Glassy Carbon Prepreg for Lightning Strike Protection

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Composite materials used in aerospace applications are vulnerable to electromagnetic hazards like lightning strikes due to low electrical conductivity in the z-direction, which can cause catastrophic damage, and existing solutions that introduce metallic conductive particles face issues like corrosion and weight increase.

Innovation Solution

A prepreg comprising structural layers of conductive fibers and outer layers of thermosetting resin with glassy carbon particles, which provide high z-direction conductivity without compromising mechanical properties, and thermoplastic particles for toughness, avoiding the problems associated with metallic particles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If metallic conductive particles are introduced to improve z-direction conductivity, then lightning strike resistance is improved, but weight increases and corrosion issues arise

Engineering Contradiction:

Improvelightning strike resistanceVSAvoidcomposite weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The patent changes the material parameter from metallic particles to glassy carbon particles, achieving the same electrical conductivity function without the associated weight and corrosion problems. This parameter substitution resolves the contradiction by maintaining reliability while eliminating the worsening effects.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses glassy carbon particles as a substitute for metallic particles, providing a lighter, corrosion-free alternative that achieves the same protective function without the long-term degradation issues of metals, effectively replacing problematic materials with superior alternatives.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Reliability

If metallic conductive particles are introduced to improve z-direction conductivity, then lightning strike resistance is improved, but corrosion and explosion hazards occur

Engineering Contradiction:

Improvelightning strike resistanceVSAvoidcorrosion and explosion hazards

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful effects of metallic particles (corrosion, explosion hazards) into beneficial properties by using glassy carbon particles that are chemically inert, non-corrosive, and non-explosive, while maintaining the essential electrical conductivity function for lightning protection.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The glassy carbon particles act as an intermediary substance that provides electrical conductivity without the harmful chemical properties of metals, serving as a safe mediator between the conductive fiber layers while eliminating corrosion and explosion risks.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If conductive elements are added to improve z-direction conductivity, then lightning strike protection is improved, but mechanical properties deteriorate

Engineering Contradiction:

Improvelightning strike protectionVSAvoidmechanical properties

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent changes the particle material from metal to glassy carbon, which has different mechanical properties that are more compatible with the composite matrix. This parameter change maintains electrical conductivity while preserving or improving mechanical strength, resolving the contradiction between protection and structural integrity.

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 solution achieves significant electrical conductivity in the z-direction while maintaining excellent mechanical properties, reducing the risk of damage from lightning strikes and preventing edge glow, making it suitable for aerospace applications without increasing weight or affecting mechanical integrity.

Implementation Method 1

the glassy carbon particles are located in the interleaf layers and act so as to provide an electrical connection between adjacent layers of conductive fibres

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

The thermoplastic particles provide toughness to the resulting laminate

Methodology Applied

Scientific EffectThermoplastic deformation: Plasticity

Implementation Method 3

the resulting laminate is cured, typically by exposure to elevated temperatures, to produce a cured composite laminate

Methodology Applied

Scientific EffectThermal curing: Heat Treatment

Data Source

PatentEP2473557B1Improvements in composite materials

Publication Date: 2015.02.25 HEXCEL COMPOSITES LTD (GB)

Figure 1~2
Figure 3

AI summary

A curable prepreg comprising a structural layer of conductive fibres and a first outer layer of thermosetting resin, the resin layer comprising thermoplastic particles and glassy carbon particles provides improved electrical conductivity and excellent mechanical properties.