Composite sandwich structure with integrated reinforcement area and method of producing the same

• US 20050208274A1
• Filed: 03/17/2005
• Published: 09/22/2005
• Est. Priority Date: 03/17/2004
• Status: Active Grant

• Current Assignee: Airbus Operations GmbH (Airbus SE)
• Original Assignee: Airbus Operations GmbH (Airbus SE)
• Inventors: Weber, Hans-Juergen, Endres, Gregor Christian
• Granted Patent: US 8,506,743 B2
• Time in Patent Office: Days
• US Class Current: 428/174
• CPC Class Codes: B31D 3/002 Methods for making cellular structures; Cellular structures B31D3/005 takes precedence
• CPC Class Codes: B32B 2307/718 Weight, e.g. weight per square meter
• CPC Class Codes: B32B 2605/18 Aircraft
• CPC Class Codes: B32B 29/002 as the main or only constituent of a layer, which is next to another layer of the same or of a different material next to a layer of a particular substance B32B9/06; next to a bituminous or tarry layer B32B11/06; next to a water-setting substance layer B32B13/08; next to a metal layer B32B15/12; next to a glass layer B32B17/065; next to a layer formed of natural mineral fibres or particles B32B19/046; next to a wood layer B32B21/06; next to a cellulosic plastic layer B32B23/06; next to a natural or synthetic rubber layer B32B25/06; next to a synthetic resin layer B32B27/10
• CPC Class Codes: B32B 3/12 characterised by a layer of regularly- arranged cells, e.g. a honeycomb structure
• CPC Class Codes: Y10T 156/1002 with permanent bending or reshaping or surface deformation of self sustaining lamina
• CPC Class Codes: Y10T 156/1003 by separating laminae between spaced secured areas [e.g., honeycomb expanding]
• CPC Class Codes: Y10T 156/1052 with cutting, punching, tearing or severing
• CPC Class Codes: Y10T 156/1056 Perforating lamina
• CPC Class Codes: Y10T 156/1057 Subsequent to assembly of laminae
• CPC Class Codes: Y10T 156/1062 Prior to assembly
• CPC Class Codes: Y10T 428/24628 Nonplanar uniform thickness material

Abstract

Producing a local reinforcement in a core structure of a composite sandwich structure involves forming a hole in a cover layer and the core of the sandwich structure, forming a hollow space in the core with a diameter the same as or preferably larger than that of the hole, introducing a spatial bounding device through the hole into the hollow space, seating the spatial bounding device in the hollow space to contact outwardly against parts of the core preferably by outwardly expanding the device, and introducing a filler material into the spatial bounding device. A sandwich structure includes a core between cover layers, and a local reinforcement including a hole in at least one of the cover layers, a space in the core with a larger diameter than the hole, a spiral sleeve in the space, and a filler material inside the spiral sleeve.

Claims

1. A method of producing a local reinforcement area in a core structure of a composite sandwich structure, comprising the steps:

a) providing a composite sandwich structure including an open three-dimensional core structure and first and second cover layers applied on opposite first and second sides of said core structure;

b) forming a hole having a hole diameter in at least said first cover layer and in said core structure;

c) forming a hollow space having a hollow space diameter in said core structure, wherein said hollow space diameter is greater than or equal to said hole diameter, and wherein said hollow space is bounded at least partially by bounding parts of said core structure at a perimeter of said hollow space;

d) introducing a spatial boundary device through said hole in said first cover layer into said hollow space in said core structure;

e) seating said spatial boundary device in said hollow space so that said spatial boundary device at least partially contacts outwardly against said bounding parts of said core structure; and

f) introducing a filler material into a bounded space formed within said spatial boundary device so as to form thereof a local reinforcement area;

2. The method according to claim 1, wherein said core structure comprises a folded core element having fold valleys forming open channels that are bounded between said folded core element and said cover layers and that extend longitudinally along said cover layers, said hollow space communicates into at least one of said open channels, and said bounding parts of said core structure at said perimeter of said hollow space are cut edges of webs of said folded core element that were cut during said forming of said hollow space.

3. The method according to claim 1, wherein said hollow space is formed to communicate and axially align with said hole.

4. The method according to claim 1, wherein said hollow space is formed so that said hollow space diameter is greater than said hole diameter.

5. The method according to claim 4, wherein said hollow space diameter is at least two times said hole diameter.

6. The method according to claim 4, wherein said hollow space diameter is from 3 to 20 times said hole diameter.

7. The method according to claim 4, wherein said hole diameter of said hole in said first cover layer established in said step b) is maintained unchanged throughout said steps c), d), e) and f).

8. The method according to claim 4, wherein said step c) of forming said hollow space comprises enlarging said hole in said core structure using an undercutting miller or an undercutting reamer reaching through said hole in said first cover layer.

9. The method according to claim 4, wherein said spatial boundary device has a variable outer diameter, said step d) is carried out with said outer diameter contracted to be smaller than or equal to said hole diameter, and said step e) involves expanding said outer diameter to be equal to said hollow space diameter.

10. The method according to claim 9, wherein said spatial boundary device comprises an inflatable hollow body, and said step e) comprises inflating said inflatable hollow body.

11. The method according to claim 9, wherein said spatial boundary device comprises a hollow body comprising a shape memory alloy metal, and said step e) comprises heating said hollow body to cause said shape memory alloy metal to expand.

12. The method according to claim 9, wherein said spatial boundary device comprises a spiral sleeve that has, in an unstressed condition, said outer diameter being larger than said hole diameter and at least as large as said hollow space diameter, said step d) involves compressing said spiral sleeve to a stressed contracted condition in which said outer diameter is smaller than or equal to said hole diameter, and said step e) involves allowing said spiral sleeve to expand out of said stressed contracted condition until said outer diameter equals said hollow space diameter.

13. The method according to claim 1, wherein said spatial boundary device comprises a spiral sleeve, said step d) involves contracting said spiral sleeve to a stressed condition and then passing said spiral sleeve through said hole in said first cover layer while said spiral sleeve is in said stressed condition, and said step e) involves expanding said spiral sleeve to an expanded condition in which said spiral sleeve is at least partially destressed relative to said stressed condition and in which said spiral sleeve contacts outwardly against said bounding parts of said core structure.

14. The method according to claim 1, wherein said spatial boundary device comprises a spiral sleeve having an outer diameter that can be varied by varying a degree of spiraling thereof.

15. The method according to claim 14, wherein said spiral sleeve has a height corresponding to a thickness of said core structure between said cover layers.

16. The method according to claim 14, wherein at least a partial area of said spiral sleeve has openings passing therethrough, and wherein said step f) further comprises discharging at least a limited amount of said filler material from said bounded space through said openings into said core structure, so that said limited amount of said filler material bonds said spiral sleeve to said core structure.

17. The method according to claim 16, wherein said openings are provided in a regular pattern into a material strip forming said spiral sleeve, so that said spiral sleeve is configured as at least one of a perforated sheet, a net, a mesh, or a woven web.

18. The method according to claim 14, wherein said spiral sleeve comprises a spiral-configured strip of a plastic material having spring-elastic properties.

19. The method according to claim 14, wherein an outer surface of said spiral sleeve has an adhesive thereon, and said step e) further comprises bonding said spiral sleeve to said core structure with said adhesive.

20. The method according to claim 14, wherein said spiral sleeve comprises a material that softens at a specified temperature, and said step e) further comprises heating said spiral sleeve to at least said specified temperature so as to soften said material and to thereby connect said spiral sleeve to said core structure by said material.

21. The method according to claim 14, wherein said spiral sleeve comprises a material that foams-up under a specified condition, and said step e) further comprises subjecting said spiral sleeve to said specified condition so as to cause said material to foam-up and to thereby connect said spiral sleeve to said core structure by said material.

22. The method according to claim 1, further comprising an additional step of integrating a securing element comprising an insert element into said local reinforcement area.

23. A composite sandwich structure comprising:

a core structure including a folded core element having fold valleys forming open channels extending longitudinally therealong;

first and second cover layers that are respectively applied on opposite first and second sides of said core structure and that cover said open channels; and

a local reinforcement area including;

a hole having a hole diameter in said first cover layer;

a space having a space diameter in said core structure aligned with said hole, wherein said space diameter is larger than said hole diameter;

a spiral sleeve arranged in said space and secured to said core structure with an outer surface of said spiral sleeve in contact with said core structure at said space diameter; and

a filler material in an interior of said spiral sleeve.

24. The composite sandwich structure according to claim 23, wherein said spiral sleeve has openings passing therethrough from said interior into said core structure, and said filler material extends outwardly from said interior through said openings into said core structure and secures said spiral sleeve to said core structure.