Conductive Composite Fuel Tank Layer for Static Dissipation

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Solution Overview

Problem

Composite materials used in aerospace structures, such as fuel tanks, lack surface conductivity, leading to static electricity buildup and increased risk of electrical discharges, which existing dissipation methods like primers and grounding technologies do not adequately address due to increased complexity, weight, and manufacturing time.

Innovation Solution

A composite structure comprising a first and second composite layer, where the second layer is designed with conductive fibers and resin to dissipate electric charges, with a resistivity range of 10^6 to 10^9 ohms-meters, integrated into the manufacturing process to form a structure that reduces static electricity buildup and electrical discharges.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If composite materials are used in aircraft structures, then weight is reduced and strength is improved, but surface conductivity is lost leading to static electricity buildup

Engineering Contradiction:
Improveaircraft structure weightVSAvoidstatic electricity dissipation capability
Core Design Contradiction:
Weight of moving objectVSReliability

Solution Approach 1:

The patent applies composite materials principle by creating a multi-layer composite structure where the second composite layer combines conductive fibers with resin matrix to achieve both structural integrity and electrical conductivity. This layer is specifically designed to dissipate static electricity while maintaining the weight advantages of composite materials.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent applies local quality principle by providing conductivity only where needed - specifically in the second composite layer that contacts the liquid cargo. This localized approach ensures static electricity dissipation capability is present at the critical interface without requiring the entire structure to be conductive, thus maintaining weight efficiency.

Inventive Principle:
Principle #3Local quality

2Reliability

If grounding technologies and additives are used to dissipate static electricity, then electric charge dissipation is improved, but device complexity and manufacturing time increase

Engineering Contradiction:
Improveelectric charge dissipationVSAvoidsystem complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the structural function with the electrical dissipation function by integrating the conductive second composite layer directly into the tank wall structure. This combination eliminates the need for separate grounding systems, external additives, or additional dissipation devices, thereby reducing overall system complexity while maintaining effective charge dissipation.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The second composite layer serves multiple functions simultaneously: it provides structural support as part of the tank wall, ensures liquid-tight sealing, and dissipates static electricity through its conductive properties. This multi-functionality eliminates the need for separate systems for each function, reducing device complexity.

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

3Reliability

If grounding technologies and additives are used to dissipate static electricity, then electric charge dissipation is improved, but manufacturing time increases

Engineering Contradiction:
Improveelectric charge dissipationVSAvoidmanufacturing time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The conductive properties are built into the composite layer during the manufacturing process itself, rather than being added as a post-processing step. The second composite layer is cured with its conductive fiber-reinforced resin matrix already in place, establishing the dissipation capability before the tank is put into service, thus eliminating additional manufacturing time.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent combines the manufacturing of the structural tank wall with the integration of the conductive dissipation layer into a single manufacturing process. Both layers are cured simultaneously in the same autoclave cycle, eliminating the need for separate grounding system installation or additive application steps, thereby reducing total manufacturing time.

Inventive Principle:
Principle #5Merging (Combining)

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 effectively dissipates electric charges and reduces the risk of electrical discharges, while minimizing weight, complexity, and manufacturing time by integrating the conductive layer into the structure, thus enhancing safety and efficiency.

Implementation Method 1

the second composite layer has a conductivity configured to dissipate an electric charge on a surface of the structure

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentEP2646322B1Electric charge dissipation system for aircraft
Publication Date: 2020.06.10 THE BOEING CO
  • EP2646322B1 patent drawingFigure 1~2
  • EP2646322B1 patent drawingFigure 3
  • EP2646322B1 patent drawingFigure 4

AI summary

A method, apparatus, and composite fuel tank for manufacturing a structure is provided. A first composite layer ( 318 ) and a second composite layer ( 320 ) are placed on a mold. The second composite layer and the first composite layer are cured. The first composite layer and the second composite layer form the structure ( 302 ). The second composite layer is configured to dissipate an electric charge on a surface ( 312 ) of the structure.