Frangible Collar Fastener Termination for Lightning Arcing Suppression
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Solution Overview
Problem
Lightweight composite materials in vehicles, such as aircraft, do not effectively conduct away extreme electrical currents and electromagnetic forces generated by lightning strikes, and metallic fastener systems used in these structures can create electromagnetic interference issues like sparking and arcing.
Innovation Solution
A fastener assembly with a termination part featuring a frangible collar that breaks under torque, exposing a metallic core coated with dielectric material to reduce electromagnetic effects, with the exposed core being spaced to prevent arcing and mitigate electromagnetic interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metallic fastener systems are used in composite structures, then structural strength and assembly reliability are improved, but electromagnetic effects such as sparking and arcing are generated
Solution Approach 1:
The termination part is segmented into a dielectric material portion and a metallic core portion. The dielectric material forms an outer layer that electrically isolates the conductive metallic core from surrounding structures, thereby maintaining structural integrity while suppressing electromagnetic effects such as sparking and arcing.
Solution Approach 2:
The termination part is constructed as a composite structure combining dielectric material and metallic core. This composite design allows the dielectric outer layer to provide electromagnetic effect suppression while the metallic inner core provides structural strength and fastening capability.
2Strength
If the metallic core is exposed to provide structural strength, then fastening capability is improved, but the risk of arcing and electromagnetic interference increases
Solution Approach 1:
The termination part exhibits local quality differentiation where the outer surface is made of dielectric material to suppress electromagnetic effects, while the inner core is metallic to provide structural strength. This localized material assignment allows each region to perform its specific function optimally.
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 effectively suppresses electromagnetic effects by breaking the frangible collar to expose a dielectric-coated metallic core, reducing the risk of arcing and enhancing protection against electromagnetic interference in vehicle assemblies.
Implementation Method 1
a metallic core (52) coated by a layer (54) of dielectric material
Data Source
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AI summary
An electromagnetic effect suppressing termination part (50) is provided for a fastener formed (40) of a metallic material, the fastener having a head, a shank, and a threaded portion opposite the head. The termination part includes a main body (56) defining an internally threaded portion (66) configured to threadably receive the threaded portion of the fastener, the internally threaded portion defining a thread major diameter. A collar (72) is coupled to a distal end of the main body by a frangible web (74), wherein the main body, collar, and frangible web are formed of a metallic core coated by a layer of dielectric material. The frangible web, when broken, presents an exposed portion of the metallic core, wherein the frangible web includes an inner surface radially outwardly offset from the thread major diameter of the internally threaded portion by a setback distance.