Composite Fluid Conduit Insulation Band for Galvanic Isolation
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Solution Overview
Problem
Galvanic corrosion risk in aircraft fluid transfer conduits made from composite materials with conductive additives, due to proximity with metal sockets in the presence of electrolytes, which can lead to component damage and reduced service life.
Innovation Solution
A non-electrically conductive band is formed on the conduit to electrically isolate the conductive outer surface from metal sockets, preventing galvanic corrosion by using a non-conductive material, such as glass-fibre reinforced resin without conductive additives, and maintaining conductivity for static dissipation and lightning protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the conduit is made from electrically conductive composite material, then weight is reduced and static dissipation is maintained, but galvanic corrosion occurs when in contact with metal sockets in the presence of electrolytes
Solution Approach 1:
The conduit is segmented into two distinct sections: an electrically conductive section for static dissipation and lightning protection, and an electrically insulating section for galvanic corrosion prevention at the socket interface. This segmentation allows each section to fulfill its specific function without compromising the other.
Solution Approach 2:
The conduit transitions from uniform conductivity to having localized different electrical properties. The insulating section is specifically positioned at the socket interface where galvanic corrosion risk exists, while the rest of the conduit maintains conductivity for static dissipation. This local quality change addresses the corrosion problem without sacrificing overall conductivity functionality.
2Reliability
If metal end fittings are used to connect the conduit, then sealing connection is achieved, but weight and production cost increase
Solution Approach 1:
The end fitting is constructed as a composite structure combining an electrically insulating material body with an electrically conductive coating layer. This composite approach provides both the sealing functionality of a robust material and the electrical conductivity needed for static dissipation and lightning protection, eliminating the need for separate metal end fittings.
Solution Approach 2:
The end fitting is designed to perform multiple functions simultaneously: providing a sealing connection, maintaining electrical conductivity for static dissipation, and preventing galvanic corrosion at the socket interface. This multi-functionality consolidates what would otherwise require separate components into a single integrated part.
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 prevents galvanic corrosion, enhances safety, and extends the service life of components while maintaining reduced weight and minimized static charge risks, ensuring reliable fluid transfer and lightning protection in aircraft applications.
Implementation Method 1
galvanic corrosion may take place in the presence of an electrolyte. Galvanic corrosion occurs when two conductors of different materials (and thus different reactivities) come into close proximity with each other in the presence of an electrolyte
Implementation Method 2
retain some conductivity for alleviating static build up due to fluid flow through the conduit
Data Source
Figure 1
Figure 2
Figure 3~6
AI summary
A fluid transfer conduit comprising: an electrically conductive tube of fibre reinforced polymer composite material which has an electrically conductive outer surface and an electrically conductive inner surface; and on at least one axial end of said conduit, a non-electrically-conductive band formed on either the outer surface or the inner surface of the electrically conductive tube. Forming a non-electrically conductive band on the end of the conduit electrically isolates the electrically conductive outer surface of the conduit from the electrically conductive metal socket into which it is to be inserted. It has been recognised that there is a potential risk with electrically conductive composite conduits being fitted into metal sockets, namely that galvanic corrosion may take place in the presence of an electrolyte. Galvanic corrosion occurs when two conductors of different materials (and thus different reactivities) come into close proximity with each other in the presence of an electrolyte. This may for example happen in aircraft when an aircraft passes through a cloud causing many surfaces e.g. within the aircraft wings (where fuel pipes are located) to become damp. The water may form an electrolyte that may cause galvanic corrosion. Similar problems may arise for example when flying near sea areas or when de-icing systems are used.