Bifurcation and Chaos Behavior of Rotor-Bearing System With Crack and Pedestal Looseness Faults

2007 ◽  
Author(s):  
Yuegang Luo ◽  
Songhe Zhang ◽  
Feng Wen ◽  
Bangchun Wen
Keyword(s):  
Critical Speed ◽  
Journal Bearings ◽  
Cracked Rotor ◽  
Bifurcation And Chaos ◽  
Coupling Faults ◽  
Speed Range ◽  
Rotor Bearing ◽  
Set Up ◽  
Bearing System ◽  
Main Influence

A dynamic model was set up for the two-span rotor-bearing system with coupling faults of crack and pedestal looseness supported on three plain journal bearings. The nonlinear dynamic behaviors that induced by crack, pedestal looseness and coupling faults are numerically studied. There is quasi-periodic motion appearing in the cracked rotor-bearing system, and it within the sub-critical speed range in the pedestal looseness rotor-bearing system. There is chaotic motion appearing within the supper-critical speed range in the pedestal looseness rotor-bearing system. The pedestal looseness fault is the main influence on the coupling faults system, and there is Period-3 motion appearing in the system. The results may bring up theoretical references for fault diagnoses, dynamic design, and security running to rotor-bearing system.

Dynamic Characteristics of Nonlinear Elastics Rotor-Bearing System With Coupling Faults of Pedestal Looseness and Rub-Impact

2009 ◽  
Author(s):  
Yuegang Luo ◽  
Songhe Zhang ◽  
Zhaohui Ren ◽  
Bangchun Wen
Keyword(s):  
Dynamic Model ◽  
Dynamic Characteristics ◽  
Critical Speed ◽  
Dynamic Design ◽  
Coupling Faults ◽  
Nonlinear Motion ◽  
Speed Range ◽  
Rotor Bearing ◽  
Set Up ◽  
Bearing System

A dynamic model of the nonlinear elastics rotor-bearing system with coupling faults of pedestal looseness and rub-impact was set up, taking the linearity and cube item as the physics nonlinear factors. The complex characteristics of the rotor-bearing system were numerically studied. There exists complex nonlinear motion of periodic, quasi-periodic and chaotic in the response of the system. The main motions of the rotor-bearing system with rub-impact fault are periodic-2, periodic-4 and quasi-periodic within the super-critical speed range, but it with coupling faults of pedestal looseness and rub-impact are periodic-3 and chaotic. The influence of oil-film force to the rotor system is weakened by the pedestal looseness fault. The results may bring up theoretical references for fault diagnoses, dynamic design, and security running to rotor-bearing system.

Nonlinear Characteristics of Two-Span Rotor-Bearing System with Three-Coupling Faults

2011 ◽  
Vol 52-54 ◽  
pp. 303-307
Author(s):  
Yue Gang Luo ◽  
Song He Zhang ◽  
Zhao Hui Ren ◽  
Bang Chun Wen
Keyword(s):  
Dynamic Characteristics ◽  
Nonlinear Dynamic ◽  
Nonlinear Characteristics ◽  
Coupling Faults ◽  
Comprehensive Method ◽  
Nonlinear Dynamic Characteristics ◽  
Speed Range ◽  
Rotor Bearing ◽  
Set Up ◽  
Bearing System

The dynamic model of two-span rotor-bearing system with three-coupling faults of rub-impact, crack and pedestal looseness faults was set up, and the influences of faults to nonlinear dynamic characteristics of the system were studied by mapping and continuation comprehensive method. There are many harmonic elements of 1/3, 1/2, 2/3, 1, 3/2 and 2 et al within the sub-critical rotate speed range. But the 3/2 and 2-harmonic elements decrease within the super-critical rotate speed range. It may the main characteristics of the system with three-coupling faults of rub-impact, crack and pedestal looseness. It should notice to diagnosis the three-coupling faults of the system when running within the super-critical rotate speed range.

Dynamic Behavior Analysis of Three-Span Rotor-Bearing System with Rub-Impact Fault

2012 ◽  
Vol 460 ◽  
pp. 160-164 ◽  
Author(s):  
Song He Zhang ◽  
Yue Gang Luo ◽  
Bin Wu ◽  
Bang Chun Wen
Keyword(s):  
Nonlinear Dynamics ◽  
Behavior Analysis ◽  
Dynamic Model ◽  
Dynamic Behavior ◽  
Rotor System ◽  
System Response ◽  
Rotor Bearing ◽  
Set Up ◽  
Bearing System ◽  
Main Influence

The dynamic model of the three-span rotor-bearing system with rub-impact fault was set up. The influence to nonlinear dynamics behaviors of the rotor-bearing system that induced by rub-impact of one disc, two discs and three discs were numerically studied. The main influence of the rotor system response by the rub-impact faults are in the supercritical rotate speed. There are mutations of amplitudes in the responses of second and third spans in supercritical rotate speed when rub-impact with one disc, and there are chaotic windows in the response of first span, and jumping changes in second and third spans when rub-impact with two or three discs.

Nonlinear Response Analysis of Three-Span Rotor-Bearing System with Three Cracks in Shafts

2013 ◽  
Vol 753-755 ◽  
pp. 1093-1097
Author(s):  
Song He Zhang ◽  
Yue Gang Luo ◽  
Bin Wu ◽  
Hong Ying Hu
Keyword(s):  
Numerical Simulation ◽  
Dynamic Characteristics ◽  
Nonlinear Response ◽  
Crack Depth ◽  
Response Analysis ◽  
Sliding Bearings ◽  
Rotor Bearing ◽  
Set Up ◽  
Bearing System ◽  
Main Influence

The model of three-span rotor-bearing system with three cracks in shaft supporting on the six sliding bearings was set up. The influences of crack faults to the responses of the rotor system were studied on numerical simulation. Along with the increase of the crack depth in first span, the main influence to the dynamic characteristics of the system is in the first span. Along with the increase of the crack depth in second span, the main influences to the response of first and third spans are in the region of critical rotate speed, and it to the second span is in the regions of critical and supercritical rotate speed. Along with the increase of the crack depth in third span, the main influences to the response of the three spans are in the region of critical rotate speed.

scholarly journals The Vibration of a Transversely Cracked Rotor Supported by Anisotropic Journal Bearings with Speed-Dependent Characteristic

2020 ◽  
Vol 10 (16) ◽  
pp. 5617
Author(s):  
Zhiguo Wan ◽  
Yu Wang ◽  
Binqiang Chen ◽  
Yihua Dou ◽  
Xinjuan Wei
Keyword(s):  
Synthesis Method ◽  
Resonance Region ◽  
Element Model ◽  
Journal Bearings ◽  
Forced Response ◽  
Cracked Rotor ◽  
High Dimensions ◽  
Rotor Bearing ◽  
Bearing System ◽  
Cracked Shaft

This paper presents the vibration of a transversely cracked rotor supported by anisotropic journal bearings, where the speed-dependent characteristic of bearing is considered. A 3D finite element model and the contact-based approach are employed for the shaft and crack. The governing differential equations of the whole cracked rotor-bearing system were obtained by synthesizing the equations of the cracked shaft, the breathing crack and the journal bearings. In order to solve the computational difficulties caused by the high dimensions of model, the free-interface complex component mode synthesis method (CMS) is employed to reduce the order of the model. On this basis, the eigenvalue and the steady-state forced response of the cracked rotor-bearing system are obtained by the Hill’s method. Finally, the effects of the anisotropic and speed-dependent characteristics of bearings on the vibration of the system are studied. Numerical results show that both the two characteristics can significantly affect the response of the system. The anisotropy in the bearing leads to the split of resonant peaks and influence the amplitudes of the peaks. The speed-dependent characteristic mainly affects the responses at the speeds close to the resonant regions, because the parametric excitation effect of the resonance region is greater than other speeds.

Stability of Two-Span Rotor-Bearing System with Coupling Faults of Crack and Rub-Impact

2007 ◽  
Vol 353-358 ◽  
pp. 2501-2504
Author(s):  
Yue Gang Luo ◽  
Song He Zhang ◽  
Xiao Dong Liu ◽  
Bang Chun Wen
Keyword(s):  
Floquet Theory ◽  
Period Doubling ◽  
Rotor System ◽  
Failure Diagnosis ◽  
Coupling Faults ◽  
Rotor Bearing ◽  
Set Up ◽  
The Stability ◽  
Shooting Algorithm ◽  
Bearing System

A dynamic model was set up for the two-span rotor–bearing system with coupling faults of crack and rub-impact. Using the continuation-shooting algorithm for periodic solution of nonlinear non-autonomous system, the stability of the system periodic motion was studied by the Floquet theory. The unstable form of the rotor system with coupling faults is Hopf bifurcation when the depth of crack is smaller. The influence to the response of the system increased along with the depth of crack, the unstable form of the rotor system with coupling faults is period-doubling bifurcation. The conclusions provide theoretic basis reference for the failure diagnosis of the rotorbearing system.

Effects of Two Cracks in Shafts on Dynamic Characteristics of Two-Span Rotor-Bearing System

2012 ◽  
Vol 271-272 ◽  
pp. 1270-1274 ◽  
Author(s):  
Yue Gang Luo ◽  
Song He Zhang ◽  
Bin Wu ◽  
Hong Ying Hu
Keyword(s):  
Dynamic Characteristics ◽  
Crack Depth ◽  
Frequency Doubling ◽  
Frequency Division ◽  
Periodic Motions ◽  
Nonlinear Dynamic Model ◽  
Speed Range ◽  
Rotor Bearing ◽  
Set Up ◽  
Bearing System

The nonlinear dynamic model of two-span rotor-bearing system with two cracks in shafts is set up, and the effects of two cracks in shafts on dynamic characteristics of the rotor-bearing system are analyzed. Along with the increase of the crack depth in first span, the chaotic and periodic motions increase, and the quasi-periodic motion decrease in the supercritical rotate speed. There are harmonic elements of 1/4, 1/2 and 3/4 frequency division within the sub-critical speed range at different crack depths. There appears the frequency doubling resonance obviously when the crack depths are larger. Along with the increase of the crack depth in second span, the main influences to the responses of system are in the second span. The chaotic regions increase and then decrease and the periodic motions region increase in the sub-critical rotate speed range.

Rotor-Bearing Dynamics With Emphasis on Attenuation

1962 ◽  
Vol 84 (4) ◽  
pp. 491-498 ◽  
Author(s):  
J. W. Lund ◽  
B. Sternlicht
Keyword(s):  
Critical Speed ◽  
Reynolds Equation ◽  
Journal Bearings ◽  
Dimensionless Form ◽  
Damping Coefficients ◽  
Transmitted Force ◽  
Rotor Bearing ◽  
Bearing Dynamics ◽  
Rotor Mass ◽  
Bearing System

This paper presents a theoretical analysis of the dynamics of a rotor-bearing system. The analysis is quite general but because of space limitations only the symmetrical rotor supported in two plain cylindrical journal bearings is considered. Furthermore, the rotor mass is concentrated at midspan giving the rotor only one degree of freedom. Limiting the analysis to small amplitudes of rotor motion the components of the fluid film force are made linear with respect to journal amplitude and velocity. The resulting 8 coefficients, denoted spring and damping coefficients, are calculated from Reynolds equation and by coupling them with the rotor, the motion and the force transmitted to the bearing pedestal are obtained. Results are presented in dimensionless form for transmitted force and for critical speed.

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

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.

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