Multilayer Inflatable Skin Bonding Through Reinforcing Fabric

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Solution Overview

Problem

Existing inflatable structures face issues with maintaining rigidity and integrity due to film detachment under high pressure, leading to leaks and reduced lifespan, particularly in applications requiring lightness and minimal volume.

Innovation Solution

A multilayer waterproof skin composed of polymer films trapping a reinforcing fabric, connected by armor wires and stitched to ensure tightness, with the reinforcing fabric covering the loops of the threads and films bonded through the fabric's meshes, allowing for prestressed structures that maintain rigidity and minimize mass.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If films are bonded to the outer surfaces of the inflatable beam, then the beam achieves initial structural integrity, but the films can detach under high internal pressure leading to leaks and loss of rigidity

Engineering Contradiction:
Improvestructural integrityVSAvoidfilm bonding stability
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

Instead of bonding films to the outer surface where detachment occurs, the patent inverts the bonding approach by bonding films to the inner surface of the inflatable structure. This inversion places the bonding interface in a region protected from external detachment forces, allowing the films to remain securely attached even under high internal pressure.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The patent implements a multilayered configuration where multiple films are nested within each other and bonded to the reinforcing fabric. This nested structure creates redundant bonding interfaces, so that even if one film detaches, others remain bonded to maintain structural integrity and prevent leaks.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Reliability

If multiple films are bonded together to ensure airtightness, then the structure maintains pressure, but the bonding process becomes complex and difficult to implement

Engineering Contradiction:
ImproveairtightnessVSAvoidbonding process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines multiple films and reinforcing fabric into a single integrated multilayered assembly. This merging simplifies the bonding process by creating a unified structure where all components are bonded together in one system, rather than requiring separate bonding operations for each film layer.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent uses composite material construction by bonding polymer films to reinforcing fabric to create a unified multilayered composite structure. This composite approach simplifies the overall bonding process while maintaining both airtightness and structural strength through the synergistic combination of materials.

Inventive Principle:
Principle #40Composite materials

3Reliability

If spray polymer solution onto reinforcing fabric, then the fabric becomes sealed, but the structure becomes relatively heavy and the spraying is difficult to achieve uniformly

Engineering Contradiction:
Improvesealing qualityVSAvoidstructure weight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The patent replaces heavy spray-applied polymer coatings with thin film structures that provide equivalent sealing functionality. These thin films achieve uniform coverage without the weight penalty of sprayed polymer, while maintaining reliable airtightness through their continuous, defect-free structure.

Inventive Principle:
Principle #30Flexible shells and thin films

4Ease of manufacture

If films are bonded to reinforcing fabric on the inside of the beam, then bonding is easier to implement, but the film can detach from the fabric when high pressure is applied

Engineering Contradiction:
Improvebonding easeVSAvoidfilm-to-fabric bonding stability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent inverts the conventional bonding arrangement by bonding films to the inner surface rather than the outer surface. This inversion changes the stress distribution at the bonding interface, allowing the film-to-fabric bonding to remain stable under high internal pressure while maintaining ease of manufacturing.

Inventive Principle:
Principle #13The other way round (Inversion)

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 effectively maintains structural rigidity over time, reduces the risk of leaks, and simplifies the film/film sizing process, enhancing the mechanical performance and lifespan of inflatable structures while minimizing weight and volume.

Implementation Method 1

a step of bonding the second film (30a, 30b) to the first film (10a, 10b) through the reinforcing fabrics (20a, 20b) using an adhesive

Methodology Applied
Scientific EffectAdhesive bonding: Adhesive

Implementation Method 2

made load-bearing by creating a prestressed state after internal pressurization

Methodology Applied
Scientific EffectPressurization: Pressurisation

Data Source

PatentEP3221138B1Inflatable structure with a multilayer tight skin and manufacturing processes thereof
Publication Date: 2020.08.12 AIRBUS (SAS)
  • EP3221138B1 patent drawingFigure 1~3
  • EP3221138B1 patent drawingFigure 4~5C
  • EP3221138B1 patent drawingFigure 6~8

AI summary

The subject matter of the invention is a multilayer sealed skin, in particular for an inflatable structure and that comprises a first polymer film (10a or 10b), a reinforcing fabric (20a or 20b) disposed on the first polymer film and a second polymer film (30a or 30b) disposed on the reinforcing fabric and adhered by means of an adhesive to the first polymer film through cavities in the reinforcing fabric. The invention can be applied to the production of an inflatable structural element such as an inflatable beam for which the skin forms an outer wall of the structural element and for which the first film (10a or 10b) of the skin forms an inner face of the outer wall of the structural element, and the second film (30a or 30b) forms an outer face of said wall.