Composite Wing Fastener Assembly for Simpler EME Protection
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Solution Overview
Problem
Current electromagnetic effect (EME) protection architectures for composite aircraft wings are complex and expensive, requiring extensive manufacturing labor and adding weight due to the need for conductive media and dielectric sealants to dissipate lightning currents, which complicates the assembly process and increases costs.
Innovation Solution
A wing design featuring a fastener system with a nut plate and fastener configuration that allows for linear movement of the nut within the plate, enabling alignment without coaxial fastener holes, and a dielectric coating for EME protection, reducing the need for additional sealants and simplifying the assembly process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conductive media and dielectric sealants are used for EME protection, then electromagnetic shielding effectiveness is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent combines the EME protection function with the fastener system by integrating a conductive coating directly onto the fastener components (nuts, bolts, washers). This merging eliminates the need for separate conductive media and dielectric sealants, reducing system complexity while maintaining shielding effectiveness through the conductive path provided by the coated fasteners.
Solution Approach 2:
The fastener system is given multiple functions: it provides mechanical fastening and simultaneously provides EME protection through its conductive coating. This multi-functionality reduces the need for additional components, simplifying the overall EME protection architecture while maintaining effective lightning current dissipation.
2Reliability
If conductive media and dielectric sealants are applied to protect against lightning currents, then electromagnetic shielding is improved, but manufacturing labor and time increase
Solution Approach 1:
The conductive coating is applied to the fastener components during the manufacturing process before assembly, rather than requiring post-assembly application of conductive media and sealants. This preliminary action integrates EME protection into the manufacturing flow, reducing additional labor steps and improving overall manufacturing efficiency.
Solution Approach 2:
The EME protection function is merged with the fastener installation process itself. The conductively coated fasteners provide lightning current dissipation as an inherent feature of the fastening operation, eliminating the need for separate application steps for conductive media and dielectric sealants, thereby improving productivity.
3Reliability
If dielectric sealant is used to fill gaps between fastener parts, then EME protection is improved, but weight increases
Solution Approach 1:
The patent extracts the dielectric sealant from the EME protection system, replacing it with conductively coated fastener components. The conductive coating on the fasteners provides the necessary EME protection through electrical continuity, eliminating the need for weight-adding dielectric sealant while maintaining or improving shielding effectiveness.
Solution Approach 2:
The fastener components utilize composite material structures with conductive coatings applied to their surfaces. This composite approach provides both mechanical fastening function and EME protection function in a single integrated component, replacing the need for separate dielectric sealant materials and reducing overall weight.
4Reliability
If two-piece fasteners with sealant injection are used, then EME protection is improved, but assembly complexity increases
Solution Approach 1:
The patent merges the EME protection function into the fastener components themselves through conductive coating, eliminating the need for two-piece fastener configurations and sealant injection systems. The conductive path is provided by the coated fastener parts, simplifying the fastener system architecture while maintaining EME protection.
Solution Approach 2:
The fastener system is designed to provide both mechanical fastening and EME protection through its conductive coating, eliminating the need for separate sealant injection mechanisms and complex two-piece configurations. This multi-functionality reduces assembly complexity while maintaining effective gap sealing and EME protection.
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 simplifies the assembly process, reduces weight, and lowers costs by eliminating the need for complex EME protection systems, while maintaining effective electromagnetic shielding.
Implementation Method 1
gaps between fastener parts (e.g., two-piece fasteners) and gaps between fastener parts and structural members may be filled with dielectric sealant that provides EME protection
Data Source
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AI summary
A wing includes a wing box including interconnected spars (102), an interior system installed within the wing box, an opposed pair of skins (130) fastened to and covering the wing box, wherein one of the skins closes out the wing, and a plurality of fastening systems configured to fasten the skins to the spars and provide protection from electromagnetic effects, wherein each one of the fastening systems includes a threaded fastener (204), a nut plate (202) including a body and a cover (210), and a nut (206) enclosed within the nut plate between the body and the cover, wherein the nut is restricted from rotation within the nut plate about a nut plate axis and is free to move linearly within the nut plate orthogonal to the nut plate axis.