Composite Fan Blade Leading Edge Sheath with Energy Absorbing Insert
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Solution Overview
Problem
Gas turbine engine blades face challenges in achieving lighter weight while maintaining impact resistance and aerodynamic efficiency, particularly due to FAA bird strike requirements.
Innovation Solution
The design incorporates a blade body made of composite material with a leading edge sheath and an energy absorbing insert. The leading edge sheath has arms that engage the blade body, creating a cavity for the energy absorbing insert, which is made of materials like non-Newtonian materials or D3O.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the blade thickness is increased proximate the leading edge to improve impact resistance, then the impact resistance is improved, but the overall weight of the blade increases and aerodynamic efficiency decreases
Solution Approach 1:
The blade is divided into distinct functional zones: a leading edge sheath structure with arms spaced apart to define a cavity, and an energy absorbing insert positioned within the cavity. This segmentation allows the leading edge to be optimized for impact resistance while the rest of the blade maintains lighter weight and optimal aerodynamic characteristics.
Solution Approach 2:
The blade incorporates composite construction with a blade body made of composite material, combined with a leading edge sheath and energy absorbing insert. This composite approach enables different regions to have optimized properties - the sheath and insert provide impact resistance while the composite blade body maintains lightweight characteristics and aerodynamic efficiency.
2Strength
If the blade thickness is increased proximate the leading edge to improve impact resistance, then the impact resistance is improved, but the aerodynamic efficiency decreases
Solution Approach 1:
The leading edge sheath is segmented with arms spaced apart rather than forming a solid thick structure. This creates a cavity that houses the energy absorbing insert while maintaining a more aerodynamic profile compared to a solid increased-thickness design, thus preserving aerodynamic efficiency while providing impact protection.
Solution Approach 2:
The blade structure is optimized locally at the leading edge with the sheath and insert configuration specifically designed for impact resistance, while the rest of the blade maintains its original aerodynamic profile and thickness. This localized approach ensures impact protection without compromising overall aerodynamic performance.
3Strength
If a leading edge sheath with spaced arms and energy absorbing insert is implemented, then the impact energy absorption capability is enhanced, but the device complexity increases
Solution Approach 1:
The leading edge sheath and energy absorbing insert are integrated as a combined protective system. The sheath arms engage the blade body to define a cavity that receives the insert, creating a unified impact protection mechanism that functions as a single system rather than separate components, thereby managing complexity.
Solution Approach 2:
The leading edge sheath structure serves multiple functions: it provides structural engagement with the blade body, defines the cavity for the energy absorbing insert, and contributes to the overall impact resistance. This multi-functionality reduces the need for additional separate components, managing device complexity while enhancing protective capability.
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 configuration reduces the overall weight of the blade while enhancing its impact resistance and aerodynamic efficiency, effectively addressing the trade-offs between weight, impact resistance, and fuel burn.
Implementation Method 1
energy absorbing insert disposed within the cavity... enhancing its impact resistance... greater impact energy absorption capability during a blade impact event
Implementation Method 2
The energy absorbing insert is made of at least one of a non-Newtonian material, D3O, polyborodimethylsiloxane, viscoelastic urethane polymers
Implementation Method 3
The blade body is made of a composite material... blades of lighter weight with greater impact energy absorption capability
Data Source
AI summary
An airfoil for a gas turbine engine includes a blade body, a leading edge sheath, and an energy absorbing insert. The blade body has a pressure side and a suction side that each between a forward portion and a trailing edge. The leading edge sheath has a leading edge portion that is spaced apart from the forward portion, a first arm that engages the pressure side, and a second arm that engages the suction side. A cavity is defined between the leading edge portion, the first arm, the second arm, and the forward portion. The energy absorbing insert is disposed within the cavity and improves the impact resistance of the airfoil.