Composite Fireproofing Skin for Aeronautical Structural Parts

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Solution Overview

Problem

Existing fire protection techniques for composite material parts in aeronautics result in significant mass addition, shape mismatch, and sensitivity to mechanical degradation, leading to reduced effectiveness in withstanding flame exposure and thermal stress.

Innovation Solution

A semi-rigid composite skin with a glass fabric ply and needled quartz fiber thermal insulation, bonded with a high-temperature adhesive and riveted for secure attachment, allowing for precise shape adaptation and moderate mass addition, while protecting against mechanical and thermal attacks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If metal sheets are used for fire protection, then thermal protection is improved, but mass addition becomes significant

Engineering Contradiction:
Improvethermal protectionVSAvoidmass addition
Core Design Contradiction:
TemperatureVSWeight of moving object

Solution Approach 1:

The patent uses a composite material consisting of a semi-rigid skin made from fiber-reinforced polymer composite material combined with thermal insulation material, replacing traditional metal sheets. This composite structure provides effective thermal protection while significantly reducing mass addition compared to metal sheet solutions.

Inventive Principle:
Principle #40Composite materials

2Temperature

If protective coatings are applied to composite material parts, then fire resistance is improved, but the coatings are susceptible to perforation and tearing

Engineering Contradiction:
Improvefire resistanceVSAvoidcoating integrity
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The patent employs a semi-rigid skin made of composite material that acts as a flexible yet protective shell around the thermal insulation. This skin provides mechanical protection against perforation and tearing while maintaining fire resistance, overcoming the fragility of conventional protective coatings.

Inventive Principle:
Principle #30Flexible shells and thin films

3Strength

If thermal insulation is protected with metal shells, then mechanical protection is improved, but thermal expansion differences generate mechanical stresses

Engineering Contradiction:
Improvemechanical protectionVSAvoidmechanical stresses
Core Design Contradiction:
StrengthVSStress or pressure

Solution Approach 1:

The patent changes the material parameters of the protective skin by using a composite material with thermal expansion properties matched to the underlying structure. The semi-rigid composite skin has thermal expansion characteristics similar to the aluminum alloy structure, preventing differential thermal expansion stresses while providing necessary mechanical protection.

Inventive Principle:
Principle #35Parameter changes

4Temperature

If conventional protective techniques are used, then fire protection is achieved, but the protective elements do not conform to the shape of the component

Engineering Contradiction:
Improvefire protectionVSAvoidshape conformity
Core Design Contradiction:
TemperatureVSShape

Solution Approach 1:

The patent uses a semi-rigid composite skin that can be formed into curved and complex geometries to precisely conform to the shape of the underlying structure. The composite material allows for shaping and molding that accommodates complex aerodynamic surfaces while maintaining fire protection effectiveness.

Inventive Principle:
Principle #14Spheroidality (Curvature)

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 provides effective thermal protection with a 25% lower mass addition compared to traditional metal sheet solutions, maintaining structural integrity and preventing perforation and ignition during 15-minute flame exposure at 1100°C, meeting aeronautical standards.

Implementation Method 1

a thermal insulator (120) interposed between the inner face of the skin (110) and the part (100)

Methodology Applied
Scientific EffectThermal insulation: Thermal Insulation

Implementation Method 2

The skin (110) is bonded to the part (100) by an adhesive (130) resistant to a temperature of at least 200 °C

Methodology Applied
Scientific EffectAdhesion: Adhesive

Data Source

PatentEP3271243B1Method and device for fireproofing a composite material part
Publication Date: 2021.07.14 DAHER AEROSPACE
  • EP3271243B1 patent drawingFigure 1~2

AI summary

The invention relates to a device for fireproofing a section of a structural part (100) formed of a composite material. Said device is characterized in that it comprises: a. a skin (110, 210) comprising an outer surface that is intended to face the flame and an inner surface, said skin being formed of a composite material that comprises a fiber reinforcement in a polymer matrix, and comprising means (111) for attachment to the structural part; and b. an inorganic needled felt layer (120) inserted between the inner surface of the skin and a surface of the structural part (100).