Composite Fuselage Barrel Conductive Layer for Lightning Current Dispersion
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Solution Overview
Problem
Composite aircraft structures face challenges in dispersing electromagnetic energy from lightning strikes due to poor conductivity and high current density at mechanical fasteners, leading to potential ignition and damage.
Innovation Solution
A composite fuselage section with a conductive layer surrounding mechanical fasteners, comprising a conductive outer layer and a conductive layer disposed over the outer layer, enhances energy distribution by providing conductive pathways.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If composite materials are used for aircraft fuselage, then weight is reduced, but electrical conductivity decreases leading to poor EME protection
Solution Approach 1:
The patent applies composite materials by combining carbon fiber reinforced plastic (CFRP) for the fuselage structure with a copper foil layer for electrical conductivity. The copper foil is bonded to the CFRP outer skin, creating a hybrid composite structure that provides both weight reduction from the composite material and excellent electrical conductivity from the copper layer, thereby protecting against lightning strikes and EME while maintaining the weight benefits of composite construction.
2Ease of manufacture
If mechanical fasteners are used to join framework to outer skin, then structural assembly is simplified, but current density increases at fastener interfaces
Solution Approach 1:
The copper foil layer serves as an intermediary between the mechanical fasteners and the CFRP outer skin. It provides a continuous conductive pathway that bridges the fastener holes, preventing current concentration at the fastener-CFRP interface. The copper foil redistributes the lightning current around the fasteners, eliminating the high current density that would otherwise occur at the discontinuous fiber-fastener interface.
3Reliability
If copper foil layer is added to enhance conductivity, then EME protection is improved, but manufacturing complexity increases
Solution Approach 1:
The copper foil is bonded to the CFRP outer skin during the preliminary manufacturing stage, before final assembly. This preliminary bonding integrates the conductive layer into the fuselage structure early in the manufacturing process, allowing subsequent installation of mechanical fasteners and framework components without requiring additional steps to add the copper foil. The conductive pathway is established in advance, simplifying overall manufacturing despite the additional material.
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 conductive layer effectively disperses lightning strike energy, reducing current density and mitigating potential damage by enhancing current mobility and preventing ignition.
Implementation Method 1
the conductive layer can include a copper or a copper alloy, and the conductive layer can have a thickness of from about 0.005 inches to about 0.020 inches... the conductive layer effectively disperses lightning strike energy, reducing current density and mitigating potential damage by enhancing current mobility
Data Source
AI summary
A composite fuselage section, including an outer skin comprising one or more composite materials, an internal framework to support the outer skin, and one or more mechanical fasteners disposed through the outer skin, wherein the internal framework is joined to the outer skin using the one or more mechanical fasteners, and wherein the outer skin includes a conductive layer surrounding at least one of the one or more mechanical fasteners to enhance an energy distribution of a lightning strike flowing across a surface of the composite fuselage section.