Flexible Mandrel with Conductive Layer for Composite Curing

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Solution Overview

Problem

Mandrels used for molding composite materials with thermosetting resins have high heat capacity, leading to prolonged curing times and increased costs due to decreased production rates and elevated electricity consumption.

Innovation Solution

A flexible mandrel with a thermally conductive layer, extending from the contacting surface to the non-contacting surface, is used to accelerate heat transfer during the curing process, comprising a material with higher thermal conductivity than the main body, such as PITCH-based CFRP or metal, to reduce heat capacity and enhance flexibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a mandrel with high heat capacity is used for molding composite materials, then the mandrel can maintain structural stability, but the curing time increases and production rate decreases

Engineering Contradiction:

Improvestructural stabilityVSAvoidproduction rate

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The mandrel is divided into two distinct layers: a main body made of flexible material (e.g., rubber or resin) that provides structural stability and flexibility, and a surface layer made of thermally conductive material (e.g., metal or carbon fiber reinforced plastic) that accelerates heat transfer. This segmentation allows each layer to fulfill its specific function without compromise.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The mandrel employs a composite structure combining materials with different properties: the flexible main body material provides mechanical stability and adaptability, while the thermally conductive surface layer material enhances heat transfer efficiency. This composite approach resolves the contradiction between structural requirements and thermal performance.

Inventive Principle:

Principle #40Composite materials

2Stability of the object's composition

If a mandrel with high heat capacity is used, then thermal stability is maintained, but the time required for temperature increase during curing increases

Engineering Contradiction:

Improvethermal stabilityVSAvoidtemperature increase time

Core Design Contradiction:

Stability of the object's compositionVSLoss of time

Solution Approach 1:

Instead of making the entire mandrel thermally conductive (which would compromise flexibility), the invention applies thermal conductivity enhancement only to the surface layer that contacts the composite material. This local quality approach ensures rapid heat transfer at the interface while the inner structure maintains its flexible, stable composition.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The mandrel structure transitions from a static, uniform material composition to a dynamic, functionally graded structure where the surface layer actively manages heat transfer while the core maintains structural integrity. This allows the system to adapt thermal properties as needed during the curing process.

Inventive Principle:

Principle #15Dynamics

3Temperature

If a metallic mandrel is used to improve thermal conductivity, then heat transfer is enhanced, but flexibility and adaptability to complex shapes are reduced

Engineering Contradiction:

Improveheat transfer efficiencyVSAvoidflexibility

Core Design Contradiction:

TemperatureVSAdaptability or versatility

Solution Approach 1:

The mandrel is segmented into a flexible core and a conductive surface layer, allowing the core to provide flexibility for complex shapes while the surface layer delivers enhanced heat transfer. This segmentation resolves the contradiction between rigidity and flexibility.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention uses a flexible main body material that can conform to complex geometries, and applies a thin thermally conductive surface layer that does not significantly restrict flexibility while providing the necessary thermal conductivity enhancement. This approach maintains adaptability to complex shapes.

Inventive Principle:

Principle #30Flexible shells and thin films

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 significantly reduces the time required for temperature increase during curing, improving production rates and reducing costs while maintaining necessary flexibility for complex shapes.

Implementation Method 1

a thermally conductive layer containing a second material having a higher thermal conductivity than the first material, the thermally conductive layer being formed so as to cover at least a portion of the main body... the heat supplied from the outside during a curing process is effectively transmitted to the composite material which is a molding target via the thermally conductive layer

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS11584095B2Flexible mandrel, and method for producing composite component

Publication Date: 2023.02.21 MITSUBISHI HEAVY IND LTD

AI summary

This flexible mandrel for molding a composite material containing a thermosetting resin includes: a main body containing a first material; and a thermally conductive layer containing a second material having a higher thermal conductivity than the first material, the thermally conductive layer being formed so as to cover at least a portion of the main body. The thermally conductive layer extends from a contacting surface of the flexible mandrel, which comes into contact with the composite material during molding, to a non-contacting surface which does not come into contact with the composite material.