Nonlinear Dynamics of Magnetic Bearing Systems

Ji, Jinchen; Hansen, Colin H.; Zander, Anthony C.

doi:10.1177/1045389x08088666

Cited by 49 publications

(22 citation statements)

References 110 publications

(120 reference statements)

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“…In comparison to rolling element bearings, which are de facto the most common type of bearings (Shen et al, 2014;Zhao et al, 2016), foil bearings have higher durability and improved vibration damping. Even though magnetic bearings can also be used in high-speed machinery (Ji et al, 2008), in particular, active magnetic bearings (Wu et al, 2018), the multi-component system of devices that are required to control the position of the rotor and a high price of such devices severely limit their usability. A somewhat new ap-proach in the field of bearing systems is the use of slide bearings with electrorheological and magnetorheological liquids as lubricants.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Gas Foil Bearings With an Adaptive and Non-Linear Structure

Żywica

Bagiński

2019

Acta Mechanica Et Automatica

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The article discusses the results of simulation-based and experimental research carried out on gas foil bearings. Owing to the use of a set of flexible thin foils in such bearings, they exhibit certain beneficial features that cannot be found in other types of bearings. They have nonlinear operational characteristics and allow the dissipation of excess energy, thus reducing the vibration level. Moreover, gas foil bearings can self-adapt themselves to the current operating conditions by changing the shape of the lubrication gap. Therefore, they can be used to improve the dynamic performance of rotors, in particular, those operating at very high rotational speeds. This article explains the mechanisms for changes of stiffness and vibration damping in compliant components of a foil bearing. The results of the analysis of the bearing’s subassemblies using advanced numerical models are presented. They are followed by conclusions that were drawn not only from these results but also from the results of the experimental research. It has been proven that the rotor supported on carefully designed foil bearings is capable of maintaining a low vibration level, even if it operates at a high rotational speed.

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Section: Introductionmentioning

confidence: 99%

Investigation of Gas Foil Bearings With an Adaptive and Non-Linear Structure

Żywica

Bagiński

2019

Acta Mechanica Et Automatica

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“…However, they offer a simplified linear approach to mathematical modelling of rotor dynamics. However, rotor systems with nonlinear bearings, including magnetic ones, are known to exhibit nonlinear effects [8,9]. Therefore, building refined mathematical models will enable increasing the accuracy of numerical computation of required dynamic parameters of rotors, magnetic bearings and control systems for active magnetic bearings.…”

Section: Introductionmentioning

confidence: 99%

Application of Nonlinear Models for a Well-Defined Description of the Dynamics of Rotors in Magnetic Bearings

Martynenko

2016

EUREKA: Physics and Engineering

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A research report has been submitted. It deals with implementing a method for a mathematical description of the nonlinear dynamics of rotors in magnetic bearings of different types (passive and active). The method is based on Lagrange-Maxwell differential equations in a form similar to that of Routh equations in mechanics. The mathematical models account for such nonlinearities as the nonlinear dependencies of magnetic forces on gaps in passive and active magnetic bearings and on currents in the windings of electromagnets; nonlinearities related to the inductances in coils; the geometric link between the electromagnets in one AMB and the link between all AMBs in one rotor, which results in relatedness of processes in orthogonal directions, and other factors. The suggested approach made it possible to detect and investigate different phenomena in nonlinear rotor dynamics. The method adequacy has been confirmed experimentally on a laboratory setup, which is a prototype of a complete combined magnetic-electromagnetic suspension in small-size rotor machinery. Different variants of linearizing the equations of motion have been considered. They provide for both linearization of restoring magnetic or electromagnetic forces in passive and active magnetic bearings, and exclusion of nonlinear motion equation terms. Calculation results for several linearization variants have been obtained. An appraisal of results identified the drawbacks of linearized mathematical models and allowed drawing a conclusion on the necessity of applying nonlinear models for a well-defined description of the dynamics of rotor systems with magnetic bearings.

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“…Comparative analysis of numerical and experimental results had shown the identity for both qualitative representation of the processes in the system and quantitative determination of their parameters: for the amplitude, the difference was within 2-3%, and for the values of resonant frequencies, the difference was within 0.2 to 0.5% [26]. The adequacy and applicability of mathematical model (1) and the algorithm of its numerical analysis for studying the nonlinear dynamics of rigid rotors in MB [27] of various types had been confirmed experimentally. This was done by comparing not only the AFR over the entire investigated range of excitation frequencies, but also by the dependencies of amplitudes of other harmonics on frequency, as well as by vibrograms, spectra and trajectories of the motion of rotor bearing points [21,24].…”

Section: Vibrograms Of Rotor Vibrations For Different Rotational Speedsmentioning

confidence: 99%

Resonance mode detuning in rotor systems employing active and passive magnetic bearings with controlled stiffness

Martynenko¹

2022

Int. J. Automot. Mech. Eng.

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In the paper, the investigator offered a method of reducing the amplitude of vibrations of turbo machinery rotors with passive and active magnetic bearings in resonances and resonance zones corresponding to one of the critical speeds ranging from zero to operating rotational ones. The method was based on the ability to vary the nonlinear force characteristic and the damping properties of active magnetic bearings and passive magnetic bearings of a novel design by changing the electric parameters of electromagnet circuits. The offered design of a passive magnetic bearing with permanent ring magnets and a control winding enabled a short-time change of rotor bearing stiffness. Such rotor bearings can realise the method of detuning from critical speeds during rotor speed-up and run-down. Earlier, this method was feasible only when active magnetic bearings were used. However, a complete magnetic suspension of a rotor with the employment of two radial passive bearings and one axial active magnetic bearing was advantageous as compared to three active magnetic bearings. The feasibility of the detuning method had been substantiated by study results. The study presented the results of numerical analysis, which simulated the process of transition through resonances of the initial system with a significant reduction of vibration amplitudes. The nonlinear system of differential magnetic-mechanical equations was solved using the 5th-order Runge-Kutta method with a validation for the duality of solutions. The results were shown as 3-dimensional spectra of displacement of bearing points and amplitude-frequency responses. These results had been confirmed by experimental data obtained for a laboratory setup that implemented a combined passive-active magnetic suspension of a rotor. The overall total relative error of measurements was maintained at less than 0.5%. The discrepancy between the experimental and design data for amplitudes was within 2-3%, and for resonance frequencies, it was less than 0.2%. Hence, these studies substantiated the feasibility of passive magnetic bearings with controlled stiffness. They also confirmed the possibility of using passive-active magnetic suspensions for lightweight rotors (e.g., expanders and compressors) with the implementation of the suggested method of detuning from resonance modes.

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Nonlinear Dynamics of Magnetic Bearing Systems

Cited by 49 publications

References 110 publications

Investigation of Gas Foil Bearings With an Adaptive and Non-Linear Structure

Investigation of Gas Foil Bearings With an Adaptive and Non-Linear Structure

Application of Nonlinear Models for a Well-Defined Description of the Dynamics of Rotors in Magnetic Bearings

Resonance mode detuning in rotor systems employing active and passive magnetic bearings with controlled stiffness

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