Internally stiffened composite panels and methods for their manufacture

• US 20040055248A1
• Filed: 09/20/2002
• Published: 03/25/2004
• Est. Priority Date: 09/20/2002
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Grillos, Emmanuel J.
• Granted Patent: US 7,197,852 B2
• Time in Patent Office: Days
• US Class Current: 52/783.1
• CPC Class Codes: B64C 1/12 Construction or attachment of skin panels
• CPC Class Codes: E04C 2/365 by honeycomb structures
• CPC Class Codes: Y10T 29/49622 Vehicular structural member making

Abstract

Internally stiffened composite panels and associated manufacturing methods. In one embodiment, an internally stiffened composite panel includes a first face sheet, a second face sheet offset from the first face sheet, and at least one core portion sandwiched between the first and second face sheets. In one aspect of this embodiment, the composite panel further includes a stiffener disposed between the first and second face sheets adjacent to the core portion. The stiffener can have a first attachment portion attached to the first face sheet, a second attachment portion attached to the second face sheet, and an intermediate portion extending between the first and second attachment portions. In another aspect of this embodiment, one or both of the first and second attachment portions is configured to engage a fastener, such as a blind fastener, for attaching a part to the composite panel.

Claims

1. A composite panel comprising:

a first face sheet;

a second face sheet offset from the first face sheet;

at least one core portion connected between the first and second face sheets; and

a stiffener disposed between the first and second face sheets adjacent to the at least one core portion, the stiffener having a first attachment portion attached to the first face sheet, a second attachment portion attached to the second face sheet, and an intermediate portion extending between the first and second attachment portions.

2. The composite panel of claim 1 wherein the stiffener further includes a third attachment portion attached to the first face sheet, the third attachment portion being offset from the second attachment portion and spaced apart from the first attachment portion.

3. The composite panel of claim 1 wherein the first attachment portion includes a first flange portion, wherein the second attachment portion includes a cap portion, and wherein the stiffener further includes a second flange portion attached to the first face sheet, the second flange portion being offset from the cap portion and spaced apart from the first flange portion, further wherein the intermediate portion includes a first web portion and a second web portion offset from the first web portion, wherein the first web portion extends between the first flange portion and the cap portion, and wherein the second web portion extends between the second flange portion and the cap portion.

4. The composite panel of claim 1 wherein the first attachment portion includes a flange portion, wherein the second attachment portion includes a cap portion, and wherein the intermediate portion includes a web portion extending between the flange portion and the cap portion.

5. The composite panel of claim 1 wherein the first attachment portion includes a first flange portion, wherein the second attachment portion includes a second flange portion, and wherein the intermediate portion includes a web portion extending between the first and second flange portions.

6. The composite panel of claim 1 wherein the first face sheet is a first arcuate panel, the second face sheet is a second arcuate panel, and the stiffener is an elongate straight member extending between the first and second face sheets.

7. The composite panel of claim 1 wherein the first face sheet is a first arcuate panel, the second face sheet is a second arcuate panel, and the stiffener is an elongate arcuate member extending between the first and second face sheets.

8. The composite panel of claim 1 wherein the second attachment portion is configured to receive and engage a fastener to fixedly attach a part to the composite panel.

9. The composite panel of claim 1 wherein the second attachment portion is configured to receive and engage a blind fastener to fixedly attach a part to the composite panel.

10. The composite panel of claim 1 wherein the at least one core portion includes a honeycomb material having a first core face and a second core face opposite the first core face, wherein the first core face is at least partially bonded to the first face sheet and the second core face is at least partially bonded to the second face sheet

11. The composite panel of claim 1 wherein the first and second face sheets include a graphite/epoxy material.

12. The composite panel of claim 1 wherein the first attachment portion is adhesively bonded to the first face sheet, and wherein the second attachment portion is adhesively bonded to the second face sheet.

13. The composite panel of claim 1, further comprising at least one adhesive layer disposed between the at least one core portion and one of the first and second face sheets, wherein the adhesive layer adhesively bonds the at least one core portion to the one of the first and second face sheets.

14. A composite panel comprising:

a first face sheet;

a second face sheet offset from the first face sheet;

at least one core portion connected between the first and second face sheets;

a first stiffener disposed between the first and second face sheets adjacent to the at least one core portion, the first stiffener having at least a first attachment portion attached to one of the first and second face sheets; and

a second stiffener disposed between the first and second face sheets adjacent to the at least one core portion, the second stiffener having at least a second attachment portion attached to one of the first and second face sheets, the second stiffener being positioned at an angle relative to the first stiffener.

15. The composite panel of claim 14 wherein the first face sheet is a first arcuate panel, the second face sheet is a second arcuate panel, the first stiffener is a straight member extending between the first and second face sheets, and the second stiffener is an arcuate member extending between the first and second face sheets.

16. The composite panel of claim 14 wherein the first face sheet is a first arcuate panel, the second face sheet is a second arcuate panel, the first stiffener is a straight member extending between the first and second face sheets, and the second stiffener is an arcuate member extending between the first and second face sheets at an angle from about 85 degrees to about 95 degrees relative to the first stiffener.

17. The composite panel of claim 14 wherein the first stiffener has a first cross-sectional shape and the second stiffener has a second cross-sectional shape, wherein the first and second cross-sectional shapes are at least generally the same.

18. The composite panel of claim 14 wherein at least one of the first and second stiffeners is configured to receive and engage a fastener to attach a part to the composite panel.

19. The composite panel of claim 14 wherein the first stiffener further includes a third attachment portion and an intermediate portion, the third attachment portion being offset from the first attachment portion, and the intermediate portion extending between the first and third attachment portions, wherein the first attachment portion is attached to the first face sheet, and the third attachment portion is attached to the second face sheet.

20. The composite panel of claim 14 wherein the first stiffener further includes a third attachment portion and an intermediate portion, the third attachment portion being offset from the first attachment portion, and the intermediate portion extending between the first and third attachment portions, wherein the first attachment portion is attached to the first face sheet, and the third attachment portion is attached to the second face sheet, and wherein at least one of the first and second attachment portions is configured to receive and engage a fastener to attach a part to the composite panel.

21. The composite panel of claim 14 wherein the first stiffener further includes a third attachment portion and an intermediate portion, the third attachment portion being offset from the first attachment portion, and the intermediate portion extending between the first and third attachment portions, wherein the first attachment portion is attached to the first face sheet, and the third attachment portion is attached to the second face sheet, and wherein the first attachment portion includes a first flange portion, the third attachment portion includes a second flange portion, and the intermediate portion includes a web portion extending between the first and second flange portions.

22. The composite panel of claim 14 wherein the first stiffener further includes a third attachment portion and an intermediate portion, the third attachment portion being offset from the first attachment portion, and the intermediate portion extending between the first and third attachment portions, wherein the first attachment portion is attached to the first face sheet, and the third attachment portion is attached to the second face sheet, and wherein the first attachment portion includes a flange portion, the third attachment portion includes a cap portion, and the intermediate portion includes a web portion extending between the flange portion and the cap portion.

23. A composite panel comprising:

a first face sheet;

a second face sheet offset from the first face sheet;

at least one core portion extending between the first and second face sheets; and

a stiffener disposed between the first and second face sheets at least proximate to the at least one core portion, the stiffener having at least one attachment portion attached to one of the first and second face sheets.

24. The composite panel of claim 23 wherein the at least one attachment portion of the stiffener includes a first flange portion attached to the first face sheet, and wherein the stiffener further includes a second flange portion offset from the second face sheet.

25. The composite panel of claim 23 wherein the at least one attachment portion of the stiffener includes a first flange portion attached to the first face sheet, and wherein the stiffener further includes a second flange portion extending from the first flange portion at least generally toward the second face sheet.

26. The composite panel of claim 23 wherein the at least one core portion includes a channel, and wherein the stiffener is positioned within the channel.

27. The composite panel of claim 23 wherein the at least one attachment portion of the stiffener is a first attachment portion attached to the first face sheet, and wherein the stiffener further includes a second attachment portion and an intermediate portion, the intermediate portion extending between the first attachment portion and the second attachment portion, wherein the second attachment portion is attached to the second face sheet, and wherein the intermediate portion includes a first web portion and a second web portion, the second web portion being spaced apart from the first web portion to define an enclosed passageway extending through the stiffener.

28. The composite panel of claim 23 wherein the at least one attachment portion of the stiffener includes a first flange portion attached to the first face sheet, wherein the stiffener further includes a cap portion and a second flange portion, the cap portion being offset from the first flange portion, and the second flange portion being offset from the cap portion and spaced apart from the first flange portion, the second flange portion being attached to the first face sheet.

29. The composite panel of claim 23 wherein the at least one attachment portion of the stiffener includes a first flange portion attached to the first face sheet, wherein the stiffener further includes a cap portion and a second flange portion, the cap portion being offset from the first flange portion, the second flange portion being offset from the cap portion and spaced apart from the first flange portion, and the second flange portion being attached to the first face sheet, and wherein the stiffener further includes a first web portion and a second web portion, the first web portion extending between the first flange portion and the cap portion, and the second web portion extending between the cap portion and the second web portion.

30. A composite panel assembly comprising:

a composite panel including;

a first face sheet;

a second face sheet offset from the first face sheet;

at least one core portion extending between the first and second face sheets;

a stiffener disposed between the first and second face sheets at least proximate to the at least one core portion, the stiffener having at least one attachment portion attached to one of the first and second face sheets;

a part positioned at least proximate to the composite panel and adjacent to the stiffener; and

at least one fastener engaging the part and extending through one of the first and second face sheets and the stiffener, wherein the at least one fastener engages the stiffener to attach the part to the composite panel.

31. The composite panel of claim 30 wherein the at least one attachment portion of the stiffener includes a first flange portion attached to the first face sheet, wherein the stiffener further includes a cap portion and a second flange portion, the cap portion being offset from the first flange portion and attached to the second face sheet, the second flange portion being offset from the cap portion and spaced apart from the first flange portion, and the second flange portion being attached to the first face sheet, and wherein the fastener is a blind fastener extending through the cap portion of the stiffener.

32. The composite panel assembly of claim 30 wherein the first face sheet is a first arcuate panel, the second face sheet is a second arcuate panel, and the stiffener is an elongate straight member extending between the first and second face sheets, wherein the at least one attachment portion of the stiffener is bonded to the second face sheet, and wherein the part is an arcuate frame member extending adjacent to the second face sheet.

33. The composite panel assembly of claim 30 wherein the at least one attachment portion of the stiffener receives and engages the fastener to fixedly attach the part to the composite panel.

34. The composite panel assembly of claim 30 wherein the at least one core portion includes a honeycomb material, and wherein the first and second face sheets include a graphite/epoxy material.

35. The composite panel assembly of claim 30 wherein the first face sheet, the second face sheet, and the stiffener include a graphite/epoxy material.

36. The composite panel assembly of claim 30 wherein the at least one attachment portion of the stiffener is adhesively bonded to the one of the first and second face sheets.

37. The composite panel assembly of claim 30, further comprising at least one adhesive layer disposed between the at least one core portion and one of the first and second face sheets, wherein the adhesive layer adhesively bonds the at least one core portion to the one of the first and second face sheets.

38. An aircraft comprising:

a fuselage; and

a wing fixedly attached to the fuselage, wherein at least one of the fuselage and the wing includes a composite panel, the composite panel including;

a first face sheet;

a second face sheet offset from the first face sheet;

at least one core portion extending between the first and second face sheets; and

a stiffener disposed between the first and second face sheets at least proximate to the at least one core portion, the stiffener having at least one attachment portion attached to one of the first and second face sheets.

39. The aircraft of claim 38 wherein the at least one attachment portion of the stiffener includes a first flange portion attached to the first face sheet, and wherein the stiffener further includes a cap portion and a second flange portion, the cap portion being offset from the first flange portion and attached to the second face sheet, the second flange portion being offset from the cap portion and attached to the first face sheet.

40. The aircraft of claim 38 wherein the composite panel is an external fuselage skin panel fixedly attached to the fuselage, wherein the first face sheet is a first arcuate panel, the second face sheet is a second arcuate panel, and the stiffener is an elongate member extending between the first and second face sheets.

41. The aircraft of claim 38 wherein the at least one attachment portion of the stiffener is configured to receive and engage a fastener to fixedly attach the composite panel to the at least one of the fuselage and the wing.

42. The aircraft of claim 38 wherein the composite panel is an external fuselage skin panel fixedly attached to the fuselage, wherein the at least one core portion includes a honeycomb material, and wherein the first and second face sheets include a graphite/epoxy material.

43. A structural panel having at least a first surface, the first surface defining a first direction and a second direction, the first direction being parallel to the first surface and the second direction being perpendicular to the first surface, the structural panel comprising:

first means for providing structural strength parallel to the first direction;

second means for providing structural strength parallel to the first direction, the second means being offset from the first means;

means for offsetting the first means from the second means in the second direction; and

means for stiffening the structural panel, wherein the means for stiffening the structural panel are disposed between the first means and the second means adjacent to the means for offsetting the first means from the second means.

44. The structural panel of claim 43 wherein the means for stiffening the structural panel are configured to receive and engage a fastener for attaching a part to the structural panel.

45. The structural panel of claim 43 wherein the means for stiffening the structural panel extend between the first means and the second means and structurally connect the first means to the second means.

46. The structural panel of claim 43 wherein the first means have a first arcuate shape, the second means have a second arcuate shape, and the means for stiffening the structural panel are at least generally straight.

47. The structural panel of claim 43 wherein the means for stiffening the structural panel are first stiffening means, the first stiffening means being at least generally straight, and wherein the structural panel further comprises second means for stiffening the structural panel, the second stiffening means being at least generally arcuate.

48. A method for manufacturing a composite panel, the method comprising:

providing a first face sheet;

positioning an attachment portion of a stiffener at least proximate to the first face sheet;

positioning at least one core portion adjacent to the first face sheet and at least proximate to the stiffener; and

positioning a second face sheet adjacent to the at least one core portion and the stiffener.

49. The method of claim 48 wherein the attachment portion of the stiffener is a first attachment portion, wherein the stiffener further includes a second attachment portion offset from the first attachment portion by an intermediate portion, and wherein the method further comprises positioning the second attachment portion at least proximate to the second face sheet.

50. The method of claim 48 wherein the at least one core portion includes a first core face and a second core face opposite the first core face, and wherein the method further comprises:

positioning a first adhesive layer between the first core face and the first face sheet; and

positioning a second adhesive layer between the second core face and the second face sheet.

51. The method of claim 48, further comprising positioning an adhesive layer between the attachment portion of the stiffener and the first face sheet.

52. The method of claim 48, further comprising:

applying pressure to one or both of the first and second face sheets; and

, simultaneously,

heating one or both of the first and second face sheets to bond the first and second face sheets to the at least one core portion and the stiffener.

53. The method of claim 48 wherein the stiffener is a first stiffener and the attachment portion is a first attachment portion, and wherein the method further comprises positioning a second attachment portion of a second stiffener at least proximate to the first face sheet and at an angle relative to the first stiffener, wherein positioning the second face sheet includes situating the second face sheet adjacent to the second stiffener.

54. The method of claim 48 wherein the stiffener is a first stiffener and the attachment portion is a first attachment portion, and wherein the method further comprises:

positioning a second attachment portion of a second stiffener at least proximate to the first face sheet and at an angle relative to the first stiffener, wherein the second stiffener has a first end portion in a first direction and a second end portion in a second direction opposite the first direction; and

attaching the first end portion of the second stiffener to the first stiffener, wherein positioning the second face sheet includes situating the second face sheet adjacent to the second stiffener.

55. A method for manufacturing a composite panel assembly, the method comprising:

providing a first face sheet;

providing a second face sheet;

providing a core portion, the core portion having a first core face and a second core face opposite the first core face;

providing a stiffener having a first attachment portion, a second attachment portion and an intermediate portion, the second attachment portion being offset from the first attachment portion, and the intermediate portion extending between the first and second attachment portions;

positioning the first attachment portion of the stiffener at least proximate to the first face sheet;

positioning the first core face of the core portion adjacent to the first face sheet and at least proximate to the stiffener; and

positioning the second face sheet at least proximate to the second core face and the second attachment portion of the stiffener.

56. The method of claim 55, further comprising:

positioning a part at least proximate to the second face sheet adjacent to the second attachment portion of the stiffener; and

inserting at least one fastener through the part, the second face sheet, and the second attachment portion of the stiffener to attach the part to the stiffener.

57. The method of claim 55 wherein inserting at least one fastener includes installing a blind fastener through the part, the second face sheet, and the second attachment portion of the stiffener.

58. The method of claim 55 wherein the stiffener is a first stiffener, and wherein the method further comprises:

providing a second stiffener having at least a third attachment portion;

positioning the third attachment portion of the second stiffener at least proximate to the second face sheet;

positioning a part at least proximate to the second face sheet adjacent to the second attachment portion of the first stiffener and the third attachment portion of the second stiffener;

inserting a first fastener through the part, the second face sheet, and the second attachment portion of the first stiffener to attach the part to the first stiffener; and

inserting a second fastener through the part, the second face sheet, and the third attachment portion of the second stiffener to attach the part to the second stiffener.

59. The method of claim 55 wherein the method further comprises:

positioning a first adhesive layer between the first core face and the first face sheet; and

positioning a second adhesive layer between the second core face and the second face sheet.

60. The method of claim 55, further comprising:

applying pressure to one or both of the first and second face sheets; and

heating one or both of the first and second face sheets to bond one or both of the first and second face sheets to the core portion and the stiffener.

61. The method of claim 55 wherein the stiffener is a first stiffener, and wherein the method further comprises positioning a third attachment portion of a second stiffener at least proximate to the first face sheet and at an angle relative to the first stiffener, wherein positioning the second face sheet at least proximate to the second core face and the second attachment portion of the first stiffener includes positioning the second face sheet at least proximate to the second stiffener.

62. The method of claim 55 wherein the stiffener is a first stiffener, and wherein the method further comprises:

positioning a third attachment portion of a second stiffener at least proximate to the first face sheet and at an angle relative to the first stiffener, wherein the second stiffener has a first end portion in a first direction and a second end portion in a second direction opposite to the first direction; and

attaching the first end portion of the second stiffener to the first stiffener, wherein positioning the second face sheet at least proximate to the second core face and the second attachment portion of the first stiffener includes positioning the second face sheet at least proximate to the second stiffener.