Method of manufacturing a composite structure

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Solution Overview

Problem

Composite structures reinforced with thermoplastic particles or interlayers suffer from reduced mechanical property retention at elevated temperatures and are prone to edge glow during lightning strikes due to electrical conductivity issues.

Innovation Solution

A method involving the creation of a fiber-modified interlayer by drawing a nonwoven fabric of continuous fibers through a slurry of discontinuous fibers, forming a network attached to the fabric, and integrating this interlayer into a reinforcing fabric configuration to enhance impact resistance and electrical conductivity, thereby reducing edge glow and maintaining mechanical properties at elevated temperatures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If thermoplastic particles or interlayers are added to enhance impact resistance, then impact resistance is improved, but electrical conductivity deteriorates causing edge glow during lightning strikes

Engineering Contradiction:

Improveimpact resistanceVSAvoidelectrical conductivity

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent uses a composite interlayer combining thermoplastic continuous fibers (for impact resistance) with conductive discontinuous fibers (for electrical conductivity). This composite structure resolves the contradiction by integrating both functional requirements into a single material system that provides both mechanical toughness and electrical pathways.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent applies different fiber types and concentrations at different locations within the interlayer structure. The discontinuous conductive fibers are distributed throughout the thermoplastic matrix, creating local conductive networks that address electrical conductivity issues while the overall thermoplastic structure maintains impact resistance.

Inventive Principle:

Principle #3Local quality

2Strength

If thermoplastic interlayers are used to increase impact resistance, then impact resistance is improved, but mechanical property retention at elevated temperatures deteriorates

Engineering Contradiction:

Improveimpact resistanceVSAvoidmechanical property retention at elevated temperatures

Core Design Contradiction:

StrengthVSTemperature

Solution Approach 1:

The patent modifies the thermal and mechanical parameters of the interlayer by selecting thermoplastic fibers with appropriate melting points and thermal stability, and by controlling the fiber orientation, density, and bonding characteristics. These parameter adjustments enable the interlayer to maintain mechanical properties at elevated temperatures while preserving impact resistance.

Inventive Principle:

Principle #35Parameter changes

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 fiber-modified interlayer effectively increases the impact resistance and electrical conductivity of composite structures, suppressing edge glow and maintaining mechanical integrity at elevated temperatures, while also dissipating electromagnetic energy efficiently.

Implementation Method 1

forming a network of discontinuous fibers attached to the nonwoven fabric

Methodology Applied

Scientific EffectAdhesion: Adhesive

Data Source

PatentEP3854924B1Method of manufacturing a composite structure

Publication Date: 2023.10.25 THE BOEING CO

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AI summary

A method for manufacturing a fiber-modified interlayer comprising drawing a nonwoven fabric formed of continuous fibers through a slurry of discontinuous fibers suspended in a dispersive liquid; forming a network of said discontinuous fibers attached to said nonwoven fabric; and forming said fiber-modified interlayer.