Induction Heating Blanket for Composite Repair

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Solution Overview

Problem

Existing methods for heating composite material surfaces during repair, such as aircraft wall elements, face challenges in achieving homogeneous heat distribution while accommodating thermal heterogeneities and preventing overheating, which can degrade the material.

Innovation Solution

An apparatus with a cover equipped with multiple inductive coils and temperature sensors allows for localized control of electromagnetic fields to regulate heating, ensuring precise and homogeneous heat distribution across the surface, using a "susceptor" heating member that converts electromagnetic energy into heat, and can be adapted for various surface geometries and materials.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a single heating blanket with uniform heating is used, then the device is simple and easy to operate, but the heat distribution is non-uniform on heterogeneous surfaces causing overheating or insufficient heating

Engineering Contradiction:
Improveheat distribution uniformityVSAvoidheating system complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The heating blanket is divided into multiple independent heating zones, each equipped with its own temperature sensor and controllable heating element. This segmentation allows independent temperature control for each zone, enabling uniform heat distribution across heterogeneous surfaces while maintaining overall system manageability through modular architecture.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Each heating zone is equipped with local temperature sensors and independent control, allowing the heating characteristics to be tailored to local requirements. Different zones can operate at different temperatures and power levels according to the specific thermal properties of the surface areas they cover, achieving optimal heat distribution without uniform complexity throughout the entire blanket.

Inventive Principle:
Principle #3Local quality

2Productivity

If heating temperature is increased to ensure polymerization, then the polymerization process is accelerated, but the composite material surface may be damaged due to overheating

Engineering Contradiction:
Improvepolymerization speedVSAvoidsurface damage from overheating
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

Temperature sensors are integrated into each heating zone to continuously monitor the actual temperature. The control system uses this feedback information to adjust the power delivered to heating elements in real-time, ensuring the temperature remains within the optimal range for polymerization without exceeding it, thus preventing surface damage while maintaining efficient curing.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The heating system transitions from static uniform heating to dynamic adaptive heating, where each zone can independently adjust its temperature and power output based on real-time conditions. This dynamic control allows the system to optimize polymerization speed in each local area while preventing overheating, adapting to variations in material properties and environmental conditions.

Inventive Principle:
Principle #15Dynamics

3Adaptability or versatility

If the heating blanket is made flexible to conform to surface geometry, then the adaptability to various surface shapes is improved, but the integration of temperature sensors and control elements becomes more difficult

Engineering Contradiction:
Improvesurface geometry adaptabilityVSAvoidsensor and control integration complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The heating blanket utilizes flexible heating elements and thin-film temperature sensors that can be integrated into a pliable substrate. This allows the blanket to conform to complex surface geometries while maintaining functional integrity. The flexible design enables easy adaptation to various aircraft skin shapes without requiring rigid structural support, and the thin-film sensors maintain close thermal contact with the surface for accurate measurement.

Inventive Principle:
Principle #30Flexible shells and thin films

4Measurement precision

If multiple independent heating zones with individual control are implemented, then the temperature control precision is improved, but the device complexity and cost increase

Engineering Contradiction:
Improvetemperature control precisionVSAvoidnumber of control elements
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The control system is designed with universal, modular components that can be replicated across multiple heating zones. Each zone uses identical sensor types, heating element designs, and control circuitry, allowing for standardized manufacturing and simplified maintenance. The modular architecture enables precise independent control of each zone while keeping the overall system manageable through repetition of proven functional units rather than requiring unique complex controls for each zone.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 solution enables efficient and controlled heating of composite material surfaces, ensuring polymerization of patches while avoiding overheating, and allows for temporary repairs with precise temperature management, suitable for heterogeneous surfaces and thermosetting materials.

Implementation Method 1

The energy produced by an electromagnetic field generated by the activation means is converted into heat by the 'suceptor' heating element

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

heating blankets incorporating an inductive coil and a 'susceptor' heating element used to heat a surface to be repaired

Methodology Applied
Scientific EffectInduction heating: Induction Heating

Implementation Method 3

The heating element, or 'susceptor,' is made of or incorporates a 'susceptor' material capable of absorbing the electromagnetic energy generated by the inductive coil

Methodology Applied
Scientific EffectElectromagnetic energy absorption: Absorption (EM radiation)

Implementation Method 4

converting this electromagnetic energy into heat

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 5

The heat produced by the heating element is used to raise the temperature of the surface to be repaired

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 6

capable of heating the surface to be repaired by conduction or convection

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 7

The blanket is also equipped with means of securing it against the surface to be repaired, such as typically vacuum devices

Methodology Applied
Scientific EffectVacuum pressure: Vacuum

Data Source

PatentEP2796265B1Apparatus for repairing a composite material by heating, by means of a susceptor heating element activated locally by a plurality of induction coils
Publication Date: 2020.07.08 EUROCOPTER FRANCE SA
  • EP2796265B1 patent drawingFigure 1~3

AI summary

The present invention relates to a heat treatment apparatus for a surface to be repaired (1) made of a composite material, by sealing a patch (2) onto the surface to be repaired (1) after it has been heated to temperature. The apparatus comprises an electromagnetic field generator (3) cooperating with a heating element (4) that heats the surface to be repaired (1) by absorbing the generated electromagnetic energy (5). The electromagnetic field generator (3) comprises a plurality of inductive coils (13) and a plurality of temperature sensors (18) distributed on a common support (17) integrated into a cover (6) affixed to the surface to be repaired (1).The temperature sensors (18) provide temperature measurements taken locally on the surface to be repaired (1) to regulate the power of electric currents individually supplying the inductive coils (13) according to the temperature measurements provided by the temperature sensors (18).