Dielectric Coated Fasteners for Lightning Current Protection
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Solution Overview
Problem
Composite aircraft structures are vulnerable to electromagnetic effects (EME) from lightning strikes, leading to arcing, sparking, and hot particle ejection due to their inability to conduct away electrical currents effectively.
Innovation Solution
The use of fasteners with dry dielectric coatings and seals at select locations to prevent arcing and sparking by blocking electrical paths, combined with conductive resin coatings to improve electrical bonding, reduces the risk of EME damage without the need for sealant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If composite materials are used for aircraft structures, then weight is reduced and fuel efficiency is improved, but the structure becomes vulnerable to electromagnetic effects from lightning strikes
Solution Approach 1:
The patent applies composite materials by combining conductive resin coating with dielectric coatings and seals to create a multi-layer protective system on fasteners. The conductive resin provides electrical bonding to divert lightning current, while dielectric layers block arcing and sparking, creating a composite protection system that addresses both weight reduction and EME vulnerability
Solution Approach 2:
The patent uses dielectric coatings and seals as intermediary elements between the conductive resin coating and the fastener metal. These dielectric intermediaries prevent direct electrical contact that would cause arcing, while the conductive resin acts as an intermediary to divert lightning current away from vulnerable areas
2Reliability
If sealant is used to fill gaps between fastener parts, then EME protection is improved, but device complexity and installation time increase
Solution Approach 1:
The patent extracts the EME protective function from the sealant and integrates it directly into the fastener components through dielectric coatings and seals. This eliminates the need for separate sealant application steps, reducing installation complexity while maintaining EME protection
Solution Approach 2:
The patent merges multiple functions into the fastener components themselves: the dielectric coating provides both EME protection and gap filling, while the conductive resin coating provides electrical bonding. This consolidation eliminates the need for separate sealant application and reduces overall system complexity
3Reliability
If thick dielectric coatings and seals are applied to fasteners, then EME protection is improved, but weight and installation complexity increase
Solution Approach 1:
The patent applies dielectric coatings and seals only at specific locations on fastener components where arcing and sparking are most likely to occur. This localized application provides effective EME protection while minimizing the amount of material used, thereby reducing weight compared to full-coverage applications
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
This solution effectively inhibits arcing and sparking, reduces weight, and simplifies installation, providing redundant EME protection in aircraft structures by using thinner coatings and seals that can be easily integrated into fastening systems, thereby enhancing safety and efficiency.
Implementation Method 1
at least one feature for protecting against EME effects. The at least one feature includes at least one of a dielectric coating and a dielectric seal partially covering the central opening at a select location
Implementation Method 2
conductive media may be provided on a surface to divert lightning current away from underlying metal fastener systems
Data Source
AI summary
Fasteners are inserted into a stack of members and terminated with parts having at least one of a dry dielectric coating and an inner dry dielectric seal at select locations to protect against electromagnetic effects (EME).