Composite Stiffener Panel Bonding via Secondary Curing

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Solution Overview

Problem

Current methods for producing composite materials for aircraft stiffener panels either require complex jigs for shape maintenance, leading to burdensome processes, or rely on adhesive bonding with variable strength, necessitating improved bonding quality.

Innovation Solution

A method involving primary curing of at least one molded product raw material, followed by assembly with another raw material via adhesive or without, and subsequent secondary curing after heating to a temperature above the glass transition point to achieve a rubberized state, allowing for integration while controlling glass transition and reaction temperatures to optimize bonding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If integral molding method is used to cure entire raw material, then strength of composite material is improved, but complex jigs are required for shape maintenance and process becomes burdensome

Engineering Contradiction:

Improvestrength of composite materialVSAvoidcomplexity of jigs and process

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The invention divides the curing process into two stages: first curing to obtain a preliminarily cured molded product with sufficient shape stability, and second curing to achieve final strength. This segmentation allows removal of complex jigs after first curing while maintaining shape, and using simpler jigs for second curing, thus resolving the contradiction between strength and device complexity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The first curing process is performed as a preliminary action before final assembly and second curing. This preliminary curing stabilizes the shape of individual molded products, enabling easier handling and assembly without requiring complex jigs during subsequent steps, while still achieving high final strength through the second curing stage.

Inventive Principle:

Principle #10Preliminary action

2Ease of operation

If co-bonding method is used with previously cured panel, then ease of handling is improved, but bonding strength depends on adhesive and quality control is difficult

Engineering Contradiction:

Improveease of handling molded productVSAvoidbonding strength of composite material

Core Design Contradiction:

Ease of operationVSStrength

Solution Approach 1:

The invention merges the bonding function with the second curing process. The adhesive bonding and secondary curing are combined into a single integrated step, where the adhesive is cured together with the molded product in the same heating process. This ensures consistent bonding quality and strength without separate quality control steps.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The invention changes the temperature parameter during the process: first curing at a temperature below the glass transition point to maintain shape stability, then second curing at a temperature above the glass transition point to achieve both bonding and final strength simultaneously, optimizing both ease of handling and bonding quality.

Inventive Principle:

Principle #35Parameter changes

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 method enhances the ease of handling and strength of composite materials for aircraft stiffener panels by ensuring excellent bonding and reduced process complexity, achieving high-strength composite materials with improved production efficiency.

Implementation Method 1

heating the assembled body to a temperature equivalent to or higher than a glass transition point of the at least one primarily cured molded product raw material to cause a phase of the at least one molded product raw material to transition to a rubberized state

Methodology Applied

Scientific EffectGlass transition: Phase Change

Implementation Method 2

by heating the assembled body to a temperature equivalent to or higher than a glass transition point

Methodology Applied

Scientific EffectThermal heating: Heating

Data Source

PatentUS10086563B2Method of producing composite material

Publication Date: 2018.10.02 MITSUBISHI HEAVY IND LTD

AI summary

A method of producing a composite material includes preparing at least one molded product raw material by primary curing; preparing an assembled body by assembling the primarily cured molded product raw material with another molded product raw material; and integrally forming the molded product raw materials by heating the assembled body to a temperature equivalent to or higher than a glass transition point of the primarily cured molded product raw material to cause a phase of the at least one molded product raw material to transition to a rubberized state, by allowing an adhesive adjacent to the molded product raw material or the other molded product raw material adjacent to the molded product raw material to coexist with the molded product raw material in the rubberized state, and by secondarily curing the primarily cured at least one molded product raw material.