Composite Structure Lightning Protection Segmentation
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Solution Overview
Problem
Composite aircraft structures are vulnerable to lightning strikes due to their lack of electrical conductivity, which can lead to electrical discharges and potential ignition of fuel tanks, highlighting the need for effective conductive pathways and isolation methods to manage edge glow phenomena.
Innovation Solution
A composite structure with discrete electrically conductive pathways and isolators, formed by introducing discontinuities in the fibre reinforcement during the laminate layup process, to control and direct electrical conductivity away from critical areas, using the same fibre reinforcement and resin matrix as the bulk structure, ensuring the isolators are several times the critical fibre length to maintain mechanical integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If continuous conductive pathways are provided throughout the composite structure, then lightning current can be effectively conducted away from the structure, but electrical discharges and edge glow may occur at exposed edges and fastener interfaces
Solution Approach 1:
The conductive pathway is segmented into discrete sections rather than being continuous. Isolators made of electrically insulating material are placed at strategic locations along the conductive pathway, dividing it into separate conductive zones. This segmentation prevents uncontrolled electrical discharge and edge glow by blocking current flow at specific points while maintaining overall conductivity for lightning protection.
Solution Approach 2:
Electrically insulating isolators are introduced as intermediary elements between conductive zones. These isolators act as mediators that control and direct the flow of electrical current, preventing harmful electrical discharges and edge glow phenomena while allowing the conductive pathway to function for lightning strike protection.
2Reliability
If metal bonding strips are used to connect conductive surface layers to ground plane, then adequate conductive paths are established, but additional components and assembly steps are required
Solution Approach 1:
The conductive pathway and isolators are integrated directly into the composite laminate structure during the manufacturing process. The isolators are positioned between plies or at specific locations within the laminate, merging the lightning protection function with the structural composite itself. This eliminates the need for separate metal bonding strips and additional assembly steps, reducing device complexity while maintaining reliable conductive paths.
Solution Approach 2:
The composite laminate structure serves multiple functions: it provides structural strength, electrical insulation between plies, and integrated lightning protection pathways. The isolators embedded within the laminate serve dual purposes of electrical insulation and structural integration, eliminating the need for separate grounding components and simplifying the overall system.
3Reliability
If conventional LSP materials like metal foils or meshes are applied to composite surfaces, then conductive pathways are provided, but the additional layers increase structure weight and complexity
Solution Approach 1:
The lightning protection functionality is merged with the existing composite laminate structure. Conductive pathways are created using the composite's own layers and embedded isolators, eliminating the need for additional metal foil or mesh layers. This integration approach maintains effective lightning strike protection while avoiding the weight penalty of conventional LSP materials.
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 protects composite aircraft structures from electrical discharges by conducting electricity away from critical parts, preventing edge glow and ensuring safe operation by controlling current paths and maintaining mechanical performance.
Implementation Method 1
discrete electrically conductive pathways... to control and direct electrical conductivity away from critical areas
Implementation Method 2
isolators for isolating the pathways from the bulk of the structure, the structure comprising fibre reinforcement and a reinforcement resin matrix... isolators comprising discontinuities in the fibre reinforcement
Data Source
Figure 1~2
AI summary
A composite structure (10) comprising one or more electrically conductive pathways (12) and one or more isolators for isolating the pathways (12) from the bulk of the structure (10).