Co-cured Flex Circuit for Lightning Protection in Composites

Solution Overview

Problem

Aerospace composite structures, such as carbon fiber reinforced plastics, face challenges in distributing lightning current and heat due to their non-conductive nature, necessitating the integration of metallic conductors for effective lightning protection, which adds weight and complexity.

Innovation Solution

Incorporating a multi-functional flex circuit with metallic circuits on a film, co-cured with the resin matrix, to dissipate lightning energy and provide a conductive path, while also enabling additional functions like sensor integration and electromagnetic interference mitigation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If metallic conductors are integrated into composite structures for lightning protection, then lightning current distribution capability is improved, but weight increases

Engineering Contradiction:

Improvelightning current distribution capabilityVSAvoidweight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The patent combines the lightning protection function with the composite structure itself by embedding flexible circuits directly into the composite material during manufacturing. This integration merges the structural and protective functions into a single unified system, eliminating separate metallic conductor layers and reducing overall weight while maintaining lightning current distribution capability.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent uses composite materials by embedding flexible circuits (containing metallic traces) within the composite matrix. This creates a multi-functional composite structure where the flexible circuit layer provides conductivity for lightning protection while the surrounding composite material provides structural integrity, achieving both functions with optimized weight.

Inventive Principle:

Principle #40Composite materials

2Reliability

If metallic conductors are added to composite structures, then lightning protection is improved, but device complexity increases

Engineering Contradiction:

Improvelightning protectionVSAvoiddevice complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges multiple functions into a single integrated component. The flexible circuit serves both as the lightning protection conductor and as part of the overall structural assembly, eliminating the need for separate metallic conductor applications and complex assembly procedures. This integration simplifies the overall device complexity while maintaining protective functionality.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The flexible circuits are embedded into the composite structure during the manufacturing process itself, before the final product is completed. This preliminary integration eliminates subsequent assembly steps and reduces the complexity of installing separate lightning protection systems after manufacturing.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If traditional appliqué-based lightning protection systems are used, then lightning current distribution is improved, but manufacturing complexity increases

Engineering Contradiction:

Improvelightning current distributionVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The flexible circuits are embedded into the composite structure during the manufacturing process itself, before the final product is completed. This preliminary integration eliminates subsequent assembly steps and reduces the complexity of installing separate lightning protection systems after manufacturing.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent combines the lightning protection function with the composite structure itself by embedding flexible circuits directly into the composite material during manufacturing. This integration merges the structural and protective functions into a single unified system, eliminating separate metallic conductor layers and reducing overall weight while maintaining lightning current distribution capability.

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 lightning energy, reduces weight, and simplifies manufacturing by integrating conductive pathways within the composite structure, enhancing both lightning protection and structural integrity.

Implementation Method 1

The metallic circuit is configured to dissipate energy generated by lightning strikes on the composite substrate

Methodology Applied

Scientific EffectLightning strike energy dissipation: Joule Heating

Implementation Method 2

The film is co-cured with the resin matrix

Methodology Applied

Scientific EffectCo-curing: Chemical Bonding

Data Source

PatentUS7883050B2Composites with integrated multi-functional circuits

Publication Date: 2011.02.08 THE BOEING CO

AI summary

An aircraft component includes a composite structure and a metallic circuit on a film. The film is co-cured with the composite structure. The metallic circuit is patterned to dissipate energy generated by lightning strikes on the composite structure. The metal circuit is also patterned to provide connectivity for multi-function apparatus.