Gas Turbine Fan Blade Root Shear Key Curved Interface
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing shear key and shear key slot arrangements in gas turbine engine fan blades are costly to treat and have high stress concentration at geometrically complex corners, making them difficult to surface treat effectively, especially for resisting bird strike impacts.
Innovation Solution
The design features a slot and key arrangement where a greater percentage of the interface is curved rather than planar, reducing stress concentration away from tight corners, allowing for reduced surface treatment time and enabling the use of low plasticity burnishing or laser peening, and providing improved resistance to bird strikes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a shear key slot arrangement with planar faces and curved corners is used to resist bird strike impact, then the resistance to bird strike impact is improved, but the surface treatment becomes more difficult and expensive due to geometrically complicated corners with high stress concentration
Solution Approach 1:
The patent applies curvature to the slot interface by defining it as an arc rather than a combination of planar faces and curved corners. This curved interface eliminates the geometrically complicated corners that create high stress concentration, while still providing the necessary structural strength to resist bird strike impacts. The curved interface is simpler to surface treat compared to the conventional planar-faced slot with curved corners.
2Reliability
If laser shock peening is used to treat the shear key slot surface to mitigate fatigue failure, then the fatigue resistance is improved, but the treatment cost increases and the treatment time increases due to the need to carefully treat complicated corner geometries
Solution Approach 1:
The curved arc interface eliminates the need to treat complicated corner geometries, significantly reducing surface treatment time. The continuous curved surface is much simpler to apply laser shock peening or other surface treatments compared to the conventional planar-faced slot with curved corners, while still providing the necessary fatigue resistance.
Solution Approach 2:
The patent applies surface treatment to a simplified geometry where the entire interface can be treated uniformly without requiring special attention to difficult-to-reach corners. This local simplification of the geometric complexity allows for more efficient and consistent surface treatment application.
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 design reduces the need for extensive surface treatment, particularly in complex geometries, and allows for the use of faster and cheaper surface treatment methods like low plasticity burnishing, while maintaining or improving resistance to bird strike impacts.
Implementation Method 1
A greater or equal percentage of the interface is curved than is planar
Implementation Method 2
An exemplary surface treatment method is laser shock peening
Implementation Method 3
allowing for the use of low plasticity burnishing or laser peening
Data Source
AI summary
A fan for gas turbine engine that includes hub and annular array of fan blades mounted to hub and extending radially outwardly from hub, each fan blade includes blade root. The hub includes a plurality of hub grooves having shape complimentary to shape of blade root and each hub groove receives and radially retains one blade root. A slot is provided on the suction side and on the pressure side of each blade root. Plurality of keys is provided, each key engages with slots in one blade root and with corresponding hub groove so as to axially retain fan blade. The key includes two arms and joining member, two arms are received in slots provided on blade root and joining member extends between the arms. Interface is defined between key arms and slots in blade root, and greater or equal percentage of interface is curved than is planar.