Co-cured stringers and associated mandrel and fabrication method

• US 20050230552A1
• Filed: 04/20/2004
• Published: 10/20/2005
• Est. Priority Date: 04/20/2004
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Morrow, Christopher J., Engwall, Dwight L.
• Granted Patent: US 7,293,737 B2
• Time in Patent Office: Days
• US Class Current: 244/133
• CPC Class Codes: B29C 33/485 cores or mandrels collapsible mandrels for shaping tube ends B29C57/02; collapsible mandrels for winding and joining B29C53/824
• CPC Class Codes: B29C 70/446 Moulding structures having an axis of symmetry or at least one channel, e.g. tubular structures, frames
• CPC Class Codes: B29D 99/0014 provided with ridges or ribs, e.g. joined ribs
• CPC Class Codes: Y02T 50/40 Weight reduction
• CPC Class Codes: Y10T 156/10 Methods of surface bonding and/or assembly therefor
• CPC Class Codes: Y10T 428/139 Open-ended, self-supporting conduit, cylinder, or tube-type article

Abstract

A co-cured composite stringer and associated apparatus and method are provided. The co-cured composite stringer includes a stringer and a mandrel positioned within a channel defined in the stringer. A plurality of strips are positioned within an opening of the mandrel, and a substrate layer, such as aircraft skin, is positioned adjacent to the stringer. During application of the substrate layer to the stringer, the mandrel and plurality of strips support the stringer.

Claims

1. A co-cured composite stringer comprising:

a stringer, the stringer defining a channel therein;

a mandrel positioned within the channel of the stringer, wherein the mandrel defines an opening therethrough;

a plurality of strips slidably positioned within the opening of the mandrel; and

a substrate layer positioned adjacent to the stringer, wherein the mandrel and plurality of strips are capable of supporting the stringer during application of the substrate layer to the stringer.

2. A co-cured composite stringer according to claim 1, wherein the plurality of strips are stacked horizontally and vertically within the opening of the mandrel such that each of the strips may slide with respect to one another.

3. A co-cured composite stringer according to claim 1, wherein the plurality of strips are positioned within the opening of the mandrel such that the strips substantially conform to the shape of the mandrel.

4. A co-cured composite stringer according to claim 1, wherein the plurality of strips are pliable such that the mandrel and strips are capable of bending to a desired contour.

5. A co-cured composite stringer according to claim 1, wherein the each of the plurality of strips is rectangular in shape.

6. A co-cured composite stringer according to claim 1, wherein the plurality of strips comprise a polymeric material.

7. A co-cured composite stringer according to claim 6, wherein the plurality of strips comprise nylon.

8. A co-cured composite stringer according to claim 1, wherein the stringer comprises uncured pre-impregnated reinforcing material.

9. A co-cured composite stringer according to claim 8, wherein the pre-impregnated reinforcing material comprises uncured epoxy graphite.

10. A co-cured composite stringer according to claim 1, wherein the mandrel and plurality of strips are capable of withstanding at least 90 psi of head pressure.

11. A co-cured composite stringer according to claim 1, wherein the mandrel comprises an elastomeric material.

12. A co-cured composite stringer according to claim 1, wherein the substrate layer comprises uncured pre-impregnated aircraft skin.

13. A collapsible lay-up mandrel assembly comprising:

a mandrel defining an opening therethrough; and

a plurality of strips slidably positioned within the opening of the mandrel.

14. A collapsible lay-up mandrel assembly according to claim 13, wherein the plurality of strips are stacked horizontally and vertically within the opening of the mandrel.

15. A collapsible lay-up mandrel assembly according to claim 13, wherein the plurality of strips are positioned within the opening of the mandrel such that the strips substantially conform to the shape of the mandrel.

16. A collapsible lay-up mandrel assembly according to claim 13, wherein the plurality of strips are pliable such that the mandrel and strips are capable of bending to a desired contour.

17. A collapsible lay-up mandrel assembly according to claim 14, wherein the each of the plurality of strips is rectangular in shape.

18. A collapsible lay-up mandrel assembly according to claim 14, wherein the plurality of strips comprise a polymeric material.

19. A collapsible lay-up mandrel assembly according to claim 18, wherein the plurality of strips comprise nylon.

20. A collapsible lay-up mandrel assembly according to claim 13, wherein the mandrel and plurality of strips are capable of withstanding at least 90 psi of head pressure.

21. A collapsible lay-up mandrel assembly according to claim 13, wherein the mandrel comprises an elastomeric material.

22. A method of fabricating co-cured stringers comprising:

providing a stringer, the stringer defining a channel therein;

positioning a plurality of strips within a mandrel;

positioning the mandrel within the channel defined in the stringer;

applying a substrate layer to the stringer, wherein the mandrel and plurality of strips are capable of supporting the stringer during the applying of the substrate layer; and

curing the stringer and the substrate layer such that the stringer and substrate layer are attached.

23. The method according to claim 22, further comprising bending the plurality of strips and mandrel to a desired contour.

24. The method according to claim 22, wherein applying comprises applying the substrate layer at a head pressure of at least 90 psi.

25. The method according to claim 22, wherein applying comprises applying uncured pre-impregnated reinforcing material.

26. The method according to claim 23, further comprising removing the plurality of strips by sliding the strips from the mandrel following curing.

27. The method according to claim 26, further comprising applying a vacuum to the mandrel following removing the plurality of strips.

28. The method according to claim 27, further comprising removing the mandrel following applying the vacuum.