scholarly journals Research on Periodic Motion Stability of Rotor-Bearing System with Dual-Unbalances

2011 ◽  
Vol 2-3 ◽  
pp. 728-732
Author(s):  
Chao Feng Li ◽  
Guang Chao Liu ◽  
Qin Liang Li ◽  
Bang Chun Wen
Keyword(s):  
Stability Analysis ◽  
Phase Difference ◽  
Periodic Motion ◽  
Initial Phase ◽  
Shooting Method ◽  
Small Eccentricity ◽  
Rotor Bearing ◽  
Large Eccentricity ◽  
The Stability ◽  
Bearing System

Multiple freedom degrees model of rotor-bearing system taking many factors into account is established, the Newmark-β and shooting method are combined during the stability analysis of periodic motion in such system. The paper focused on the influence law of two eccentric phase difference on the instability speed of rotor-bearing system. The results have shown that the instability speed rises constantly with the eccentric phase difference angle increasing in small eccentricity system. When the two unbalance be in opposite direction, the system reached its maximum instability speed. However, the unstable bifurcation generates mutation phenomenon for large eccentricity system with the eccentric phase difference angle increasing. In summary, the larger initial phase angle can inhibit system instability partly. The conclusions have provided a theoretical reference for vibration control and stability design of the more complex rotor-bearing system.

Research on Periodic Motion Stability of Multi-DOF Rotor-Bearing System with Crack Fault

2011 ◽  
Vol 148-149 ◽  
pp. 3-6 ◽  
Author(s):  
Chao Feng Li ◽  
Qin Liang Li ◽  
Jie Liu ◽  
Bang Chun Wen
Keyword(s):  
Stability Analysis ◽  
Vibration Control ◽  
Shooting Method ◽  
Crack Depth ◽  
Continuous System ◽  
Oil Film ◽  
Rotor Bearing ◽  
The Stability ◽  
The Impact ◽  
Bearing System

Multi-DOF model of double-disc rotor-bearing system taking crack and oil film support into account is established, and the continuation shooting method combined with Newmark is also applied to stability analysis of continuous system. This paper mainly studied the variation law of five parameters domain in crack depth and location, then a number of conclusions are found: first, it’s feasible to study the stability of nonlinear rotor-bearing system with crack faults using FEM; secondly, the crack depth and location has a certain impact on instability speed, but the impact is not great and owns its certain law. As the crack depth and location is getting close to the middle position of rotor, due to its impact on the oil film support, the instability speed of system increases. This method and results in this paper provides a theoretical reference for stability analysis and vibration control in more complex relevant rotor-bearing system with crack fault.

Nonlinear Dynamic Analysis of a Flexible Rod Fastening Rotor Bearing System

2010 ◽  
Author(s):  
Heng Liu ◽  
Chen Li ◽  
Weimin Wang ◽  
Xiaobin Qi ◽  
Minqing Jing
Keyword(s):  
Periodic Motion ◽  
Great Influence ◽  
Periodic Motions ◽  
Stability And Bifurcation ◽  
Mass Eccentricity ◽  
Rotor Bearing ◽  
Rod Fastening Rotor ◽  
The Stability ◽  
Tie Rods ◽  
Bearing System

This paper is concerned the stability and bifurcation of a flexible rod-fastening rotor bearing system (FRRBS). Here the shaft is considered as an integral or continuous structure and be modeled by using Timoshenko beam-shaft element which can take the effects of axial load into consideration. And using Hamilton’s principle, model tie rods distributed along the circumference as a constant stiffness matrix and an add-moment which caused by unbalanced pre-tightening forces. Then the model is reduced by a component mode synthesis method, which can conveniently account for nonlinear oil film forces of the bearing. This study focuses on the influence of nonlinearities on the stability and bifurcation of T periodic motion of the FRRBS subjected to the influence of mass eccentricity. The periodic motions and their stability margin are obtained by shooting method and path-following technique. The local stability and bifurcation behaviors of periodic motions are obtained by Floquet theory. The results indicate that mass eccentricity and unbalanced pre-tightening forces of tie rods have great influence on nonlinear stability and bifurcation of the T periodic motion of system, cause the spillover of system nonlinear dynamics and degradation of stability and bifurcation of T periodic motion.

scholarly journals Nonlinear Vibration of a Continuum Rotor with Transverse Electromagnetic and Bearing Excitations

2012 ◽  
Vol 19 (6) ◽  
pp. 1297-1314 ◽  
Author(s):  
Haiyang Luo ◽  
Yuefang Wang
Keyword(s):  
Nonlinear Vibration ◽  
Periodic Motion ◽  
Primary Resonance ◽  
Period Doubling ◽  
Time History ◽  
Oil Film ◽  
Rotor Bearing ◽  
Transverse Electromagnetic ◽  
The Stability ◽  
Bearing System

The nonlinear vibration of a rotor excited by transverse electromagnetic and oil-film forces is presented in this paper. The rotor-bearing system is modeled as a continuum beam which is loaded by a distributed electromagnetic load and is supported by two oil-film bearings. The governing equation of motion is derived and discretized as a group of ordinary differential equations using the Galerkin's method. The stability of the equilibrium of the rotor is analyzed with the Routh-Hurwitz criterion and the occurrence of the Andronov-Hopf bifurcation is pointed out. The approximate solution of periodic motion is obtained using the averaging method. The stability of steady response is analyzed and the amplitude-frequency curve of primary resonance is illustrated. The Runge-Kutta method is adopted to numerically solve transient response of the rotor-bearing system. Comparisons are made to present influences of electromagnetic load, oil-film force and both of them on the nonlinear vibration response. Bifurcation diagrams of the transverse motion versus rotation speed, electromagnetic parameter and bearing parameters are provided to show periodic motion, quasi-periodic motion and period-doubling bifurcations. Diagrams of time history, shaft orbit, the Poincaré section and fast Fourier transformation of the transverse vibration are presented for further understanding of the rotor response.

Bifurcation and Stability of the Periodic Motion of a Rotor Bearing System With Pedestal Looseness and Rub-Impact

2009 ◽  
Author(s):  
Changli Liu ◽  
Xiuli Zhang ◽  
Li Cui ◽  
Pengru Xie ◽  
Jianrong Zheng
Keyword(s):  
Periodic Solution ◽  
Hopf Bifurcation ◽  
Vibration Control ◽  
Periodic Motion ◽  
Autonomous System ◽  
Shooting Method ◽  
The Past ◽  
Rotor Bearing ◽  
Bifurcation And Stability ◽  
Bearing System

A rotor bearing system usually has various faults that could simultaneously exist (e.g., rub-impact, pedestal looseness etc), but, in the past, individual fault has been mostly modeled and analyzed separately. In this paper, the dynamic model of rotor bearing system with rub-impact and pedestal looseness is formulated. Continuation-shooting method for the periodic solution of nonlinear non-autonomous system is used to obtain the bifurcation and stability of the periodic motion of the rotor-bearing system. The effect of the unbalance and rotor/stator clearance on the bifurcation and stability of the periodic motion of the rotor bearing system are analyzed respectively. It has been observed that the periodic motion of the system lose stability by Hopf and doubling bifurcation respectively under the small and large unbalance; the system with coupling faults has the same way of losing stability as the system with rub-impact only. The Hopf bifurcation set is broadened with the rotor/stator clearance decreases. The results of the paper may provide theory references to fault diagnoses, vibration control and security operating of the rotor system.

On the Bifurcation and Stability of Periodic Motion of the Rotor-Bearing System with Rub-Impact and Oil Whirl

2009 ◽  
Vol 626-627 ◽  
pp. 517-522
Author(s):  
Chang Li Liu ◽  
X.L. Zhang ◽  
L. Cui ◽  
J. Jiang ◽  
J.R. Zheng
Keyword(s):  
Periodic Solution ◽  
Dynamic Model ◽  
Periodic Motion ◽  
Autonomous System ◽  
Shooting Method ◽  
Oil Whirl ◽  
Rotor Bearing ◽  
Bifurcation And Stability ◽  
Bearing System

In this paper, the dynamic model of rotor bearing system with rub-impact and oil whirl is formulated. Continuation-shooting method for the periodic solution of nonlinear non-autonomous system is used to obtain the bifurcation and stability of the periodic motion of the rotor-bearing system. The effect of the unbalance and rotor/stator clearance on the bifurcation and stability of the periodic motion of the rotor bearing system are analyzed respectively. The results obtained are compared with those of rotor-bearing system with oil whirl fault.

Stability Analysis of Nonlinear Stiffness Rotor-Bearing System with Pedestal Looseness Fault

2013 ◽  
Vol 483 ◽  
pp. 285-288 ◽  
Author(s):  
Yue Gang Luo ◽  
Song He Zhang ◽  
Bin Wu ◽  
Hong Ying Hu
Keyword(s):  
Periodic Solution ◽  
Stability Analysis ◽  
Autonomous System ◽  
Floquet Theory ◽  
Nonlinear Stiffness ◽  
Rotor Bearing ◽  
Set Up ◽  
The Stability ◽  
Shooting Algorithm ◽  
Bearing System

The dynamic model of nonlinear stiffness rotor-bearing system with pedestal looseness fault was set up, taking the linearity and cube item as the physics nonlinear factors. The periodic solution of system was analyzed by continuation-shooting algorithm for periodic solution of nonlinear non-autonomous system, and the stability of system periodic motion and unsteady law are discussed by Floquet theory. The unstable form of it is Hopf bifurcation. In the region of critical rotate speed, the main motion of the system is periodic-4; and it of ultra critical rotate speed, the main motion of the system is periodic-3 and chaotic motion. The conclusions provide theoretic basis reference for the fault diagnosis of the rotor-bearing system.

Stability of periodic motion on the rotor-bearing system with coupling faults of crack and rub-impact

2007 ◽  
Vol 21 (6) ◽  
pp. 860-864 ◽  
Author(s):  
Yue-Gang Luo ◽  
Zhao-Hui Ren ◽  
Hui Ma ◽  
Tao Yu ◽  
Bang-chun Wen
Keyword(s):  
Periodic Motion ◽  
Coupling Faults ◽  
Rotor Bearing ◽  
Bearing System
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