Porosity Gradient Preform for Uniform Gas 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, resulting in components with more than 10% porosity.

Innovation Solution

A porosity gradient fibrous preform is created by arranging fabric-resin layers with a decreasing resin weight ratio percentage from the center to the outer surface, allowing for uniform gas infiltration during densification. This is achieved through a manufacturing method involving the stacking of fabric-resin layers with varying resin content and subsequent pyrolysis to create a path for fluid infiltration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a dry fabric preform is used with uniform fiber distribution, then the preform structure is simple and easy to manufacture, but gas infiltration is non-uniform and pathways to the center are insufficient

Engineering Contradiction:

Improveuniformity of gas infiltrationVSAvoidpreform architecture complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The preform is designed with spatially varying resin content, creating regions of different porosity throughout the structure. The resin concentration decreases from the outer surfaces toward the center, establishing a gradient that optimizes gas flow pathways locally in different regions of the preform.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The resin is strategically placed in the preform before densification to pre-establish gas infiltration pathways. This preliminary arrangement of resin creates a controlled porosity gradient that guides gas flow toward the center during the densification process, preventing the infiltration uniformity problem.

Inventive Principle:

Principle #10Preliminary action

2Quantity of substance

If resin content is uniformly distributed throughout the preform, then the preform is easier to manufacture, but porosity is insufficient for adequate gas flow paths

Engineering Contradiction:

Improvegas flow pathwaysVSAvoidpreform fabrication complexity

Core Design Contradiction:

Quantity of substanceVSEase of manufacture

Solution Approach 1:

Different regions of the preform contain different amounts of resin, with higher resin content at the periphery and lower content toward the center. This local variation in resin quantity creates the necessary porosity gradient to establish adequate gas flow pathways while maintaining manufacturability through controlled resin placement.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The resin content parameter is varied spatially throughout the preform structure. By changing the resin concentration from uniform to gradient distribution, the preform achieves optimized porosity characteristics that enable sufficient gas flow pathways without requiring complex manufacturing processes.

Inventive Principle:

Principle #35Parameter changes

3Strength

If fiber volume percentage is increased to improve structural integrity, then mechanical strength improves, but porosity decreases and gas infiltration becomes more difficult

Engineering Contradiction:

Improvepreform structural integrityVSAvoidporosity for gas flow

Core Design Contradiction:

StrengthVSQuantity of substance

Solution Approach 1:

The preform structure allows different fiber-resin ratios in different regions. Regions with lower fiber volume contain more resin, creating higher local porosity for gas flow, while regions with higher fiber volume provide structural integrity. This spatial differentiation resolves the contradiction between strength and porosity.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The preform utilizes a composite fiber-resin structure where the resin phase serves dual purposes: binding fibers for structural integrity and creating porosity for gas flow pathways. The optimized resin distribution ensures both mechanical strength and adequate porosity are achieved simultaneously.

Inventive Principle:

Principle #40Composite materials

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 fluid infiltration, leading to more uniform and increased part density during the densification process, thereby improving the quality of high temperature composite components.

Implementation Method 1

the resin is configured to be pyrolyzed to create a porosity gradient. Stated differently, the porosity gradient can be formed in response to the porosity gradient fibrous preform undergoing a pyrolysis process.

Methodology Applied

Scientific EffectPyrolysis: Pyrolysis

Data Source

PatentUS20250026690A1Porosity gradient preform architecture for high temperature composites

Publication Date: 2025.01.23 ROHR INC

AI summary

A porosity gradient fibrous preform includes at least one first fabric-resin layer and a second fabric-resin layer, each including a plurality of fibers and a resin. The second fabric-resin layer is positioned on top of the at least one first fabric-resin layer. A weight ratio percentage of the resin sequentially decreases from a center of the porosity gradient fibrous preform toward an outer surface of the porosity gradient fibrous preform to create a path through the porosity gradient fibrous preform for infiltration of a fluid.