Aircraft fuselage shell component with crack propagation resistance

• US 6,595,467 B2
• Filed: 11/30/2000
• Issued: 07/22/2003
• Est. Priority Date: 06/28/2000
• Status: Expired due to Fees

• Current Assignee: Airbus Operations GmbH (Airbus SE)
• Original Assignee: Airbus Deutschland GmbH (Airbus SE)
• Inventors: Schmidt, Hans-Juergen
• Primary Examiner(s): Eldred, J. Woodrow
• Application Number:
  US09/727,830
• Publication Number:
  US 20020000492A1
• Time in Patent Office: 964 Days
• Field of Search: 244/119, 244/120, 244/125, 244/132, 244/133, 428/98, 428/221, 298/972
• US Class Current: 244/119
• CPC Class Codes: B23K 31/02 relating to soldering or welding dip or wave soldering in the manufacture of printed circuits H05K3/34
• CPC Class Codes: B64C 1/12 Construction or attachment of skin panels

Abstract

When stiffening members, such as stringers and frame members, are welded onto a skin sheet to form an aircraft fuselage shell, a crack originating in the skin sheet tends to propagate through the weld joints into the stiffening members. In order to prevent crack propagation into a stiffening member, the stiffening member is reinforced with a web doubler plate or a tension band made of high strength steel or titanium alloys or fiber-reinforced composites. The doubler plate is riveted or adhesively bonded onto a stiffening member web, or the tension band is crimped into the stiffening member web. The resulting fuselage shell structure has crack stopping properties and thus an increased residual strength, so it can be used with welded joints at all areas of the fuselage shell, including the top and sides as well as the bottom of the fuselage.

Claims

1. An aircraft fuselage structural shell component comprising:

a skin sheet;

a plurality of stiffening profile members arranged and joined onto said skin sheet, at least partly by respective weld joints, and wherein said stiffening profile members each extend lengthwise in a lengthwise direction of said stiffening profile members and each respectively comprise at least one profile member web; and

a plurality of strengthening elements that respectively extend continuously in said lengthwise direction along respective ones of said profile member webs, and that are respectively non-integrally secured onto said respective profile member webs, and that are respectively discrete non-integral components relative to said profile member webs with respective non-integral boundary interfaces therebetween adapted to hinder any crack formed in said skin sheet or said profile member webs from propagating into said strengthening elements so that said strengthening elements respectively hold together said stiffening profile members even if one or more cracks form in said stiffening profile members.

2. The aircraft fuselage structural shell component according to claim 1, wherein said stiffening profile members comprise stringers extending in an aircraft longitudinal direction and frame members extending perpendicularly to said stringers in an aircraft circumferential direction.

3. The aircraft fuselage structural shell component according to claim 1, wherein said strengthening elements comprise reinforcing doubler elements that are arranged and secured respectively onto at least one side of each of said respective ones of said profile member webs.

4. The aircraft fuselage structural shell component according to claim 3, further comprising at least one of rivets and an adhesive arranged to secure said reinforcing doubler elements onto said profile member webs.

5. The aircraft fuselage structural shell component according to claim 3, wherein said reinforcing doubler elements consist of a different material than said profile member webs.

6. The aircraft fuselage structural shell component according to claim 3, wherein said reinforcing doubler elements consist of one of a high strength aluminum alloy and a fiber-reinforced metal laminate.

7. The aircraft fuselage structural shell component according to claim 3, wherein said reinforcing doubler elements respectively have an ∥

-profile cross-section.

8. The aircraft fuselage structural shell component according to claim 1, wherein said strengthening elements comprise tension bands that are arranged and secured respectively onto said respective ones of said profile member webs.

9. The aircraft fuselage structural shell component according to claim 8, wherein said respective ones of said stiffening profile members each respectively further comprise a thickened material portion that integrally protrudes laterally outwardly from at least one side of said profile member web thereof, and wherein a respective one of said tension bands is received and secured in each respective one of said thickened material portions.

10. The aircraft fuselage structural shell component according to claim 9, wherein said thickened material portions respectively have through-holes therein, and said tension bands are received and secured in said through-holes.

11. The aircraft fuselage structural shell component according to claim 8, wherein each of said respective ones of said profile member webs is a respective split web including two web legs joined to each other while forming an opening therebetween, and wherein said tension bands are received and secured in said openings of said split webs.

12. The aircraft fuselage structural shell component according to claim 8, wherein said tension bands respectively have a polygon cross-section.

13. The aircraft fuselage structural shell component according to claim 8, wherein said tension bands respectively have a round cross section.

14. The aircraft fuselage structural shell component according to claim 8, wherein said tension bands respectively have a roughened outer surface.

15. The aircraft fuselage structural shell component according to claim 8, wherein said tension bands respectively are twisted along their lengths.

16. The aircraft fuselage structural shell component according to claim 8, wherein said tension bands consist of a different material than said respective ones of said profile member webs.

17. The aircraft fuselage structural shell component according to claim 8, wherein said tension bands consist of at least one of high strength steel alloys, titanium alloys, and fiber-reinforced composite materials.

18. A method of making the aircraft fuselage structural shell component of claim 1, comprising the following steps:

a) arranging and securing said strengthening elements onto said respective ones of said profile member webs, so as to make stiffening profile structures that each respectively include at least one of said strengthening elements secured onto said profile member web of a respective one of said stiffening profile members; and

b) after said step a), joining said stiffening profile structures onto said skin sheet by welding respective roots of said stiffening profile members onto said skin sheet.

19. The method according to claim 18, wherein said step of securing said strengthening elements comprises at least one of riveting and adhesively bonding said strengthening elements onto said respective ones of said profile member webs.

20. The method according to claim 18, further comprising:

a preliminary step of fabricating said stiffening profile members to include said profile member webs and respective thickened material portions that integrally protrude laterally outwardly from at least respective first sides of said profile member webs; and

another preliminary step of providing said strengthening elements as respective tension bands; and

wherein said step of securing said strengthening elements comprises arranging and fixing said tension bands in said thickened material portions.

21. The method according to claim 20, further comprising forming through-holes in said thickened material portions, and wherein said step of arranging said tension bands in said thickened material portions comprises inserting said tension bands into said through-holes.

22. The method according to claim 21, wherein said step of securing said tension bands in said thickened material portions comprises twisting said tension bands after said inserting of said tension bands into said through-holes.

23. The method according to claim 18, further comprising:

a preliminary step of fabricating said stiffening profile members so that said profile member webs are respective split webs that each include two web legs joined to each other while forming an opening therebetween, and

another preliminary step of providing said strengthening elements as respective tension bands; and

wherein said step of securing said strengthening elements comprises inserting and securing said tension bands into said openings between said two web legs of said split webs.

24. The method according to claim 18,

further comprising a preliminary step of providing said strengthening elements as respective tension bands;

and

wherein said step of securing said strengthening elements onto said respective ones of said profile member webs comprises pressing and crimping said profile member webs onto said tension bands so as to establish a form-locked connection between said tension bands and said profile member webs.

25. The method according to claim 18, further comprising heat treating said stiffening profile structures by a solution annealing process.

36. The aircraft fuselage structural shell component according to claim 1, wherein said strengthening elements are respectively secured only to said stiffening profile members and not to said skin sheet.

26. A stiffening profile structure for an aircraft fuselage shell component, comprising:

a stiffening profile member that extends lengthwise in a lengthwise direction of said stiffening profile member, and that includes at least one profile member web; and

at least one strengthening element that extends continuously in said lengthwise direction along said profile member web, and that comprises a discrete non-integral component relative to said profile member web with a non-integral boundary interface therebetween adapted to hinder any crack formed in said profile member web from propagating into said strengthening element so that said strengthening element holds together said stiffening profile member even if one or more cracks form in said stiffening profile member, wherein said discrete non-integral component is a component selected from the group consisting of a reinforcing doubler element and a tension band arranged and non-integrally secured onto said profile member web.

27. The stiffening profile structure according to claim 26, wherein said discrete non-integral component is said reinforcing doubler element, which is arranged and secured onto at least one side of said profile member web.

28. The stiffening profile structure according to claim 27, wherein said reinforcing doubler element consists of a different material than said profile member web.

29. The stiffening profile structure according to claim 27, wherein said reinforcing doubler element consists of one of a high strength aluminum alloy and a fiber-reinforced metal laminate.

30. The stiffening profile structure according to claim 27, further comprising at least one of rivets and an adhesive arranged to secure said reinforcing doubler element onto said profile member web.

31. The stiffening profile structure according to claim 26, wherein said discrete non-integral component is said tension band, which is arranged and secured onto said profile member web.

32. The stiffening profile structure according to claim 31, wherein said tension band consists of a different material than said profile member web.

33. The stiffening profile structure according to claim 31, wherein said tension band consists of at least one of high strength steel alloys, titanium alloys, and fiber-reinforced composites.

34. The stiffening profile structure according to claim 31, wherein said stiffening profile member further includes a thickened material portion that integrally protrudes laterally outwardly from one side of said profile member web and that has an opening therein, and wherein said tension band is received and secured in said opening in said thickened material portion.

35. The stiffening profile structure according to claim 31, wherein said profile member web is a split web including two web legs joined to each other while forming an opening therebetween, and wherein said tension band is received and secured in said opening between said web legs.