Composite Fuselage Joints via Adhesive Bonding

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Solution Overview

Problem

The use of metallic fasteners in composite aircraft fuselage joints increases weight, reducing fuel efficiency and increasing operational costs, while composite fasteners may not withstand desired loads and require redesign due to different material characteristics.

Innovation Solution

The implementation of bonded joints using composite sections with varying properties for different fuselage sections, where the joints are designed to withstand specific loads and reduce weight by optimizing toughness and stiffness based on load expectations, and the use of reinforcing structures to enhance load-bearing capacity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If metallic fasteners are used to join composite fuselage sections, then the joint strength and reliability are improved, but the weight of the fuselage increases

Engineering Contradiction:

Improvejoint strengthVSAvoidfuselage weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The patent replaces metallic mechanical fasteners (screws, bolts, or other metal fastening hardware) with a composite joint structure consisting of a composite section and adhesive bonding. This substitution eliminates the need for heavy metal fasteners while maintaining joint strength through the combination of composite materials and adhesive bonding, directly resolving the contradiction between joint reliability and fuselage weight.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent employs composite materials (such as carbon fiber reinforced polymer) for the joint structure itself, creating a composite section that bonds to the fuselage sections. This use of composite materials allows the joint to achieve sufficient strength without the weight penalty of metallic fasteners, as the composite section is integrated into the fuselage structure rather than being separate hardware.

Inventive Principle:

Principle #40Composite materials

2Weight of moving object

If composite fasteners are used to join fuselage sections, then the weight is reduced, but the load-bearing capacity and reliability are insufficient

Engineering Contradiction:

Improvefuselage weightVSAvoidload-bearing capacity

Core Design Contradiction:

Weight of moving objectVSReliability

Solution Approach 1:

The patent uses composite materials for the joint structure, specifically a composite section with adhesive bonding surfaces. This composite construction provides both weight reduction (avoiding metal fasteners) and sufficient load-bearing capacity (through proper composite material selection and bonding), resolving the contradiction between weight reduction and reliability.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent modifies the properties of the joint structure by changing parameters such as adhesive type, composite material composition, and bonding surface characteristics. These parameter changes optimize the joint's load-bearing capacity to match or exceed that of metallic fasteners while maintaining the weight advantages of composite construction.

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If uniform composite sections are used throughout the fuselage, then the manufacturing process is simplified, but the weight cannot be optimized for specific load requirements

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidfuselage weight

Core Design Contradiction:

Ease of manufactureVSWeight of moving object

Solution Approach 1:

The patent applies different composite section configurations to different locations in the fuselage based on load requirements. High-load areas use reinforced composite sections with additional strengthening features, while low-load areas use lighter composite sections. This local differentiation optimizes weight distribution without requiring complete redesign of the entire fuselage structure, balancing manufacturing complexity with weight optimization.

Inventive Principle:

Principle #3Local quality

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 reduces aircraft weight, enhances fuel efficiency, and minimizes inconsistencies in fuselage sections, allowing for lighter components with sufficient resistance to applied loads, thereby reducing manufacturing time and costs.

Implementation Method 1

a composite section having a cylindrical shape and an outer wall configured to be bonded to an inner wall of a fuselage section

Methodology Applied

Scientific EffectAdhesive bonding: Adhesive

Data Source

PatentUS8960604B1Composite fuselage system with composite fuselage sections

Publication Date: 2015.02.24 THE BOEING CO

AI summary

A method and apparatus comprising a composite section. The composite section has a cylindrical shape. The composite section also has an outer wall configured to be bonded to a first inner wall of a first composite cylindrical fuselage section and a second inner wall of a second composite cylindrical fuselage section for an aircraft.