Sacrificial Fire Shield Composite for Aircraft Firewall
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Solution Overview
Problem
Aircraft components require fire protection that is lightweight, resistant to fatigue, and has low thermal conductivity, while metallic shielding is undesirable due to structural issues and close clearance limitations, and existing thermal protection systems may not adequately meet these requirements.
Innovation Solution
A sacrificial fire shield comprising a fiberglass layer, a ceramic fiber layer with heat-resistant fibers pre-impregnated with rubber, and a durable outer layer of aramid fibers, which is designed to be lightweight, flexible, and capable of press curing into a form factor, providing effective fire protection by creating a tortuous path for heat energy and burning away during a fire event to contain flames within a compartment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metallic shielding is used to provide fire protection, then fire resistance is improved, but weight increases and structural issues arise
Solution Approach 1:
The patent uses a composite material consisting of ceramic fibers embedded in a polymer matrix (such as polyimide or PEEK). This composite provides fire resistance comparable to metallic shielding while significantly reducing weight. The ceramic fibers (e.g., alumina, silica) provide thermal stability and fire protection, while the polymer matrix provides structural integrity and flexibility, achieving a lightweight fire-resistant shielding solution.
Solution Approach 2:
The patent employs flexible fire-resistant coatings or thin film structures made from polymer-ceramic composites. These flexible shields can be applied as conformal layers on aircraft components, providing fire protection without the rigid weight and structural constraints of metallic shielding. The flexibility allows for close clearances and complex geometries while maintaining fire resistance.
2Reliability
If metallic shielding is used to provide fire protection, then fire resistance is improved, but structural issues and clearance limitations occur
Solution Approach 1:
The flexible polymer-ceramic composite shields can conform to complex geometries and tight clearances that rigid metallic shields cannot accommodate. The material's flexibility allows it to be installed in confined spaces and on curved surfaces, providing fire protection without interfering with surrounding structures or mechanical movements.
Solution Approach 2:
The patent modifies the physical and chemical parameters of the shielding material by using polymer matrices with specific thermal properties (such as high glass transition temperature of PEEK or polyimide). These parameter changes enable the material to maintain structural integrity at elevated temperatures while remaining flexible, thus adapting to various structural configurations without the rigidity constraints of metals.
3Reliability
If existing thermal protection systems are used, then fire protection is provided, but they do not adequately meet lightweight and fatigue resistance requirements
Solution Approach 1:
The polymer-ceramic composite structure provides both fire protection and fatigue resistance. The ceramic fibers reinforce the polymer matrix, creating a composite that is resistant to thermal degradation and mechanical fatigue. This composite structure maintains its protective properties through repeated thermal cycles and mechanical loading, addressing the fatigue resistance requirement that existing systems fail to meet.
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 sacrificial fire shield effectively reduces certification costs by ensuring the firewall remains intact, containing fires within one compartment and providing extended fireproof life to fire seals, while being lightweight and resistant to structural interference, thus addressing the limitations of metallic shielding.
Implementation Method 1
a ceramic fiber layer including heat-resistant fibers that is positioned on the fiberglass layer
Implementation Method 2
The sacrificial fire shield is designed to be lightweight, flexible, and capable of press curing into a form factor, providing effective fire protection by creating a tortuous path for heat energy and burning away during a fire event
Data Source
AI summary
An example sacrificial fire shield for shielding an aircraft part during a fire event includes a fiberglass layer, a ceramic fiber layer including heat-resistant fibers that is positioned on the fiberglass layer. The ceramic fiber layer and the fiberglass layer comprise a stack-up and the stack-up is pre-impregnated with rubber. The sacrificial fire shield also includes a durable outer layer comprising aramid fibers. The durable outer layer is positioned on the ceramic fiber layer to enable press curing into a form factor.