Conductive Composite Lightning Protection Without Metal Fasteners

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Solution Overview

Problem

The use of metal fasteners in composite structures for lightning protection increases the weight of the structure, which is a significant drawback.

Innovation Solution

A composite structure comprising laminated first and second composite materials with conductive reinforcing fibers and an insulating adhesive layer, along with conductive members that connect the composite sheets to distribute lightning current without increasing weight.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If metal fasteners are used for lightning protection in composite structures, then lightning protection is achieved, but the weight of the structure increases

Engineering Contradiction:

Improvelightning protectionVSAvoidweight of composite structure

Core Design Contradiction:

ReliabilityVSWeight of stationary object

Solution Approach 1:

The patent extracts the lightning protection function from traditional metal fasteners and relocates it to conductive fibers integrated within the composite material itself. The conductive fibers are embedded in the resin matrix of the composite sheets, allowing the composite material to provide both structural and lightning protection functions without requiring additional metal fasteners.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent merges the lightning protection function with the structural composite material by incorporating conductive fibers into the resin matrix. This integration allows the composite material to simultaneously serve as both the structural element and the lightning protection pathway, eliminating the need for separate metal fasteners.

Inventive Principle:

Principle #5Merging (Combining)

2Weight of stationary object

If adhesive bonding is used to join composite materials, then cost is reduced and weight is decreased, but electrical conductance in the orthogonal direction becomes smaller

Engineering Contradiction:

Improveweight of composite structureVSAvoidelectrical conductance

Core Design Contradiction:

Weight of stationary objectVSReliability

Solution Approach 1:

The patent applies local quality by making the adhesive layer conductive in specific regions where electrical connectivity is needed. The adhesive layer contains conductive particles or fibers that provide electrical conductance in the orthogonal direction (through the thickness of the bonded surfaces) while maintaining the overall insulating properties of the adhesive in other directions.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent introduces a conductive adhesive layer as an intermediary between the composite materials. This conductive adhesive serves as a mediator that provides both mechanical bonding and electrical conductance in the orthogonal direction, resolving the contradiction between the insulating nature of traditional adhesives and the need for electrical connectivity.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 configuration effectively provides lightning protection while maintaining weight reduction, ensuring uniform current flow and reducing potential differences across the structure.

Implementation Method 1

a first composite material in which a plurality of first composite sheets in each of which a first reinforcing fiber having conductivity is impregnated with a first resin are laminated

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

an insulating adhesive layer disposed between the first composite material and the second composite material to bond the first composite material and the second composite material

Methodology Applied

Scientific EffectAdhesion: Adhesive

Data Source

PatentUS20230078838A1Composite material structure

Publication Date: 2023.03.16 MITSUBISHI HEAVY IND LTD

AI summary

This composite material structure is provided with: a first composite material that is obtained by stacking a plurality of first composite material sheets, each of which is obtained by impregnating electroconductive first reinforcing fibers with a first resin; a second composite material which is obtained by impregnating electroconductive second reinforcing fibers with a second resin; an insulating bonding layer that is arranged between the first composite material and the second composite material, thereby bonding the first composite material and the second composite material to each other; and an electroconductive member that connects the plurality of first composite material sheets.