Shape Memory Bearing Support for Turbomachine Shaft Guidance
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Solution Overview
Problem
Existing solutions for guiding rotor shafts in turbomachines, such as aircraft bypass turbojet engines, fail to effectively manage imbalance forces caused by foreign object ingestion, leading to potential damage and structural risk when one bearing is decoupled, while also increasing engine mass with additional support mechanisms.
Innovation Solution
A bearing support made of shape memory material that deforms under excessive loads to absorb energy and decouple from the casing, reverting to its initial shape when loads decrease, allowing the shaft to be recentred and maintaining axial retention, with optional heating means to facilitate this process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the upstream bearing is decoupled from the stator to avoid transferring imbalance forces to the engine structure, then the structure is protected from damage, but the shaft can no longer be centred and the downstream bearing is at risk of breaking
Solution Approach 1:
The bearing support employs a shape memory alloy annular part that dynamically changes its mechanical properties based on load conditions. Under normal operation, the material maintains a rigid austenitic phase to centre the shaft. When excessive imbalance forces occur, it transforms to a flexible martensitic phase, allowing decoupling to protect the downstream bearing, then reverts to austenitic phase to restore centring capability.
Solution Approach 2:
The invention changes the physical state of the bearing support material through temperature control. By heating the shape memory alloy above its transformation temperature, it switches from martensitic to austenitic phase, altering its rigidity and enabling it to recentre the shaft after decoupling. This parameter change allows the system to adapt between protection mode and centring mode.
2Reliability
If additional support mechanisms are added to allow shaft recentring after bearing decoupling, then the downstream bearing is protected, but the engine mass increases penalizing performance
Solution Approach 1:
The invention uses temperature-induced phase transformation of shape memory alloy to change the mechanical properties of the bearing support in-situ. By controlling the temperature parameter, the material transitions between rigid and flexible states, enabling recentring functionality without adding separate mechanical components, thus avoiding mass penalties.
Solution Approach 2:
The bearing support utilizes shape memory alloy, an intelligent composite material that combines structural and functional properties. This material integrates both load-bearing capability and shape recovery functionality into a single component, eliminating the need for additional recentring mechanisms and reducing overall system mass.
3Stability of the object's composition
If the upstream bearing support is made rigid to maintain shaft centring, then the shaft remains centred, but imbalance forces are transferred to the engine structure causing potential damage
Solution Approach 1:
The bearing support transitions from a static rigid structure to a dynamic adaptive structure. The shape memory alloy enables the support to switch between rigid (austenitic) and flexible (martensitic) states based on operational conditions, allowing it to centre the shaft during normal operation and become flexible during imbalance events to protect the engine structure.
Solution Approach 2:
The bearing support autonomously responds to load conditions through the shape memory effect. When excessive forces are detected through deformation, the material self-transforms to absorb energy and protect the structure. Upon cooling and load reduction, it automatically reverts to its original shape, restoring centring capability without external intervention.
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 solution effectively absorbs and manages imbalance forces during foreign object ingestion, preventing damage to the turbojet engine structure and allowing the shaft to be recentred once autorotation speed is reached, thereby protecting the downstream bearing and maintaining engine stability without significant mass penalties.
Implementation Method 1
an annular part made of a shape memory material which retains an initial shape when the load applied to it remains below a threshold value and which deforms, absorbing energy when the applied load becomes at least equal to the threshold value, this annular part being capable of reverting at least approximately to its initial shape when the applied load drops back below the threshold value
Implementation Method 2
the bearing support comprises controlled means of heating the shape memory annular part to cause this annular part to revert to its initial shape when the applied load is below the threshold value
Data Source
AI summary
A support for a bearing that guides a shaft in a turbomachine is disclosed. The support includes an annular part made of a shape memory material which retains an initial shape when the load applied to it remains below a threshold value and which deforms, absorbing energy when the applied load becomes at least equal to the threshold value. The annular part is capable of reverting at least approximately to its initial shape when the applied load drops back below the threshold value.