Conductive Adhesive for Composite Fastener Lightning Protection
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Solution Overview
Problem
Current composite materials used in aircraft structures face the risk of arcing and potential ignition due to disrupted electrical conductivity around fasteners, particularly during lightning strikes, which increases maintenance costs and reduces aircraft reliability.
Innovation Solution
A method is developed to maintain electrical conductivity by embedding an electrically conductive material beneath the surface of fibre reinforced composite components, ensuring exposure within countersunk recesses for fasteners, using a hard base tool with abutments and additional layers to ensure continuous contact and prevent arcing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metallic fasteners are used to attach components, then structural assembly is achieved, but electrical conductivity is disrupted and arcing risk increases during lightning strikes
Solution Approach 1:
An electrically conductive adhesive is introduced as an intermediary material between the metallic fastener and the composite structure. This adhesive maintains electrical conductivity continuity across the fastener interface, preventing arcing during lightning strikes while still providing structural assembly functionality.
Solution Approach 2:
The electrical properties of the bonding interface are changed by using a conductive adhesive with specific electrical conductivity parameters. This modifies the interface from an insulating state (standard adhesive) to a conductive state, enabling lightning strike protection while maintaining fastener functionality.
2Reliability
If additional protective measures are implemented to prevent arcing, then lightning strike protection is improved, but component weight and production cost increase
Solution Approach 1:
The bonding process itself provides the protective function by using a conductive adhesive that inherently prevents arcing. The adhesive serves dual purposes: structural bonding and electrical conductivity maintenance, eliminating the need for separate protective layers or additional weight-bearing protective structures.
Solution Approach 2:
The protective function against lightning strikes is merged with the bonding function of the adhesive. Instead of adding separate protective layers, the conductive adhesive performs both structural assembly and electrical protection simultaneously, avoiding additional weight.
3Ease of manufacture
If conventional bonding methods are used, then manufacturing simplicity is maintained, but electrical conductivity continuity around fasteners is disrupted
Solution Approach 1:
A conductive adhesive intermediary is used that maintains the simplicity of the bonding process while adding the critical function of electrical conductivity. The application method remains similar to conventional adhesives, but the material properties provide continuous electrical path around fasteners.
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 effectively prevents arcing and ensures safe lightning strike dispersion, reducing damage to composite structures and maintaining aerodynamic smoothness, while avoiding weight and cost increases associated with previous solutions.
Implementation Method 1
infusion of low viscosity structural resin into dry carbon fibre preforms
Implementation Method 2
as a result of the pressure applied by the bagging blanket, and the control of operating temperature, the resin is cured
Implementation Method 3
control of operating temperature, the resin is cured to form the finished component
Data Source
AI summary
In the formation of a fiber reinforced composite material component produced by a resin transfer infusion process such as to have an electrically conductive surface layer for lightning strike protection wherein the component is to be drilled and countersunk to receive an electrically conductive fastener, a localized part of the electrically conductive mesh is deformed so as to be relocated in the countersunk recess thus to ensure electrical contact with the fastener when inserted and to eliminate any gap between the mesh and the fastener, thus determining the electrical conductive integrity of the mesh to avoid arcing in the event of lightning strike attachment.