Two-Cycle Composite Curing Process for Exothermic Heat Management

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Solution Overview

Problem

The exothermic chemical reaction during polymerization in the manufacture of composite materials for aeronautical structures often leads to overheating, which can cause material brittleness and safety issues, and existing techniques to mitigate this are either ineffective or costly, such as slow temperature increases which prolong manufacturing processes.

Innovation Solution

A process involving a first curing cycle in an autoclave at a maximum temperature between the resin gelling and curing temperatures to release over 50% of the exothermal components, followed by a second curing cycle at 90-100% of the resin curing temperature to minimize residual exothermicity and reduce manufacturing time and costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the autoclave temperature is increased quickly to reduce manufacturing time, then productivity is improved, but the exothermic reaction causes overheating and material brittleness

Engineering Contradiction:

Improvecuring cycle timeVSAvoidoverheating

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The curing process is divided into two distinct cycles: a first curing cycle that releases over 50% of exothermic components, and a second curing cycle that completes the curing at lower temperatures. This segmentation prevents temperature runaway by handling the exothermic peak in separate stages.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The first curing cycle is performed as a preliminary action to release the majority of exothermic reaction heat before the component is assembled into the final structure. This preliminary treatment reduces the risk of overheating during the subsequent second curing cycle.

Inventive Principle:

Principle #10Preliminary action

2Object-affected harmful factors

If slow or step-wise temperature increase is used to control exothermic reaction, then overheating is prevented, but manufacturing time increases

Engineering Contradiction:

Improveoverheating controlVSAvoidmanufacturing time

Core Design Contradiction:

Object-affected harmful factorsVSProductivity

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The process changes temperature parameters between cycles: the first cycle operates at temperatures that maximize exothermic release, while the second cycle operates at lower temperatures (90-100% of resin curing temperature) to complete curing safely after the exothermic peak has been managed.

Inventive Principle:

Principle #35Parameter changes

3Object-affected harmful factors

If instruments for measuring controlled variables and periodic recalculation of optimal temperature are implemented, then overheating control is improved, but device complexity and manufacturing cost increase

Engineering Contradiction:

Improveoverheating controlVSAvoidmeasurement and control system complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The process uses the material's own exothermic reaction characteristics to guide the curing process. By pre-determining the exothermic profile and designing the two-cycle process accordingly, the system eliminates the need for complex real-time measurement and control instruments, achieving self-regulation through process design.

Inventive Principle:

Principle #25Self-service

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 process effectively reduces the first curing cycle time, minimizing overheating and exothermic effects, thereby saving costs and ensuring material integrity by releasing part of the exothermicity in the first cycle, leaving less to be released in the second cycle without excessive temperature increase.

Implementation Method 1

the drawback considered due to the exothermicity of the chemical reaction taking place during the polymerization of the resin during curing in the autoclave

Methodology Applied

Scientific EffectExothermic reaction: Exothermic Reaction

Data Source

PatentEP2055464B1Method for producing pieces of compound materials with two curing cycles

Publication Date: 2018.11.21 AIRBUS OPERATIONS SL

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AI summary

This invention relates to a process for manufacturing a piece of composite material made with a polymer resin and fiber reinforcement from at least two subcomponents comprising the following steps: a) providing the first subcomponent partially cured in a curing cycle in an autoclave at a maximum temperature T1, comprised between the resin gelling temperature GT and the resin curing temperature CT, applied for a predetermined time PT1 such that the exothermal component is released from the first subcomponent in a degree exceeding 50%; b) providing the second subcomponent in a fresh or cured state; c) assembling the two subcomponents and then joining them to one another in a curing cycle in an autoclave at a maximum temperature T2 comprised between 90% and 100% of the resin curing temperature CT, applied for a predetermined time PT2.