Composite Fan Case with Segmented Polymer Mounting

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Solution Overview

Problem

Metallic fan cases are heavy and do not efficiently manage thermal expansion, which can lead to inefficiencies and potential damage in gas turbine engines, while existing composite fan cases face challenges in precise manufacturing and integration with metallic components.

Innovation Solution

A composite fan case with a carbon fiber-reinforced body and segmented fiber-filled polymer members for mounting, which provides galvanic isolation and allows for precise machining, addressing thermal expansion and manufacturing ease through segmentation and molding techniques.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If a metallic fan case is used, then the containment capability is sufficient, but the weight increases undesirably

Engineering Contradiction:

Improvefan case weightVSAvoidcontainment capability

Core Design Contradiction:

Weight of moving objectVSStrength

Solution Approach 1:

The fan case uses a composite structure combining carbon fiber-reinforced polymer for the main body with fiberglass layers at mounting surfaces. This composite material approach reduces weight while maintaining containment capability through the high strength-to-weight ratio of carbon fiber and the protective function of fiberglass layers.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

Different material properties are applied at different locations: carbon fiber provides structural strength for containment, while fiberglass layers are specifically placed at mounting surfaces to provide galvanic isolation and machinability. This local differentiation optimizes both weight reduction and functional requirements.

Inventive Principle:

Principle #3Local quality

2Reliability

If fiberglass layers are added to composite fan cases for mounting surfaces, then galvanic isolation and machining margin are provided, but the device complexity increases

Engineering Contradiction:

Improvegalvanic isolationVSAvoidcomposite layup complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The fiberglass mounting layers are integrated directly into the composite layup process during manufacturing, merging the mounting surface preparation with the main structural fabrication. This eliminates separate assembly steps and reduces overall device complexity despite adding functional layers.

Inventive Principle:

Principle #5Merging (Combining)

3Weight of moving object

If a composite fan case is used, then weight is reduced, but manufacturing precision challenges arise

Engineering Contradiction:

Improvefan case weightVSAvoiddimensional precision

Core Design Contradiction:

Weight of moving objectVSManufacturing precision

Solution Approach 1:

The fiberglass layers act as an intermediary material that provides a machinable surface on top of the composite structure. This intermediate layer allows for precise dimensional adjustments and finishing operations, enabling high manufacturing precision while maintaining the weight benefits of composite materials.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Adaptability or versatility

If the liner is configured to have different thermal expansion than the composite structural portion, then the liner can closely accommodate the fan across operating conditions, but thermal management complexity increases

Engineering Contradiction:

Improvethermal accommodationVSAvoidthermal expansion management

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The design intentionally utilizes differential thermal expansion between the liner and composite structural portion to maintain clearance accommodation across operating conditions. The liner is selected with specific thermal expansion properties that allow it to expand or contract relative to the composite case, ensuring continuous contact with the rotating fan without binding or excessive clearance.

Inventive Principle:

Principle #37Thermal expansion

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 reduces weight, maintains containment capability, and accommodates thermal expansion, enhancing engine efficiency and manufacturing cost-effectiveness by using segmented polymer members to integrate with metallic components and manage thermal expansion.

Implementation Method 1

fiberglass layers inboard and outboard may serve to galvanically isolate the structural carbon fiber material from the metallic components

Methodology Applied

Scientific EffectGalvanic isolation:

Implementation Method 2

The buildup of fiberglass may also provide a margin for machining an otherwise imprecise composite to precise dimensions

Methodology Applied

Scientific EffectMachining:

Implementation Method 3

The liner may be configured to have different thermal expansion than the composite structural portion of the fan case. The difference allows the liner to closely accommodate the fan across a range of operating conditions

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS10221718B2Fan cases and manufacture methods

Publication Date: 2019.03.05 RTX CORP

AI summary

A turbine engine fan case (48) comprises a composite body member (300) circumscribing an axis (500) and having an annular mounting portion (310, 410), a segmented polymer member (320, 330, 420, 440) along the annular mounting portion, and integrated therewith.