Aircraft Structure Lightning Protection via Embedded Conductive Objects

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Solution Overview

Problem

Aircraft structures face challenges in preventing sparks during lightning strikes, particularly when using clearance fit fasteners, which can lead to damage and increased labor due to manufacturing errors and the risk of electrical conductivity through metallic fasteners, while interference fit methods cause wear and damage to composite panels.

Innovation Solution

Incorporating conductive objects embedded within structural members to create a current pathway that diverts lightning current away from fasteners, ensuring they remain electrically non-contact, thereby preventing sparks and reducing the risk of damage to composite materials.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If clearance fit fasteners are used to couple panels, then ease of manufacture and assembly are improved, but the risk of sparks during lightning strikes increases due to electrical conductivity through metallic fasteners

Engineering Contradiction:

Improveease of manufactureVSAvoidspark risk

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a non-conductive fastener as an intermediary component between metal panels. This non-conductive fastener includes a threaded rod with a non-conductive coating layer, allowing it to mechanically couple panels while preventing electrical conductivity and spark generation during lightning strikes, thus resolving the contradiction between ease of manufacture and spark risk.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If interference fit fasteners are used to couple panels, then electrical continuity is improved for lightning current flow, but damage to composite panels and fastener wear increase

Engineering Contradiction:

Improveelectrical continuityVSAvoidpanel damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The non-conductive fastener acts as a mediator that provides mechanical coupling without electrical conductivity. The threaded rod with non-conductive coating allows panels to be securely fastened while preventing direct metal-to-metal contact, thereby eliminating panel damage and fastener wear associated with interference fit methods while maintaining structural integrity.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Object-affected harmful factors

If non-conductive fasteners are used to prevent sparks, then spark risk is reduced, but electrical continuity for lightning current flow between panels deteriorates

Engineering Contradiction:

Improvespark riskVSAvoidelectrical continuity

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent segments the lightning protection function from the mechanical fastening function. The non-conductive fastener handles mechanical coupling while a separate conductive bridge layer (attached to the non-conductive fastener or panel) provides electrical continuity pathways for lightning current, allowing both spark prevention through fasteners and maintained electrical continuity through dedicated conductive elements.

Inventive Principle:

Principle #1Segmentation

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 prevents sparks during lightning strikes, reduces the risk of damage to composite panels, and simplifies the attachment and detachment process of fasteners, improving maintenance efficiency and reducing labor costs.

Implementation Method 1

The conductive object prevents a spark between the fastener and each of the first structural member and the second structural member by forming a current pathway that leads current, flowing inside the at least either one of the first structural member and the second structural member inside which the at least the part is embedded, to the other structural member.

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS9957063B2Structure for aircraft, method of manufacturing structure for aircraft and method of making design information of structure for aircraft

Publication Date: 2018.05.01 SUBARU CORP

AI summary

According to one implementation, a structure for an aircraft includes a first structural member, a second structural member coupled to the first structural member, a fastener and a conductive object. The fastener couples the first structural member to the second structural member. The fastener is inserted into an insertion hole formed in a portion where the first structural member is overlapped with the second structural member. The fastener is in electrically non-contact with the first and second structural members in the insertion hole. The conductive object is embedded inside at least either one of the first and second structural members. The conductive object prevents a spark between the fastener and each of the first and second structural members by forming a current pathway that leads current, flowing inside the at least either one of the first and second structural members, to the other structural member.