Bifurcation of a Cracked Rotor-bearing System under Unbalanced Magnetic Pull

2011 ◽  
Vol 47 (13) ◽  
pp. 59 ◽  
Author(s):  
Zhiwei HUANG
Keyword(s):  
Cracked Rotor ◽  
Unbalanced Magnetic Pull ◽  
Rotor Bearing ◽  
Bearing System

Unbalanced Response of Cracked Rotor-Bearing System Under Time-Dependent Base Movements

2013 ◽  
Author(s):  
Qinkai Han ◽  
Fulei Chu
Keyword(s):  
Harmonic Balance Method ◽  
Response Spectra ◽  
Element Model ◽  
Time Dependent ◽  
Cracked Rotor ◽  
Transverse Cracks ◽  
Response Characteristics ◽  
Equivalent Time ◽  
Rotor Bearing ◽  
Bearing System

Unbalanced response of cracked rotor-bearing system under time-dependent base movements is studied in this paper. Three base angular motions, including the rolling, pitching and yawing motions, are assumed to be sinusoidal perturbations superimposed upon constant terms. Both the open and breathing transverse cracks are considered in the analysis. The finite element model is established for the base excited rotor-bearing system with open or breathing cracks. Considering the time-varying base movements and transverse cracks, the second order differential equations of the system will not only have time-periodic gyroscopic and stiffness coefficients, but also the multi-frequency external excitations. An improved harmonic balance method is introduced to obtain the steady-state response of the system under both base and unbalance excitations. The whirling frequencies of the equivalent time-invariant system, orbits of shaft center, response spectra and frequency response characteristics, are analyzed accordingly. The effects of various base angular motions, frequency and amplitude of base excitations, and crack depths on the system dynamic behaviors are considered in the discussions.

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.

scholarly journals Bifurcation analysis of a flexible balanced cracked rotor–bearing system

2016 ◽  
Vol 344 (9) ◽  
pp. 661-671 ◽  
Author(s):  
Nizar Ferjaoui ◽  
Sami Naimi ◽  
Mnaour Chouchane
Keyword(s):  
Bifurcation Analysis ◽  
Cracked Rotor ◽  
Rotor Bearing ◽  
Bearing System

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.

Experimental Investigation of Active Control of Cracked Rotor-Bearing System Equipped With Magnetic Bearing

2019 ◽  
Author(s):  
Nilakshi Sarmah ◽  
Rajiv Tiwari
Keyword(s):  
Dynamic Behavior ◽  
Active Control ◽  
Transverse Crack ◽  
Vibration Suppression ◽  
Radial Force ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Cracked Rotor ◽  
Rotor Bearing ◽  
Bearing System

Abstract The present work investigates the online vibration control of a cracked rotor-bearing system incorporated with AMB. A fatigue crack, which exhibits the opening and closure behavior of cracked faces while rotation, is introduced artificially in the shaft to understand the dynamic behavior of a cracked rotor system. For this, three-point bending tests were performed to obtain edge transverse crack in the shaft. An eight-pole electromagnetic actuator was used to apply control forces directly on to the shaft in the radial direction. The radial force was used to assist vibration suppression in the rotor. In order to achieve active control to mechanical vibration and other disturbances, a simple PID control strategy is used. Closed loop tests are conducted on the d-SPACE DS1202 platform using the differential driving mode of the PID controller to suppress the vibration of a shaft containing a transverse crack integrated with an AMB supported on two conventional bearings. The comparison of the dynamic behavior of the laboratory test rig with and without active magnetic bearing (AMB) with the numerically simulated data is analyzed. The vibration suppression is found to be achieved satisfactorily in the presence of the unbalance force, bow force, crack force, and with other forces on the rotor-bearing system.

Numerical investigation on the nonlinear dynamics of a breathing cracked rotor supported by flexible bearings

2019 ◽  
Vol 233 (19-20) ◽  
pp. 6815-6826 ◽  
Author(s):  
Zhaoli Zheng ◽  
Yonghui Xie ◽  
Di Zhang ◽  
Fahui Zhu
Keyword(s):  
Crack Depth ◽  
Three Dimensional ◽  
Harmonic Balance Method ◽  
Element Model ◽  
Induced Response ◽  
Cracked Rotor ◽  
Tangent Stiffness Matrix ◽  
Rotor Bearing ◽  
Breathing Mechanism ◽  
Bearing System

The steady-state response and breathing mechanism of a cracked rotor supported by flexible bearings are investigated in this paper. The generalized and efficient method proposed in this paper can be used to study the dynamics of complicated cracked structures without much modification. First, a three-dimensional finite element model of the cracked rotor-bearing system is established in the rotating frame and a general contact model for modeling the breathing crack is proposed. A component mode synthesis is used to form a reduced-order model. Then, a procedure combining multi-harmonic balance method with arc-length method is used to search the response solution. To accelerate the calculation, the analytical formulations for calculating the tangent stiffness matrix are used. Finally, the gravity induced response and breathing mechanism of a cracked rotor-bearing system are obtained. Interesting result is that the rotational speed and the crack depth will influence the breathing mechanism even if the load remains unchanged.

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