Stiffened structures and associated methods

• US 7,080,805 B2
• Filed: 05/05/2004
• Issued: 07/25/2006
• Est. Priority Date: 05/05/2004
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Friddell, S. Douglas, Prichard, Alan K.
• Primary Examiner(s): BAREFOOT, GALEN L
• Application Number:
  US10/839,573
• Publication Number:
  US 20050247818A1
• Time in Patent Office: 811 Days
• Field of Search: 244/123, 244/117.R, 244/119, 244/133, 244/132, 244/131
• US Class Current: 244/117.00R
• CPC Class Codes: B64C 1/12 Construction or attachment of skin panels
• CPC Class Codes: B64C 3/182 Stringers, longerons
• CPC Class Codes: B64C 3/24 Moulded or cast structures

Abstract

Stiffened structures and associated methods are disclosed. In one embodiment, an elongated metallic stiffening member can be attached to a composite sheet and positioned to resist bending of the composite sheet. In another embodiment, a structural system can include an elongated composite element attached between a composite sheet and a metallic stiffening member. In still another embodiment, the structural system is formed without attaching a honeycomb stiffening arrangement.

Claims

1. A structural system, comprising:

a composite sheet having a first surface facing a first direction and a second surface facing a second direction at least approximately opposite the first direction;

an elongated metallic stiffening member having a transverse flange, the elongated metallic stiffening member being attached to the first surface of the composite sheet and positioned to resist bending of the composite sheet; and

an elongated composite element attached to the metallic stiffening member, wherein;

(A) the transverse flange of the elongated metallic stiffening member is attached directly to the first surface of the composite sheet via an adhesive;

or

(B) the transverse flange is attached directly the elongated composite element via an adhesive and the elongated composite element is attached directly to the first surface of the composite sheet via an adhesive.

2. The system of claim 1 wherein the second surface of the composite sheet forms a portion of an external flow body.

3. The system of claim 1 wherein the second surface of the composite sheet forms an exterior surface of a wing panel of an aircraft.

4. The system of claim 1 wherein the metallic stiffening member includes an elongated titanium member.

5. The system of claim 1 wherein the metallic stiffening member is elongated along a first axis and the elongated composite element is elongated along a second axis with filaments oriented generally parallel to the second axis, and wherein the composite element is attached to the metallic stiffening member so that the first and second axes are at least approximately parallel.

6. The system of claim 1 wherein the elongated composite element includes an elongated carbon boron fiber element.

7. The system of claim 1 wherein the composite sheet includes a carbon fiber sheet.

8. The system of claim 1 wherein the metallic stiffening member is elongated along an axis and wherein at least a portion of the metallic stiffening member extending generally along the axis and at least approximately perpendicular to the first surface of the composite sheet extends in and out of a flat plane extending along the axis and at least approximately perpendicular to the first surface of the composite sheet.

9. The system of claim 1 wherein the metallic stiffening member is elongated along an axis and wherein a portion of the metallic stiffening member extending generally along the axis and at least approximately perpendicular to the first surface of the composite sheet describes a sinusoidal shape.

10. The system of claim 1 wherein the first surface of the composite sheet has a curved section and wherein at least a portion of the elongated metallic stiffening member is at least approximately conformed to at least a portion of the curved section.

11. The system of claim 1 wherein the metallic stiffening member is adhesively attached to the composite sheet in a generally continuous manner.

12. The system of claim 1 wherein the composite sheet includes a first composite sheet and wherein the system further comprises a second composite sheet attached to the elongated metallic member opposite the first composite sheet.

13. The system of claim 1, further comprising a vehicle, the vehicle including the composite sheet, the elongated composite element, and the metallic stiffening member.

14. A structural system, comprising:

a composite sheet having a first surface facing a first direction and a second surface facing a second direction at least approximately opposite the first direction, with no honeycomb stiffening arrangement attached to the composite sheet; and

an elongated metallic stiffening member having at least one web and at least one transverse flange, the transverse flange being directly attached to the first surface of the composite sheet via an adhesive, the elongated metallic stiffening member being positioned to resist bending of the composite sheet.

15. The system of claim 14 wherein the second surface of the composite sheet forms a portion of an external flow body.

16. The system of claim 14 wherein the metallic stiffening member includes multiple metallic portions coupled together to form the at least one web and the at least one transverse flange.

17. The system of claim 14, further comprising an elongated composite element attached to the metallic stiffening member.

18. The system of claim 14 wherein the composite sheet includes a first composite sheet and wherein the system further comprises a second composite sheet attached to the elongated metallic member opposite the first composite sheet, the second composite sheet having no attached honeycomb stiffening arrangement.

19. The system of claim 14, further comprising a vehicle, the vehicle including the composite sheet and the metallic stiffening member.

20. An aircraft, comprising:

a fuselage portion;

a wing portion;

at least one control surface, with the wing portion, the fuselage portion, and the at least one control surface forming at least part of an external flow body of the aircraft, the external flow body including;

a composite skin having a first surface facing a first direction and a second surface facing a second direction at least approximately opposite the first direction;

a metallic stiffener having a transverse flange, the metallic stiffener being attached to the first surface of the skin and positioned to resist bending of the composite skin; and

an elongated composite element attached to the metallic stiffener, wherein;

(A) the transverse flange of the metallic stiffener is attached directly to the first surface of the skin via an adhesive;

or

(B) the transverse flange is attached directly the elongated composite element via an adhesive and the elongated composite element is attached directly to the first surface of the skin via an adhesive.

21. The system of claim 20 wherein:

the metallic stiffener includes a titanium stiffener;

the composite skin includes a carbon fiber skin; and

the elongated composite element includes a carbon boron fiber element.

22. An aircraft, comprising:

a fuselage portion;

a wing portion;

at least one control surface, with the wing portion, the fuselage portion, and the at least one control surface forming at least part of an external flow body of the aircraft, the external flow body including;

a composite skin having a first surface facing a first direction and a second surface facing a second direction at least approximately opposite the first direction, the composite skin having no attached honeycomb stiffening arrangement; and

a metallic stiffener having at least one web and at least one transverse flange, the transverse flange being directly attached to the first surface of the skin via an adhesive, the metallic stiffener being positioned to resist bending of the composite skin.

23. The system of claim 22 wherein:

the metallic stiffener includes a titanium stiffener; and

the composite skin includes a carbon fiber skin.

24. A method for producing a structural system, comprising:

providing a composite sheet having a first surface facing a first direction and a second surface facing a second direction at least approximately opposite the first direction;

positioning an elongated metallic stiffening member having a transverse flange at least proximate to the first surface of the composite sheet;

attaching the metallic stiffening member to the first surface of the composite sheet; and

attaching an elongated composite element to the metallic stiffening member,

wherein;

(A) the transverse flange of the metallic stiffener is attached directly to the first surface of the skin via an adhesive;

or

(B) the transverse flange is attached directly the elongated composite element via an adhesive and the elongated composite element is attached directly to the first surface of the skin via an adhesive.

25. The method of claim 24, further comprising forming a portion of an external flow body with the second surface of the composite sheet.

26. The method of claim 24, further comprising:

forming a wing panel with the composite sheet, the elongated metallic stiffening member, and the elongated composite element; and

installing the wing panel on an aircraft.

27. The method of claim 24 wherein positioning an elongated metallic stiffening member includes positioning an elongated titanium member.

28. The method of claim 24 wherein positioning a metallic stiffening member includes positioning a metallic stiffening member having multiple metallic portions coupled together to form the at least one web and the at least one transverse flange.

29. The method of claim 24 wherein positioning a metallic stiffening member includes positioning a metallic stiffening member that is elongated along an axis and attaching an elongated composite element includes attaching an elongated composite element having filaments, and wherein the method further comprises orienting the filaments of the elongated composite element to extend at least approximately parallel to the axis along which the metallic stiffening member is elongated.

30. The method of claim 24 wherein attaching an elongated composite element includes attaching an elongated carbon boron fiber element to the elongated metallic stiffening member.

31. The method of claim 24 wherein providing a composite sheet includes providing a carbon fiber sheet.

32. The method of claim 24 wherein positioning a metallic stiffening member includes positioning a metallic stiffening member that is elongated along an axis and wherein a portion of the metallic stiffening member extending generally along the axis and at least approximately perpendicular to the first surface of the composite sheet extends into and out of a flat plane extending along the axis and at least approximately perpendicular to the first surface of the composite sheet.

33. The method of claim 24 wherein positioning an elongated metallic stiffening member includes positioning an elongated metallic stiffening member that is elongated along an axis and wherein a portion of the metallic stiffening member extending generally along the axis and at least approximately perpendicular to the first surface of the composite sheet describes a sinusoidal shape.

34. The method of claim 24 wherein attaching an elongated composite element includes adhesively attaching an elongated composite element to the elongated metallic stiffening member.

35. The method of claim 24, further comprising forming a vehicle that includes the composite sheet, an elongated metallic stiffening member, and an elongated composite element.

36. The method of claim 24 wherein providing a composite sheet includes providing a composite sheet having a first surface that is not flat, and wherein the method further comprises conforming the metallic stiffening member to at least a portion of the first surface.

37. The method of claim 24 wherein at least one of attaching the metallic stiffening member to the first surface and attaching an elongated composite element to the metallic stiffening member includes using an adhesive and applying heat during an adhesive curing process.

38. The method of claim 24 wherein at least one of attaching the metallic stiffening member to the first surface and attaching an elongated composite element to the metallic stiffening member includes using an adhesive and applying heat and pressure during an adhesive curing process.

39. The method of claim 24 wherein attaching the metallic stiffening member to the first surface includes adhesively attaching the metallic stiffening member to the first surface in a generally continuous manner.

40. The method of claim 24 wherein:

providing the composite sheet includes providing a first composite sheet; and

attaching the metallic stiffening element to the first surface includes attaching the metallic stiffening member to the first surface of the first composite sheet, and wherein the method further comprises;

providing a second composite sheet;

positioning the elongated metallic stiffening member at least proximate to the second composite sheet; and

attaching the metallic stiffening member to the second composite sheet.

41. A method for producing a structural system, comprising:

providing a composite sheet having a first surface facing a first direction and a second surface facing a second direction at least approximately opposite the first direction, the composite sheet having no attached honeycomb stiffening arrangement;

positioning an elongated metallic stiffening member at least proximate to the first surface of the composite sheet, the metallic stiffening member having at least one web and at least one transverse flange; and

attaching the at least one transverse flange of the metallic stiffening member directly to the first surface of the composite sheet via an adhesive.

42. The method of claim 41, further comprising forming a portion of an external flow body with the second surface of the composite sheet.

43. The method of claim 41, further comprising attaching an elongated composite element to the metallic stiffening member.

44. The method of claim 41, further comprising forming a vehicle that includes the composite sheet and the elongated metallic stiffening member.

45. The method of claim 41 wherein:

providing the composite sheet includes providing a first composite sheet; and

attaching the at least one transverse flange of the metallic stiffening element to the first surface includes attaching the at least one transverse flange of the metallic stiffening member to the first surface of the first composite sheet, and wherein the method further comprises;

providing a second composite sheet, the second composite sheet having no attached honeycomb stiffening arrangement;

positioning the elongated metallic stiffening member at least proximate to the second composite sheet; and

attaching the metallic stiffening member to the second composite sheet.