Open Access. Powered by Scholars. Published by Universities.®
- Discipline
Articles 1 - 2 of 2
Full-Text Articles in Mechanical Engineering
Nonlinear Prediction Of Rotordynamic Coefficients For A Hydrodynamic Journal Bearing, Jerzy Sawicki, T.V.V.L. Rao
Nonlinear Prediction Of Rotordynamic Coefficients For A Hydrodynamic Journal Bearing, Jerzy Sawicki, T.V.V.L. Rao
Jerzy T. Sawicki
In the analysis of hydrodynamic journal bearings, linearized stiffness and damping coefficients are widely used for the evaluation of stability and dynamic response characteristics. Under given operating conditions, these coefficients vary along the locus of the orbital response, and are not valid at large amplitudes (40% of the bearing clearance) of the journal motion. The time history of journal bearing motion for large vibrations is accurately predicted herein using nonlinear (time-transient) analysis. This paper discusses the adequacy of bearing analysis based on linearized coefficients and presents the significance of variation of the coefficients under the dynamic conditions. A method to …
Unbalance Response Prediction For Accelerating Rotors With Load-Dependent Nonlinear Bearing Stiffness, David Fleming, Jerzy Sawicki, J. Poplawski
Unbalance Response Prediction For Accelerating Rotors With Load-Dependent Nonlinear Bearing Stiffness, David Fleming, Jerzy Sawicki, J. Poplawski
Jerzy T. Sawicki
Rolling-element bearing forces vary nonlinearly with bearing deflection. Thus an accurate rotordynamic analysis requires that bearing forces corresponding to the actual bearing deflection be utilized. Previous papers have explored the transient effect of suddenly applied imbalance and the steady-state unbalance response, using bearing forces calculated by the rolling-element bearing analysis code COBRA-AHS. The present work considers the acceleration of a rotor through one or more critical speeds. The rotordynamic analysis showed that for rapid acceleration rates the maximum response amplitude may be considerably less than predicted by steady-state analysis. Above the critical speed, transient vibration at the rotor natural frequency …