Concave Conductive Grid for Composite Aircraft Lightning Protection
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Solution Overview
Problem
Aircraft made from composite materials face increased risk of damage from lightning strikes due to non-conductive paint layers suppressing the vaporization of sacrificial lightning strike protection materials, leading to higher energy dissipation into the composite material, and incorporating conductive components in paint can be costly and affect paint properties.
Innovation Solution
A lightweight, electrically-conductive grid with a concave outward-facing surface for enhanced lightning strike dissipation, allowing focused vaporization and easier rupture of overlying layers, potentially using interwoven wires or expanded mesh with specific dimensions and aspect ratios, and optionally incorporating conductive metals like copper or aluminum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a non-conductive paint layer is applied to the lightning strike protection material, then the aesthetic appearance and corrosion protection are improved, but the vaporization of the sacrificial material is suppressed leading to increased energy dissipation into the composite material
Solution Approach 1:
The paint layer is made locally conductive at the nodes where grid-forming members intersect, while remaining non-conductive in other areas. This is achieved by selectively applying conductive material to the nodes during the painting process, creating zones of different electrical properties within the same paint layer.
Solution Approach 2:
A conductive component acts as an intermediary element within the paint layer, providing a localized conductive path at the nodes without requiring the entire paint layer to be conductive. This intermediary conductive material allows vaporization to occur at critical points while maintaining the protective and aesthetic functions of the non-conductive paint elsewhere.
2Reliability
If the thickness of the non-conductive paint layer is increased to improve corrosion protection and aesthetics, then the protective function is enhanced, but the dissipation of electrical energy from lightning strikes is reduced increasing damage risk
Solution Approach 1:
The paint layer exhibits spatially varying electrical conductivity: non-conductive in the spaces between nodes for corrosion protection, and locally conductive at the nodes for energy dissipation. This local quality variation allows the same paint layer to perform both protective and conductive functions simultaneously.
Solution Approach 2:
The paint layer's conductive function is segmented to specific locations (nodes) rather than being uniformly distributed. This segmentation allows the majority of the paint layer to remain non-conductive and protective, while discrete conductive elements at the nodes provide the necessary electrical pathways for energy dissipation.
3Object-affected harmful factors
If conductive components are incorporated into the paint to maintain vaporization effectiveness, then the lightning strike protection is improved, but the paint properties are adversely affected and costs increase
Solution Approach 1:
Conductive components are incorporated locally at the nodes rather than throughout the entire paint layer. This localized incorporation minimizes the impact on overall paint properties while providing sufficient conductive pathways for vaporization at the critical intersection points where energy concentration occurs.
Solution Approach 2:
The conductive components are used in minimal quantities only where absolutely necessary (at the nodes), representing a small sacrificial investment to maintain the overall effectiveness of the lightning strike protection system without compromising the bulk paint properties.
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 concave surface design reduces the likelihood of damage to underlying composite materials by facilitating the rupture of paint layers and dissipating lightning energy effectively, while allowing for the use of thicker paint layers without increasing damage risk, and is suitable for aircraft and other structures susceptible to lightning strikes.
Implementation Method 1
it is suspected that the concave shape of the outward-facing surface focuses the vaporization of metal in the event of a lightning strike so that any overlying layers, such as paint or other coatings, may be ruptured more easily
Implementation Method 2
an electrically-conductive grid comprising a multiplicity of grid-forming members and a multiplicity of nodes where grid-forming members overlap or intersect
Data Source
AI summary
A lightning strike protection material for an aircraft includes an electrically-conductive grid with grid-forming members and nodes where grid-forming members overlap or intersect. A plurality of the grid-forming members and/or nodes include an outward-facing surface, and at least a portion of the outward-facing surface is concave.