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Nonlinear Vibration Analysis of a Rotor with Nonlinear Pedestal by use of Jeffcott Model

Farzanmehr, Younes | 2018

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 50746 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Haddadpour, Hassan; Dehghani Firouzabadi, Rouhollah
  7. Abstract:
  8. The present research aims to achieve two major objectives in the Rotordynamic phenomenon. The first one is to study the linear and nonlinear dynamic characteristics of tilting pad journal bearings and calculating their dynamic coefficients like damping and stiffness, and the second one, studies the linear and nonlinear behavior of rotors standing on nonlinear pedestal, say nonlinear tilting pad journal bearing. By use of Partial Derivative method along with Perturbation method the linear dynamic coefficients are calculated for three different model of tilting pad journal bearing and these results are validated with the results presented by previous researches. The presented procedure is developed for tilting pad journal bearing in order to calculate nonlinear dynamic coefficients including pad and journal perturbation. The full and reduced order linear as well as nonlinear dynamic coefficients are evaluated for two kinds of five-pad tilting pad journal bearings and the obtained results are compared with other researches in order to confirm the reliability of present procedure. As the present procedure reveals, the dynamic coefficients are dimensionless and are independent of viscosity of lubricant oil, therefore, the results are capable to be used in a Thermoelastohydrodynamic analysis. On the other hand, the Jeffcott rotor model has been used in order for stability analysis to be carried out through the Rotordynamic analysis. The Perturbation method has been used to analyze the nonlinear dynamic equations of motion of Jeffcott rotor and results are presented for assumed parameters as well as for two kinds of five-pad tilting pad journal bearings including LBP and LOP
  9. Keywords:
  10. Nonlinear Vibration ; Rotor Dynamics ; Multiple Scales Method (MMS) ; Perturbation Theory ; Jeffcott Rotor ; Nonlinear Tilting Pad Journal Bearing (TPJB)

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