Composite Fastener Lightning Protection via Conductive Layering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Composite materials used in aircraft structures, such as fiber-reinforced plastics, pose a higher risk of spark occurrence when coupled with electrically conductive fasteners due to the difficulty in allowing electric current flow, potentially leading to ignition of fuel during lightning strikes.
Innovation Solution
Incorporating an electrically-conductive composite member with increased thickness around fasteners and using a hybrid stack of fiber-reinforced resin layers, including electrically-conductive and non-conductive materials, to guide lightning currents away from the fasteners and reduce spark probability, while also enhancing structural strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If composite materials are used for aircraft structures, then weight is reduced and strength is improved, but the risk of spark occurrence increases during lightning strikes
Solution Approach 1:
The patent applies local quality by creating a hybrid stack structure where electrically-conductive fiber-reinforced resin layers and non-conductive fiber-reinforced resin layers are arranged in specific patterns. The electrically-conductive layers are positioned to guide lightning currents away from fasteners, while non-conductive layers are placed in regions where spark prevention is less critical. This localized functional differentiation allows the composite structure to provide lightning protection where needed while maintaining overall weight efficiency.
Solution Approach 2:
The patent employs composite materials by combining electrically-conductive fiber-reinforced resin layers (containing conductive fillers like carbon black or metal particles) with non-conductive fiber-reinforced resin layers in a hybrid stack configuration. This composite approach creates a multi-functional structure that simultaneously provides mechanical strength, weight reduction, and selective electrical conductivity for lightning current guidance, resolving the contradiction between using lightweight composites and preventing spark occurrence.
2Object-affected harmful factors
If electrically-conductive composite members with increased thickness around fasteners are used, then spark probability is reduced, but material cost increases
Solution Approach 1:
The patent implements local quality by concentrating electrically-conductive fiber-reinforced resin layers specifically in regions where lightning current guidance is most effective—away from fasteners—rather than uniformly throughout the entire composite structure. The non-conductive layers are positioned in areas where spark prevention is less critical. This strategic local differentiation reduces the overall quantity of expensive electrically-conductive materials needed while maintaining effective lightning protection.
Solution Approach 2:
The patent applies partial action by providing lightning protection only in the specific regions and orientations where it is most needed for spark prevention, rather than making the entire composite structure uniformly electrically-conductive. The hybrid stack uses a controlled number of conductive layers (e.g., 1-3 layers out of 10-20 total layers) strategically positioned to guide currents away from fasteners, achieving adequate protection with minimal conductive material usage.
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 reduces the likelihood of spark occurrence between fasteners and composite members, preventing fuel ignition and enhancing structural strength to bear local loads, while minimizing the use of costly electrically-conductive materials.
Implementation Method 1
Incorporating an electrically-conductive composite member with increased thickness around fasteners and using a hybrid stack of fiber-reinforced resin layers, including electrically-conductive and non-conductive materials, to guide lightning currents away from the fasteners
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A composite structure includes a composite member and a fastener. The composite member has a through hole. The fastener is inserted in the through hole and couples the composite member and another part to each other. The composite member includes an electrically-conductive composite member provided at least in part or all of a through-hole portion. The through-hole portion is a portion, of the composite member, having the through hole. The electrically-conductive composite member has a thickness that is greater in a portion, of the electrically-conductive composite member, included in the through-hole portion than in a portion, of the electrically-conductive composite member, other than the through-hole portion.