Lightning Strike Protection Layer Butt Joint Design
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Solution Overview
Problem
Aircraft with complex geometries face challenges in lightning strike protection due to the need for multiple discrete layers, which can lead to electrical disconnection and increased thickness at joints, causing manufacturing inefficiencies and potential structural damage.
Innovation Solution
A lightning strike protection layer comprising two fibre reinforced polymer composite layers with electrically conductive metal layers, joined at a butt joint with a butt-strap for electrical connection, minimizing thickness increase and ensuring electrical continuity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple discrete lightning strike protection layers are used to cover complex aircraft geometries, then the aircraft surface can be adequately protected, but electrical connection between layers becomes difficult to ensure
Solution Approach 1:
The lightning strike protection system is divided into multiple discrete portions that can be separately manufactured and then assembled, allowing coverage of complex aircraft geometries while maintaining manageable fabrication processes for each individual portion
Solution Approach 2:
Adjacent portions are joined through butt joints where the metal layers abut and are electrically connected, merging multiple discrete protection layers into a continuous electrical pathway that maintains protection across the entire aircraft surface
2Area of stationary object
If multiple discrete lightning strike protection layers are used, then complex aircraft geometries can be covered, but the joint thickness increases
Solution Approach 1:
Thin metal layers are used in the lightning strike protection portions, and when joined at butt joints, they overlap to provide electrical connection without creating significant thickness buildup, maintaining a relatively uniform overall thickness across the protection layer
3Area of stationary object
If multiple discrete lightning strike protection layers are used, then aircraft surfaces can be covered, but manufacturing complexity and costs increase
Solution Approach 1:
The protection layer is segmented into multiple portions that can be manufactured using standard composite fabrication processes and then assembled, making the overall system more manageable while maintaining manufacturing efficiency
Solution Approach 2:
Adjacent portions are joined in the plane of the protection layer through butt joints, rather than stacking layers vertically, which avoids increasing thickness and simplifies the manufacturing process by working within the same dimensional plane
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 reduces manufacturing costs and lead times, minimizes thickness and defects at joints, and ensures effective electrical connection for efficient lightning strike energy dissipation.
Implementation Method 1
the electrical conductivity of metals is significantly larger than that of conventional composite laminates... electrical potential from the lightning strike flows through the lightning strike protection layer
Data Source
AI summary
A lightning strike protection layer for an aircraft is disclosed having a first portion and a second portion, the first portion includes a first fibre reinforced polymer composite layer and a first electrically conductive metal layer and the second portion includes a second fibre reinforced polymer composite layer and a second electrically conductive metal layer, and the first and second portions are joined at a butt joint, with the first and second fibre reinforced polymer composite layers abutting and the first and second electrically conductive metal layers abutting; and a butt-strap extending across the butt joint, the butt-strap comprising a third electrically conductive metal layer electrically connected to the first and second electrically conductive metal layers.