Gallium-Based Conductive Paste for Aircraft Fastener Grounding
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Solution Overview
Problem
Aircraft constructed with composite materials like carbon fiber reinforced plastic (CFRP) face challenges in preventing electrostatic charge buildup between metallic fasteners and structural elements during lightning strikes, as traditional grounding methods are either costly, structurally compromising, or ineffective in providing reliable electrical conductivity.
Innovation Solution
A gallium-based metal structure is applied as a slurry to the surface of fasteners and CFRP fibers, forming a conductive connection that grounds the fastener to the structural element, using a mixture of liquid gallium alloy with solid metals or alloys to create a durable and conductive bond.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fasteners are coated with electrically insulating sealant material, then electrostatic force build-up is prevented, but manufacturing complexity and cost increase significantly
Solution Approach 1:
The patent introduces an electrically conductive paste as an intermediary material between the metallic fastener and the CFRP structural element. This paste contains conductive particles (such as silver, copper, or carbon) suspended in a matrix material, creating a reliable electrical connection that grounds the fastener to the structural element, preventing electrostatic charge buildup while simplifying the manufacturing process compared to traditional sealant coating methods
Solution Approach 2:
The patent changes the electrical conductivity parameter of the interface between fastener and structural element by using a conductive paste instead of an insulating sealant. The paste's conductivity can be adjusted by varying the concentration and type of conductive particles, allowing optimization of electrical grounding while maintaining structural integrity and simplifying application procedures
2Strength
If traditional metallic fasteners are used with CFRP structural elements, then structural integrity is maintained, but electrical conductivity is insufficient leading to electrostatic discharge
Solution Approach 1:
The patent employs a composite material system consisting of conductive particles (such as metal powders or carbon particles) embedded in a matrix material (such as epoxy or polymer). This composite paste combines the structural properties needed for mechanical bonding with the electrical conductivity required for lightning strike protection, effectively bridging the gap between metallic fasteners and CFRP structural elements
3Reliability
If conductive adhesive is used between fastener and CFRP material, then electrical conductivity is improved, but charge build-up occurs due to resistive conductivity
Solution Approach 1:
The patent optimizes the electrical conductivity parameter by using a conductive paste with higher conductivity than conventional adhesives. The paste contains a high concentration of conductive particles (such as silver or copper powders) that create extensive conductive pathways, reducing electrical resistance to levels that prevent charge buildup during lightning strikes while maintaining adequate structural bonding
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 provides a reliable, cost-effective, and structurally sound electrical conductivity between fasteners and CFRP structural elements, preventing electrostatic discharge and maintaining structural integrity during lightning strikes.
Implementation Method 1
A gallium-based metal structure is applied as a slurry to the surface of fasteners and CFRP fibers, forming a conductive connection that grounds the fastener to the structural element
Data Source
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AI summary
A structural assembly of an aircraft which includes a structural element constructed of a composite material which includes a matrix material and plurality of fibers positioned to extend through the matrix material, wherein at least a portion of the plurality of fibers are accessible from a surface of the structural element. A fastener secures the structural element to a structural component. A metal structure comprising gallium is positioned in contact with a surface of the fastener. The metal structure extends from the surface of the fastener and contacts at least a portion of the at least a portion of the plurality of fibers. Also included is a method for assembling a structure.