Composite Resin Window Frame for Aircraft Fuselage

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Solution Overview

Problem

Airplane window frame assemblies made from composite resin face challenges in strength, weight, and manufacturing complexity due to the need for an upstanding reinforcement leg, which adds weight, cost, and complexity, and is difficult to mold.

Innovation Solution

A composite resin window frame design that eliminates the upstanding leg, utilizing a thicker composite fuselage skin to carry loads, allowing the frame to be lighter, easier to manufacture, and more cost-effective, while maintaining structural integrity through the strength of the composite fuselage skin and stringers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If an upstanding reinforcement leg is added to the composite resin window frame, then the strength and stability of the frame is improved, but the weight and manufacturing complexity increase

Engineering Contradiction:
Improveframe strengthVSAvoidframe weight
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The patent removes the upstanding reinforcement leg from the composite resin window frame design. Instead of adding a perpendicular flange to provide strength, the invention relies on the inherent strength of the composite fuselage skin and the optimized flat frame structure to carry the loads, thereby reducing weight while maintaining structural integrity.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the structural parameters of the window frame by eliminating the vertical leg component and redistributing the load-bearing function to the flat frame structure and fuselage skin. This parameter change reduces the number of parts and overall weight while maintaining strength through proper load path design.

Inventive Principle:
Principle #35Parameter changes

2Stability of the object's composition

If an upstanding reinforcement leg is added to the composite resin window frame, then the stability of the frame is improved, but the manufacturing difficulty and cost increase

Engineering Contradiction:
Improveframe stabilityVSAvoidmanufacturing ease
Core Design Contradiction:
Stability of the object's compositionVSEase of manufacture

Solution Approach 1:

The patent extracts the upstanding reinforcement leg from the design, simplifying the molding process. The flat frame configuration without perpendicular protrusions is easier to mold, assemble, and install, reducing manufacturing complexity and cost while maintaining frame stability through the composite skin and optimized geometry.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent merges the frame structure directly with the fuselage skin interface, eliminating the need for separate reinforcement legs. The outer flange of the frame integrates with the fuselage structure, providing stability through this unified connection rather than through additional perpendicular support elements.

Inventive Principle:
Principle #5Merging (Combining)

3Weight of moving object

If the window frame is made flat without an upstanding leg, then the weight and manufacturing complexity are reduced, but the strength to carry loads may be compromised

Engineering Contradiction:
Improveframe weightVSAvoidload-carrying strength
Core Design Contradiction:
Weight of moving objectVSStrength

Solution Approach 1:

The patent utilizes composite materials for both the window frame and fuselage skin, leveraging the high strength-to-weight ratio of composites. The composite construction allows the flat frame design to achieve sufficient load-carrying strength without the additional weight of metal reinforcement legs, as the composite structure can be optimized at the material level.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent makes the fuselage skin multi-functional by having it serve both as the external shell and as a structural reinforcement element. The thicker composite skin at the window aperture carries the loads that would traditionally require separate reinforcement legs, integrating the skin into the load-bearing system and eliminating the need for additional weight.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP2069130B1Improved composite resin window frame construction for airplanes and method of producing the same
Publication Date: 2018.12.19 THE BOEING CO
  • EP2069130B1 patent drawingFigure 1~2
  • EP2069130B1 patent drawingFigure 3~5
  • EP2069130B1 patent drawingFigure 5A~5C

AI summary

A composite resin window frame for installation in a composite resin airplane fuselage has an inner flange for receiving and securely affixing an aircraft window transparency and an outer flange adapted for connection to the airplane fuselage structure. The frame has a generally flat configuration which does not require any additional strength enhancing member such as an additional flange perpendicular to the structure. The composite resin window frame has sufficient strength to securely affix a window transparency to a composite resin fuselage.