Nonlinear vibration mitigation of a flexible rotor shaft carrying a longitudinally dispositioned unbalanced rigid disc

2021 ◽  
Author(s):  
Javad Taghipour ◽  
Morteza Dardel ◽  
Mohammad Hadi Pashaei
Keyword(s):  
Nonlinear Vibration ◽  
Flexible Rotor ◽  
Vibration Mitigation ◽  
Rotor Shaft ◽  
Rigid Disc

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.

Active Vibration Control of Flexible Rotor-Shaft System Subject to Earthquake

2012 ◽  
Author(s):  
P. Sharma ◽  
S. Gupta ◽  
A. S. Das ◽  
J. K. Dutt
Keyword(s):  
Numerical Simulation ◽  
System Stability ◽  
Control Action ◽  
Electromagnetic Actuator ◽  
Control Force ◽  
Base Excitation ◽  
Flexible Rotor ◽  
Friction Forces ◽  
Rotor Shaft ◽  
Shaft System

This paper presents the results of a numerical simulation to actively control transverse vibration of a flexible rotor shaft subject to seismic base excitation. The active control force is applied over an air gap by an electromagnetic actuator. Equations of motion of the rotor-shaft-system have been drawn up after discretizing the rotor continuum with finite beam elements and taking into account rotor flexibility, internal friction forces due to rotor material damping, inertial forces due to base motion, gyroscopic forces and non-linear electromagnetic control forces from the actuator in addition to harmonic excitation due to unbalance in the steadily spinning rotor-disc. A MATLAB code in the SIMULINK domain has been created for this purpose and the equations developed are solved numerically in the time domain to get the response at each nodal point. Numerical simulation of vibration response of the disc in a single-disc rotor-shaft-system is compared with and without the control action when the rotor base is excited with the El-Centro earthquake data. The comparison shows a remarkable reduction of response amplitude and improvement of rotor-shaft-system stability in comparison with no control action. Hence the usefulness of an electromagnetic actuator is proposed for safe and sound operation of rotor-shaft systems even under the seismic base excitation.

A Digital Absorber for Nonlinear Vibration Mitigation

2020 ◽  
pp. 105-108
Author(s):  
Ghislain Raze ◽  
Sylvain Guichaux ◽  
Andy Jadoul ◽  
Valery Broun ◽  
Gaetan Kerschen
Keyword(s):  
Nonlinear Vibration ◽  
Vibration Mitigation

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

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Nuntaphong Koondilogpiboon ◽  
Tsuyoshi Inoue
Keyword(s):  
Nonlinear Vibration ◽  
Journal Bearing ◽  
Rolling Element Bearing ◽  
Flexible Rotor ◽  
Large Disk ◽  
Subcritical Bifurcation ◽  
Whirling Motion ◽  
Vibration Prediction ◽  
Rotor Bearing ◽  
Bearing System

Abstract 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 rolling element bearing (REB) and an axial groove journal bearing (JB) of length-to-diameter ratio (L/D) = 0.6. Three positions of the large disk: 410, 560, and 650 mm measured from the REB, are investigated. Numerical integration of the rotor-bearing system which is modally reduced to the first forward (FWD) 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 (IB) 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. Finally, the experiments at the same three large disk positions are performed. Subcritical bifurcation with the contact between the journal and the IB side of the bearing is observed in all large disk positions, which conforms with the calculation result of model A. Hence, model A is essential in nonlinear vibration analysis of a highly flexible rotor system.

Nonlinear Vibration Analysis of a Flexible Rotor Supported by a Journal Bearing Considering Journal Angular Motion

2019 ◽  
Author(s):  
Nuntaphong Koondilogpiboon ◽  
Tsuyoshi Inoue
Keyword(s):  
Nonlinear Vibration ◽  
Ball Bearing ◽  
Journal Bearing ◽  
Angular Motion ◽  
Experimental Result ◽  
Flexible Rotor ◽  
Large Disk ◽  
Rotor Bearing ◽  
Bearing Force ◽  
Bearing System

Abstract The effect of bearing length to diameter (L/D) ratio and large disk position on nonlinear vibration (limit cycle and bifurcation type) of a flexible rotor-bearing system is investigated. The rotor consists of a shaft modeled by 1-D finite elements (FE), two small disks and a large disk. It is supported by a self-aligning ball bearing and an axial-groove journal bearing with L/D ratio of 0.4 and 0.6. Two large disk positions: 340 and 575 mm measured from the ball bearing are investigated. The journal angular motion, which is essential for the highly flexible rotor but typically not considered in the previous nonlinear vibration literature; is considered in nonlinear bearing force calculation. The degrees of freedom (DOF) of the rotor-bearing system are reduced to those of the node that the nonlinear journal bearing force and moment act on by real mode component mode synthesis (CMS) that retains only the 1st forward and backward modes. Shooting method and Floquet multiplier analysis are applied to the reduced rotor-bearing system to obtain limit cycles and their stability of each bearing L/D ratio and large disk position case. Numerical results indicate that supercritical Hopf bifurcation only occurs in the case of L/D = 0.4 and large disk position 575 mm, otherwise subcritical occurs. However, if the typical bearing model that does not consider journal angular motion is used, the bifurcation type for the case of L/D = 0.6 with large disk position 575 mm will change to supercritical. Lastly, the experiments with the same L/D ratio and large disk position investigated in the calculation are performed as a validation. The experimental result of each case shows the same bifurcation type as the calculation result using the bearing model that considers the journal angular motion.

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