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Analysis of Rotor-Bearing Systems by Considering Hybrid Model for Rolling Bearings

Abbaszadeh Chekan, Jafar | 2011

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 42347 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Zohoor, Hassan
  7. Abstract:
  8. Rotor-dynamics is an important field of study in dynamical systems. Because of demands for rotary machines with high speeds such as turbines, pumps, fans, spindle machines and so on, the dynamic and stability analysis of these systems are considered over a hundred years. As some of the rotor systems are supported by rolling bearings with radial clearance, the dynamic and stability analysis of such systems can be helpful in the corresponding areas of the industry. In this thesis by utilizing regional stsbility concept, the Hybrid analysis of system is performed. The system includes a rigid and symmetric rotor which has two degrees of freedom. The bearings are considered to be tapered roller bearing and ball bearing and are modeled by utilizing Hertzian contact theory. Due to the possibility that each rolling element could be in contact with both of inner and outer races (under compression) or lose its contact, the system would have switching phenomena in its dynamic equations, so this system is categorized into Hybrid system. In this study Multiple Lyapunov Function Method is applied to analyze stability region of the system and Hamilton Function is used as the candidate Lyapunov Functions. The main contribution of this study is; considering switching phenomena in stability of rotor- rolling bearing systems and regional stability analysis of such systems, which are not reported before. The effects of some parameters such as; rotation speed of the rotor, roller elements’ contact angle, and number of roller elements of bearings on regional stability of the system on regional stability of the system are investigated. Also comparison between bearings with roller and ball elements are also studied and results are shown in graphs as well. At the end the obtained results from Hybrid analysis of system are validated via solution of system’s nonlinear equations of motion
  9. Keywords:
  10. Rolling Bearing ; Rotor-Bearing System ; Stability Analysis ; Switching Algorithm ; Hybrid Dynamical System ; Multiple Lyapunov Function Method

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