Compression Molded Chopped Prepreg Fan Case Ice Panel

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Solution Overview

Problem

Current composite constructions for ice panel facesheets in gas turbine engine fan cases are time-consuming and expensive to manufacture due to the need for manual layup of multiple layers of woven aramid fiber/epoxy resin prepreg fabric, with suboptimal material utilization and costly autoclaving processes.

Innovation Solution

The use of chopped prepreg tape, comprising non-continuous unidirectional fibers such as carbon or aramid fibers in an epoxy resin matrix, which is cured by compression molding to form a facesheet that is thicker and more efficient to produce, reducing the number of layers required and eliminating the need for manual orientation and excess material trimming.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If woven aramid fiber/epoxy resin prepreg fabric is used for ice panel facesheet, then impact resistance is improved, but manufacturing time and cost increase due to manual layup of multiple layers

Engineering Contradiction:

Improveimpact resistanceVSAvoidmanufacturing time

Core Design Contradiction:

StrengthVSLoss of time

Solution Approach 1:

The patent segments the continuous woven fabric into discontinuous chopped strands that are randomly distributed within the thermoplastic matrix. This segmentation allows the material to be processed as a bulk molding compound rather than requiring layer-by-layer manual layup, dramatically reducing manufacturing time while maintaining impact resistance through the random fiber distribution.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent replaces the manual mechanical layup process with a compression molding process. The chopped fiber/thermoplastic composite is placed in a mold and compressed under heat and pressure to form the facesheet, eliminating the time-consuming manual placement and orientation of multiple prepreg layers.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Strength

If woven aramid fiber/epoxy resin prepreg fabric is used for ice panel facesheet, then impact resistance is improved, but manufacturing cost increases due to expensive material and autoclaving process

Engineering Contradiction:

Improveimpact resistanceVSAvoidmanufacturing cost

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The patent changes the material parameters by substituting epoxy resin with thermoplastic resin and transitioning from continuous woven fibers to discontinuous chopped fibers. This parameter change enables the use of compression molding instead of autoclaving, reducing manufacturing cost while maintaining structural integrity.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses discontinuous chopped fibers instead of expensive continuous woven fabric, accepting the trade-off of using shorter, less expensive fiber segments that are randomly distributed. This approach reduces material cost and eliminates the need for expensive autoclaving equipment and processes.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Length of stationary object

If multiple thin plies of prepreg fabric are used to achieve desired thickness, then facesheet thickness is improved, but material utilization decreases due to trimming and disposal of excess material

Engineering Contradiction:

Improvefacesheet thicknessVSAvoidmaterial utilization

Core Design Contradiction:

Length of stationary objectVSLoss of substance

Solution Approach 1:

The patent performs preliminary action by pre-mixing the chopped fibers with the thermoplastic resin to create a bulk molding compound with the desired thickness and fiber content. This preliminary preparation eliminates the need for subsequent trimming and disposal of excess material, as the final part is formed directly to specification through compression molding.

Inventive Principle:

Principle #10Preliminary action

4Strength

If manual orientation of each prepreg layer is performed to allocate fiber reinforcement in multiple directions, then structural strength is improved, but manufacturing complexity increases

Engineering Contradiction:

Improvestructural strengthVSAvoidmanufacturing complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The patent applies homogeneity by randomly distributing chopped fibers throughout the thermoplastic matrix, creating a uniform material structure without directional bias. This homogeneous distribution provides isotropic mechanical properties, eliminating the need for complex manual orientation of layers while maintaining structural strength in multiple directions.

Inventive Principle:

Principle #33Homogeneity

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 simplifies the production process, increases material utilization, and reduces costs while maintaining the impact resistance of traditional ice panel facesheets, with fewer plies needed to achieve the same thickness and improved directional strength without compromising performance.

Implementation Method 1

which is cured by compression molding to form a facesheet

Methodology Applied

Scientific EffectCompression molding: Compression

Data Source

PatentEP3058199B1Compression molded fiber reinforced fan case ice panel

Publication Date: 2021.06.30 RTX CORP

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AI summary

An ice panel for a fan case of a gas turbine engine is disclosed. The ice panel may comprise a facesheet located on an inner surface of the fan case and it may comprise a chopped prepreg tape that is cured. The chopped prepreg tape may comprise randomly oriented chips of fibers impregnated with a resin matrix.