Expandable Slit Breather Sheet for Complex Composite Surfaces

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Solution Overview

Problem

Existing vacuum bag equipment struggles to efficiently cover complex contoured surfaces during composite part fabrication, leading to material waste and increased labor due to the need for multiple breather strips, which can result in bridging issues.

Innovation Solution

A single sheet of nonwoven breather material with multiple expandable slits is used, allowing it to conform to complex surfaces by stretching during compaction, reducing the need for multiple strips and minimizing waste.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple breather strips are used to cover complex contoured surfaces, then bridging is avoided, but labor time and material waste increase

Engineering Contradiction:
Improvecoverage qualityVSAvoidinstallation time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The breather material is segmented into multiple slits within a single continuous sheet, allowing each slit to independently expand and conform to surface contours while maintaining overall sheet integrity. This segmentation enables the material to adapt to complex geometries without requiring multiple separate strips to be manually positioned.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The breather sheet transitions from a rigid, fixed-state configuration to a dynamic, expandable state through the slits. During vacuum bagging, the slits allow the material to dynamically expand and stretch, automatically conforming to the contoured surface features without manual intervention.

Inventive Principle:
Principle #15Dynamics

2Reliability

If multiple breather strips are used to cover complex contoured surfaces, then bridging is avoided, but material waste increases

Engineering Contradiction:
Improvecoverage qualityVSAvoidmaterial waste
Core Design Contradiction:
ReliabilityVSLoss of substance

Solution Approach 1:

Multiple functional elements (breather strips) are merged into a single continuous sheet with integrated slits. This unified structure eliminates the gaps and overlaps that occur when multiple separate strips are used, reducing material waste while maintaining effective coverage of complex surfaces.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The physical parameters of the breather material are changed by introducing slits that allow controlled expansion. This parameter change enables the material to stretch and conform to surface contours, achieving reliable coverage without the need for excessive material or multiple separate pieces.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If a single breather sheet is used, then installation time is reduced, but bridging occurs over complex surface features

Engineering Contradiction:
Improveinstallation speedVSAvoidcoverage quality
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The single breather sheet is segmented into multiple slits that act as expansion zones. This segmentation allows different regions of the sheet to independently expand and conform to local surface features, preventing bridging while maintaining the simplicity of a single-piece installation.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The breather sheet incorporates dynamic expansion capability through the slits, allowing it to transition from a flat, compact state during installation to an expanded, conforming state during vacuum bagging. This dynamic behavior enables a single sheet to adapt to complex geometries without manual adjustment.

Inventive Principle:
Principle #15Dynamics

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

The solution enables quicker installation, reduces material waste, and effectively covers complex surfaces without bridging, improving the efficiency of vacuum bag processing for composite parts.

Implementation Method 1

Multiple slits are cut in a single sheet of breather material. The slits allow the breather sheet to expand by stretching to a length longer than its original length.

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

surface breathers may be positioned over a surface of a part layup that is subsequently processed under vacuum beneath a sealed vacuum bag

Methodology Applied
Scientific EffectVacuum: Vacuum

Data Source

PatentEP2594390B1Combination of a composite part and a breather, and method of fabricating a composite part
Publication Date: 2020.04.08 THE BOEING CO
  • EP2594390B1 patent drawingFigure 1
  • EP2594390B1 patent drawingFigure 2~3
  • EP2594390B1 patent drawingFigure 4~5

AI summary

A breather for use in vacuum bag processing a composite part comprises a sheet of permeable material having at least one slit therein.