METHOD AND APPARATUS FOR FABRICATING HIGHLY CONTOURED COMPOSITE STIFFENERS WITH REDUCED WRINKLING

• US 20120076989A1
• Filed: 09/23/2010
• Published: 03/29/2012
• Est. Priority Date: 09/23/2010
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: BLAND, JAMEL R.
• Granted Patent: US 8,795,567 B2
• Time in Patent Office: Days
• US Class Current: 428/174
• CPC Class Codes: B29C 33/38 characterised by the material or the manufacturing process B29C33/44 takes precedence
• CPC Class Codes: B29C 33/76 Cores B29C33/02 - B29C33/70, B29C41/40, B29C53/74, B29C53/82 take precedence
• CPC Class Codes: B29C 70/205 the structure being shaped to form a three-dimensional configuration
• CPC Class Codes: B29C 70/342 using isostatic pressure
• CPC Class Codes: B29C 70/345 using matched moulds
• CPC Class Codes: B29C 70/549 Details of caul plates, e.g. materials or shape
• CPC Class Codes: B29D 99/0003 Producing profiled members, e.g. beams
• CPC Class Codes: B29L 2031/001 Profiled members, e.g. beams, sections
• CPC Class Codes: B29L 2031/3076 Aircrafts blades, propellers B29L2031/08
• CPC Class Codes: B64C 1/064 Stringers; Longerons
• CPC Class Codes: B64C 2001/0072 from composite materials
• CPC Class Codes: Y02T 50/40 Weight reduction
• CPC Class Codes: Y10T 428/24628 Nonplanar uniform thickness material

Abstract

A mandrel having an out-of-plane curvature and a corresponding in-plane change in mandrel geometry is used to fabricate substantially wrinkle-free, fiber reinforced stiffeners having an out-of-plane curvature.

Claims

1. A method of fabricating a substantially wrinkle-free fiber reinforced composite stiffener having an out-of-plane curvature, comprising:

providing a tool having the desired out-of-plane curvature and a corresponding in-plane curvature;

forming a lay-up over the tool by laying up a plurality of fiber reinforced composite plies over the tool, including conforming the plies to the out-of-plane curvature and to the corresponding in-plane curvature of the tool; and

compacting the lay-up.

2. The method of claim 1, wherein the reinforcing fibers in each of the plies have a substantially unidirectional fiber orientation.

3. The method of claim 2, wherein conforming the plies to the out-of-plane curvature includes allowing the fibers in each of the plies to deform generally from a nominal linear orientation to a deformed orientation determined by the out-of-plane curvature of the tool.

4. The method of claim 3, wherein conforming the plies to the in-plane curvature of the tool includes allowing the fibers in each of the plies to deform generally from their nominal linear orientation to a deformed orientation determined by the in-plane curvature of the tool.

5. The method of claim 3, wherein compacting the lay-up includes compacting the plies to substantially eliminate any wrinkles in the plies and to set the deformed fiber orientations into the ply.

6. The method of claim 1, wherein the fibers in at least certain of the plies extend substantially continuously through the length of the stiffener.

7. A fiber reinforced composite stiffener fabricated by the method of claim 1.

8. A method of fabricating a substantially wrinkle-free fiber reinforced composite stringer having a hat-shaped cross section and an out-of-plane curvature along its length, comprising:

assembling a lay-up by laying up fiber reinforced composite plies on a forming tool;

using the forming tool to form the out-of-plane curvature in the lay-up; and

using the tool to form a corresponding in-plane change in geometry in the lay-up.

9. The method of claim 8, wherein the hat shaped stringer includes a cap, sidewalls and bottom flanges, and wherein the out-of-plane curvature is formed in the flanges of the stringer.

10. The method of claim 8, wherein the corresponding in-plane change in geometry is formed in the sidewalls of the stringer

11. The method of claim 8, wherein forming the out-of-plane curvature and corresponding in-plane change in geometry in the lay-up includes allowing the fibers in each of the plies to deform generally from a nominal linear orientation to a deformed orientation determined by the out-of-plane curvature and the corresponding in-plane change in geometry.

12. A stringer fabricated by the method of claim 8.

13. A method of making a mandrel for laying up a substantially wrinkle-free fiber reinforced composite stiffener having an out-of-plane curvature, comprising:

forming at least one out-of-plane curvature in a mandrel body; and

forming an in-plane curvature in the mandrel body substantially corresponding to the out-of-plane for compensating for the effects of the out-of-plane curvature on composite plies laid up over the mandrel body.

14. The method of claim 13, wherein:

the at least one out-of-plane curvature is formed in a first tool face on the mandrel body, and

the in-plane curvature is formed in a second tool face adjacent the first tool face.

15. Apparatus for forming a substantially wrinkle-free fiber reinforced composite stiffener having an out-of-plane curved section along its length, comprising:

a mandrel on which fiber reinforced composite plies may be formed,

the mandrel having a first tool face including a section substantially matching the out-of-pane curved section of the stiffener,

the mandrel having a second tool face, the second tool face including a section having an in-plane curved section substantially corresponding to the out-of-plane curved section in the first tool face.

16. The apparatus of claim 15, wherein the first and second tool faces extend traverse to each other.

17. The apparatus of claim 16, wherein the first and second tool faces are contiguous to each other.

18. The apparatus of claim 15, further comprising:

tooling for compacting the plies against the first and second tool faces, the tooling including a curved surface substantially matching the out-of-plane curved section of the first tool face, and a curved surface substantially matching the section of the second tool face having the in-plane change in geometry.

19. Apparatus for fabricating a fiber reinforced, substantially wrinkle-free composite stringer having an out-of-plane curvature:

a stringer mandrel having an out-of-plane curvature and a corresponding in-plane change in mandrel geometry.

20. The apparatus of claim 19, wherein the stringer is hat shaped in cross section and the mandrel includes:

a top face for forming a cap of the stringer,

side faces for respectively forming opposite sides of the stringer, and

a pair of bottom faces for forming oppositely extending flanges of the stringer.

21. The apparatus of claim 20, wherein:

the top face and each of the bottom faces includes a section having the out-of-plane curvature, and

each of the side faces includes a section having the corresponding in-plane change in geometry.

22. The apparatus of claim 19, wherein:

the mandrel includes a top, sides and a base,

the out-of-plane curvature is defined in the base of the mandrel, and

the corresponding in-plane change in geometry is defined as a widening of the sides of the mandrel.

23. The apparatus of claim 19, wherein the stringer mandrel includes tool faces for forming a stringer cross section selected from the group consisting of an I, a J, a Z, an L, a C, and a hat.

24. A method of fabricating a substantially wrinkle-free fiber reinforced composite stringer for aircraft having a hat-shaped cross section and an out-of-plane curvature along its length, comprising:

providing a mandrel tool having a pair of bottom tool faces, a pair of side tool faces and a top tool face, wherein the bottom tool faces have an out-of-plane curvature, and each of the side tool faces and the top tool face has a corresponding change in geometry;

assembling a lay-up by draping unidirectional fiber reinforced composite plies over the mandrel, including generally conforming the plies to the out-of-plane curvature in the bottom tool faces and to the corresponding change in geometry in the side tool faces and the top tool face;

compacting the layup against the mandrel, including deforming the fibers in each of the plies generally from a nominal linear orientation to first and second deformed orientations respectively determined by the out-of-plane curvature on the bottom tool face and the corresponding change in geometry in the side tool face and the top tool face of the mandrel; and

curing the compacted lay-up.

25. Apparatus for forming a substantially wrinkle-free fiber reinforced composite stringer having an out-of-plane curved section along its length, comprising:

a mandrel on which fiber reinforced composite plies may be formed,

the mandrel having a first tool face including a section substantially matching the out-of-pane curved section of the stiffener,

the mandrel having a second tool face contiguous and extending traverse to the first tool face, the second tool face including a section having an in-plane change in geometry substantially corresponding to the out-of-plane curved section in the first tool face; and

a pair of compaction tools for compacting the plies against the first and second tool faces, the compaction tools each including a curved surface substantially matching the out-of-plane curved section of the first tool face, and a curved surface substantially matching the section of the second tool face having the in-plane change in geometry.