Aircraft Spar Co-Curing Without Adhesive or Peel Ply

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Solution Overview

Problem

Manufacturing spars or ribs for aircrafts with stiffeners on both sides of the spar web is complex due to the need for peel ply and adhesive, leading to increased complexity in the manufacturing process and tooling.

Innovation Solution

A method involving co-curing the stiffener and spar web outside a vacuum bag, eliminating the need for adhesive and peel ply, and allowing for partial curing between 60-80% to simplify the process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If peel ply and adhesive are used to bond stiffeners to spar web, then bond quality is ensured, but manufacturing process complexity and tooling complexity increase

Engineering Contradiction:
Improvebond qualityVSAvoidmanufacturing process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention extracts and eliminates the peel ply and adhesive from the manufacturing process. By using a co-curing method where the spar web and stiffeners are cured simultaneously as an integrated structure, the need for separate bonding materials and processes is removed, thereby reducing manufacturing complexity while maintaining structural integrity

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention merges the curing process of the spar web and stiffeners into a single co-curing operation. Instead of separate bonding steps requiring peel ply and adhesive, the components are cured together as one integrated process, simplifying both the manufacturing process and tooling requirements

Inventive Principle:
Principle #5Merging (Combining)

2Reliability

If stiffeners are co-bonded in a subsequent cycle, then bond quality is ensured, but curing time increases

Engineering Contradiction:
Improvebond qualityVSAvoidcuring time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The invention performs preliminary positioning of stiffeners on the spar web before the curing process begins. By pre-placing the stiffeners in their final positions and then co-curing everything simultaneously, the need for subsequent bonding cycles is eliminated, reducing total curing time while ensuring proper bond quality through the integrated curing process

Inventive Principle:
Principle #10Preliminary action

3Strength

If adhesive ply is used between stiffener feet and spar web, then bond strength is ensured, but manufacturing simplicity is reduced

Engineering Contradiction:
Improvebond strengthVSAvoidmanufacturing simplicity
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The invention extracts and eliminates the adhesive ply from the assembly. By designing the spar web and stiffeners to be co-cured as an integrated structure, the need for separate adhesive materials and application processes is removed, simplifying manufacturing while maintaining structural strength through the direct monolithic bond created during co-curing

Inventive Principle:
Principle #2Taking out (Extraction)

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

Simplifies the manufacturing process by eliminating the need for adhesive and peel ply, reducing curing time, and simplifying tooling while ensuring a strong bond between the stiffener and spar web.

Implementation Method 1

placing a vacuum bag on the at least one stiffener and the spar web

Methodology Applied
Scientific EffectVacuum: Vacuum

Data Source

PatentEP4467328B1Method for manufacturing spars or ribs for aircrafts
Publication Date: 2025.11.05 AIRBUS OPERATIONS SL
  • EP4467328B1 patent drawingFigure 1~2
  • EP4467328B1 patent drawingFigure 3

AI summary

The method for manufacturing spars (1) or ribs for aircrafts comprises the following steps: - placing at least one stiffener (3) on one side of a spar web (2); - placing a vacuum bag (4) on the at least one stiffener (3) and the spar web (2); and - co-curing the at least one stiffener (3) and the spar web (2). It permits the elimination of peel ply and/or adhesive and/or curing cycles.