Porosity Gradient Preform Architecture for Composite Infiltration

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Solution Overview

Problem

In high temperature composite manufacturing, achieving uniform gas infiltration into the center of fibrous preforms is challenging due to variables such as fiber volume and lack of adequate gas flow paths, leading to components with greater than 10% enclosed porosity.

Innovation Solution

A porosity gradient fibrous preform is created using fabric-resin layers with varying volumes of pore formers, where the volume of pore formers increases from the center to the outer surface. These pore formers are configured to be volatilized or pyrolyzed, creating interconnected pathways for fluid infiltration during densification.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a dry fabric preform is used for high temperature composite manufacturing, then the preform structure is simple and easy to manufacture, but the gas infiltration is non-uniform and enclosed porosity exceeds 10%

Engineering Contradiction:

Improvepreform manufacturing simplicityVSAvoidgas infiltration uniformity

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The preform incorporates fabric-resin layers with spatially varying pore former volumes, creating a porosity gradient where inner layers have lower porosity and outer layers have higher porosity. This local variation in pore structure enables uniform gas infiltration throughout the preform while maintaining manufacturability through layered construction.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The invention uses pore formers (such as hollow microspheres or expandable beads) dispersed within fabric-resin layers to create controlled porous structures. These porous materials provide defined pathways for gas infiltration, transforming the dense dry fabric structure into a controlled porous medium that facilitates uniform fluid penetration.

Inventive Principle:

Principle #31Porous materials

2Manufacturing precision

If pore formers are added to create infiltration pathways, then gas infiltration uniformity improves, but the preform structure and composition become more complex

Engineering Contradiction:

Improvegas infiltration uniformityVSAvoidpreform structure complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The preform is divided into multiple fabric-resin layers, each containing pore formers with specific volume characteristics. This segmentation allows independent control of pore former volume in each layer, enabling systematic creation of porosity gradients while maintaining modular manufacturability and reducing overall structural complexity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention systematically varies the volume of pore formers across different fabric-resin layers to create a porosity gradient. By changing this single parameter (pore former volume) in a controlled manner from inner to outer layers, uniform gas infiltration is achieved without requiring complex multi-parameter variations in the preform structure.

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If the volume of pore formers increases from center to outer surface, then numerous pathways for uniform gas infiltration are created, but the composition variation across layers increases

Engineering Contradiction:

Improvegas infiltration uniformityVSAvoidresin and pore former composition consistency

Core Design Contradiction:

Manufacturing precisionVSStability of the object's composition

Solution Approach 1:

The preform is constructed from discrete fabric-resin layers, each with a specific pore former volume content. This segmentation allows the composition to vary systematically across layers while maintaining consistency within each layer, achieving both composition stability at the layer level and controlled variation at the component level for uniform gas infiltration.

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

The porosity gradient fibrous preform provides numerous pathways for uniform gas infiltration, enhancing the densification process and achieving more uniform and increased part density in high temperature composite components.

Implementation Method 1

The plurality of pore formers is configured to be volatilized from the porosity gradient fibrous preform to create a path through the porosity gradient fibrous preform for infiltration of a fluid

Methodology Applied

Scientific EffectVolatilization: Evaporation

Implementation Method 2

at least a portion of the resin is configured to be pyrolyzed from the porosity gradient fibrous preform to create the path through the porosity gradient fibrous preform for infiltration of the fluid

Methodology Applied

Scientific EffectPyrolysis: Pyrolysis

Implementation Method 3

In response to applying heat to the first fabric-resin layer and the second fabric-resin layer, the second portion of the plurality of pore formers is configured to expand

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS20250026049A1Porosity gradient preform architecture for high temperature composites

Publication Date: 2025.01.23 ROHR INC

AI summary

A porosity gradient fibrous preform includes a plurality of fabric-resin layers and a plurality of pore formers. Each fabric-resin layer includes a plurality of fibers and a resin. A volume of the plurality of pore formers sequentially increases from a center of the porosity gradient fibrous preform toward an outer surface of the porosity gradient fibrous preform. The pore formers can be pyrolyzed from the preform to create paths through the porosity gradient fibrous preform for infiltration of a fluid.