scholarly journals Nonlinear Vibration Analysis and Experiments of a Vertical Rigid Rotor-Magnetic Bearing System (Case Considering the Delay of Control Force)

2005 ◽  
Vol 71 (707) ◽  
pp. 2106-2112 ◽  
Author(s):  
Tsuyoshi INOUE ◽  
Yukio ISHIDA ◽  
Shin MURAKAMI
Keyword(s):  
Nonlinear Vibration ◽  
Vibration Analysis ◽  
Magnetic Bearing ◽  
Control Force ◽  
Rigid Rotor ◽  
Bearing System

Nonlinear Vibration Analysis of an Elastic Rotor Supported on Angular Contact Ball Bearings Considering Six Degrees of Freedom and Waviness on Balls and Races

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
C. K. Babu ◽  
N. Tandon ◽  
R. K. Pandey
Keyword(s):  
Nonlinear Vibration ◽  
Elastic Deformation ◽  
Vibration Analysis ◽  
Degrees Of Freedom ◽  
Ball Bearings ◽  
Rigid Rotor ◽  
Six Degrees Of Freedom ◽  
Extension Work ◽  
Inner Race ◽  
Rotor Model

Nonlinear vibration analysis of an elastically deformable shaft supported on two lubricated angular contact ball bearings is reported herein considering six-degrees of freedom (6-DOF) and waviness on races and balls. This is an extension work of the investigation published by the authors Babu, C. K., Tandon, N., and Pandey, R. K., 2012, “Vibration Modeling of a Rigid Rotor Supported on the Lubricated Angular Contact Ball Bearings Considering Six Degree of Freedom and Waviness on Balls and Races,” ASME J. Vib. Acoust., 134, p. 011006. Elastic deformation of shaft, frictional moment, and waviness on races and balls have been incorporated in the model for the vibration investigations of rotor's CG. Two noded 3D Timoshenko beam element having 6-DOF has been employed in the computation of the shaft's deformation. Governing equations with appropriate boundary conditions have been solved using 4th order Runge–Kutta method. It is observed that vibration amplitude enhances considerably after incorporating the elastic deformation in comparison to the amplitude achieved using rigid rotor model approach. Moreover, the influence of outer race's radial waviness is large on the amplitudes of vibrations in comparison to radial waviness of inner race. However, it is worth noting here that in case of rigid rotor model the presence of radial waviness on inner race yields high amplitudes of vibrations.

Nonlinear Vibration in a Vertical Rigid Rotor Supported by the Magnetic Bearing: Case Considering the Delays of Both Electric Current and Magnetic Flux

2007 ◽  
Author(s):  
Tsuyoshi Inoue ◽  
Motoki Sugiyama ◽  
Yasuhiko Sugawara ◽  
Yukio Ishida
Keyword(s):  
Magnetic Flux ◽  
Electric Current ◽  
Magnetic Force ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Nonlinear Phenomena ◽  
Control Force ◽  
Rigid Rotor ◽  
Rotating Speed ◽  
First Order

Active magnetic bearing (AMB) becomes to be widely used in various kinds of rotating machinery. However, as the magnetic force is nonlinear, nonlinear phenomena may occur when the rotating speed becomes higher and delay of control force increases. In this paper, the magnetic force is modeled by considering both the second order delay of the electric current and the first order delay of the magnetic flux, and the AMB force is represented by a power series function of the electric current and shaft displacement. The nonlinear theoretical analysis of the vertical rigid rotor supported by AMB is demonstrated. The effects of the delays and other AMB parameters on the nonlinear phenomena are clarified theoretically and experimentally.

Vibration control of a flexible rotor/magnetic bearing system subject to direct forcing and base motion disturbances

1998 ◽  
Vol 212 (7) ◽  
pp. 535-546 ◽  
Author(s):  
M O T Cole ◽  
P S Keogh ◽  
C R Burrows
Keyword(s):  
Gas Turbines ◽  
Controller Design ◽  
Magnetic Bearing ◽  
Pid Controllers ◽  
Control Force ◽  
Flexible Rotor ◽  
Current State ◽  
Direct Forcing ◽  
State Of Research ◽  
Bearing System

During operation, a rotor/magnetic bearing system may be subject to various sources of vibration, either directly applied to the rotor or transmitted through the bearings owing to base motion. This paper considers controller designs that are capable of attenuating vibration arising from either source. It advances the current state of research in the area since other controller designs have considered only the direct forcing case. If base motion is not considered in the design of the controller then this disturbance may cause the bearing clearance limits to be reached. Controller design is formulated as an H∞ optimization problem, with mixed design objectives. A new controller is derived that can simultaneously reduce vibration and minimize the effect of base motion on relative rotor to bearing displacement. Account is taken of the fact that the bearings can apply only limited control force. The design study was complemented by a programme of experimental work. The base of a rig was subjected to impulse inputs and the results show the effectiveness of the new controller design. It is demonstrated that proportional, integral and derivative (PID) controllers, or controllers designed for unbalance vibration attenuation only, may result in rotor contact with retainer bushes, while the new controller may prevent contact. The potential now exists for continuing safe operation of flexible rotor/magnetic bearing systems such as compressors, gas turbines, generators, etc., in transport applications, during seismic events or in environments with expected base input disturbances.

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