Elastomer Layer Fan Blade Vibration Damping
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Solution Overview
Problem
Aircraft engine fan blades face significant weight and cost increases due to the need to compensate for fan blade loss, with existing hybrid solutions like honeycomb fillings and elastomer-filled grooves being unsuitable for damping vibrations and prone to cracking during bird strikes.
Innovation Solution
A fan blade design featuring a large-area elastomer layer on the suction side, which increases in thickness radially, providing continuous stiffness transition and reducing weight, impact, and imbalance loads, while avoiding cracking risks through its cohesive, cavity-free structure and lower modulus of elasticity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all-metal fan blades are used, then strength and reliability are improved, but weight increases and impact forces in case of blade loss become high
Solution Approach 1:
The fan blade combines metal base body with elastomer material to create a hybrid construction. The metal provides structural strength while the elastomer reduces weight and dampens vibrations, resolving the contradiction between strength and weight requirements.
Solution Approach 2:
The elastomer material is applied selectively in specific regions of the fan blade where weight reduction and vibration damping are most beneficial, while maintaining metal construction in areas requiring high strength, achieving local optimization of the strength-weight balance.
2Weight of moving object
If hybrid fan blades with honeycomb filling are used, then weight is reduced, but vibration damping capability is insufficient and cracking risk increases
Solution Approach 1:
The elastomer material properties are specifically selected to provide optimal vibration damping characteristics and resistance to bird strike impacts, changing the material parameters from rigid honeycomb structures to flexible elastomeric compounds that can absorb energy without cracking.
Solution Approach 2:
The elastomer's flexibility and lower stiffness, which might seem to reduce structural rigidity, actually convert impact energies from bird strikes and vibrations into beneficial damping effects, preventing crack propagation and improving overall reliability.
3Reliability
If grooves filled with elastomer are introduced, then vibration damping is improved, but cracking risk in event of overstretching increases
Solution Approach 1:
Instead of introducing grooves into the metal blade body and filling them with elastomer (which creates stress concentration points), the invention applies elastomer as a surface layer or coating on the blade exterior, inverting the traditional approach to eliminate crack initiation sites while maintaining vibration damping benefits.
4Reliability
If fan blade loss compensation structures are added, then engine safety is improved, but engine weight and cost increase significantly
Solution Approach 1:
The elastomer layer on the fan blade itself provides vibration damping and impact resistance, making the blade self-protecting and reducing the need for additional heavy compensation structures in the engine assembly, as the blade inherently contributes to its own safety.
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 design reduces impact and imbalance loads by up to 30% during fan blade loss, effectively dampens vibrations, and is resistant to wear, making it suitable for aircraft engines.
Implementation Method 1
The at least partial formation of the suction side of the blade by an elastomer layer has the advantage that the weight of the fan blade is reduced by the elastomer layer due to its comparatively low density
Implementation Method 2
the elastomer layer, which increases outwards at least in sections, is accompanied by a thickness of a metal base body of the fan blade, to which the elastomer layer is applied
Implementation Method 3
the elastomer layer, which increases outwards at least in sections, is accompanied by a thickness of a metal base body of the fan blade, to which the elastomer layer is applied decreasing at least in sections or constantly outwards
Data Source
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AI summary
The invention relates to a fan blade (12) for an aircraft propulsion system, comprising a leading edge (121), a trailing edge (122), a suction side (124), a pressure side (125), and a blade tip (123). The fan blade (12) is provided to have a large-area elastomer layer (14) that forms at least 20% of the surface area of the suction side (124) of the fan blade (12) and whose thickness increases at least section by section in the radial direction towards the outside.