الفهرس 
CHAPTER 1: INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Active magnetic bearing (AMB) is a new type of bearing, and it is an essential part of many industrial rotating machine. It is unlike conventional bearings, which based on mechanical forces creating from fluid films or physical contact to support bearing
loads. AMB systems using controllable electromagnetic force caused by electromagnet to levitate and support a shaft in an air gap between the bearing stator and rotor without any physical or mechanical contact. The research towards AMB is increasing because it has a several advantages such as contact free operation, no lubrication, no wear, high speed, decreased vibration, low bearing losses, lower maintenance costs and longer life time. Due to these advantages, AMB is used widely in many fields such as transportations, high speed machine tool and aerospace. AMB
is utilizing in many industrial applications like turbomolecular vacuum pump, artificial heart blood pump, natural gas pipelines, etc. This thesis aimed to study the magnetic analysis of AMBs and determine various magnetic properties such as magnetic field, magnetic flux, and magnetic flux density. The effect of changing coil current, air gap and number of turns on different magnetic properties has been studied. Dynamic analysis of rotor system with active magnetic bearing has been presented, as well as natural frequencies were evaluated by two methods (Ansys Workbench and finite element method based on Matlab code). A
comparative study is done between the results that obtained from the previous study using experimental and finite element method and the current study using Ansys Workbench. This comparison is made to illustrate the accuracy of using Ansys Workbench in the analysis of rotor bearing system. However, the influence of changing the boundary conditions of rotor system on the dynamic properties has been studied.
In this work, Ansys Maxwell software is used to create the 3D simulation of an
eight-pole active magnetic bearing. The simulation has been performed using finite element method (FEM). Ansys Workbench is used to perform the dynamic analysis of rotor system with active magnetic bearing. The numerical finite element technique based on matlab code is utilized for computing the natural frequencies. A comparative study is made between the results that were obtained from the previous study using experimental and the finite element method and the current study using
Ansys Workbench. In addition to, the effect of changing the boundary conditions of rotor system on the dynamic properties has been carried out using Ansys Workbench. Magnetic properties have been presented in a 3D simulation and the influence of
changing in the magnetic parameters on the magnetic properties has been studied. The natural frequencies, mode shapes and frequency response of rotor system are computed, and the results demonstrated that the natural frequencies increase with the
increase of bearing stiffness, and the higher modes do not differ much when the
bearing stiffness increases. The calculated natural frequencies that obtained from Ansys Workbench and the finite element based on matlab code are in a very close agreement. In addition to, the numerical results that obtained from Ansys Workbenchshow a very close agreement with the results that obtained from the previous study of “Liyunlu” using experimental and the finite element method. By studying the effect of changing the boundary conditions of rotor system it is observed that the natural frequency increases with the increase of the bearing fixation and the results of simply supported beam are very close to the results of active magnetic bearings so AMB is considered a simply support.