LTA Hull Laminate with Melt-Bonded EVOH for Weight Reduction
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Solution Overview
Problem
Current lighter-than-air vehicle hull materials face challenges in achieving a balance between weight reduction and strength enhancement while maintaining gas impermeability, UV resistance, and chemical stability, especially at high altitudes.
Innovation Solution
A laminate structure incorporating a reinforcing fibre layer with Ethylene Vinyl Alcohol (EVOH) films melt-bonded directly onto the fibre layer, combined with a metallized polymer film for additional protection, and a polyethylene terephthalate (PET) gas barrier layer, optimized for weight reduction and enhanced strength-to-weight ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional multi-layer laminate structures with multiple adhesive layers are used, then gas barrier properties are improved, but weight increases and manufacturing complexity increases
Solution Approach 1:
The patent combines the gas barrier function and adhesive function into a single EVOH layer. The EVOH film is melt-bonded directly to the fibre reinforcement layer, eliminating the need for separate adhesive layers while maintaining both gas barrier properties and structural adhesion. This reduces the number of layers and overall weight of the hull material.
Solution Approach 2:
The EVOH layer serves multiple functions simultaneously: it provides the gas barrier function to prevent helium permeation, acts as an adhesive layer through melt-bonding to the fibre layer, and contributes to the mechanical strength of the laminate. This multi-functionality reduces the need for additional specialized layers.
2Reliability
If traditional multi-layer laminate structures with multiple adhesive layers are used, then gas barrier properties are improved, but device complexity increases
Solution Approach 1:
The patent merges the gas barrier layer and adhesive layer into a single EVOH layer that performs both functions. This reduces the number of discrete layers from three or more to just two (fibre layer and EVOH layer), simplifying the overall laminate structure while maintaining gas barrier integrity.
Solution Approach 2:
The EVOH layer is designed to provide multiple functions within a single layer: gas barrier properties to prevent helium permeation and adhesive properties through melt-bonding to the fibre reinforcement. This multi-functionality reduces the complexity of the laminate structure by eliminating the need for separate functional layers.
3Strength
If Zylon fibres are used for high strength, then tensile strength is improved, but susceptibility to photo-degradation increases
Solution Approach 1:
The EVOH layer acts as an intermediary protective barrier between the Zylon fibres and the external environment. It shields the Zylon fibres from UV radiation and photo-degradation while maintaining the high tensile strength properties of the Zylon fibre reinforcement. This protective intermediary layer allows the use of high-performance Zylon fibres without their susceptibility to environmental degradation.
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 laminate achieves a significant reduction in weight while maintaining high tensile strength, excellent gas barrier properties, and resistance to UV radiation, ozone, and thermal degradation, with a superior strength-to-weight ratio compared to existing materials.
Implementation Method 1
a first Ethylene Vinyl Alcohol, EVOH, film melt-bonded into the fibre layer on one side of the fibre layer
Data Source
AI summary
A lighter than air vehicle with a hull, a laminate for such hull and a method of production of such laminate A lighter-than-air vehicle comprising a hull of a laminate material with a reinforcing fibre layer, for example Zylon®, and a first, and optionally second, Ethylene Vinyl Alcohol film melt-bonded into the fibre layer. A weathering layer protects the fibres against UV degradation.