Fan Blade Composite Ribs for Impact Resistance
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Solution Overview
Problem
Traditional fan blades for gas turbine engines lack sufficient impact resistance, leading to potential damage and premature failure from bird strikes or foreign object impacts, despite efforts to reduce weight and maintain strength.
Innovation Solution
A fan blade design featuring a composite rib integrated with the blade body and cover, where the composite rib is adhered to both the blade body and cover, with a groove to increase contact surface area, and optionally filled with lightweight filler material, enhancing structural integrity and impact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional titanium fan blades are used, then strength is maintained, but weight increases and manufacturing cost increases
Solution Approach 1:
The patent employs a hybrid construction combining titanium blade body with composite material ribs and cover. The composite rib (made from carbon fiber reinforced polymer or similar materials) is adhered to the titanium blade body using adhesive bonding. This composite approach maintains the strength requirements while significantly reducing the overall weight compared to solid titanium construction.
2Weight of moving object
If weight is reduced by machining pockets and adding covers, then weight decreases, but impact resistance deteriorates
Solution Approach 1:
The patent incorporates a recessed lip structure around the perimeter of the blade body that serves as a cushioning element. This lip is designed to absorb and distribute impact forces from bird strikes or foreign object damage before they reach the critical blade structure. The composite rib and cover assembly work together with this lip to provide beforehand cushioning, maintaining impact resistance while enabling weight reduction through the pocketed construction.
3Strength
If composite rib with groove is added, then adhesive surface area increases and structural integrity improves, but device complexity increases
Solution Approach 1:
The patent introduces a groove feature on the composite rib that corresponds to the shape of the blade rib. This groove creates an interlocking geometry between the composite rib and the blade body, transforming a simple surface bonding problem into a three-dimensional mechanical interlock. The groove allows the adhesive to be contained and distributed more effectively, increasing the effective bonding surface area and creating a mechanically interlocked structure that enhances structural integrity without requiring excessively complex assembly procedures.
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 provides improved impact resistance and durability, allowing for a stronger and lighter fan blade assembly that resists shear and tension forces, reducing the risk of damage from bird strikes and other impacts.
Implementation Method 1
the composite rib is adhered to the bottom surface of the pocket and to an interior surface of the cover
Data Source
Figure 1
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AI summary
A fan blade has a blade body, a composite rib and a cover. The blade body extends from a blade root to an opposed blade tip along a longitudinal axis. The blade body defines a leading edge and a trailing edge. A first airfoil surface extends from the leading edge to the trailing edge A pocket is defined between the leading edge, the trailing edge, the blade root, and the blade tip. The pocket has a bottom surface that opposes the first airfoil surface across the blade body. The composite rib is disposed in the pocket. The cover is mounted to the composite rib and the blade body to form a second airfoil surface opposed to the first airfoil surface.