Thermoplastic Structure Consolidation Using Induction Heating

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Solution Overview

Problem

Current methods for forming composite structures using thermoset materials are time-consuming and inefficient, particularly in achieving non-planar thermoplastic structures with closed cross-sections, as they require lengthy curing processes and resistive heating, which limits processing speed and quality.

Innovation Solution

A method utilizing a tool with die liners configured to generate heat in response to a magnetic field for consolidating thermoplastic materials, applying a magnetic field to heat the structure to a consolidation temperature, and optionally using a metallic bladder for compressive force and cooling to produce high-quality thermoplastic structures with non-planar cross-sections.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If thermoset materials are used to create composite structures, then the structures can be formed with proper curing, but the process time becomes excessively long (several hours for curing plus heating up and cooling down)

Engineering Contradiction:

Improvecuring qualityVSAvoidtotal process time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent changes the material parameter from thermoset to thermoplastic, which fundamentally alters the processing mechanism. Thermoplastic materials can be consolidated quickly through heating and pressure without requiring lengthy curing cycles, thus reducing total process time while maintaining structural integrity

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the chemical curing process of thermoset materials with a physical consolidation process using thermoplastic materials. This substitution eliminates the need for chemical reactions and extended curing times, achieving rapid formation of composite structures through controlled heating and pressure application

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of manufacture

If resistive heating is used to consolidate thermoplastic material, then the material can be processed, but the heating time remains undesirable and reduces productivity

Engineering Contradiction:

Improveconsolidation capabilityVSAvoidprocessing speed

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

The patent replaces resistive heating with induction heating technology. Induction heating uses electromagnetic fields to directly heat the material through induced eddy currents, providing rapid and efficient heating that significantly reduces consolidation time compared to traditional resistive heating methods

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The induction heating system uses periodic electromagnetic fields at specific frequencies to efficiently transfer energy to the thermoplastic material. This periodic action enables controlled and rapid heating cycles that maintain material quality while minimizing processing time

Inventive Principle:

Principle #19Periodic action

3Shape

If stamp forming is used to create non-planar thermoplastic structures, then the structures can be formed, but the method is limited for closed cross-sections and complex geometries

Engineering Contradiction:

Improvenon-planar structure capabilityVSAvoidgeometry flexibility

Core Design Contradiction:

ShapeVSAdaptability or versatility

Solution Approach 1:

The patent introduces an internal bladder element that can be inflated to provide three-dimensional shaping capability. This allows the formation of complex closed cross-sections and non-planar geometries that cannot be achieved with conventional stamp forming, adding a dimensional aspect to the forming process

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent uses an internal bladder as an intermediary element between the tooling and the thermoplastic material. The bladder transmits pressure and shape information to the material, enabling complex geometry formation while maintaining process control and material quality

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 approach significantly reduces the time and energy required for consolidating thermoplastic structures, enabling faster production of high-quality thermoplastic structures with improved processing of ply drops and other features, while maintaining desirable physical properties.

Implementation Method 1

The tool has a number of die liners configured to generate heat in response to a magnetic field. Consolidating comprises applying a magnetic field to the number of die liners to heat the structure to a consolidation temperature.

Methodology Applied

Scientific EffectMagnetic field heating: Induction Heating

Data Source

PatentUS10618230B2Thermoplastic structures

Publication Date: 2020.04.14 THE BOEING CO

AI summary

A method of forming a consolidated structure. The method comprises placing a thermoplastic material onto a forming tool to form a structure; positioning the structure within a tool; and consolidating the structure to form the consolidated structure. The tool has a number of die liners configured to generate heat in response to a magnetic field. Consolidating comprises applying a magnetic field to the number of die liners to heat the structure to a consolidation temperature.