Study of Catcher Bearings for High Temperature Magnetic Bearing Application
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The Electron Energy Corporation (EEC) along with National Aeronautics and Space Administration (NASA) in collaboration with Vibration Control and Electro mechanics Lab (VCEL), Texas A & M University, College Station, TX are researching on high temperature permanent magnet based magnetic bearings. The magnetic bearings are made of high temperature resistant permanent magnets (up to 1000 degrees F). A test rig has been developed to test these magnetic bearings. The test rig mainly consists of two radial bearings, one axial thrust bearing and two catcher bearings. The test rig that the catcher bearing is inserted in is the first ultra-high temperature rig with permanent magnet biased magnetic bearings and motor. The magnetic bearings are permanent magnet based which is a novel concept. The Graphalloy bearings represent a new approach for ultra-high temperature backup bearing applications. One of the main objectives of this research is to insure the mechanical and electrical integrity for all components of the test rig. Some assemblies and accessories required for the whole assembly need to be designed. The assembly methods need to be designed. The preliminary tests for coefficient of friction, Young's modulus and thermal expansion characteristics for catcher bearing material need to be done. A dynamic model needs to be designed for studying and simulating the rotor drop of the shaft onto the catcher bearing using a finite element approach in MATLAB. The assembly of the test rig was completed successfully by developing assembly fixtures and assembly methods. The components of the test rig were tested before assembly. Other necessary systems like Sensor holder system, Graphalloy press fit system were designed, fabricated and tested. The catcher bearing material (Graphalloy) was tested for coefficient of friction and Young's modulus at room and high temperatures. The rotor drop was simulated by deriving a dynamic model, to study the effect of system parameters like clearance, coefficient of friction, negative stiffness, initial spin speed on system behavior. Increasing the friction increases the backward whirl and decreases the rotor stoppage time. Increasing the clearance reduces the stoppage time and increases the peak bearing force. Increasing the initial spin speed increases the rotor stoppage time. The maximum stress encountered for as built conditions is more than allowable limits.
Narayanaswamy, Ashwanth (2011). Study of Catcher Bearings for High Temperature Magnetic Bearing Application. Master's thesis, Texas A&M University. Available electronically from