Composite Airfoil Cladding Roughness for Turbine Reliability

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Solution Overview

Problem

Turbine engines face challenges with composite airfoil components under extreme loading conditions, such as ingestion of foreign materials, which can lead to deflection and separation of cladding from the skin.

Innovation Solution

A composite airfoil assembly is developed, featuring a woven core and laminate skin with cladding having an arithmetic average roughness (Ra) of at least 100, improving connectivity between the cladding and skin to enhance structural integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If cladding is added to composite airfoil to protect against foreign material ingestion, then reliability improves, but device complexity increases

Engineering Contradiction:

Improveresistance to deflection and separation during extreme loadingVSAvoidstructure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The airfoil is divided into distinct functional segments: a core structure, a skin layer, and a cladding layer. Each segment serves a specific protective or structural function, allowing the complex protection requirement to be distributed across simpler, specialized components rather than requiring a single complex structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The airfoil employs a composite construction with a core made of composite material and a skin made of metal or composite material. This composite approach combines the advantages of different materials to achieve both structural integrity and protection against foreign material ingestion, resolving the contradiction between reliability and complexity.

Inventive Principle:

Principle #40Composite materials

2Reliability

If cladding is added to composite airfoil to protect against foreign material ingestion, then reliability improves, but manufacturing precision requirements increase

Engineering Contradiction:

Improveresistance to deflection and separation during extreme loadingVSAvoidsurface roughness requirement

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The cladding interior surface is deliberately modified to have a controlled roughness parameter (Ra of at least 100). This parameter change transforms the surface from smooth to rough, which paradoxically improves bonding effectiveness. The controlled modification of this physical parameter resolves the contradiction by making the surface roughness an intentional design feature rather than a manufacturing defect.

Inventive Principle:

Principle #35Parameter changes

3Strength

If cladding interior surface is roughened to improve bonding, then strength improves, but manufacturing precision worsens

Engineering Contradiction:

Improvebonding strength between cladding and skinVSAvoidsurface roughness control

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

Instead of attempting to achieve perfect smoothness (which would maximize manufacturing precision), the design intentionally changes the surface roughness parameter to Ra of at least 100. This counterintuitive parameter change prioritizes bonding strength over manufacturing precision, as the rough surface provides mechanical interlocking that exceeds the benefits of extreme smoothness.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS12304614B2Composite airfoil assembly and method of forming a composite airfoil assembly

Publication Date: 2025.05.20 GENERAL ELECTRIC CO

AI summary

A composite airfoil assembly for a gas turbine engine. The composite airfoil assembly includes a composite airfoil defined by a core and a skin. The composite airfoil assembly further includes cladding. The core defines a core exterior, where the skin is applied to at least a portion of the core exterior. The cladding is prepared before being coupled or adhered to the composite airfoil.