Cold Spray Leading Edge Sheath for Fan Blades

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Solution Overview

Problem

Existing methods for protecting the leading edges of fan blades and rotor blades from foreign object impacts and erosion, such as bird strikes, often result in galvanic corrosion and limitations in heat treatment due to direct material bonding, and are inefficient in manufacturing complex shapes.

Innovation Solution

A method involving the formation of a metallic sheath using a cold spray process on mandrels, with a skrim sheet for separation and heat treatment, providing a dense, strong, and erosion-resistant protection while avoiding galvanic corrosion, and allowing for lightweight materials with improved aerodynamic efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a metallic sheath is directly bonded to the leading edge of an airfoil, then protection from foreign object impact and erosion is achieved, but galvanic corrosion occurs between the sheath and the airfoil material

Engineering Contradiction:
Improveprotection from foreign object impact and erosionVSAvoidgalvanic corrosion
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an intermediate layer between the metallic sheath and the airfoil leading edge. This intermediate layer acts as a mediator that prevents direct contact between dissimilar metals, thereby eliminating galvanic corrosion while maintaining the protective function of the sheath against foreign object impact and erosion.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If traditional manufacturing methods are used to form sheaths, then protection is provided, but manufacturing complex shapes is inefficient and time-consuming

Engineering Contradiction:
Improveprotection from impact and erosionVSAvoidmanufacturing efficiency for complex shapes
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent employs additive manufacturing technology to form the metallic sheath, representing a fundamental change in the manufacturing parameter from traditional subtractive or assembly methods. This enables efficient production of complex three-dimensional shapes that would be difficult or time-consuming to manufacture using conventional methods, while maintaining the protective integrity of the sheath.

Inventive Principle:
Principle #35Parameter changes

3Strength

If heavy materials are used for the sheath, then strength and erosion resistance are improved, but the overall weight of the blade increases

Engineering Contradiction:
Improvestrength and erosion resistance of sheathVSAvoidweight of blade
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The patent applies the metallic sheath specifically to the leading edge region of the airfoil where impact and erosion protection is most critical, rather than covering the entire blade. This localized application provides the necessary strength and erosion resistance at the high-stress leading edge while minimizing the additional weight that would result from sheathing the entire blade structure.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent creates a composite structure by bonding a metallic sheath to the airfoil leading edge, combining the erosion and impact resistance properties of the metal with the aerodynamic properties of the airfoil material. This composite approach optimizes the protective function while managing the overall weight characteristics of the blade assembly.

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 method achieves enhanced strength, stiffness, and erosion resistance for leading edges, enabling the use of lightweight materials with optimal performance under impact and erosion conditions, while preventing galvanic corrosion and simplifying the manufacturing process.

Implementation Method 1

A method involves forming a sheath using a cold spray process on mandrels

Methodology Applied
Scientific EffectCold spray:

Implementation Method 2

providing a dense, strong, and erosion-resistant protection while avoiding galvanic corrosion

Methodology Applied
Scientific EffectGalvanic corrosion prevention:

Implementation Method 3

with a skrim sheet for separation and heat treatment

Methodology Applied
Scientific EffectHeat treatment: Heat Treatment

Data Source

PatentEP2823085B1Method of making leading edge protection
Publication Date: 2018.08.08 UNITED TECH CORP
  • EP2823085B1 patent drawingFigure 1
  • EP2823085B1 patent drawingFigure 2A
  • EP2823085B1 patent drawingFigure 2B~2C

AI summary

A method of forming a leading edge protection component includes depositing particles using a cold spray process on a mandrel to form a leading edge protection component; and removing the leading edge protection structure from the mandrel. The leading edge protection can be formed in one or more pieces and involve using one or more mandrels.