Segmented Leading Edge Cladding for Controlled Fan Blade Tip Separation
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Solution Overview
Problem
Composite fan blades used in turbine engines are prone to brittle fracture and delamination during foreign object impacts due to their low ductility, and conventional cladding designs fail to separate the blade tips from the body during rub events, potentially causing further damage.
Innovation Solution
The airfoil design incorporates a cladding element with a tip portion and a body portion that meet at a boundary, where the leading edge is configured to fail near the boundary when a predetermined force is applied, allowing the tip portion to separate from the body portion, thereby controlling damage and preventing further engine damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional cladding is applied to composite fan blades, then impact resistance is improved, but the cladding fails to separate during rub events causing further engine damage
Solution Approach 1:
The cladding is divided into a body portion and a tip portion that can separate from each other. The body portion remains attached to the composite blade body while the tip portion is configured to separate during rub events, allowing controlled failure that prevents further engine damage.
Solution Approach 2:
Different portions of the cladding have different mechanical properties and failure characteristics. The body portion is designed to remain intact and provide ongoing protection, while the tip portion is designed to fail at a predetermined load to prevent catastrophic damage during rub events.
2Strength
If carbon composite materials are used for fan blades, then specific strength and light weight are improved, but brittle fracture and delamination susceptibility worsen
Solution Approach 1:
The solution uses a composite structure combining carbon composite material for the blade body with metal cladding elements. The carbon composite provides high specific strength and light weight, while the metal cladding provides ductility and resistance to brittle fracture and delamination.
Solution Approach 2:
The metal cladding is applied specifically to critical areas (leading edge, tip, and trailing edge) where impact and delamination risks are highest, rather than covering the entire blade. This provides localized protection where needed while maintaining the lightweight composite structure elsewhere.
Data Source
AI summary
An airfoil that includes an airfoil body having a root and a tip, and convex and concave sides that extend between a leading edge and a trailing edge. The airfoil also includes at least a first cladding element that is attached to the airfoil body. The first cladding element includes a first portion and a second portion. The second portion is configured to separate from the first portion when the first cladding element encounters a force of at least a predetermined amount.