FLEX CIRCUIT LIGHTNING PROTECTION APPLIQUE SYSTEM FOR SKIN FASTENERS IN COMPOSITE STRUCTURES

Abstract

A lightning protection appliqué incorporates a plurality of conductive plies adhesively affixed to a composite surface, at least a first one of the plies providing conductive characteristics sufficient to divert electrical energy from a lightning strike and at least a second one of the plies comprising operational circuitry. A dielectric ply is fixed to the composite surface over and completely covering at least one metal surface feature between the plurality of conductive plies and the composite surface.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will be better understood for exemplary embodiments by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. 1 is a cross section of an exemplary multiple functionality appliqué incorporating the elements of the present invention;

FIG. 2 a is a cross sectional profile view of an appliqué according to the present invention having two conductive layers;

FIG. 2 b is a cross sectional profile view of an appliqué according to the present invention having 4 conductive layers;

FIG. 3 is a peeled sectional view of an appliqué according to the present invention incorporating a deicing heating element as an outer layer of the flex circuit; and,

FIG. 4 is an exemplary diagram of an application of the inventive system to an aircraft.

Claims

1. A lightning protection appliqué comprising: a plurality of conductive plies adhesively affixed to a composite surface, at least a first one of said plies having conductive characteristics sufficient to divert electrical energy from a lightning strike and at least a second one of said plies comprising operational circuitry;a dielectric ply fixed to the composite surface over and completely covering at least one metal surface feature intermediate said plurality of conductive plies and said composite surface.

2. A lightning protection appliqué as defined in claim 1 wherein each conductive ply incorporates a conductive layer and a dielectric layer intermediate the conductive layer and an adjacent conductive ply.

3. A lightning protection appliqué as defined in claim 1 wherein a bottom conductive ply incorporates an attachment backing layer for securing said plurality of conductive plies to the composite surface and the dielectric ply.

4. A lightning protection appliqué as defined in claim 1 wherein said first one of said conductive plies is connected to a platform ground.

5. A lightning protection appliqué as defined in claim 1, wherein the conductive layer of said first one of said conductive plies comprises a 0.0007″ (0.018 mm) thick minimum metal conductor.

6. A lightning protection appliqué as defined in claim 1, wherein said dielectric ply comprises: a layer of said dielectric film; anda pressure sensitive adhesive layer attaching said layer of dielectric film to said composite surface.

7. A lightning protection appliqué as in claim 6, wherein said dielectric film is a film of dielectric material selected from a group of materials consisting of a fluoropolymer, a polyester, a polyimide, and polyurethane.

8. A lightning protection appliqué as defined in claim 2, wherein said dielectric layer in each said conductive ply is selected from a group of materials consisting of a fluoropolymer, a polyester, a polyimide, and polyurethane.

9. A lightning protection appliqué as defined in claim 1, further comprising: a platform ground; andan external connection to said platform ground, said first of said conductive plies contacting said external connection, current from lightning strikes dispersing through said platform ground.

10. A lightning protection appliqué as defined in claim 1 wherein the operational circuitry of said second one of said conductive plies is a deicing heater element.

11. A lightning protection appliqué as defined in claim 1 wherein the operational circuitry of said second one of said conductive plies is an antenna.

12. A lightning protection appliqué as defined in claim 1 wherein the operational circuitry of said second one of said conductive plies is a sensor.

13. An aircraft lightning protection system comprising: an appliqué having a plurality of conductive plies adhesively affixed to a composite surface on an aircraft, at least a first one of said plies having conductive characteristics sufficient to divert electrical energy from a lightning strike and at least a second one of said plies comprising operational circuitry for electrical interconnection with aircraft systems;a dielectric ply fixed to the composite surface over and completely covering at least one metal surface feature on the aircraft, said dielectric ply intermediate said plurality of conductive plies and said composite surface.

14. An aircraft lightning protection system as defined in claim 13 wherein each conductive ply incorporates a conductive layer and a dielectric layer intermediate the conductive layer and an adjacent conductive ply.

15. An aircraft lightning protection system as defined in claim 13 wherein a bottom conductive ply of the appliqué incorporates an attachment backing layer for securing said plurality of conductive plies to the composite surface and the dielectric ply.

16. An aircraft lightning protection system as defined in claim 13, wherein the conductive layer of said first one of said conductive plies comprises a 0.0007″ (0.018 mm) thick minimum metal conductor.

17. An aircraft lightning protection system as defined in claim 13, wherein said dielectric ply comprises: a layer of said dielectric film; anda pressure sensitive adhesive layer attaching said layer of dielectric film to said composite surface.

18. An aircraft lightning protection system as in claim 17, wherein said dielectric film is a film of dielectric material selected from a group of materials consisting of a fluoropolymer, a polyester, a polyimide, and polyurethane.

19. An aircraft lightning protection system as defined in claim 14, wherein said dielectric layer in each said conductive ply is selected from a group of materials consisting of a fluoropolymer, a polyester, a polyimide, and polyurethane.

20. An aircraft lightning protection system as defined in claim 13, further comprising: a platform ground; andan external connection to said platform ground, said first one of said conductive plies contacting said external connection to direct current from lightning strikes to disperse through said platform ground.

21. An aircraft lightning protection system as defined in claim 13 wherein the operational circuitry of said second one of said conductive plies is a deicing heater element.

22. An aircraft lightning protection system as defined in claim 13 wherein the operational circuitry of said second one of said conductive plies is an antenna.

23. An aircraft lightning protection system as defined in claim 13 wherein the operational circuitry of said second one of said conductive plies is a sensor.

24. A method for lightning protection of an aircraft comprising the steps of: providing a dielectric ply;fixing said dielectric ply to a composite surface over and completely covering at least one metal surface feature on the aircraft;providing an appliqué having a plurality of conductive plies, at least a first one of said plies having conductive characteristics sufficient to divert electrical energy from a lightning strike and at least a second one of said conductive plies comprising operational circuitry for electrical interconnection with aircraft systems;adhesively affixing said appliqué to the composite surface of the aircraft completely covering said dielectric ply;connecting said second one of said conductive plies to an electrical system on the aircraft.

25. A method as defined in claim 24 wherein the step of providing and appliqué includes the steps of assembling for each conductive ply in the appliqué a conductive layer and a dielectric layer intermediate the conductive layer and an adjacent conductive ply.

26. A method as defined in claim 24 wherein the step of adhesively affixing the appliqué further includes the steps of providing an external connection to a platform ground; andconnecting said first one of said conductive plies to said external connection to direct current from lightning strikes to disperse through said platform ground.

27. A method as defined in claim 24 wherein the operational circuitry comprises a deicing heater element and the step of connecting said second one of said conductive plies comprises connecting a current source and control to said second one of the conductive plies for aircraft deicing.