Radius fillers for composite structures, composite structures that include radius fillers, and systems and methods of forming the same

Patent metadata

Field	Value
Publication number	US-10035309-B2
Application number	US-201414244690-A
Country	US
Kind code	B2
Filing date	Apr 3, 2014
Priority date	Apr 3, 2014
Publication date	Jul 31, 2018
Grant date	Jul 31, 2018

Abstract

Radius fillers for composite structures, composite structures that include radius fillers, and systems and methods of forming the same are disclosed herein. The methods include determining a transverse cross-sectional shape of an elongate void space, which extends within a transition region that is defined by a plurality of plies of composite material, and determining a material property field of the transition region. The methods further include forming the radius filler by combining a plurality of lengths of composite tape to define a radius filler cross-sectional shape, which corresponds to the transverse cross-sectional shape of the elongate void space, and orienting a plurality of lengths of reinforcing fiber in each of the plurality of lengths of composite tape based, at least in part, on the material property field of the transition region. The radius fillers include radius fillers with selectively oriented reinforcing fibers. The composite structures include the radius fillers.

First claim

The invention claimed is:

1. A method of forming a radius filler for a composite structure, wherein the composite structure includes a plurality of plies of composite material that converge within a transition region to define an elongate void space, and further wherein the radius filler is configured to extend within the elongate void space, the method comprising:
determining a transverse cross-sectional shape of the elongate void space;
determining a material property gradient of the transition region, wherein the material property gradient of the transition region includes a mathematical description of a variation in at least one material property with direction within the transition region; and
forming the radius filler, wherein the forming includes:
combining a plurality of lengths of composite tape to define a radius filler transverse cross-sectional shape that corresponds to the transverse cross-sectional shape of the elongate void space, wherein each of the plurality of lengths of composite tape includes a respective plurality of lengths of reinforcing fibers and a resin material, and further wherein each of the plurality of lengths of composite tape defines a fiber axis direction;
and orienting the respective plurality of lengths of reinforcing fibers of each of the plurality of lengths of composite tape based, at least in part, on the material property gradient of the transition region.

2. The method of claim 1 , wherein the determining the transverse cross-sectional shape of the elongate void space includes at least one of modeling the composite structure and determining a desired transverse cross-sectional shape for the elongate void space.

3. The method of claim 1 , wherein the determining the material property gradient of the transition region includes at least one of modeling the transition region, modeling curing of the transition region, modeling the transition region during operation of the composite structure, modeling the composite structure, modeling curing of the composite structure, and modeling the composite structure during operation of the composite structure.

4. The method of claim 1 , wherein the orienting includes orienting such that a material property gradient of the radius filler corresponds to the material property gradient of the transition region.

5. The method of claim 1 , wherein the orienting includes orienting such that a material property gradient of the radius filler matches the material property gradient of the transition region to within 20% of the material property gradient of the transition region at an interface between the transition region and the radius filler.

6. The method of claim 1 , wherein the determining the material property gradient of the transition region includes at least one of determining a two-dimensional material property gradient of the transition region and determining a three-dimensional material property gradient of the transition region.

7. The method of claim 1 , wherein the material property gradient of the transition region includes a stiffness gradient of the transition region.

8. The method of claim 1 , wherein the material property gradient of the transition region includes a coefficient of thermal expansion gradient of the transition region.

9. The method of claim 1 , wherein the material property gradient of the transition region includes a stress gradient of the transition region.

10. The method of claim 1 , wherein the determining the material property gradient of the transition region includes determining a principal stress region within the transition region and determining a principal stress direction within the principal stress region, and further wherein the orienting includes orienting such that at least one of the plurality of lengths of composite tape defines a respective fiber axis direction that extends within a portion of the radius filler that is located within the principal stress region and at least substantially parallel to the principal stress direction.

11. The method of claim 1 , where, prior to the combining, the method further includes determining the fiber axis direction within each of the plurality of lengths of composite tape based, at least in part, on at least one of the transverse cross-sectional shape of the elongate void space and the material property gradient of the transition region.

12. The method of claim 1 , where, prior to the combining, the method further includes establishing a relative location of each of the plurality of lengths of composite tape within the radius filler based, at least in part, on at least one of the transverse cross-sectional shape of the elongate void space and the material property gradient of the transition region.

13. The method of claim 1 , wherein the combining includes combining such that each of the plurality of lengths of composite tape that defines an outer surface of the radius filler defines the fiber axis direction that is parallel to a longitudinal axis of the radius filler.

14. The method of claim 1 , wherein the combining includes:
(i) receiving the plurality of lengths of composite tape into a plurality of first openings on a first side of a forming die;
(ii) pressing the plurality of lengths of composite tape against one another within the forming die to form the radius filler; and
(iii) withdrawing the radius filler from a second opening on a second side of the forming die, wherein the receiving, the pressing, and the withdrawing are performed concurrently.

15. The method of claim 1 , wherein the method further includes locating the radius filler within the composite structure.

16. The method of claim 1 , wherein the determining the material property gradient of the transition region includes at least one of:
(i) determining the material property gradient of the transition region in two orthogonal directions; and
(ii) determining the material property gradient of the transition region in three orthogonal directions.

17. The method of claim 1 , wherein the orienting includes orienting such that the fiber axis direction of at least one length of composite tape in the plurality of lengths of composite tape extends at a skew angle relative to a radius filler longitudinal axis of the radius filler.

Assignees

• Boeing Co

Inventors

• Mccarville Douglas A
• Guzman Juan C
• Birkland Jordan Oliver
• Tidwell Ryan Shaw
• Anderson Robert L

Classifications

• B29L2031/3085

  Wings · CPC title

• B29C70/14 Primary

  oriented · CPC title

• B29C70/52 Primary

  Pultrusion, i.e. forming and compressing by continuously pulling through a die · CPC title

• Y10T428/24521

  with component conforming to contour of nonplanar surface · CPC title

• B29L2031/3082

  Fuselages · CPC title