Thin-Walled Seal Cap for Lightning and Corrosion Protection
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Solution Overview
Problem
Existing fastener protection methods fail to effectively prevent lightning strikes and corrosion while providing adequate electrical insulation and fluid barrier properties, especially in applications like aircraft fuel tanks, where they need to be lightweight and have high dielectric breakdown strength.
Innovation Solution
A method involving a seal cap made of a material with a dielectric breakdown strength greater than 30.0 kV/mm and an average wall thickness of less than 1.5 mm, filled with a THV polymer and uncured sealant, which is applied over the fastener to provide protection and binding, and cured to form a strong bond.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the seal cap wall thickness is reduced to decrease weight, then the weight decreases, but the dielectric breakdown strength and lightning strike protection capability deteriorate
Solution Approach 1:
The patent employs THV polymer as a specialized material that provides high dielectric breakdown strength (>30.0 kV/mm) in thin-walled constructions. This composite material approach allows the seal cap to achieve both weight reduction and maintained lightning strike protection capability, resolving the contradiction between lightweight design and reliability.
2Weight of moving object
If the seal cap wall thickness is reduced to decrease weight, then the weight decreases, but the corrosion protection capability deteriorates
Solution Approach 1:
The patent utilizes a thin-film seal cap construction with average wall thickness less than 1.5 mm that incorporates THV polymer material providing both corrosion resistance and dielectric strength. The flexible yet protective thin film structure achieves weight reduction while maintaining adequate corrosion protection through the material's inherent properties and sealant integration.
3Ease of manufacture
If the seal cap wall thickness is reduced, then the manufacturing complexity and material usage decrease, but the fluid barrier properties deteriorate
Solution Approach 1:
The patent combines THV polymer material with integrated sealant to create a composite sealing system that achieves adequate fluid barrier properties in thin-walled constructions. This composite approach allows simplified manufacturing of thin caps while the combined material system maintains fluid barrier functionality through the synergistic properties of the polymer and sealant.
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 protects fasteners from lightning strikes and corrosion, maintains lightweight and thin-walled design, and allows for visual inspection, while ensuring electrical insulation and fluid barrier functionality.
Implementation Method 1
the seal cap comprises a material having a dielectric breakdown strength of greater than 30.0 kV/mm
Implementation Method 2
the interior of the seal cap additionally contains the cured sealant which binds the seal cap to the fastener
Data Source
Figure 1~2c
Figure 3a~3b
AI summary
The present disclosure provides methods and articles useful in sealing fasteners, including seal caps and methods of their use, and in particular light weight seal caps having higher dielectric breakdown strength, lower weight, and/or lower wall thickness. In some embodiments, the seal caps according to the present invention are made of a material having a dielectric breakdown strength of greater than 1.0 kV/mm, in some embodiments greater than 15.0 kV/mm, and in some embodiments greater than 50.0 kV/mm. In some embodiments, the seal caps according to the present invention are thin-walled, having an average wall thickness of less than 1.5 mm and in some embodiments less than less than 0.5 mm. In some embodiments, the seal cap comprises a polyurethane polymer, a polythioether polymer, a polysulfide polymer, a fluorinated thermoplastic polymer, a THV polymer, a fluorinated thermoset polymer, an engineering thermoplastic, and/or a PEEK polymer.