Stability of a Flexible Rotor-Bearing System with a Transverse Crack

2019 ◽  
pp. 3363-3373
Author(s):  
Abed Salam Ahmed ◽  
Bahrami Mohammad Reza ◽  
Thijel Jassim Farij
Keyword(s):  
Transverse Crack ◽  
Flexible Rotor ◽  
Rotor Bearing ◽  
Bearing System

Nonlinear Dynamics of Flexible Rotors Supported on Journal Bearings—Part I: Analytical Bearing Model

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Mohammad Miraskari ◽  
Farzad Hemmati ◽  
Mohamed S. Gadala
Keyword(s):  
Journal Bearing ◽  
Nonlinear Coefficient ◽  
Journal Bearings ◽  
Flexible Rotor ◽  
Dynamic Coefficients ◽  
Flexible Rotors ◽  
Rotor Bearing ◽  
Bearing Force ◽  
Derivatives Of ◽  
Bearing System

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.

Nonlinear Vibration Prediction of a Highly Flexible Rotor Supported by an Axial Groove Journal Bearing Considering Journal Angular Whirling Motion

2019 ◽  
Author(s):  
Nuntaphong Koondilogpiboon ◽  
Tsuyoshi Inoue
Keyword(s):  
Nonlinear Vibration ◽  
Ball Bearing ◽  
Journal Bearing ◽  
Flexible Rotor ◽  
Large Disk ◽  
Subcritical Bifurcation ◽  
Whirling Motion ◽  
Vibration Prediction ◽  
Rotor Bearing ◽  
Bearing System

Abstract In this study, the difference in dynamic behavior of the rotor-bearing system supported by the bearing model that considers both lateral and angular whirling motions of the journal (model A), and the model that considers only lateral whirling motion (model B) is investigated. The rotor model consists of a slender shaft, a large disk and two small disks supported by a self-aligning ball bearing and an axial groove journal bearing of L/D = 0.6. Three positions of the large disk: 410, 560, and 650 mm measured from the ball bearing, are investigated. Numerical integration of the rotor-bearing system which is modally reduced to the 1st forward mode is performed at above the onset speed of instability until either a steady state journal orbit or contact between the journal and the bearing occurs to identify the bifurcation type. Numerical results using model A indicate subcritical bifurcation with the contact between the journal and the inboard side of the bearing in all three large disk positions, whereas those of model B indicate subcritical bifurcation when the large disk position is at 410 mm, and supercritical bifurcation is observed in the other two cases. Lastly, the experiments at the same three large disk positions are performed. Subcritical bifurcation with the contact between the journal and the inboard side of the bearing is observed in all large disk positions, which conforms with the calculation result of model A. As a result, model A is essential in nonlinear vibration analysis of a highly flexible rotor system.

scholarly journals Balancing of a Flexible Rotor : 4th Report, Some Experiments on a Seven-Disked Flexible Rotor / Bearing System

1974 ◽  
Vol 40 (332) ◽  
pp. 934-944
Author(s):  
Shuzo MIWA ◽  
Takafumi NAKAI ◽  
Ichiro MIMURA ◽  
Yuichi MINAMI
Keyword(s):  
Flexible Rotor ◽  
Rotor Bearing ◽  
Bearing System

Robust optimization of a flexible rotor-bearing system using the Campbell diagram

2011 ◽  
Vol 43 (1) ◽  
pp. 77-96 ◽  
Author(s):  
T. G. Ritto ◽  
R. H. Lopez ◽  
R. Sampaio ◽  
J. E. Souza de Cursi
Keyword(s):  
Robust Optimization ◽  
Flexible Rotor ◽  
Campbell Diagram ◽  
Rotor Bearing ◽  
Bearing System
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