Polymeric Aircraft Transparency Hoop Load Bushing
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Solution Overview
Problem
Polymeric windows are not mechanically strong enough to be used in hoop load bearing applications in aircraft, despite their lighter weight and ease of forming complex shapes, due to their inability to effectively resist the stress caused by pressure differentials in aircraft fuselages.
Innovation Solution
A hoop load bearing aircraft transparency design featuring at least one polymeric ply with a bore and a bushing in direct contact with the ply, where the bushing is made of materials like metals, ceramics, or composites, and is tapered or cylindrical to efficiently transfer load, allowing for the use of polymeric windows in hoop load bearing applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If glass windows are used for hoop loaded applications, then mechanical strength is sufficient, but weight is excessive
Solution Approach 1:
The invention uses composite material structures consisting of multiple polymeric plies (such as acrylic) bonded together with interlayers. This composite construction provides enhanced mechanical strength comparable to glass while maintaining the weight advantage of polymeric materials, thereby resolving the contradiction between weight reduction and strength requirements for hoop loaded window applications
2Weight of moving object
If polymeric windows are used to reduce weight, then weight decreases, but mechanical strength becomes insufficient for hoop load bearing
Solution Approach 1:
Multiple polymeric plies are bonded together with interlayers to create a composite structure that significantly enhances hoop load bearing capacity while maintaining lightweight characteristics
Solution Approach 2:
Metallic reinforcement elements (such as straps or rings) are strategically positioned at critical locations around the window periphery where hoop stresses are highest. This localized reinforcement provides the necessary strength enhancement only where needed, rather than uniformly throughout the entire window structure
3Ease of manufacture
If polymeric windows are used for ease of forming complex shapes, then manufacturing flexibility improves, but structural integrity under pressure differential deteriorates
Solution Approach 1:
The composite construction of multiple bonded polymeric plies with interlayers provides the structural integrity necessary to withstand pressure differentials, while the inherent formability of polymeric materials allows for complex shape fabrication, thus resolving the contradiction between manufacturing flexibility and structural reliability
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 design enables efficient load transfer and reduces stress concentration, allowing polymeric windows to effectively resist hoop loads and maintain structural integrity, even under pressure differentials, without the need for additional gaskets or sleeves.
Implementation Method 1
A bushing is located in the at least one bore and is in direct contact with the at least one ply... This bushing can be made of any material that is able to transfer load to the bore wall
Data Source
AI summary
An aircraft transparency includes a first ply having a first major surface and a second major surface. A second ply is spaced from the first ply and has a third major surface and a fourth major surface. A polymeric interlayer is located between the first and second plies. At least one bore extends through the first and second plies and the interlayer. A high strength bushing is located in the bore, with an outer sidewall of the bushing in direct contact with the material of the first and second plies. In one embodiment, the bore is a tapered bore and the bushing has a tapered outer sidewall. In another embodiment, the bore is a cylindrical bore and the bushing has a cylindrical outer sidewall.