Graphene-Coated Inflatable Fabric for Lighter Evacuation Slides
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Solution Overview
Problem
Conventional inflatable aircraft evacuation slides are heavy due to the weight of their fabric, which limits their weight reduction efforts, as increasing inflation pressure to reduce size increases stress on the fabric, necessitating heavier gauge materials to maintain strength.
Innovation Solution
A lightweight, high-strength inflatable structure using a flexible fabric coated with a polyurethane resin containing graphene nanoplatelets and a phosphorus-based flame retardant, which improves tensile and gas barrier properties without adding weight, allowing for a 25% weight savings while maintaining strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the physical size of structural members is reduced by increasing inflation pressure, then the size of the evacuation slide is reduced, but the stress on the slide fabric increases requiring heavier gauge material
Solution Approach 1:
The patent applies composite materials by incorporating graphene nanoplatelets into the polyurethane coating matrix to create a nanocomposite material that provides enhanced mechanical strength and stiffness. This allows the fabric to withstand higher inflation pressures and stresses while maintaining a lighter weight and smaller size, resolving the contradiction between reducing slide size and managing fabric stress
Solution Approach 2:
The patent changes the physical and chemical parameters of the coating material by adding graphene nanoplatelets at the nanoscale level. This fundamental material parameter change enables the coating to provide superior strength-to-weight ratio, allowing the fabric to handle increased stress from higher inflation pressures without requiring heavier gauge material
2Strength
If heavier gauge fabric is used to maintain strength under increased inflation pressure, then the fabric strength is maintained, but the overall weight of the evacuation slide increases
Solution Approach 1:
The patent uses composite materials by integrating graphene nanoplatelets into the polyurethane coating to create a nanocomposite with enhanced mechanical properties. This composite approach provides superior strength and stiffness at the nanoscale, enabling the use of lighter gauge fabric that can still withstand the required stresses, thereby reducing overall slide weight while maintaining fabric strength
Solution Approach 2:
The patent applies local quality by concentrating the reinforcement at the molecular level within the coating matrix rather than throughout the entire fabric structure. The graphene nanoplatelets are dispersed within the polyurethane coating to provide localized strength enhancement where the coating interfaces with the fabric, allowing weight reduction in other areas while maintaining overall fabric strength
3Reliability
If multiple layers of coating are applied to the base fabric, then the fabric meets flame retardant and air-impervious requirements, but the areal weight of the fabric increases
Solution Approach 1:
The patent applies composite materials by incorporating graphene nanoplatelets into the polyurethane coating matrix. The graphene provides enhanced barrier properties and structural reinforcement, allowing for a thinner, lighter coating that still achieves the required air-impervious and flame retardant performance standards, thereby reducing fabric areal weight while maintaining reliability
Solution Approach 2:
The patent changes the functional parameters of the coating by adding graphene nanoplatelets that provide multifunctional properties including enhanced barrier performance, structural strength, and flame retardancy. This parameter enhancement allows the coating to achieve multiple performance requirements at reduced thickness, reducing the areal weight contribution of the coating layers
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 results in a lightweight evacuation slide with enhanced strength and gas barrier properties, reducing the payload capacity required for aircraft while ensuring safe passenger evacuation during emergencies.
Implementation Method 1
a polyurethane resin having at least 0.01% by weight graphene nanoplatelets
Implementation Method 2
The addition of fully-dispersed graphene nanoplatelets to the organic polymer matrix yields gas barrier and tensile properties not heretofore seen in slide fabrics of comparable weight
Implementation Method 3
at least 0.05% by weight of a phosphorus-based flame retardant added thereto
Implementation Method 4
the phosphorus based flame retardant acts as a dispersant to improve the uniform dispersion of the graphene nanoplatelets within the matrix
Implementation Method 5
Graphene oxide, which is a polar molecule, has an affinity for the polar molecules that make up the phosphorus based flame retardant
Implementation Method 6
thermal exfoliation of graphene nanoplatelets yields graphene nanoplatelets with residual graphene oxide
Data Source
AI summary
A high-strength, lightweight inflatable structure is formed of at least one flexible fabric member that, in an inflated condition, forms a self-supporting structure. The flexible fabric member is formed from a bare fabric having an areal weight of less than 4.5 oz/yd2. The fabric is coated with air-impervious resin coating comprising a polyurethane resin having a mixture of graphene nanoplatelets and a phosphorus-based flame retardant added thereto. The thermally exfoliated graphene nanoplatelets contain residual graphene oxide. Graphene oxide, which is a polar molecule, has an affinity for the polar molecules that make up the phosphorus based flame retardant. Accordingly, in addition to its inherent flame-retardant properties, the phosphorus based flame retardant acts as a dispersant to improve the uniform dispersion of the graphene nanoplatelets within the matrix, thus reducing or eliminating the need to use additional dispersants.