Composite Laminate Breather Paths for Out-of-Autoclave Curing

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Solution Overview

Problem

Conventional methods for manufacturing fiber-reinforced composite laminates require high compaction pressures and extended processing times, making them costly and inefficient for large-scale production, especially since they often necessitate the use of autoclaves to achieve low porosity and high strength.

Innovation Solution

The method involves laying up composite material in layers with engineered gaps that form a fluidly interconnected network of breather paths, allowing for the evacuation of air, moisture, and volatiles during consolidation and curing, while applying heat and compaction pressure, without the need for an autoclave, using automated fiber placement and vacuum bagging techniques.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If high compaction pressure is applied in an autoclave to achieve low porosity, then porosity is reduced and strength is improved, but processing time is extended and manufacturing cost increases

Engineering Contradiction:

ImproveporosityVSAvoidproduction rate

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The patent segments the consolidation process into two distinct phases: a high-pressure phase (greater than 1 atmosphere) to evacuate volatiles and reduce porosity, followed by a low-pressure phase (1 atmosphere or less) to complete curing. This segmentation allows the laminate to achieve low porosity quickly under high pressure, then maintains quality under lower pressure for extended curing, thereby improving production rate without sacrificing manufacturing precision

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent dynamically adjusts compaction pressure during the curing process rather than maintaining constant high pressure. The pressure is increased above 1 atmosphere during initial consolidation to remove volatiles, then reduced to 1 atmosphere or less during subsequent curing. This dynamic pressure adjustment optimizes both porosity reduction and production efficiency

Inventive Principle:

Principle #15Dynamics

2Manufacturing precision

If high compaction pressure is applied in an autoclave to achieve low porosity, then porosity is reduced and strength is improved, but manufacturing cost increases

Engineering Contradiction:

ImproveporosityVSAvoidmanufacturing cost

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent applies high compaction pressure (greater than 1 atmosphere) only partially during the process - specifically during the initial consolidation phase to evacuate volatiles - rather than maintaining it throughout the entire curing process. This partial application of excessive pressure achieves the necessary porosity reduction while avoiding the continuous high cost associated with sustained autoclave pressure, thereby improving ease of manufacture while maintaining manufacturing precision

Inventive Principle:

Principle #16Partial or excessive action

3Manufacturing precision

If extended periods of heat and compaction pressure are applied in an autoclave, then porosity is reduced and strength is improved, but processing time is extended

Engineering Contradiction:

ImprovestrengthVSAvoidprocessing time

Core Design Contradiction:

Manufacturing precisionVSDuration of action of moving object

Solution Approach 1:

The patent performs preliminary volatile evacuation under high pressure before the main curing phase. By removing volatiles and reducing porosity in advance during the high-pressure consolidation phase, the subsequent low-pressure curing phase can proceed more efficiently, reducing the total processing time required to achieve the desired strength while maintaining manufacturing precision

Inventive Principle:

Principle #10Preliminary action

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 manufacturing costs and increases production rates by achieving low porosity and improved mechanical properties comparable to autoclave-cured laminates, while allowing for out-of-autoclave processing with pressures as low as 1 atmosphere, resulting in laminates with less than 2% porosity by volume.

Implementation Method 1

The gaps may be fluidly interconnected or coupled, and may form at least one breather path that opens to an exterior of the composite layup

Methodology Applied

Scientific EffectFluid flow through gaps:

Implementation Method 2

curing the composite laminate in response to the application of heat

Methodology Applied

Scientific EffectThermal curing: Heating

Implementation Method 3

consolidating the composite laminate in response to the application of compaction pressure

Methodology Applied

Scientific EffectMechanical compression: Compression

Data Source

PatentUS9855733B2Method for achieving low porosity in composite laminates

Publication Date: 2018.01.02 THE BOEING CO

AI summary

A method of manufacturing a composite laminate may include laying up bands of composite material in layers to form a composite layup. At least one layer may have at least one gap between an adjacent pair of bands. The gap may extend continuously along a lengthwise direction of the band. The gap in two or more of the layers may be fluidly interconnected and may form at least one breather path that opens to an exterior of the composite layup.