Preformed Dielectric Inserts for Composite Lightning Protection
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Solution Overview
Problem
Current methods for lightning strike protection in aircraft composite structures are labor-intensive, interfere with aerodynamic dimensional tolerances, and generate waste due to the in-place curing and shaving of dielectric sealants, which are not suitable for all production environments and can damage the surface.
Innovation Solution
The use of preformed dielectric inserts with a complimentary shape to recessed fasteners, coated with adhesive, which are inserted and secured to provide a smooth surface, reducing installation and inspection time, and improving precision in meeting dimensional tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If in-place curing and shaving of dielectric sealant is used, then lightning strike protection is provided, but labor intensity increases and aerodynamic dimensional tolerances are affected
Solution Approach 1:
The dielectric insert is pre-formed with a contour that matches the recess geometry before installation. This preliminary preparation eliminates the need for on-site curing and shaving operations, reducing labor intensity while maintaining aerodynamic dimensional tolerances. The insert is ready for direct installation into the recessed fastener.
2Reliability
If in-place curing and shaving of dielectric sealant is used, then lightning strike protection is provided, but surface damage may occur
Solution Approach 1:
The dielectric insert is pre-formed with the correct contour and surface finish before installation. This eliminates the need for on-site shaving operations that could damage the composite aircraft surface. The insert is designed to fit precisely into the recess without requiring destructive removal of material.
3Manufacturing precision
If mechanical devices with reciprocating metal blades are used for shaving, then dielectric sealant can be flushed with surface, but the devices cannot be utilized in certain production environments
Solution Approach 1:
The dielectric insert is pre-formed with a contour that matches the recess geometry, eliminating the need for on-site shaving operations. This approach is compatible with all production environments including automated assembly lines, whereas mechanical shaving devices require specific manual operation conditions and cannot be used in automated or constrained production settings.
4Reliability
If sealant application is made integral to assembly process, then lightning strike protection is achieved, but labor and time increase
Solution Approach 1:
The dielectric insert is pre-formed and prepared before assembly, allowing it to be installed as a discrete component rather than requiring integral sealant application during the assembly process. This separation of operations reduces the time and labor required for assembly while maintaining the lightning strike protection function.
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 method reduces installation and inspection time, minimizes waste, and enhances precision in meeting aerodynamic dimensional tolerances, providing better lightning strike protection while avoiding surface damage and allowing for automation and easier integration into production processes.
Implementation Method 1
coating at least one of a head of the fastener and a preformed dielectric insert with an adhesive, inserting the preformed dielectric insert into the recess such that the adhesive engages both contours of the recess and the preformed dielectric insert
Data Source
AI summary
A fabrication method for providing a relatively smooth surface associated with lightning strike protection for composite materials joined with fasteners recessed below the surface is described. The method includes coating at least one of a head of the fastener and a preformed dielectric insert with an adhesive, inserting the preformed dielectric insert into the recess such that the adhesive engages both contours of the recess and the preformed dielectric insert, and removing any excess adhesive from the surface area of the composite material and a top surface of the insert.