SMA Recoupler for Hybrid Bearing Support
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Solution Overview
Problem
Gas turbine engines face challenges in managing the high loads and vibrations induced by fan bladeout events, which can lead to increased stress and inefficiency, as existing load reduction systems either increase engine weight or exacerbate vibration during windmilling.
Innovation Solution
A hybrid bearing support system incorporating a shape memory alloy (SMA) recoupler device that alters stiffness in response to load conditions, allowing for reduced loads during fan bladeout events and regained stiffness during windmilling, thereby managing imbalance loads effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If support components are sized to provide additional strength for the fan support system, then the strength and reliability are improved, but the overall weight of the engine increases and overall efficiency decreases
Solution Approach 1:
The patent applies dynamics by making the bearing support stiffness variable rather than fixed. The bearing support is designed to be stiff during normal operation to support engine weight efficiently, but becomes compliant during windmilling to reduce vibration. This dynamic adaptation resolves the contradiction by having the system automatically adjust its mechanical properties based on operational conditions, eliminating the need for permanently oversized components.
Solution Approach 2:
The patent changes the stiffness parameter of the bearing support based on operational phase. During normal operation, the bearing support maintains high stiffness for efficient load bearing. During windmilling, the stiffness parameter is reduced to allow vibration reduction. This parameter change enables the system to achieve both strength and weight efficiency at different times, resolving the contradiction between having strong support structures and maintaining low weight.
2Strength
If the radial and pitching rotation stiffness of the number two bearing position are softened or released during the FBO, then the high bending stresses are relieved, but the LRD increases vibration within the engine during windmilling
Solution Approach 1:
The patent implements dynamic stiffness control where the bearing support transitions from a stiff state during normal operation to a compliant state during windmilling. This dynamic behavior allows the system to relieve bending stresses during FBO events while simultaneously reducing vibration during windmilling, as the compliance is actively managed based on operational conditions rather than being a fixed property.
Solution Approach 2:
The bearing support system is designed to automatically adjust its stiffness characteristics based on the operational phase without external intervention. The system self-regulates to provide appropriate stiffness during normal operation and compliance during windmilling, eliminating the need for external control systems and enabling the component to serve multiple functions across different operational modes.
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 SMA recoupler device reduces fan bladeout loads, minimizes vibration, and maintains engine efficiency by adjusting stiffness according to operational conditions, thus reducing engine weight and improving fuel efficiency.
Implementation Method 1
a shape memory alloy (SMA) recoupler device that alters stiffness in response to load conditions
Implementation Method 2
The SMA recoupler device reduces fan bladeout loads, minimizes vibration, and maintains engine efficiency by adjusting stiffness according to operational conditions
Data Source
AI summary
A hybrid bearing support system includes a shaft extension fixedly coupled to a rotatable member at a radial inner end of the shaft extension, a radial outer end of the shaft extension fixedly coupled to a rotatable race of a bearing supporting the rotatable member, and a recoupler device formed of a shape memory alloy (SMA) material coupled in parallel with at least a portion of the shaft extension between the radial inner end and the radial outer end.