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.

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.

Cyclic Spectrum Analysis on Rolling-Element Bearing with Inner-Race Point Defect

2011 ◽  
Vol 291-294 ◽  
pp. 1469-1473
Author(s):  
Wei Ke ◽  
Yong Xiang Zhang ◽  
Lin Li
Keyword(s):  
Point Defect ◽  
Signal To Noise Ratio ◽  
Vibration Signal ◽  
Rolling Element Bearing ◽  
Bearing Fault ◽  
Rolling Element ◽  
Element Bearing ◽  
Simulation Signal ◽  
Inner Race ◽  
Cyclic Spectrum

Vibration signal of rolling-element bearing is random cyclostationarity when a fault develops, the proper analysis of which can be used for condition monitor. Cyclic spectrum is a common cyclostationary analysis method and has a great many algorithms which have distinct efficiency in different application circumstance, two common algorithms (SSCA and FAM) are compared in the paper. The FAM is recommended to be used in diagnosing rolling-element bearing fault via calculation of simulation signal in different signal to noise ratio. The cyclic spectrum of practice signal of rolling-element bearing with inner-race point defect is analyzed and a new characteristic extraction method is put forward. The preferable result is acquired verify the correctness of the analysis and indicate that the cyclic spectrum is a robust method in diagnosing rolling-element bearing fault.

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.

Effect of Waviness on Vibration and Acoustic Features of Rolling Element Bearing

2012 ◽  
Author(s):  
Yimin Shao ◽  
Pei Wang ◽  
Zaigang Chen
Keyword(s):  
Dynamic Model ◽  
Computational Cost ◽  
Element Model ◽  
Mapping Method ◽  
Rolling Element Bearing ◽  
Acoustic Features ◽  
Rigid Displacement ◽  
Outer Race ◽  
Deep Groove ◽  
Rolling Element

Waviness of rolling element bearings, as one of the most concerned factors, would greatly influence the dynamic and acoustic performances of machines. In this paper, a new algorithm of vibro-acoustic coupling, which is based on the displacement mapping method by applying the displacement history obtained from a 6-DOF bearing dynamic model to be as the boundary condition of the finite element model of the bearing housing, is developed to predict the effect of waviness on the vibration and acoustic features of the bearing. The displacement excitation of the circumferential surface of bearing housing can be obtained by vector synthesis of bearing rigid displacement from the 6-DOF bearing dynamic model. This new method enables not only the reduction in computational cost, but also simulation of the bearing waviness under different sizes. A 6308 deep groove ball bearing model with outer race waviness is taken as an example case to examine the effectiveness of the new algorithm. The simulation results show that the new algorithm is able to predict the vibration and acoustic features of the bearing with waviness.

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.

Advanced Rolling-Element Bearing Diagnostics Based on Cyclic Spectral Analysis

2007 ◽  
Vol 347 ◽  
pp. 265-270
Author(s):  
Jerome Antoni ◽  
Roger Boustany
Keyword(s):  
Background Noise ◽  
Rolling Element Bearing ◽  
Outer Race ◽  
Spectral Signatures ◽  
Bearing Diagnostics ◽  
Rolling Element ◽  
Cyclical Behaviour ◽  
Element Bearing ◽  
Incipient Fault ◽  
Inner Race

Rolling-element bearing vibrations are random cyclostationary, that is they exhibit a cyclical behaviour of their statistical properties while the machine is operating. This property is so symptomatic when an incipient fault develops that it can be efficiently exploited for diagnostics. This paper gives a synthetic but comprehensive discussion about this issue. First, the cyclostationarity of bearing signals is proved from a simple phenomenological model. Once this property is established, the question is then addressed of which spectral quantity can adequately characterise such vibration signals. In this respect, the cyclic coherence - and its multi-dimensional extension in the case of multi-sensors measurements -- is shown to be twice optimal: first to evidence the presence of a fault in high levels of background noise, and second to return a relative measure of its severity. These advantages make it an appealing candidate to be used in adverse industrial environments. The use and interpretation of the proposed tool are then illustrated on actual industrial measurements, and a special attention is paid to describe the typical "cyclic spectral signatures" of inner race, outer race, and rolling-element faults.

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