Co-curing Composite Stiffened Panels Single Autoclave Cycle

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Solution Overview

Problem

The existing methods for manufacturing aeronautical panels with load-bearing surfaces and longitudinal stiffening elements are costly due to the separate production and curing of stringers and skins, requiring multiple autoclave cycles.

Innovation Solution

A method where pairs of wet stringers and skins are formed and assembled together, subjected to a single curing cycle in an autoclave, allowing for simultaneous polymerization and reducing production costs by manufacturing two panels at once.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If stringers are manufactured separately from skins and cured in multiple autoclave cycles, then manufacturing precision and quality control are improved, but production time and recurring costs increase

Engineering Contradiction:
Improvequality controlVSAvoidproduction time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent merges the manufacturing of stringers and skins into a single integrated process. Wet stringers are formed by folding and assembling preimpregnated strips, then both stringers and skins are cured simultaneously in one autoclave cycle, eliminating the need for separate manufacturing and multiple curing cycles while maintaining quality control through the co-curing process

Inventive Principle:
Principle #5Merging (Combining)

2Ease of manufacture

If separate manufacturing processes are used for stringers and skins, then ease of manufacture is improved, but productivity decreases

Engineering Contradiction:
Improveprocess simplicityVSAvoidproduction output
Core Design Contradiction:
Ease of manufactureVSProductivity

Solution Approach 1:

The patent segments the stringer manufacturing process into modular steps (forming wet stringers from preimpregnated strips, assembling them on skins) that can be performed independently before final curing. This segmentation allows for easier manufacturing while the simultaneous curing of multiple components in one autoclave cycle significantly boosts productivity by producing complete stiffened panels in a single operation

Inventive Principle:
Principle #1Segmentation

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 approach reduces recurring costs and streamlines the manufacturing process by eliminating the need for multiple autoclave cycles and enabling the simultaneous production of two stiffened panels.

Implementation Method 1

subjecting the pair of wet panels arranged above each other and provided with respective wet stringers to a same curing cycle

Methodology Applied
Scientific EffectPolymerization: Photopolymerisation

Data Source

PatentEP3280587B1Method for manufacturing stiffened panels of composite material by means of co-curing
Publication Date: 2020.06.10 LEONARDO SPA
  • EP3280587B1 patent drawingFigure 1~4
  • EP3280587B1 patent drawingFigure 5~7
  • EP3280587B1 patent drawingFigure 8~12

AI summary

Method for manufacturing stiffened panels (71, 73), comprising the following steps: forming a first and a second wet skin (51, 53), each comprising a plurality of plies of preimpregnated composite material; forming a plurality of pairs of wet stringers (17, 19), comprising a plurality of plies of preimpregnated material, wherein forming each pair of wet stringers comprises: a) forming an assembly (15) having a central web extending between opposite end flanges, and b) cutting the assembly (15) along a median plane (P) so as to form a pair of wet stringers (17, 19), placing the pairs of wet stringers (17, 19) on the first wet skin (51) by means of re¬ movable supporting members (40); turning the second wet skin (53) over and placing it on the pairs of stringers (17, 19), so as to obtain a pair of wet panels (71, 73) arranged above each other; and subjecting the pair of wet panels (71, 73) to a same curing cycle.