Thermally Expandable Conductive Prepreg for Aircraft Lightning Protection

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Solution Overview

Problem

Current composite materials used in aircraft fuselage structures lack sufficient burn-through protection and lightning strike protection, requiring additional insulation materials that increase weight and cost, and do not provide complete protection against external fires.

Innovation Solution

A composite panel with a thermally expandable and electrically conductive fiber layer, embedded in a curable matrix resin, provides both burn-through resistance and lightning strike protection by using metal-coated carbon fibers and thermally expandable graphite flakes, eliminating the need for additional insulation materials.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If additional insulation materials are added to composite fuselage structures to improve burn-through protection, then burn-through resistance is improved, but weight and device complexity increase

Engineering Contradiction:

Improveburn-through protectionVSAvoidweight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The patent combines burn-through protection and lightning strike protection functions into a single integrated top surfacing layer. This layer contains thermally expandable particles for burn-through resistance and electrically conductive fibers for lightning protection, eliminating the need for separate insulation materials and reducing overall weight and complexity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The top surfacing layer is designed to perform multiple functions simultaneously: thermal insulation during fire exposure, electrical conductivity for lightning strike protection, and structural reinforcement. This multi-functional design replaces what would traditionally require multiple separate components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If additional insulation materials are added to composite fuselage structures to improve burn-through protection, then burn-through resistance is improved, but device complexity increases

Engineering Contradiction:

Improveburn-through protectionVSAvoiddevice complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If thermal insulating layers are applied to the exterior surface to provide burn-through protection, then burn-through resistance is improved, but lightning strike protection deteriorates

Engineering Contradiction:

Improveburn-through protectionVSAvoidlightning strike protection

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The top surfacing layer incorporates electrically conductive fibers specifically positioned to provide lightning strike protection while maintaining thermal insulation properties. This local addition of conductive material to an insulating matrix resolves the contradiction by providing both thermal and electrical protection in the same layer.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent uses a composite material system combining thermally expandable particles, electrically conductive fibers, and matrix resin. This composite structure provides both thermal insulation (from the expandable particles) and electrical conductivity (from the conductive fibers) simultaneously, resolving the contradiction between burn-through and lightning strike protection.

Inventive Principle:

Principle #40Composite materials

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 solution achieves a burn-through protection time of at least 5 minutes and integrates lightning strike protection without additional components, reducing weight and cost while providing improved thermal insulation and electromagnetic shielding.

Implementation Method 1

thermally expandable graphite flakes

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

provides improved burn-through protection

Methodology Applied

Scientific EffectThermal insulation: Thermal Insulation

Implementation Method 3

metal-coated carbon fibers

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 4

curable matrix resin

Methodology Applied

Scientific EffectPolymerization: Photopolymerisation

Data Source

PatentEP3334591B1Prepreg material capable of providing lightning strike protection and burn-through resistance and method for its manufacture

Publication Date: 2021.11.03 CYTEC IND INC

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AI summary

A thermally expandable and electrically conductive material capable of providing lightning strike protection and burn-through resistance, containing electrically conductive fibers; thermally expandable particles; and a curable matrix resin comprising one or more thermoset resins, wherein the electrically conductive fibers and the thermally expandable particles are embedded in the curable matrix resin.