To determine the bifurcation types in a rotor-bearing system, it is required to find higher order derivatives of the bearing forces with respect to journal velocity and position. As closed-form expressions for journal bearing force are not generally available, Hopf bifurcation studies of rotor-bearing systems have been limited to simple geometries and cavitation models. To solve this problem, an alternative nonlinear coefficient-based method for representing the bearing force is presented in this study. A flexible rotor-bearing system is presented for which bearing force is modeled with linear and nonlinear dynamic coefficients. The proposed nonlinear coefficient-based model was found to be successful in predicting the bifurcation types of the system as well as predicting the system dynamics and trajectories at spin speeds below and above the threshold speed of instability.
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March 2018
Research-Article
Nonlinear Dynamics of Flexible Rotors Supported on Journal Bearings—Part I: Analytical Bearing Model
Mohammad Miraskari,
Mohammad Miraskari
Mechanical Engineering Department,
University of British Columbia,
2054-6250 Applied Science Lane,
Vancouver, BC V6T 1Z4, Canada
e-mail: m.miraskari@alumni.ubc.ca
University of British Columbia,
2054-6250 Applied Science Lane,
Vancouver, BC V6T 1Z4, Canada
e-mail: m.miraskari@alumni.ubc.ca
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Farzad Hemmati,
Farzad Hemmati
Mechanical Engineering Department,
University of British Columbia,
054-6250 Applied Science Lane,
Vancouver, BC V6T 1Z4, Canada
e-mail: farhemmati@alumni.ubc.ca
University of British Columbia,
054-6250 Applied Science Lane,
Vancouver, BC V6T 1Z4, Canada
e-mail: farhemmati@alumni.ubc.ca
Search for other works by this author on:
Mohamed S. Gadala
Mohamed S. Gadala
Mechanical Engineering Department,
University of British Columbia,
2054-6250 Applied Science Lane,
Vancouver, BC V6T 1Z4, Canada;
Mechanical Engineering Department,
Abu Dhabi University,
Abu Dhabi, United Arab Emirates
e-mail: gadala@mech.ubc.ca
University of British Columbia,
2054-6250 Applied Science Lane,
Vancouver, BC V6T 1Z4, Canada;
Mechanical Engineering Department,
Abu Dhabi University,
Abu Dhabi, United Arab Emirates
e-mail: gadala@mech.ubc.ca
Search for other works by this author on:
Mohammad Miraskari
Mechanical Engineering Department,
University of British Columbia,
2054-6250 Applied Science Lane,
Vancouver, BC V6T 1Z4, Canada
e-mail: m.miraskari@alumni.ubc.ca
University of British Columbia,
2054-6250 Applied Science Lane,
Vancouver, BC V6T 1Z4, Canada
e-mail: m.miraskari@alumni.ubc.ca
Farzad Hemmati
Mechanical Engineering Department,
University of British Columbia,
054-6250 Applied Science Lane,
Vancouver, BC V6T 1Z4, Canada
e-mail: farhemmati@alumni.ubc.ca
University of British Columbia,
054-6250 Applied Science Lane,
Vancouver, BC V6T 1Z4, Canada
e-mail: farhemmati@alumni.ubc.ca
Mohamed S. Gadala
Mechanical Engineering Department,
University of British Columbia,
2054-6250 Applied Science Lane,
Vancouver, BC V6T 1Z4, Canada;
Mechanical Engineering Department,
Abu Dhabi University,
Abu Dhabi, United Arab Emirates
e-mail: gadala@mech.ubc.ca
University of British Columbia,
2054-6250 Applied Science Lane,
Vancouver, BC V6T 1Z4, Canada;
Mechanical Engineering Department,
Abu Dhabi University,
Abu Dhabi, United Arab Emirates
e-mail: gadala@mech.ubc.ca
1Corresponding author.
Contributed by the Tribology Division of ASME for publication in the JOURNAL OF TRIBOLOGY. Manuscript received November 25, 2016; final manuscript received August 14, 2017; published online October 4, 2017. Assoc. Editor: Alan Palazzolo.
J. Tribol. Mar 2018, 140(2): 021704 (15 pages)
Published Online: October 4, 2017
Article history
Received:
November 25, 2016
Revised:
August 14, 2017
Citation
Miraskari, M., Hemmati, F., and Gadala, M. S. (October 4, 2017). "Nonlinear Dynamics of Flexible Rotors Supported on Journal Bearings—Part I: Analytical Bearing Model." ASME. J. Tribol. March 2018; 140(2): 021704. https://doi.org/10.1115/1.4037730
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