Method of repairing honeycomb core using pourable structural foam

• US 9,015,941 B2
• Filed: 10/30/2012
• Issued: 04/28/2015
• Est. Priority Date: 10/30/2012
• Status: Active Grant

• Current Assignee: Bell Helicopter Textron Incorporated (Textron Inc)
• Original Assignee: Bell Helicopter Textron Incorporated (Textron Inc)
• Inventors: Thiagarajan, Ramesh, Chris, Robert Mark, McCullough, John R., Mishra, Suvankar
• Primary Examiner(s): COZART, JERMIE E
• Application Number:
  US13/663,925
• Publication Number:
  US 20140115853A1
• Time in Patent Office: 910 Days
• Field of Search: 298/891, 294/020.4, 294/020.5, 294/020.6, 294/020.9, 294/021.8, 295/271, 428/117
• US Class Current: 29/889.1
• CPC Class Codes: B23P 2700/00 Indexing scheme relating to the articles being treated, e.g. manufactured, repaired, assembled, connected or other operations covered in the subgroups
• CPC Class Codes: B23P 6/00 Restoring or reconditioning objects straightening or restoring form of sheet metal, metal rods, metal tubes, metal profiles, or specific articles made therefrom B21D1/00, B21D3/00; repairing defective or damaged objects by casting techniques B22D19/10
• CPC Class Codes: B23P 6/002 Repairing turbine components, e.g. moving or stationary blades, rotors, B23P6/045 takes precedence
• CPC Class Codes: B29C 2073/264 for cutting out or grooving the area to be repaired
• CPC Class Codes: B29C 44/18 Filling preformed cavities B29C44/1204 takes precedence
• CPC Class Codes: B29C 73/063 expandable
• CPC Class Codes: B29C 73/10 using patches sealing on the surface of the article B29C73/14 takes precedence
• CPC Class Codes: B29L 2031/082 Blades, e.g. for helicopters
• CPC Class Codes: B29L 2031/608 Honeycomb structures
• CPC Class Codes: Y10T 29/49318 Repairing or disassembling
• CPC Class Codes: Y10T 29/49723 including reconditioning of part
• CPC Class Codes: Y10T 29/49725 by shaping
• CPC Class Codes: Y10T 29/49726 Removing material
• CPC Class Codes: Y10T 29/49732 by attaching repair preform, e.g., remaking, restoring, or patching
• CPC Class Codes: Y10T 29/49734 and removing damaged material
• CPC Class Codes: Y10T 29/49746 by applying fluent material, e.g., coating, casting
• CPC Class Codes: Y10T 428/24157 Filled honeycomb cells [e.g., solid substance in cavities, etc.]

Abstract

A method of the present disclosure includes of repairing a core stiffened structure with structural foam. Another method includes splicing core members together using structural foam. Another method includes joining a core member to a structure using structural foam. Another method includes using structural foam to stabilize a core member during a machining process. Another method includes stabilizing a core member with structural foam to prevent the core member from crushing in autoclave pressure. The present disclosure further includes a core stiffened structure have a core member with structural foam therein.

Claims

1. A method of repairing a core stiffened structure, the method comprising:

removing a damaged portion of the core stiffened structure;

depositing a foam mixture into a cavity, the cavity being created by the step of removing the damaged portion of the core stiffened structure;

allowing the foam mixture to expand and fill the cavity so as to form an expanded foam;

trimming the expanded foam, wherein trimming the expanded foam comprises reducing an upper surface of the expanded foam until the upper surface of the expanded foam corresponds to a skin surface of the core stiffened structure; and

placing a skin patch on the expanded foam.

2. The method according to claim 1, wherein the damaged portion includes a portion of a honeycomb core configured for providing stiffness to the core stiffened structure.

3. The method according to claim 1, wherein the damaged portion includes a portion of a foam core configured for providing stiffness to the core stiffened structure.

4. The method according to claim 1, wherein the step of removing the damaged portion of core stiffened structure comprises using a hole saw to create a circular shaped cavity in the core stiffened structure.

5. The method according to claim 1, wherein the step of trimming the expanded foam comprises sanding, cutting, or machining an upper surface of the expanded foam to a desired contour.

6. The method according to claim 1, wherein the step of placing a skin patch on the expanded foam comprises laying up a plurality of uncured composite layers on the expanded foam.

7. The method according to claim 1, wherein the skin patch is of a composite material.

8. The method according to claim 1, wherein the step of placing a skin patch on the expanded foam comprises laying up a composite layers across the expanded foam and an adjacent skin surface.

9. The method according to claim 1, further comprising:

curing the skin patch.

10. The method according to claim 9, wherein the step of curing the skin patch includes curing the skin patch at an ambient temperature.

11. The method according to claim 9, wherein the step of curing the skin patch creates a bond between the expanded foam and an inner surface of the skin patch.

12. The method according to claim 9, wherein the step of curing the skin patch includes allowing a resin in the skin patch forming a structural bond between the expanded foam and the skin patch.

13. The method according to claim 9, wherein the step of curing the skin patch does not require an artificial heat source.

14. A method of repairing a core stiffened structure having a first skin, a core member, and a second skin, the method comprising:

removing a damaged portion of the first skin and the core member;

pouring a foam mixture into a cavity, the cavity being created by the step of removing the damaged portion of the first skin and the core member;

allowing the foam mixture to expand and fill the cavity so as to form an expanded foam;

placing a skin patch on the expanded foam.

15. The method according to claim 14, further comprising:

preparing a foam mixture;

wherein the step of preparing the foam mixture includes mixing a first resin component with a second resin component so as to form a homogenious mixture.

16. The method according to claim 14, further comprising:

restricting the expansion of the foam mixture with a mold tool, the mold tool having an interior surface that resembles the desired outer contour of the expanded foam.

17. The method according to claim 14, further comprising:

cleaning the cavity prior to pouring the foam mixture into the cavity.

18. The method according to claim 14, wherein the step of placing the skin patch on the expanded foam includes laying up a plurality of composite layers over the skin patch.

19. The method according to claim 18, wherein the composite layers are uncured pre-preg composite material.