Composite material suitable for a morphing skin

Patent metadata

Field	Value
Publication number	US-10479478-B2
Application number	US-201313989453-A
Country	US
Kind code	B2
Filing date	Mar 28, 2013
Priority date	Mar 30, 2012
Publication date	Nov 19, 2019
Grant date	Nov 19, 2019

Abstract

A morphing skin for an air vehicle structure, the skin being formed by a composite material which includes: a multiplicity of fibers, a matrix incorporating the fibers, and a thermo-sensitive material, such as a thermo-plastic. The thermo-sensitive material can be reversibly transitionable in response to a change in temperature, between (i) an ambient temperature mode in which the thermo-sensitive material is capable of transferring loads in the composite material, and (ii) a heated mode in which the ability of the thermo-sensitive material to transfer the loads is reduced. This can allow the stiffness of the skin to be temporarily reduced to enable the skin to be morphed into a different shape.

First claim

The invention claimed is:

1. A morphing skin for an air vehicle structure, the skin comprised of a composite material comprising:
a multiplicity of fibers coated with a thermo-sensitive material which is reversibly transitionable in response to a change in temperature, between: (i) an ambient temperature mode in which the thermo-sensitive material will transfer loads in the composite material, and (ii) a heated mode in which an ability of the thermo-sensitive material to transfer loads is reduced, and
a matrix material that incorporates said fibers coated with a thermo-sensitive material, the matrix material remaining stiff when the thermo-sensitive material is heated;
wherein:
the thermo-sensitive material reduces skin stiffness in the heated mode, allowing a change in shape of the skin in the heated mode and maintaining a changed shape of the skin in the ambient mode.

2. A morphing skin according to claim 1 , wherein the thermo-sensitive material is a thermoplastic.

3. A morphing skin according to claim 1 , wherein when in the heated mode, the thermo-sensitive material is at a temperature above a transition temperature, such that the thermo-sensitive material has changed state.

4. A morphing skin according to claim 1 , wherein the composite material comprises:
a first layer comprising said multiplicity of fibers coated with the thermo-sensitive material and incorporated into said matrix material; and
a layer of thermo-sensitive material, adjacent to the first layer.

5. A morphing skin according to claim 4 , wherein the composite material comprises:
a plurality of layers, each of which comprises said multiplicity of fibers coated with the thermo-sensitive material and incorporated into said matrix material, the plurality of layers interleaved with layers of thermo-sensitive material.

6. A morphing skin according to claim 1 wherein the fibers in said multiplicity of fibers are uni-directional.

7. A morphing skin according to claim 1 , wherein the skin comprises, or is configured for connection to, a heating apparatus for heating the thermo-sensitive material from the ambient temperature mode to the heated mode.

8. A morphing skin according to claim 7 , wherein the fibers in said multiplicity of fibers are electrically conductive and the heating apparatus is configured to pass a current through the multiplicity of fibers to heat the thermo-sensitive material.

9. A morphing skin according to claim 1 , wherein the fibers in said multiplicity of fibers are carbon fibers.

10. A morphing skin according to claim 1 , comprising: an actuator for changing and reverting a shape of the skin when the thermo-sensitive material is in the heated mode.

11. A method of morphing a skin on an air vehicle, comprising:
(i) heating the skin, the skin being configured to reversibly reduce in stiffness in reaction to an increase in temperature;
(ii) deforming the skin; and
(iii) cooling the skin in the deformed state, the skin being configured to return to higher stiffness in reaction to a decrease in temperature;
wherein the skin comprises a composite material comprised of a multiplicity of fibers coated with a thermo-sensitive material, and a matrix material that incorporates said fibers coated in a thermo-sensitive material;
wherein the thermo-sensitive material is reversibly transitionable in response to a change in temperature, between: (i) an ambient temperature mode in which the thermo-sensitive material will transfer loads in the composite material, and (ii) a heated mode in which an ability of the thermo-sensitive material to transfer loads is reduced, thereby reducing skin stiffness;
the matrix material remaining stiff when the thermo-sensitive material is heated, and
the thermo-sensitive material thereby reducing a stiffness of the composite material in the heated mode, allowing a change in shape of the skin in the heated mode, and maintaining a changed shape of the skin in the ambient mode.

12. A method according to claim 11 wherein heating of the skin comprises passing an electrical current through the multiplicity of fibers.

13. An article comprising a composite material which comprises:
a multiplicity of fibers coated with a thermo-sensitive material, and
a matrix material that incorporates said fibers coated in a thermo-sensitive material;
wherein the thermo-sensitive material is reversibly transitionable in response to a change in temperature, between: (i) an ambient temperature mode in which the thermo-sensitive material will transfer loads in the composite material; and (ii) a heated mode in which an ability of the material to transfer the loads is reduced, thereby reducing a stiffness of the composite material;
the matrix material remaining stiff when the thermo-sensitive material is heated,
the thermo-sensitive material thereby reducing a stiffness of the composite material in the heated mode, allowing a change in shape of the article in the heated mode, and maintaining a changed shape of the article in the ambient mode.

14. The morphing skin according to claim 1 , wherein said thermo-sensitive material is a thermoplastic polymer and said matrix is an epoxy matrix.

15. The morphing skin according to claim 14 , wherein said thermoplastic polymer is selected from poly(methyl methacrylate-co-acrylamide), polystyrene, and liquid crystal polymer.

Assignees

• Mbda Uk Ltd
• Imperial College Sci Tech & Medicine

Inventors

• Hussain Mohammed Azad
• Machell Anthony
• Robinson Paul
• Maples Henry Alexander
• Tridech Charnwit
• Bismarck Alexander

Classifications

• C08L33/26

  Homopolymers or copolymers of acrylamide or methacrylamide · CPC title

• B64C3/20 Primary

  Integral or sandwich constructions · CPC title

• B29C70/086

  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 title

• B64C3/48 Primary

  by relatively-movable parts of wing structures · CPC title

• C08L63/00

  Compositions of epoxy resins; Compositions of derivatives of epoxy resins · CPC title