Nonwoven Flexible Composites for Inflatable Devices
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Solution Overview
Problem
Current woven substrates used in inflatable emergency devices like evacuation slides and life rafts suffer from crimp effects that compromise mechanical performance, lead to unnecessary weight, and require multiple layers of coating, increasing weight and cost.
Innovation Solution
The use of nonwoven materials with straight laid fibers and isocyanate-based adhesives or primers, coated with polyurethane on both sides, which minimizes crimp effects and allows for a thinner, lighter, and stronger composite material with improved adhesion and air-holding properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If woven substrates are used for inflatable structures, then strength and rigidity are provided, but crimp effects reduce mechanical performance and increase weight
Solution Approach 1:
The patent changes the fundamental structural parameter from woven architecture to nonwoven architecture. This eliminates the crimp effect inherent in woven fabrics where yarns must interlace, creating undulations that consume load before tension is developed. The nonwoven structure with straight, parallel fibers provides full load-bearing capacity from the start, achieving higher mechanical performance at lower weight.
Solution Approach 2:
The patent creates a composite material system combining nonwoven fabric substrate with polymeric coatings (such as polyurethane). This composite approach allows the nonwoven fabric to provide structural strength while the coating provides air-holding properties, eliminating the need for heavy multiple coating layers required on woven substrates and achieving optimal weight-strength balance.
2Strength
If woven construction is used, then fabric structure is formed, but yarn crimp reduces tensile and compressive properties
Solution Approach 1:
The patent fundamentally changes the fabric structure parameter from woven (interlacing yarns) to nonwoven (random or oriented fibers bonded together). This eliminates the crimp effect where yarns must bend over and under each other, allowing fibers to remain straight and bear full tensile and compressive loads without geometric inefficiency.
3Reliability
If multiple layers of coating are applied to woven substrates, then air-holding properties are achieved, but weight and cost increase
Solution Approach 1:
The patent changes the substrate surface topology parameter from the peak-valley structure of woven fabrics to the relatively flat surface of nonwoven fabrics. This eliminates voids between interlacing yarns, allowing single or fewer coating layers to achieve complete coverage and effective air-holding properties, reducing both weight and material cost.
Solution Approach 2:
The patent creates an optimized composite where the nonwoven fabric substrate works synergistically with thinner polymeric coating layers. The nonwoven structure's inherent porosity and surface characteristics allow effective coating adhesion and air-trapping with minimal coating thickness, achieving reliable air-holding with reduced weight compared to multiple heavy coatings on woven substrates.
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
This approach results in a high-strength, lightweight material with reduced coating needs, achieving up to 50% less weight and maintaining structural integrity under high inflation pressures while meeting FAA requirements for tensile strength and durability.
Implementation Method 1
an isocyanate-based adhesive or primer
Implementation Method 2
a first layer of polyurethane on one surface of the substrate of nonwoven material and a second layer of polyurethane on a second surface of the substrate of nonwoven material
Data Source
AI summary
Embodiments of the present invention provide systems and methods for using nonwoven materials for evacuation slides, life rafts, life vests, and other life-saving inflatable devices. The nonwoven materials have a substrate layer with continuous filament fibers formed in various directions. The substrate layer then has a first and second layer of polyurethane. The first and second layers of polyurethane may be laminated or coated to a nonwoven substrate of the filament fibers. An isocyanate-based adhesive or primer may be particularly useful in causing cross-linking of the materials to one another.