Composite Wing Joint Isolation Plate for Galvanic Corrosion

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Solution Overview

Problem

Direct attachment of carbon-fiber reinforced composite materials to aluminum structures in aircraft wings leads to galvanic corrosion due to electrochemical potential differences, necessitating the use of costly titanium components to prevent corrosion.

Innovation Solution

A structural wing joint assembly that uses a metallic plate to separate composite wing panels from aluminum structures, reducing direct contact and employing fewer, smaller fasteners, thereby reducing manufacturing costs and weight while preventing corrosion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If carbon-fiber reinforced composite materials are directly attached to aluminum structures, then manufacturing costs are reduced and weight is decreased, but galvanic corrosion occurs due to electrochemical potential differences

Engineering Contradiction:

Improveaircraft weightVSAvoidgalvanic corrosion

Core Design Contradiction:

Weight of moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an intermediate isolation layer (such as epoxy coating, anodized layer, or polymer coating) between the carbon-fiber reinforced composite material and the aluminum structure. This intermediary prevents direct galvanic contact while allowing the lightweight composite material to be used, thus reducing aircraft weight without suffering from galvanic corrosion. The coating acts as a barrier that eliminates the electrochemical reaction pathway between the two dissimilar metals.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If titanium components are used to prevent corrosion at composite-aluminum joints, then corrosion resistance is improved, but manufacturing costs and weight significantly increase

Engineering Contradiction:

Improvecorrosion resistanceVSAvoidaircraft weight

Core Design Contradiction:

Object-affected harmful factorsVSWeight of moving object

Solution Approach 1:

The patent replaces expensive titanium components with cheaper alternative corrosion prevention methods such as epoxy coatings, anodized aluminum layers, or polymer coatings. These sacrificial protective layers can be applied economically and provide sufficient corrosion protection without the weight and cost penalty of titanium. The coating serves as a disposable barrier that protects the aluminum structure from galvanic corrosion.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent changes the protective approach from using a different metal material (titanium) to using surface treatment or coating parameters. By modifying the surface properties of aluminum through anodization or applying epoxy coatings, the patent achieves corrosion resistance without changing the base material, thus avoiding the weight and cost increase associated with titanium components.

Inventive Principle:

Principle #35Parameter changes

3Weight of moving object

If fewer and smaller fasteners are used in the wing joint assembly, then manufacturing costs and weight are reduced, but structural strength may be compromised

Engineering Contradiction:

Improvejoint assembly weightVSAvoidjoint strength

Core Design Contradiction:

Weight of moving objectVSStrength

Solution Approach 1:

The patent applies preliminary surface treatments (such as anodization or epoxy coating) to the aluminum structure before fastener installation. This preliminary protective action prevents galvanic corrosion at the fastener interface, allowing the use of fewer and smaller fasteners without compromising structural integrity. The pre-applied coating ensures that the reduced fastener configuration still maintains adequate strength while preventing corrosion initiation.

Inventive Principle:

Principle #10Preliminary action

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 significantly reduces corrosion, decreases manufacturing costs, and lightens the aircraft by approximately 800 lbs, while maintaining or increasing the strength of the wing joint assembly.

Implementation Method 1

directly attaching carbon composites such as carbon-fiber reinforced plastics to aluminum structures can induce corrosion (e.g., galvanic corrosion) due to chemical and electro-chemical reactions with the surrounding environment

Methodology Applied

Scientific EffectGalvanic corrosion: Crevice Corrosion

Data Source

PatentEP2824030B1Apparatus and methods for joining composite structures of aircrafts

Publication Date: 2017.09.20 THE BOEING CO

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AI summary

Apparatus and method for joining composite structures of aircrafts are disclosed. An example apparatus disclosed herein includes an inboard composite wing panel having a first end portion configured to be coupled to upper and lower inboard fittings composed of a metallic material and an outboard composite wing panel having a first end portion configured to be coupled to upper and lower outboard fittings composed of a metallic material. A side of body rib has a plate shaped first end portion composed of a metallic material. A fuselage frame is configured to be joined at one end of the upper inboard fitting, and the upper and lower inboard fittings and the upper and lower outboard fittings are coupled to the side of body rib at the plate shaped first end portion.