Conductive Coating for Mitigating Edge Glow in CFRP Structures

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Solution Overview

Problem

Existing methods for mitigating edge glow in carbon fiber reinforced plastic (CFRP) structures are labor intensive, time-consuming, and add significant weight, which increases fuel consumption and reduces payload in aerospace applications.

Innovation Solution

Applying one or more thin layers of conductive coating material with a conductivity of at least 10^4 Siemens/meter over exposed fiber surfaces to reduce inter-ply voltage potential and eliminate edge glow intensity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If non-conductive sealant material is applied to exposed fiber surfaces to mask edge glow, then edge glow is contained, but the structure adds significant weight and requires labor-intensive multi-layer application

Engineering Contradiction:

Improveedge glow containmentVSAvoidstructure weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The patent changes the electrical conductivity parameter of the coating material from non-conductive (insulating) to conductive. The conductive coating material has a conductivity of at least 10^-4 Siemens/meter, which allows it to equalize voltage potential between composite layers and eliminate edge glow through electrical conduction rather than physical containment, thereby reducing weight while maintaining reliability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

Instead of using non-conductive material to physically block and contain edge glow, the patent inverts the approach by using conductive material to electrically connect exposed fiber surfaces to the composite structure, equalizing voltage potential and eliminating the edge glow phenomenon through electrical conduction rather than physical containment

Inventive Principle:

Principle #13The other way round (Inversion)

2Reliability

If non-conductive sealant material is applied to exposed fiber surfaces to mask edge glow, then edge glow is contained, but labor and time requirements increase due to multi-layer application and curing

Engineering Contradiction:

Improveedge glow containmentVSAvoidmanufacturing time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent changes the electrical conductivity parameter of the coating material from non-conductive to conductive, which fundamentally alters the mechanism of edge glow mitigation from physical containment to electrical conduction. This change eliminates the need for thick multi-layer applications and extended curing times, reducing manufacturing time while maintaining reliability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The conductive coating material is applied as a thin layer (0.00254 cm to 0.00762 cm thick) that provides sufficient electrical conductivity to equalize voltage potential at the exposed fiber surfaces. The thin film nature of the coating reduces application complexity and curing time compared to thick non-conductive sealant layers, while the conductive property ensures effective edge glow mitigation

Inventive Principle:

Principle #3Local quality

3Reliability

If non-conductive sealant material is applied to exposed fiber surfaces to mask edge glow, then edge glow is contained, but the complexity of the manufacturing process increases

Engineering Contradiction:

Improveedge glow containmentVSAvoidmanufacturing process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent changes the electrical conductivity parameter of the coating material from non-conductive to conductive, which simplifies the manufacturing process. The conductive coating material can be applied as a thin layer that cures quickly, eliminating the need for complex multi-layer application procedures and extended curing cycles required by non-conductive sealants, thereby reducing process complexity while maintaining reliability

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The method reduces labor and time requirements while providing weight savings, effectively eliminating edge glow and preventing fuel ignition risks in fuel environments, thereby improving manufacturing efficiency and reducing aircraft fuel consumption.

Implementation Method 1

one or more layers of conductive coating material having a conductivity of at least 10^-4 Siemens/meter is applied over an exposed fiber surface to reduce any inter-ply voltage potential that may exist between composite layers of the carbon fiber reinforced plastic during a lightning strike

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentEP3000736B1Method for mitigating edge glow and resulting composite structure

Publication Date: 2019.05.29 THE BOEING CO

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AI summary

Composite structures and methods for mitigating edge glow resulting from lightning strikes on composite structures, such as aerospace structures, containing carbon fiber reinforced plastic components. One or more thin layers of conductive coating material is applied over a cut edge or drop off of the carbon fiber reinforced plastic components to reduce inter-ply voltage potential between composite layers of the carbon fiber reinforced plastic component. The conductive coating (308) material is made of a conductive doping material (310) dispersed in a carrier medium.