Flexible Mandrel With Holes Reduces Heat Capacity

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Solution Overview

Problem

The mandrel used for molding composite materials with thermosetting resin has a high heat capacity, leading to prolonged temperature rise times during thermal curing, reducing production rates and increasing costs.

Innovation Solution

A flexible mandrel with holes formed on its non-contact surface is used, reducing heat capacity while ensuring contact with the composite material, allowing for faster temperature rise and improved production efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a metal mandrel with high heat capacity is used for molding composite material, then the mandrel can provide structural support and flexibility, but the temperature rise time for thermal curing is prolonged

Engineering Contradiction:

Improvetemperature rise timeVSAvoidheat capacity

Core Design Contradiction:

TemperatureVSUse of energy by moving object

Solution Approach 1:

The mandrel incorporates a porous inner layer with multiple voids or holes that reduce the overall heat capacity of the mandrel structure. This porous configuration allows the mandrel to maintain its structural support function while significantly decreasing the amount of heat energy stored in the mandrel itself, thereby reducing the temperature rise time required for thermal curing of the composite material.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The mandrel is constructed as a composite structure with an inner porous layer and an outer solid layer. This composite configuration enables the mandrel to achieve optimal balance between heat capacity reduction (through the porous inner layer) and structural integrity (provided by the outer solid layer), resolving the contradiction between fast temperature rise and adequate structural support.

Inventive Principle:

Principle #40Composite materials

2Temperature

If holes are formed in the mandrel to reduce heat capacity, then temperature rise time is reduced, but contact between mandrel and composite material may be compromised

Engineering Contradiction:

Improvetemperature rise timeVSAvoidcontact quality

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The mandrel is segmented into functionally distinct layers: an inner porous layer containing holes for heat capacity reduction, and an outer solid layer that provides continuous contact surface with the composite material. This segmentation allows each layer to fulfill its specific function without compromising the other, ensuring both fast temperature rise and reliable contact quality.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The porous structure with holes is localized to the inner layer of the mandrel, while the outer layer maintains solid, continuous material composition. This local application of porosity ensures that heat capacity is reduced where it affects thermal response, while contact quality is preserved at the interface with the composite material through the solid outer layer.

Inventive Principle:

Principle #3Local quality

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 flexible mandrel with holes enables faster thermal curing, enhancing production rates and reducing costs by efficiently transferring heat to the composite material.

Implementation Method 1

efficiently transferring heat to the composite material

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS11148326B2Flexible mandrel and method of manufacturing composite material part

Publication Date: 2021.10.19 MITSUBISHI HEAVY IND LTD

AI summary

A flexible mandrel for molding a composite material containing a thermosetting resin includes: a body including a contact surface configured to come into contact with the composite material during molding and a non-contact surface configured not to come into contact with the composite material during molding; and at least one hole formed from the non-contact surface toward an inside of the body.