Polyurethane Foam Gasket With Selective Tack and Moisture Barrier
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Solution Overview
Problem
Existing gaskets used in aircraft, particularly between antennas and the aircraft skin, fail to prevent moisture penetration, leading to corrosion, and exhibit non-selective retentivity issues, where parts stick to the aircraft skin or antenna, causing destruction upon removal.
Innovation Solution
A gasket material comprising a foam core with a tacky, cured polyurethane gel and a moisture-impermeable PTFE layer, providing elasticity, low water absorption, and selective retentivity, ensuring a waterproof seal and easy separation without damaging the aircraft surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a gasket is compressed between mating surfaces to prevent moisture penetration, then sealing effectiveness is improved, but the gasket material absorbs moisture which encourages corrosion formation
Solution Approach 1:
The gasket combines a foam core material with a polyurethane gel layer. The foam provides compressibility and sealing capability, while the gel layer provides moisture resistance and corrosion protection. This composite structure allows the gasket to maintain sealing effectiveness without absorbing harmful amounts of moisture.
Solution Approach 2:
The polyurethane gel is applied specifically to the surfaces of the foam core that contact the mating surfaces. This localized application provides moisture resistance at the critical sealing interface while maintaining the compressibility of the foam core, addressing the contradiction between sealing effectiveness and moisture absorption.
2Reliability
If a gasket material provides high retentivity to stick to mating surfaces, then sealing effectiveness is improved, but the gasket sticks non-selectively to both the aircraft skin and antenna causing destruction upon removal
Solution Approach 1:
The polyurethane gel is applied only to specific surfaces of the foam core, creating selective adhesion. The gel provides strong bonding at the sealing interface while the foam core remains relatively non-adhesive, allowing for clean removal without destruction of the gasket or damage to mating surfaces.
Solution Approach 2:
The gasket is divided into two functional components: the foam core for structural support and compression, and the gel layer for selective adhesion and sealing. This segmentation allows each component to perform its specific function without the negative effects of the other.
3Duration of action of stationary object
If a gasket material is made flexible and compliant to accommodate temperature and pressure cycling, then durability is improved, but the gasket may deform excessively under compression
Solution Approach 1:
The foam core provides dimensional stability and resistance to excessive compression, while the gel layer provides flexibility and compliance. This composite structure allows the gasket to accommodate temperature and pressure cycling without excessive deformation or loss of shape.
Solution Approach 2:
The gel layer's viscoelastic properties allow it to change its mechanical parameters in response to temperature and pressure changes. Under compression, the gel softens to accommodate the load, then recovers its shape when the load is removed, providing durability without permanent deformation.
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 gasket material effectively prevents moisture ingress, maintains seal integrity under temperature and pressure cycling, and allows for easy removal without sticking issues, ensuring a long-lasting, effective seal.
Implementation Method 1
a cured polyurethane gel layer on the upper and/or lower surfaces, the cured polyurethane gel layer at least partly penetrating the body of the foam carrier
Implementation Method 2
a moisture impervious layer, such as a PTFE layer, on top of one of either the upper or lower surfaces of the cured polyurethane layer
Implementation Method 3
When the fasteners are tightened down, they compress the gasket typically with some deformation or gasket 'squeeze out'
Implementation Method 4
a tacky, cured polyurethane gel... maintaining sufficient retentivity of a gel to gasket carrier
Data Source
AI summary
A number of tacky polyurethane or other gel comprising composites are provided. The composites have foam carriers, which may be open cell, semi-open cell, reticulated or closed-cell foam. The tacky gel which, in one embodiment, may be polyurethane, typically comprising a thin surface coating on the foam gel and the foam is partially or fully saturated with the same gel comprising the thin surface layer of the foam. The skeletons may be included in the composite to provide additional structure integrity, and a moisture proof layer may be added to the top and/or bottom surfaces of the foam/gel.