Composite Structure Having Reinforced Core and Method of Making Same

• US 20100151189A1
• Filed: 02/15/2010
• Published: 06/17/2010
• Est. Priority Date: 07/31/2007
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Chakrabarti, Buddhadev
• Granted Patent: US 8,431,214 B2
• Time in Patent Office: Days
• US Class Current: 428/119
• CPC Class Codes: B29C 70/086 and with one or more layers of pure plastics material, e.g. foam layers applying a non-preformed coating, e.g. a gel-coat, B29C37/0025; with foam blocks B29C70/86
• CPC Class Codes: B29C 70/24 oriented in at least three directions forming a three dimensional structure
• CPC Class Codes: B32B 3/08 characterised by added members at particular parts layer formed of separate pieces of material which are juxtaposed side-by-side B32B3/14, B32B3/18
• CPC Class Codes: B32B 38/00 Ancillary operations in connection with laminating processes
• CPC Class Codes: E04C 2/296 composed of insulating material and non-metallic or unspecified sheet-material E04C2/288 takes precedence
• CPC Class Codes: E04C 2/3405 spaced apart by profiled spacer sheets
• CPC Class Codes: E04C 2002/3488 spaced apart by frame like structures
• CPC Class Codes: Y10T 156/1002 with permanent bending or reshaping or surface deformation of self sustaining lamina
• CPC Class Codes: Y10T 29/49616 Structural member making
• CPC Class Codes: Y10T 29/49622 Vehicular structural member making
• CPC Class Codes: Y10T 29/49632 Metal reinforcement member for nonmetallic, e.g., concrete, structural element
• CPC Class Codes: Y10T 428/24174 including sheet or component perpendicular to plane of web or sheet
• CPC Class Codes: Y10T 428/24273 including aperture
• CPC Class Codes: Y10T 428/24331 including nonapertured component
• CPC Class Codes: Y10T 428/249923 Including interlaminar mechanical fastener

Abstract

A polymer-based composite sandwich includes a reinforced core bonded between a pair of composite facesheets. The core includes a truss formed by groups of composite pins held in place by a layer of structural foam. The pins in the groups are radially arranged around nodes. The ends of the pins are splayed and sandwiched between the foam layer and the facesheets.

Claims

1. A composite sandwich, comprising:

first and second composite facesheets; and

a reinforced core sandwiched between the first and second facesheets, the reinforced core including—

(i) a plurality of pins arranged in groups forming a truss, each of the pins including medial portions extending between the first and second facesheets and distal portions respectively extending generally parallel with and bonded to the first and second facesheets, and

(ii) a carrier surrounding the pins.

2. The composite sandwich of claim 1, wherein the pins in each group are spaced from each other and are distributed around a node.

3. The composite sandwich of claim 2, wherein distal portions of the pins in each of the groups radiate outwardly from the node.

4. The composite sandwich of claim 2, wherein the nodes of the groups are spaced substantially equidistant from each other.

5. The composite sandwich of claim 1, wherein the distal portions of each of the pins are splayed and are sandwiched between the core and one of the facesheets.

6. The composite sandwich of claim 1, wherein:

each of the pins includes carbon fiber reinforced resin, and

each of the first and second facesheets includes laminated plies of carbon fiber reinforced resin.

7. The composite sandwich of claim 1, wherein the pins in each of the groups are inclined relative to the planes of the facesheets.

8. The composite sandwich of claim 1, wherein the carrier includes rigid foam.

9. The composite sandwich of claim 1, wherein the carrier is closed cell foam, and the core has a density of between approximately 6.9 and 12 pounds per cubic foot.

10. An aircraft structure incorporating the composite sandwich of claim 1.

11. A reinforced composite sandwich core formable into a curved shape, comprising:

a plurality of pins arranged in groups forming a truss; and

a flexible carrier for supporting the pins, wherein the pins in each of the groups are spaced apart from and displaceable relative to each other within the carrier upon forming of the carrier into the curved shape.

12. The reinforced composite sandwich core of claim 11, wherein the pins in each group are radially distributed around a node.

13. The reinforced composite sandwich core of claim 11, wherein:

the carrier includes a layer of uncured thermoset foam, and

the pins are a thermoset prepreg.

14. The reinforced composite sandwich core of claim 11, wherein:

the carrier includes a layer of foam,

each of the pins includes medial portions held within the layer of foam and distal portions extending outside of the foam layer.

15. The reinforced composite sandwich core of claim 14, wherein the distal portions of each of the pins are splayed and lie substantially flush along a face of the foam layer.

16. A method of fabricating a reinforced composite sandwich, comprising:

fabricating a core, including—

(i) arranging structural pins into groups forming a truss,

(ii) supporting the pins in the groups by surrounding the pins with a layer of uncured structural foam,

forming the core into a curved shape;

applying a pair of facesheets respectively to opposite faces of the core; and

curing the core and the facesheets.

17. The method of claim 16, wherein arranging the pins includes inserting the pins into the layer of foam at differing angles.

18. The method of claim 16, wherein fabricating the core further comprises bending ends of the pins onto the faces of the core.

19. The method of claim 18, wherein fabricating the core further comprises flaying the ends of the pins.

20. The method of claim 19, wherein fabricating the core further comprises sandwiching the flayed ends of the pins between the faces of the foam layer and the facesheets.

21. The method of claim 16, wherein forming the core into a curved shape includes:

bending the foam layer, and

displacing the pins in each group relative to each other as the foam layer is being bent.

22. A method of fabricating a reinforced composite sandwich core, comprising:

producing a layer of structural foam; and

inserting reinforcement pins into the foam layer, including arranging the pins into groups forming a truss within the foam layer.

23. The method of claim 22, wherein arranging the pins into groups includes placing the pins in each group in spaced apart relationship radiating outwardly from a node.

24. A composite sandwich structure, comprising:

first and second generally parallel composite facesheets; and

a reinforced structural core sandwiched between and joined to the first and second facesheets, the reinforced core including—

(i) a layer of closed cell foam having a density of between approximately 6.9 and 12 pounds per cubic foot,

(i) a plurality of composite pins arranged in a plurality of groups forming a truss, the pins in each of the groups being circumferentially and spaced radially spaced from each other and extending radially outward from a node, each of the pins including medial portions extending between the first and second facesheets at angles relative to the planes of the facesheets and splayed distal portions respectively extending generally parallel to and sandwiched between the foam layer and one of the facesheets.

25. A method of fabricating a reinforced composite sandwich, comprising:

forming a layer of closed cell, uncured structural foam having a density between approximately 6.9 and 12 pounds per cubic foot;

forming groups of uncured composite pins within the core defining a truss, including inserting the pins through the foam layer at respectively differing angles around nodes such that the pins in each of the groups are radially and circumferentially spaced from each other;

splaying the ends of the pins,

bending the spayed ends of the pins onto opposite faces of the foam layer;

placing the core between the facesheets, including sandwiching the splayed ends of the pins between the foam layer and one of the facesheets; and

co-curing the foam layer, the pins and the facesheets.