scholarly journals Dynamic Modelling and Response Characteristics of a Magnetic Bearing Rotor System With Auxiliary Bearings

1995 ◽  
Author(s):  
April M. Free ◽  
George T. Flowers ◽  
Victor S. Trent
Keyword(s):  
Dynamic Modelling ◽  
Magnetic Bearing ◽  
Rotor System ◽  
Rolling Element Bearing ◽  
Test Facility ◽  
Iron Core ◽  
Critical Feature ◽  
Response Characteristics ◽  
Rolling Element ◽  
Auxiliary Bearing

Abstract Auxiliary bearings are a critical feature of any magnetic bearing system. They protect the soft iron core of the magnetic bearing during an overload or failure. An auxiliary bearing typically consists of a rolling element bearing or bushing with a clearance gap between the rotor and the inner race of the support. The dynamics of such systems can be quite complex. It is desired to develop a rotordynamic model which describes the dynamic behavior of a flexible rotor system with magnetic bearings including auxiliary bearings. The model is based upon an experimental test facility. Some simulation studies are presented to illustrate the behavior of the model. In particular, the effects of introducing sideloading from the magnetic bearing when one coil fails is studied. These results are presented and discussed.

scholarly journals Response analysis of random base excitation ona magnetic bearing rotor system

2019 ◽  
Vol 293 ◽  
pp. 04004
Author(s):  
Jinping Chen ◽  
Li Zhang ◽  
Yanyan Luo ◽  
Haining Zhang ◽  
Jun Liu
Keyword(s):  
Collision Detection ◽  
Random Excitation ◽  
Magnetic Bearing ◽  
Rotor System ◽  
Response Analysis ◽  
Random Response ◽  
Practical Application ◽  
External Disturbances ◽  
Response Characteristics ◽  
Auxiliary Bearing

The magnetic bearing-rotor system is subject to various external disturbances in practical application. Under certain control conditions, the random response characteristics of the magnetic bearing-rotor system are a particular concern. This paper analyzes the response characteristics of base of the magnetic bearing subjected to acceleration random excitation in the horizontal direction. First, the magnetic bearing-rotor system model is deduced. Then, the random response of the rotor under acceleration random excitation is derived. The probability of the collision of the rotor between the auxiliary bearing is calculated and the example is given. The paper conclusion provides a theoretical basis for the collision detection and prediction of the magnetic bearing-rotor system.

Traction Characteristics of a Rolling Element Bearing Under Rapid Acceleration and Implications for Auxiliary Operation in Magnetic Bearing Systems

2006 ◽  
Author(s):  
Matthew O. T. Cole ◽  
Theeraphong Wongratanaphisan
Keyword(s):  
Dynamic Behavior ◽  
Magnetic Bearing ◽  
Rolling Element Bearing ◽  
Elastic Behavior ◽  
Friction Forces ◽  
Auxiliary Operation ◽  
Rolling Element ◽  
Rolling Elements ◽  
Auxiliary Bearing ◽  
Bearing Assembly

The application of rolling element bearings for auxiliary operation in magnetic bearing systems is quite common, yet such operation is very different to that for which standard bearings are designed. During initial touchdown of a spinning rotor with an auxiliary bearing, rapid acceleration of the bearing inner race results in large inertial and friction forces acting on the rolling elements. Complex dynamic behavior of the bearing assembly and resulting traction forces are difficult to predict but, nonetheless, have important implications for both rotor dynamic behavior and thermo-elastic behavior of the bearing components. The aim of this work is to obtain an insight into bearing behavior by analyzing component interaction forces that would arise based on the assumption that the overall bearing traction torque is dependent only on instantaneous load, speed and acceleration. How such an analysis can be verified by experimental measurements of traction during rapid acceleration is discussed and some initial experimental results are presented. The implications for modeling and prediction of rotor-magnetic bearing system behavior during touchdown are also discussed.

Zero Clearance Auxiliary Bearings for Magnetic Bearing Systems

1997 ◽  
Author(s):  
H. Ming Chen ◽  
James Walton ◽  
Hooshang Heshmat
Keyword(s):  
Magnetic Bearing ◽  
Rolling Element Bearing ◽  
Prototype System ◽  
Successful Operation ◽  
Composite Support ◽  
Rotor Systems ◽  
Rolling Element ◽  
Traction Coefficient ◽  
Auxiliary Bearing ◽  
Open Position

Active magnetic bearings (AMBs) while offering many unique design and operational opportunities for advanced rotor systems, require some form of backup or auxiliary bearing in the event of a component failure or the onset of high transient loads. A zero clearance auxiliary bearing (ZCAB) has recently been conceived and a prototype system tested. The ZCAB presented in this paper uses a series of interconnected rollers to surround a shaft. In the open position, a clearance exists between the ZCAB rollers and the shaft. When the shaft drops on the ZCAB due to either an AMB failure or transient shock, the rollers move circumferentially and radially inward to eliminate the clearance and re-center the shaft. Besides centering the shaft, the law shaft-to-ZCAB traction coefficient and composite support dynamic characteristics eliminate the possibility of backward whirl. This paper presents the design methodology used, results of an analytical design study, including time transient analysis, as well as preliminary feasibility prototype testing under simulated AMB failure and transient shock conditions. The test rotor was supported by a rolling element bearing at one end and an integrated magnetic bearing/ZCAB support system at the other end. Both rotor drop and shock tests were performed with this configuration. Experimental results under simulated AMB failure and transient shock conditions demonstrated successful operation of the ZCAB.

The Dynamic Behavior of a Rolling Element Auxiliary Bearing Following Rotor Impact

2001 ◽  
Vol 124 (2) ◽  
pp. 406-413 ◽  
Author(s):  
M. O. T. Cole ◽  
P. S. Keogh ◽  
C. R. Burrows
Keyword(s):  
Dynamic Behavior ◽  
Angular Acceleration ◽  
Element Model ◽  
Magnetic Bearing ◽  
Rolling Element Bearing ◽  
Linear Matrix ◽  
Rolling Element ◽  
Non Linear ◽  
In Series ◽  
Inner Race

The dynamic behavior of a rolling element bearing under auxiliary operation in rotor/magnetic bearing systems is analyzed. When contact with the rotor occurs, the inner race experiences high impact forces and rapid angular acceleration. A finite element model is used to account for flexibility of the inner race in series with non-linear ball stiffnesses arising from the ball-race contact zones. The dynamic conditions during rotor/inner race contact, including ball/race creep, are deduced from a non-linear matrix equation. The influences of bearing parameters are considered together with implications for energy dissipation in the bearing.

scholarly journals Design and Analysis of a Sensorless Magnetic Damper

1995 ◽  
Author(s):  
H. Ming Chen
Keyword(s):  
Analytical Method ◽  
Magnetic Bearing ◽  
Rolling Element Bearing ◽  
Displacement Sensors ◽  
Vertical Rotor ◽  
Rolling Element ◽  
Element Bearing

An analytical method for designing magnetic bearing controllers with no displacement sensors has been developed and laboratory tested. The method was applied to the design of a sensorless magnetic damper for replacing a rolling element bearing of a vertical rotor with a large unbalance. The synchronous vibration force transmitted to ground was predicted to be reduced by a factor of ten.

Design and Analysis of a Sensorless Magnetic Damper

1997 ◽  
Vol 119 (1) ◽  
pp. 174-177
Author(s):  
H. M. Chen
Keyword(s):  
Analytical Method ◽  
Magnetic Bearing ◽  
Rolling Element Bearing ◽  
Displacement Sensors ◽  
Vertical Rotor ◽  
Rolling Element ◽  
Element Bearing

An analytical method for designing magnetic bearing controllers with no displacement sensors has been developed and laboratory tested. The method was applied to the design of a sensorless magnetic damper for replacing a rolling element bearing of a vertical rotor with a large unbalance. The synchronous vibration force transmitted to ground was predicted to be reduced by a factor of ten.

scholarly journals Identification of the Quadrature Resonances Using Modal Nonsynchronous Perturbation Testing and Dynamic Stiffness Approach for an Anisotropic Rotor System with Fluid Interaction

1996 ◽  
Vol 2 (3) ◽  
pp. 187-199 ◽  
Author(s):  
Eungu Jang ◽  
Agnes Muszynska ◽  
Young-Pil Park ◽  
Chang-Ho Kim
Keyword(s):  
Dynamic Stiffness ◽  
Rotor System ◽  
Rolling Element Bearing ◽  
Resonance Phenomenon ◽  
Rolling Element ◽  
Stiffness Anisotropy ◽  
Symmetric Rotor ◽  
Element Bearing ◽  
Fluid Interaction ◽  
Strong Agreement

The paper presents the dynamic analysis of an anisotropic rotor system with fluid interaction by using modal nonsynchronous perturbation testing and dynamic stiffness approaches. The anisotropic rotor system produces more complex rotor behavior than an isotropic system. In particular, the existence of the quadrature resonance phenomenon for backward precession is demonstrated. A symmetric rotor supported anisotropically by one fluid lubricated bearing and one rolling element bearing simulates rotating machinery behavior. A dynamic stiffness anisotropy algorithm which includes fluid terms is used to process experimental data in order to identify lightly loaded journal fluid film force parameters. The existence of the quadrature resonance for backward precession obtained from the experiment is compared with the analytical model. The results from modeling show strong agreement with experimental results.

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