Composite Aircraft Window Frame Bonding Without Rivet Holes

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Solution Overview

Problem

The existing methods for connecting a window frame to an aircraft fuselage, particularly those made of fiber composite materials, are time and labor intensive due to the use of rivet connections, which provide a punctual load transfer and require extensive processing steps.

Innovation Solution

A method involving a curable connecting layer around the window opening, where a hardened window frame made of fiber composite material is integrated with the fuselage skin through a curing process, creating a continuous and integral connection that eliminates the need for rivet holes and associated processing steps.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If rivet connections are used to connect the window frame to the fuselage skin, then the connection strength is sufficient, but the manufacturing time and labor intensity increase significantly

Engineering Contradiction:
Improveconnection strengthVSAvoidmanufacturing efficiency
Core Design Contradiction:
StrengthVSProductivity

Solution Approach 1:

The patent replaces the mechanical rivet connection system with a chemical bonding system using a curable connecting layer. The window frame is bonded to the fuselage skin through a continuous adhesive layer that is cured in place, eliminating the need for mechanical fasteners and associated processing steps like drilling, countersinking, and rivet installation.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent extracts and eliminates the rivet holes and associated mechanical connection elements from the assembly process. By using a continuous bonding layer, the discrete rivet holes are removed entirely, simplifying the manufacturing process and reducing labor intensity while maintaining connection strength.

Inventive Principle:
Principle #2Taking out (Extraction)

2Reliability

If rivet holes are created and processed to establish rivet connections, then the connection is secure, but the number of processing steps increases

Engineering Contradiction:
Improveconnection reliabilityVSAvoidprocessing complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent removes the entire rivet hole processing sequence from the manufacturing process. Instead of drilling, countersinking, cleaning, and installing rivets, the process uses a continuous bonding layer that is applied and then cured, eliminating multiple discrete processing steps while ensuring reliable connection.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent substitutes mechanical fastening operations with a chemical bonding process. The curable connecting layer provides the bonding function that previously required mechanical rivets, and the curing process replaces the mechanical insertion and tightening operations.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Ease of manufacture

If a continuous bonding layer is used instead of rivet connections, then the manufacturing process is simplified, but the connection must provide sufficient structural support

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidstructural support capability
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The patent replaces the mechanical load transfer through discrete rivets with a continuous chemical bond through the curable connecting layer. This continuous bonding provides distributed load transfer across the entire interface between the window frame and fuselage skin, ensuring sufficient structural support while simplifying manufacturing.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses a composite structure consisting of the window frame, curable connecting layer, and fuselage skin that are jointly cured to form an integral component. This composite approach ensures that the bonding layer becomes structurally integrated with both components, providing sufficient structural support.

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 method results in a more resilient and simplified connection with improved deformation behavior, allowing for reduced effort in construction and potentially shorter fiber lengths, while ensuring a strong and permanent bond between the window frame and the fuselage skin.

Implementation Method 1

arranging a curable connecting layer around the window opening, pressing the window frame onto the connecting layer, curing the composite of fuselage skin, connecting layer and window opening

Methodology Applied
Scientific EffectCuring process: Photopolymerisation

Data Source

PatentEP4470907A1Method for connecting a window frame to a fuselage skin of an aircraft made of a fibre composite material
Publication Date: 2024.12.04 PREMIUM AEROTECH GMBH
  • EP4470907A1 patent drawingFigure 1a~1b
  • EP4470907A1 patent drawingFigure 2~3
  • EP4470907A1 patent drawing

AI summary

A method for joining a window frame (6) to a fuselage skin (2) of an aircraft made of a fiber composite material is proposed, the method comprising providing the window frame, making a window opening in the fuselage skin, arranging a curable bonding layer (8) around the window opening (4), pressing the window frame onto the bonding layer, and curing the composite of fuselage skin, bonding layer and window opening.