Core for a composite structure and method of fabrication thereof

Patent metadata

Field	Value
Publication number	US-9453420-B2
Application number	US-201113881917-A
Country	US
Kind code	B2
Filing date	Oct 25, 2011
Priority date	Oct 26, 2010
Publication date	Sep 27, 2016
Grant date	Sep 27, 2016

Abstract

A flexible core for a composite structure is described. The core includes a first core layer, a second core layer, and a ground plane between the first and second core layers. A plurality of slits is provided in the core, and each slit extends through one of the first of second core layers and through the ground plane. The core may be the core of a sandwich panel, for example a sandwich panel of the type used in the composite construction of wind turbine blades.

First claim

The invention claimed is:

1. A core for a composite structure, the core comprising:
a first core layer;
a second core layer; and
a ground plane between the first and second core layers, the ground plane including a layer of conductive material;
wherein a plurality of slits is provided in the core, and each slit extends through one of the first or second core layers, through the ground plane, and through less than the entire core.

2. The core of claim 1 , wherein each slit extends at least partially through the other of the first or second core layers.

3. The core of claim 1 , wherein the ground plane comprises electrically conductive foam.

4. The core of claim 1 , wherein the first core layer comprises a dielectric material.

5. The core of claim 1 , wherein the first and/or second core layers are made of foam.

6. The core of claim 1 , wherein an impedance layer is provided on an outer surface of the core, in spaced apart relation with the ground plane such that the impedance layer and the ground plane form radar absorbing material.

7. A composite structure of sandwich panel construction and comprising a sandwich-panel core as claimed in claim 1 .

8. The composite structure of claim 7 , comprising an impedance layer spaced-apart from the ground plane.

9. The composite structure of claim 8 , wherein the core is arranged within the composite structure such that the first core layer is located between the ground plane and the impedance layer.

10. The composite structure of claim 7 , wherein the thickness of the first core layer is substantially uniform across the composite structure.

11. The composite structure of claim 7 , wherein the thickness of the second core layer varies across the composite structure to vary the overall thickness of the core.

12. A blade for a wind turbine, the blade comprising the composite structure of claim 7 .

13. The wind turbine having a blade according to claim 12 , or a wind farm comprising at least one such wind turbine.

14. A core for a composite structure, the core comprising:
a first core layer;
a second core layer; and
a ground plane between the first and second core layers, the ground plane including a layer of carbon;
wherein a plurality of slits is provided in the core, and each slit extends through one of the first or second core layers and through the ground plane.

15. A composite structure of sandwich panel construction comprising:
a core comprising a first core layer, a second core layer, and a ground plane between the first and second core layers, the ground plane including a layer of conductive material, a first outer surface facing the first core layer, and a second outer surface facing the second core layer,
wherein a plurality of slits is provided in the ground plane, each slit extending through less than the entire core, and the first and second outer surfaces are covered by the first and second core layers, respectively.

16. The composite structure of claim 15 , wherein each slit extends at least partially through the other of the first or second core layers.

17. The composite structure of claim 15 , wherein the ground plane includes a layer of carbon.

18. The composite structure of claim 15 , wherein the ground plane comprises electrically conductive foam.

19. The composite structure of claim 15 , wherein an impedance layer is provided on an outer surface of the core, in spaced apart relation with the ground plane such that the impedance layer and the ground plane form radar absorbing material.

20. The composite structure of claim 19 , wherein the core is arranged within the composite structure such that the core is located between the ground plane and the impedance layer.

21. A method of manufacturing a core for a composite structure, the method comprising:
bonding a ground plane including a layer of conductive material between first and second core layers to form a unitary split-core structure, and
forming a plurality of slits in the core so that each slit extends through one of the first or second core layers, through the ground plane, and through less than the entire core.

Assignees

• Appleton Steve
• Vestas Wind Sys As

Inventors

• Appleton Steve

Classifications

• B29D99/0028

  hollow blades · CPC title

• B32B2309/105

  Thickness · CPC title

• B29C70/086 Primary

  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 title

• H01Q15/148

  with means for varying the reflecting properties (H01Q15/147 takes precedence) · CPC title

• B32B38/1866

  conforming the layers or laminate to a convex or concave profile · CPC title