scholarly journals Synchronous Dynamics of a Coupled Shaft/Bearing/Housing System With Auxiliary Support From a Clearance Bearing: Analysis and Experiment

1997 ◽  
Vol 119 (2) ◽  
pp. 430-435 ◽  
Author(s):  
J. L. Lawen ◽  
G. T. Flowers
Keyword(s):  
Dynamic Behavior ◽  
Magnetic Bearing ◽  
Dynamic Responses ◽  
Housing System ◽  
Vibration Modes ◽  
Simulation Studies ◽  
Flexible Rotor ◽  
Shaft Vibration ◽  
Rotor Dynamic ◽  
Bearing Analysis

This study examines the response of a flexible rotor supported by load sharing between linear bearings and an auxiliary clearance bearing. The objective of the work is to develop a better understanding of the dynamic behavior of a magnetic bearing supported rotor system interacting with auxiliary bearings during a critical operating condition. Of particular interest is the effect of coupling between the bearing/housing and shaft vibration on the rotor-dynamic responses. A simulation model is developed and a number of studies are performed for various parametric configurations. An experimental investigation is also conducted to compare and verify the rotor-dynamic behavior predicted by the simulation studies. A strategy for reducing sychronous shaft vibration through appropriate design of coupled shaft/bearing/housing vibration modes is identified. The results are presented and discussed.

scholarly journals Synchronous Dynamics of a Coupled Shaft/Bearing/Housing System With Auxiliary Support From a Clearance Bearing: Analysis and Experiment

1995 ◽  
Author(s):  
James L. Lawen ◽  
George T. Flowers
Keyword(s):  
Experimental Investigation ◽  
Simulation Model ◽  
Dynamical Behavior ◽  
Magnetic Bearing ◽  
Housing System ◽  
Vibration Modes ◽  
Simulation Studies ◽  
Flexible Rotor ◽  
Shaft Vibration ◽  
Bearing Analysis

This study examines the response of a flexible rotor supported by load sharing between linear bearings and an auxiliary clearance bearing. The objective of the work is to develop a better understanding of the dynamical behavior of a magnetic bearing supported rotor system interacting with auxiliary bearings during a critical operating condition. Of particular interest is the effect of coupling between the bearing/housing and shaft vibration on the rotordynamical responses. A simulation model is developed and a number of studies are performed for various parametric configurations. An experimental investigation is also conducted to compare and verify the rotordynamic behavior predicted by the simulation studies. A strategy for reducing sychronous shaft vibration through appropriate design of coupled shaft/bearing/housing vibration modes is identified. The results are presented and discussed.

Dynamic responses of the rotor supported by a new type zero-clearance catcher bearing

2017 ◽  
Vol 31 (19-21) ◽  
pp. 1740014
Author(s):  
Yi-Li Zhu ◽  
Zhong-Qiao Zheng
Keyword(s):  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Dynamic Responses ◽  
Failure Event ◽  
Long Time ◽  
New Type ◽  
Amb System ◽  
Rotor Dynamic

Catcher bearings (CB) are required to support the rotor rotating for some time when a failure event of active magnetic bearing (AMB) system occurs. For this purpose, a new type zero-clearance catcher bearing (NTZCB) is proposed. The influences of different parameters of NTZCB on the rotor dynamic responses are theoretically and experimentally analyzed. The results indicate that choosing relatively soft spring and heavy moveable supporting pedestal can effectively buffer the rotor vibrations, which makes it possible for the rotor to keep rotating with the support of the CB system for a long time.

BIFURCATION ANALYSIS IN FLEXIBLE ROTOR SUPPORTED BY ACTIVE MAGNETIC BEARING

2001 ◽  
Vol 11 (08) ◽  
pp. 2163-2178 ◽  
Author(s):  
MING-JYI JANG ◽  
CHA'O-KUANG CHEN
Keyword(s):  
Dynamic Behavior ◽  
Bifurcation Analysis ◽  
Coupling Effect ◽  
Power Spectra ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Flexible Rotor ◽  
Factors Affecting ◽  
Operational Conditions ◽  
Amb System

In this paper, bifurcation analysis of the dynamic response of active magnetic bearing (AMB) with flexible rotor is presented, which includes the coupling effect between X-Y directions caused by rotational motion. The AMB systems include many nonlinear factors, such as mass imbalance, mass ratio with disk and journal, material property of shaft, and magnetic forces, etc., and its dynamic behavior are inherently nonlinear. Bifurcation diagrams of shaft journal's center, trajectories, power spectra, and Poincaré maps are used to analyze the dynamic behavior of the AMB system under different operational conditions. The key factors affecting the dynamic characteristics of the AMB system are identified. It will be beneficial to the design of AMB system.

Thermoelastic Growth of an Auxiliary Bearing Surface Due to Repeated Rotor Dynamic Contact and Rubbing

2007 ◽  
Author(s):  
Woon Yik Yong ◽  
Patrick S. Keogh
Keyword(s):  
Large Scale ◽  
Surface Deformation ◽  
Dynamic Contact ◽  
Magnetic Bearing ◽  
Dynamic Responses ◽  
Temperature Changes ◽  
Auxiliary Bearing ◽  
Transient Events ◽  
Individual Contact ◽  
Rotor Dynamic

There are a number of important issues relating to rotor/auxiliary contact in magnetic bearing systems. Primarily, an auxiliary bearing must prevent rotor/stator contact during events such as system power failure and large scale input disturbances. The auxiliary bearing may experience repeated contacts ranging from short timescale transient events to longer timescale rubs. While many studies of the rotor dynamic responses have been undertaken and reported in the open literature, the associated problems relating to thermoelastic distortion have received relatively little attention. These are important since high initial slip speeds will lead to localized heating that may cause large and highly transient surface temperature changes. Repeated contact events or repeated rubbing over a surface deformation may also lead to an accumulative increase in the level of surface distortion. This paper presents a study of the methodology that could be used to assess the overall thermoelastic distortion between a rotor and an auxiliary bearing. It shows that an assessment of the dynamic accumulation of distortion is possible from fundamental studies of individual contact events. The results from case studies highlight the possible problems that could be caused by clearance reductions during operation.

An Experimental Investigation of the Effect of an Active Magnetic Damper on Reducing Subsynchronous Vibrations in Rotating Machinery

2005 ◽  
Author(s):  
M. Kasarda ◽  
H. Mendoza ◽  
R. G. Kirk ◽  
A. Wicks
Keyword(s):  
Magnetic Bearing ◽  
Rotating Machinery ◽  
Active Magnetic Bearing ◽  
Flexible Rotor ◽  
Test Rig ◽  
Stability Margins ◽  
Analysis And Design ◽  
Rotor Support ◽  
Rotor Dynamic ◽  
Mass Test

Presented here are results from an experimental study investigating the reduction of subsynchronous vibrations in rotating machinery by adding a single active magnetic bearing actuator to a flexible rotor-bearing system. In this scenario, the Active Magnetic Bearing (AMB) actuator is used as an Active Magnetic Damper (AMD) and is not utilized for rotor support. The AMD can be used to increase stability margins by adding more damping in strategic locations on a rotor allowing for increased tolerance to instability mechanisms and enabling increased performance and efficiency in turbomachinery. Results from an experimental 3-mass test rig supported in fluid-film bushings are presented here. The study shows that subsynchronous vibrations are reducible with an AMD located near the mid-span of the rotor and up to a 98% reduction in the amplitude of subsynchronous vibrations is demonstrated. The overall results from this work demonstrate that reduction in subsynchronous response is feasible and that full rotor dynamic analysis and design is critical for the successful application of this approach as critical speed locations can be altered.

Dynamic analysis of a helical gear reduction by experimental and numerical methods

2020 ◽  
Vol 68 (1) ◽  
pp. 48-58
Author(s):  
Chao Liu ◽  
Zongde Fang ◽  
Fang Guo ◽  
Long Xiang ◽  
Yabin Guan ◽  
...  
Keyword(s):  
Numerical Methods ◽  
Dynamic Analysis ◽  
Dynamic Behavior ◽  
Fourth Order ◽  
Numerical Models ◽  
Helical Gear ◽  
Operating Conditions ◽  
Dynamic Responses ◽  
Lumped Mass ◽  
Gear Mesh

Presented in this study is investigation of dynamic behavior of a helical gear reduction by experimental and numerical methods. A closed-loop test rig is designed to measure vibrations of the example system, and the basic principle as well as relevant signal processing method is introduced. A hybrid user-defined element model is established to predict relative vibration acceleration at the gear mesh in a direction normal to contact surfaces. The other two numerical models are also constructed by lumped mass method and contact FEM to compare with the previous model in terms of dynamic responses of the system. First, the experiment data demonstrate that the loaded transmission error calculated by LTCA method is generally acceptable and that the assumption ignoring the tooth backlash is valid under the conditions of large loads. Second, under the common operating conditions, the system vibrations obtained by the experimental and numerical methods primarily occur at the first fourth-order meshing frequencies and that the maximum vibration amplitude, for each method, appears on the fourth-order meshing frequency. Moreover, root-mean-square (RMS) value of the acceleration increases with the increasing loads. Finally, according to the comparison of the simulation results, the variation tendencies of the RMS value along with input rotational speed agree well and that the frequencies where the resonances occur keep coincident generally. With summaries of merit and demerit, application of each numerical method is suggested for dynamic analysis of cylindrical gear system, which aids designers for desirable dynamic behavior of the system and better solutions to engineering problems.

Nonlinear Dynamics Behavior of Tethered Submerged Buoy under Wave Loadings

2020 ◽  
Vol 21 (1) ◽  
pp. 11-21
Author(s):  
Lin Zhao ◽  
Weihao Meng ◽  
Zhongqiang Zheng ◽  
Zongyu Chang
Keyword(s):  
Nonlinear Dynamics ◽  
Dynamic Behavior ◽  
Coupling Factor ◽  
Dynamic Responses ◽  
Mooring Line ◽  
Second Law ◽  
Largest Lyapunov Exponent ◽  
Nonlinear Characteristic ◽  
Runge Kutta Method ◽  
Marine Engineering

AbstractTethered submerged buoy is used extensively in the field of marine engineering. In this paper considering the effect of wave, the nonlinear dynamics behavior of tethered submerged buoy is debated under wave loadings. According to Newton’s second law, the dynamic of the system is built. The coupling factor of the system is neglected, the natural frequency is calculated. The dynamic responses of the system are analyzed using Runge–Kutta method. Considering the variety of the steepness kA, the phenomenon of dynamic behavior can be periodic, double periodic and quasi-periodic and so on. The bifurcation diagram and the largest Lyapunov exponent are applied to judge the nonlinear characteristic. It is helpful to understand the dynamic behavior of tethered submerged buoy and design the mooring line of tethered submerge buoy.

Dynamic Analysis of Flexible Rotor Suspended by Active Magnetic Bearings With LQR Controller

2018 ◽  
Author(s):  
Yixin Su ◽  
Yanhui Ma ◽  
Qian Shi ◽  
Suyuan Yu
Keyword(s):  
Dynamic Characteristics ◽  
Beam Theory ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Flexible Rotor ◽  
Linear Quadratic ◽  
State Response ◽  
Lagrange’S Equation ◽  
Linear Quadratic Regulation ◽  
Lqr Controller

Dynamic characteristics of active magnetic bearing (AMB)-flexible rotor system are closely related to control law. To analyze dynamic characteristics of flexible rotor suspended by AMBs with linear quadratic regulation (LQR) controller, a simple and effective method based on numerical calculation of unbalanced response is proposed in this article. The model of flexible rotor is established based upon Euler-Bernoulli beam theory and Lagrange’s equation. Disc on the rotor and its Gyro effect are taken into account. LQR controller based on error and its derivative is developed to control electromagnetic force of AMB at each degree of freedom (DOF) in real time. Under the unbalanced exciting force, the steady-state response and transient response in time domain of each node of flexible rotor at 0–4000 rad/s are calculated numerically. The critical speeds of rotor are obtained by identification method quickly and easily.

scholarly journals The Active Magnetic Bearing Enables Optimum Damping of Flexible Rotor

1984 ◽  
Author(s):  
Helmut Habermann ◽  
Maurice Brunet
Keyword(s):  
Control System ◽  
Rotation Axis ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Flexible Rotor ◽  
Mechanical Contact ◽  
Electronic Control System ◽  
Electromagnetic Coils ◽  
Automatic Balancing ◽  
Ferromagnetic Ring

The active magnetic bearing is based on the use of forces created by a magnetic field to levitate the rotor without mechanical contact between the stationary and moving parts. A ferromagnetic ring fixed on the rotor “floats” in the magnetic fields generated by the electromagnets, which are mounted as two sets of opposing pairs. The current is transmitted to the electromagnetic coils through amplifiers. The four electromagnets control the rotor’s position in response to the signals transmitted from the sensors. The rotor is maintained in equilibrium under the control of the electromagnetic forces. Its position is determined by means of sensors which continuously monitor any displacements through an electronic control system. As in every control system, damping of the loop is provided by means of a phase advance command from one or more differenciating circuits of the position error signal. The capability of modifying the electromagnetic force both in terms of amplitude and phase leads to the benefit of specific properties for the application, in particular: - automatic balancing characterized by the rotation of the moving part around its main axis of inertia, and not around the axis of the bearings allowing operation without vibrations, - adjustable damping of the suspension allowing easy passing of the critical speeds of the rotor, - high and adjustable stiffness yielding maximum accuracy of rotor equilibrium position, - permanent diagnosis of machine operation due to the knowledge of all rotation characteristics (speed, loads on the bearings, position of the rotation axis, eccentricity, out-of-balance, disturbance frequency).

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