longitudinal direction of said body,

wherein said second plurality of fibers define a negative angle greater than about −45° relative to said first direction, and

wherein when said heating mat is laid substantially in a plane, said first plurality of fibers extend in a first direction and said second plurality of fibers extend in a second direction different from the first direction.

24. A rotor blade of a helicopter comprising:

a body; and

a heating mat arranged in said body and configured to supply heat to said body, said heating mat including a first plurality of fibers and a second plurality of fibers electrically connected to said first plurality of fibers;

wherein said first plurality of fibers define a positive angle smaller than about +45° relative to a first direction perpendicular to a longitudinal direction of said body,

wherein said second plurality of fibers define a negative angle greater than about −45° relative to said first direction, and

wherein said first plurality of fibers and said second plurality of fibers define a plurality of trapezoids, said plurality of trapezoids being configured to scissor open or close when subject to strain.

25. The rotor blade of claim 24 , wherein when a surface of the body is in compression, the plurality of trapezoids shrink along a direction of the strain and expand along a direction perpendicular to the direction of the strain, and when the surface of the body is in tension, the plurality of trapezoids expand along the direction of the strain and shrink along the direction perpendicular to the direction of the strain.