Method for fabricating highly contoured composite stiffeners with reduced wrinkling

• US 8,795,567 B2
• Filed: 09/23/2010
• Issued: 08/05/2014
• Est. Priority Date: 09/23/2010
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Bland, Jamel R.
• Primary Examiner(s): SCHIFFMAN, BENJAMIN A
• Application Number:
  US12/888,758
• Publication Number:
  US 20120076989A1
• Time in Patent Office: 1,412 Days
• Field of Search: None
• US Class Current: 264/258
• 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 fiber reinforced composite stiffener that is substantially wrinkle-free, the method comprising:

using a tool, the tool having a sidewall, the sidewall including a first portion along a first length that is less than a total length of the sidewall, the sidewall further including a second portion along a second length that is less than the total length and a third portion along a third length that is less than the total length, the first portion being between the second portion and the third portion, the first portion having an out-of-plane curvature and an in-plane curvature, the second portion having a second curvature different than the in-plane curvature and the out-of-plane curvature, the third portion having the second curvature, the tool further having a bottom tool face along the sidewall and connected to the sidewall at an angle, the bottom tool face also having the out-of-plane curvature along the first length, and the bottom tool face further having the second curvature along the second length and the third length;

using includes forming a lay-up over the tool by laying up a plurality of fiber reinforced composite plies over the tool, including simultaneously conforming the plurality of fiber reinforced composite plies to the first length and the second length along both the sidewall and the bottom tool face; and

compacting the lay-up.

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

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

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

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

6. The method of claim 1, wherein fibers in at least certain of the plurality of fiber reinforced composite plies extend substantially continuously through a length of the substantially wrinkle-free fiber reinforced composite stiffener.

7. The method of claim 1 wherein the first portion is lower in height relative to the second portion, in both the sidewall and the bottom tool face.

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

assembling a lay-up by laying up fiber reinforced composite plies on a forming tool, the forming tool having a sidewall, the sidewall including a first portion along a first length that is less than a total length of the sidewall, the sidewall further including a second portion along a second length that is less than the total length and a third portion along a third length that is less than the total length, the first portion being between the second portion and the third portion, the first portion having the out-of-plane curvature and the in-plane curvature, the second portion having a second curvature different than the in-plane curvature and the out-of-plane curvature, the third portion having the second curvature, the forming tool further having a bottom tool face along the sidewall and connected to the sidewall at an angle, the bottom tool face also having the out-of-plane curvature along the first length, and the bottom tool face further having the second curvature along the second length and the third length;

forming the out-of-plane curvature in the lay-up along both the sidewall and the bottom tool face using the forming tool; and

while forming the out-of-plane curvature, also forming the in-plane curvature in the lay-up along both the sidewall and the bottom tool face using the forming tool, such that forming the out-of-plane curvature and forming the in-plane curvature also forms the hat-shaped cross section in a manner such that different cross sections along the length change dimensions relative to each other as a result of the out-of-plane curvature.

9. The method of claim 8, wherein the substantially wrinkle-free fiber reinforced composite stringer includes a cap, sidewalls, and bottom flanges, and wherein the out-of-plane curvature is formed in the bottom flanges of the stringer.

10. The method of claim 8, wherein the in-plane curvature is formed in the sidewalls of the substantially wrinkle-free fiber reinforced composite stringer.

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

12. The method of claim 8 wherein the first portion is lower in height relative to the second portion, in both the sidewall and the bottom tool face.