Sandwich Window Panel with Foam Core for Aircraft

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Solution Overview

Problem

Current production and assembly techniques for fibre-reinforced polymer composite window panels in aircraft and spacecraft are labor-intensive and time-consuming, requiring complex riveting procedures and substantial production effort.

Innovation Solution

A sandwich-structured window panel with fibre-reinforced polymer skins and a lightweight foam core, allowing for a simplified assembly process by eliminating the need for rigid window frames and enabling integration of insulation and system components through the panel core, using a method that includes resin infusion and curing to form a monolithic structure with reduced residual stresses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If traditional rigid window frames with riveting procedures are used, then structural strength is ensured, but production time and assembly effort increase substantially

Engineering Contradiction:
Improvestructural strengthVSAvoidproduction time
Core Design Contradiction:
StrengthVSProductivity

Solution Approach 1:

The patent merges the window frame structure with the panel skin by integrating the aperture surround directly into the composite panel manufacturing process. The reinforcement layers are embedded within the composite structure during resin infusion, eliminating the need for separate frame assembly and riveting operations. This integration maintains structural strength while dramatically reducing production time and assembly effort.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent employs fibre-reinforced polymer composite materials with embedded reinforcement layers (such as glass fibre, carbon fibre, or aramid fibre mats) to create a monolithic panel structure that incorporates the aperture surround. This composite construction provides both structural strength and aperture definition in a single manufactured component, replacing traditional multi-part metal frame assemblies.

Inventive Principle:
Principle #40Composite materials

2Reliability

If complex riveting procedures are employed for window assembly mounting, then reliable attachment is achieved, but assembly effort and time delays increase

Engineering Contradiction:
Improveattachment reliabilityVSAvoidassembly effort
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The window aperture surround is merged into the panel structure itself through embedded reinforcement layers that are cured as part of the composite manufacturing process. This creates a permanent, integrated attachment point that eliminates the need for separate riveting or fastening operations, thereby maintaining reliable attachment while greatly simplifying assembly procedures.

Inventive Principle:
Principle #5Merging (Combining)

3Strength

If substantial production effort is invested in traditional composite panel assembly, then structural integrity is maintained, but production efficiency decreases

Engineering Contradiction:
Improvestructural integrityVSAvoidproduction efficiency
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The reinforcement layers for the aperture surround are placed and embedded into the panel during the initial composite manufacturing process, before final curing. This preliminary integration of structural elements into the monolithic panel structure eliminates subsequent assembly steps, thereby maintaining structural integrity while significantly improving production efficiency.

Inventive Principle:
Principle #10Preliminary action

4Reliability

If traditional window frame structures are used, then aerodynamic performance is maintained, but vehicle mass increases

Engineering Contradiction:
Improveaerodynamic performanceVSAvoidvehicle mass
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The patent uses fibre-reinforced polymer composite materials for the panel structure, which provide high strength-to-weight ratio and can be tailored to maintain aerodynamic performance. The integrated aperture surround design eliminates heavy metal frames while preserving the necessary structural and aerodynamic characteristics through optimized composite layup and reinforcement placement.

Inventive Principle:
Principle #40Composite materials

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 significantly simplifies and accelerates the mounting of window assemblies, reduces thermal insulation needs, and provides a lighter aircraft structure with increased cabin space and reduced mass, while maintaining structural integrity and aerodynamic performance.

Implementation Method 1

the layers of reinforcement fibres are impregnated with a polymer resin material

Methodology Applied
Scientific EffectResin infusion: Permeation

Implementation Method 2

the impregnated layers of reinforcement fibres are cured to bond together with minimal residual stresses in the foam core

Methodology Applied
Scientific EffectCuring: Photopolymerisation

Data Source

PatentEP2842865B1Window panel for an airframe and method of producing same
Publication Date: 2019.12.18 AIRBUS OPERATIONS GMBH
  • EP2842865B1 patent drawingFigure 1~4
  • EP2842865B1 patent drawingFigure 5(a)~7
  • EP2842865B1 patent drawingFigure 8(a)~9

AI summary

The present invention provides a window panel (1) for a body structure of a vehicle (V), especially an airframe of an aircraft or spacecraft, comprising: a first skin (2) which extends over a first side (3) of the panel (1) to form an outer skin of the vehicle body structure; a second skin (4) which extends over a second side (5) of the panel (1) to form an inner skin of the vehicle body structure; and a core (6), especially a foam core, located between and covered by the first and second skins (2, 4) in a sandwich structure. The window panel (1) includes at least one window aperture (7) formed through the first layer (2), the core (6), and the second layer (4). The core (6) may be confined to or extends over a limited extent, region or part of the panel (1). Thus, the first skin (2) and/or the second skin (4) may extend over or cover/s a greater area of the panel (1) than the core (6).