Use of dFRFs for Diagnosis of Asymmetric/Anisotropic Properties in Rotor-Bearing System

1996 ◽  
Vol 118 (1) ◽  
pp. 64-69 ◽  
Author(s):  
Chee-Young Joh ◽  
Chong-Won Lee
Keyword(s):  
Diagnostic Method ◽  
Experimental Results ◽  
Flexible Rotor ◽  
Coordinate Systems ◽  
Anisotropic Properties ◽  
Rotor Systems ◽  
Input And Output ◽  
Rotor Bearing ◽  
The Asymmetry ◽  
Bearing System

The diagnostic method, which utilizes the dFRFs defined in the stationary and rotating coordinate systems, is tested with a laboratory flexible rotor-bearing system, in order to verify its effectiveness in detection of the asymmetry in shaft and the anisotropy in stator. The experimental results indicate that the dFRFs can be effectively used for the diagnosis of anisotropy and/or asymmetry in rotor systems by the investigation of two kinds of dFRF estimates using the complex input and output signals defined in the stationary and rotating coordinate systems.

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.

An analysis method to determine how changes in dynamic complexity impact on rotor-bearing systems

2020 ◽  
pp. 095440622095488
Author(s):  
Mian Jiang ◽  
Shuangqi Liu ◽  
Yuhua Wang
Keyword(s):  
Condition Monitoring ◽  
Lubricating Oil ◽  
Analysis Method ◽  
Dynamic Complexity ◽  
Rotor Systems ◽  
Methodological Choices ◽  
Rotor Bearing ◽  
Nonlinearity Measures ◽  
Monitoring Performance ◽  
Bearing System

Condition monitoring performance and diagnosis of rotor-bearing systems depend not only on the methods used, but also on the dynamic complexity of the system itself. Thus, it is important to analyze how changes in parameters under various working conditions impact on dynamic complexity. Most of previous research efforts on this topic have been focused on the analysis of nonlinear dynamics of rotor-bearing systems with different parameters. In this paper, a nonlinearity quantification based analysis method is presented to determine how parameter dynamics impact the complexity of rotor-bearing systems. The dynamic complexity of rotor system is estimated using defined nonlinearity measures. To validate this method, a sliding rotor-bearing system with a loose pedestal is used. The estimates (nonlinearity degrees) and the states of motion are matched with increasing rotational speeds. It is then investigated, how the eccentricities, lubricating oil viscosities, and bearing clearances impacted the dynamic complexity at several critical rotational speeds. These results can guide methodological choices for condition monitoring and diagnosis of rotor systems.

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.

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

Subcritical Twice-Running-Speed Vibrations of a Non-Ideal Rotor-Bearing-System: Simulation and Experiments

2012 ◽  
Author(s):  
Janne E. Heikkinen ◽  
Jussi T. Sopanen ◽  
Aki M. Mikkola
Keyword(s):  
Simulation Model ◽  
Paper Machine ◽  
Flexible Rotor ◽  
Running Speed ◽  
Measurement Results ◽  
Rotor Bearing ◽  
Existing Structure ◽  
Speed Response ◽  
Bearing System

Subcritical twice-running-speed resonances of a paper machine tube roll are studied in this paper. Resonances arise partly from the non-idealities of the rotor and partly from the non-idealities of the bearings. Resonances are affecting the quality of end product and therefore have to be studied precisely. The complex rotor-bearing system is modeled by using a flexible multibody simulation approach. Non-idealities of the rotor-bearing system are measured from the existing structure under investigation and the parameters of the real structure are emulated as accurately as possible in the simulation model. The simulation model is verified using the results from experimental modal analysis and the measurement results for the subcritical twice-running-speed response of the roll. The inertia modeling of the flexible rotor is also studied. It is found that inertia coupling between the rigid body rotation and body deformation must be included into analysis in order to achieve accurate results.

Stability and response analysis of symmetrical single-disk flexible rotor-bearing system

2005 ◽  
Vol 38 (8) ◽  
pp. 749-756 ◽  
Author(s):  
Sanxing Zhao ◽  
Hua Xu ◽  
Guang Meng ◽  
Jun Zhu
Keyword(s):  
Response Analysis ◽  
Flexible Rotor ◽  
Rotor Bearing ◽  
Single Disk ◽  
Bearing System
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