Self-Excited Vibration of a Rotating Hollow Shaft Partially Filled with Liquid

1980 ◽  
Vol 102 (1) ◽  
pp. 185-192 ◽  
Author(s):  
S. Saito ◽  
T. Someya
Keyword(s):  
Viscous Liquid ◽  
Rotor System ◽  
The Self ◽  
Hollow Shaft ◽  
Excited Vibration ◽  
Negative Damping ◽  
The Stability

The self-excited vibration of a rotating hollow shaft partially filled with viscous liquid is investigated. The motion of liquid and the liquid force is analyzed. The stability of the rotor system is calculated and the influences of factors on the stability are studied. Moreover, the mechanism causing the negative damping which is the reason for the instability is discussed.

Self-Excited Vibration of a Plate Supported by Air Pressure in a Floating Conveying Machine

2017 ◽  
Author(s):  
Masakazu Takeda ◽  
Masahiro Watanabe
Keyword(s):  
Air Pressure ◽  
The Self ◽  
Plate Motion ◽  
Bottom Surface ◽  
Fluid Force ◽  
Gap Flow ◽  
Excited Vibration ◽  
Unsteady Fluid ◽  
The Stability ◽  
Work Done

This paper presents experiments and an analysis on self-excited vibration of a plate supported by air pressure in a floating conveying machine. In this study, the instability conditions are examined by theoretical analysis in consideration of the effect of compressibility of air in a chamber. The system’s characteristic equation is derived from the plate motion coupled with equations of the gap flow between the plate and the chamber surface. The vibration characteristics and the instability conditions of the self-excited vibration are examined through experiments. The stability of the plate is affected by an air flow rate, a mass of the plate, a spring stiffness of the plate. We clarified those influences on the instability conditions of the self-excited vibration. The unsteady fluid force acting on the plate (bottom surface) is investigated by measuring the unsteady pressure. The local work done by the unsteady fluid force is also clarified. Lastly, the instability mechanism and important parameters of the self-excited vibration are discussed based on the theoretical model and experimental results.

Analysis of the Frictional Vibration of a Cleaning Blade in Laser Printers Based on a Two-Degree-Of-Freedom Model

2011 ◽  
Vol 7 (1) ◽  
Author(s):  
Go Kono ◽  
Yoshinori Inagaki ◽  
Hiroshi Yabuno ◽  
Tsuyoshi Nohara ◽  
Minoru Kasama
Keyword(s):  
Frictional Coefficient ◽  
The Self ◽  
Laser Printer ◽  
Hamiltonian Hopf Bifurcation ◽  
Excited Vibration ◽  
Negative Damping ◽  
Link Model ◽  
Unstable Vibration ◽  
Two Degree Of Freedom ◽  
Frictional Vibration

This research aims to analyze the dynamics of the self-excited vibration of a cleaning blade in a laser printer. First, it is experimentally indicated that that the self-excited vibration is not caused by the negative damping effect based on friction. Next, the excitation mechanism and dynamics of the vibration are theoretically clarified using an essential 2DOF link model, with emphasis placed on the contact between the blade and the photoreceptor. By solving the equations governing the motion of the analytical model, five patterns of static equilibrium states are obtained, and the effect of friction on the static states is discussed. It is shown that one of five patterns corresponds to the shape of the practical cleaning blade, and it is clarified through linear stability analysis that this state becomes dynamically unstable, due to both effects of friction and mode coupling. Furthermore, the amplitude of the vibration in the unstable region is determined through nonlinear analysis. The obtained results show that this unstable vibration is a bifurcation classified as a supercritical Hamiltonian-Hopf bifurcation, and confirms the occurrence of mode-coupled self-excited vibration on a cleaning blade when a constant frictional coefficient is assumed.

The Influence of Oil-Film Journal Bearings on the Stability of Rotating Machines

1946 ◽  
Vol 13 (3) ◽  
pp. A211-A220
Author(s):  
A. C. Hagg
Keyword(s):  
Rotational Frequency ◽  
Journal Bearings ◽  
The Self ◽  
Stability Criteria ◽  
Oil Film ◽  
Oil Whip ◽  
Upper Limit ◽  
Excited Vibration ◽  
Tilting Pad ◽  
The Stability

Abstract The self-excited vibration caused by the lubricating films of journal bearings and commonly called oil-film whirl or oil whip is discussed. The upper limit of whirling frequency has been found to be one-half rotational frequency in the general case; actually the phenomenon will manifest itself at a frequency which is invariably below this limit. Stability criteria have been developed for certain common systems in terms of bearing and rotor parameters. The tilting-pad bearing of Michell has been established as a so-called “stable” or “nonwhirling” bearing. This bearing and related types are probably the only oil-film journal bearings which are incapable of exciting oil whip, regardless of the system to which they are applied. Qualitatively the results of the paper appear to be in agreement with observations. In certain cases, results have been substantiated experimentally.

scholarly journals The Modeling and Analysis for the Self-Excited Vibration of the Maglev Vehicle-Bridge Interaction System

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Jinhui Li ◽  
Jie Li ◽  
Danfeng Zhou ◽  
Lianchun Wang
Keyword(s):  
Ride Comfort ◽  
Interaction Model ◽  
Control Unit ◽  
The Self ◽  
Modeling And Analysis ◽  
Maglev Vehicle ◽  
Interaction System ◽  
Excited Vibration ◽  
Vibration Problems ◽  
The Stability

This paper addresses the self-excited vibration problems of maglev vehicle-bridge interaction system which greatly degrades the stability of the levitation control, decreases the ride comfort, and restricts the cost of the whole system. Firstly, two levitation models with different complexity are developed, and the comparison of the energy curves associated with the two models is carried out. We conclude that the interaction model with a single levitation control unit is sufficient for the study of the self-excited vibration. Then, the principle underlying the self-excited vibration is explored from the standpoint of work acting on the bridge done by the levitation system. Furthermore, the influences of the parameters, including the modal frequency and modal damping of bridge, the gain of the controller, the sprung mass, and the unsprung mass, on the stability of the interaction system are carried out. The study provides a theoretical guidance for solving the self-excited vibration problems of the vehicle-bridge interaction systems.

Self-excited Vibration Control of the Flexible Planar Parallel 3-RRR Robot

2018 ◽  
Vol 25 (2) ◽  
pp. 351-361
Author(s):  
Zhi-cheng Qiu ◽  
Jie Yang ◽  
Xian-min Zhang
Keyword(s):  
High Speed ◽  
Parallel Robot ◽  
The Self ◽  
Flexible Robot ◽  
Nonlinear Controller ◽  
Control Approach ◽  
Excited Vibration ◽  
Improve Accuracy ◽  
The Stability ◽  
Fuzzy Control Algorithm

A self-excited vibration active control approach for a 3-RRR flexible planar parallel robot is developed to improve accuracy and stability. The 3-RRR parallel flexible robot experimental setup is constructed. From the motion experiments, it is demonstrated that the residual vibration can be converted to self-excited vibration at a high-speed motion, which will affect the stability and positioning precision of the platform. To suppress the self-excited vibration owing to flexibility, friction, backlash, coupling, and other nonlinear factors, a nonlinear controller and a fuzzy control algorithm are designed to attenuate the self-excited vibration. Experiments are conducted in different positions of the 3-RRR flexible parallel robot. The experimental results demonstrate that the investigated control methods can suppress the self-excited vibration effectively.

Vibration Analysis of the Self-Excited Vibration in the Rotor System Due to Ball Balancer

2009 ◽  
Author(s):  
Tsuyoshi Inoue ◽  
Hideaki Niimi ◽  
Yukio Ishida
Keyword(s):  
Vibration Suppression ◽  
Rotor System ◽  
The Self ◽  
Excited Vibration ◽  
Amplitude Vibration ◽  
Speed Range ◽  
Large Amplitude Vibration ◽  
Fundamental Equations ◽  
Ball Mass ◽  
Ball Motion

The ball balancer has been used as the vibration suppression device in rotor system. It has a superior characteristic that the vibration amplitude is reduced to zero at the rotational speed range higher than the major critical speed. However, the ball balancer may cause a self-excited vibration when the balls rotate in the balancer, and this self-excited vibration results in the large amplitude vibration. In this paper, the occurrence region and vibration characteristics of the self-excited vibration are investigated. The theoretical analysis is performed and a set of the fundamental equations governing the self-excited vibration is obtained. The influences of the parameters, such as, damping of the ball motion, ball mass, and radius of the ball orbit are explained. As the result, it is shown that the damping of the ball motion and the ball mass have the effect on decreasing the occurrence region of the self-excited vibration.

scholarly journals On the Existence of Self-Excited Vibration in Thin Spur Gears: A Theoretical Model for the Estimation of Damping by the Energy Method

Symmetry ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 664 ◽  
Author(s):  
Yanrong Wang ◽  
Hang Ye ◽  
Long Yang ◽  
Aimei Tian
Keyword(s):  
Axial Force ◽  
Traveling Wave ◽  
The Self ◽  
Spur Gears ◽  
Contact Ratio ◽  
Symmetric Structure ◽  
Modal Damping ◽  
Excited Vibration ◽  
Cyclic Symmetric ◽  
The Stability

The gear is a cyclic symmetric structure, and each tooth is subjected to a periodic mesh force. These mesh forces have the same phase difference tooth by tooth, which can excite gear vibrations. The mechanism of additional axial force caused by gear bending is shown and examined, which can significantly affect the stability of a self-excited thin spur gears vibration. A mechanical model based on energy balance is then developed to predict the contribution of additional axial force, leading to the proposed numerical integration method for vibration stability analysis. By analyzing the change in the system energy, the occurrence of the self-excited vibration is validated. A numerical simulation is carried out to verify the theoretical analysis. The impacts of modal damping, contact ratio, and the number of nodal diameters on the stability boundaries of the self-excited vibration are revealed. The results prove that the backward traveling wave of the driven gear as well as the forward traveling wave of the driving gear encounter self-excited vibration in the absence of sufficient damping. The model can be used to predict the stability of the gear self-excited vibration.

Characteristic Variation of Self-Excited Vibration in the Vertical Rotor System due to the Flexible Support of the Journal Bearing

2016 ◽  
Author(s):  
Atsushi Nishimura ◽  
Tsuyoshi Inoue ◽  
Yusuke Watanabe
Keyword(s):  
Journal Bearing ◽  
Vibration Characteristics ◽  
Rotor System ◽  
The Self ◽  
Radial Clearance ◽  
Fluid Viscosity ◽  
Rotating Shaft ◽  
Characteristic Variation ◽  
Excited Vibration ◽  
Pump Shaft

Various vibration problems occur in rotating machinery. Specifically, the amplitude of shaft motion can be large in the case of vertical pump using a journal bearing. In such case, rotor motion such as self-excited vibration is not able to be predicted accurately without considering both rotordynamic fluid force and contact phenomena to the bearing surfaces or boundary lubrication condition. Moreover, in an actual vertical pump, the stationary side structure that supports the pump shaft may be relatively flexible. However, the vibration characteristics in such situations have not been so far explained simply. The purpose of this paper is a development of the simple and quantitative method for evaluating vibration characteristics of a vertical rotating shaft with journal bearing. In this study, the rotor system flexibly supported by a journal bearing at the axial center is considered. Eigenvalue analysis is demonstrated for the linearized system, and steady-state vibration analysis of the self-excited vibration is carried out for the nonlinear system. As a result, the effect on the vibration characteristics of the system by changing fluid viscosity, radial clearance, stiffness and damping of the support is clarified. Moreover, the obtained experimental results correspond to the theoretical results of the self-excited vibration qualitatively.

Rotor Stability Evaluation for High Pressure Multi-Stage Pump by Excitation Diagnosis Method

2017 ◽  
Author(s):  
Shichao Peng ◽  
Akira Arai ◽  
Takaki Fukuchi ◽  
Taiju Katayama ◽  
Osami Matsushita
Keyword(s):  
High Pressure ◽  
Rotor System ◽  
The Self ◽  
System Stability ◽  
Circumferential Velocity ◽  
High Rotational Speed ◽  
Multi Stage ◽  
Excited Vibration ◽  
Annular Seal ◽  
Water Test

High pressure multi-stage pump is one of the most important machinery in various plants. Due to the high rotational speed, there are cases where excessive vibration problems occur. Especially, the self-excited vibration arises from the fluid force, which exists within the clearance of the oil film bearings and balancing drum (annular seal). In order to evaluate the rotor system stability, we developed an excitation method based on Bently-Muszynska model, and applied this method to the air test and water test. Through the test results, the onset (threshold) of instability (self-excited vibration) can be evaluated by the rotor system natural frequency and the fluid average angular circumferential velocity within the clearance of the bearings and balancing drum. Moreover, the balancing drum had a significant effect on the rotor stability, and the resulting frequency of the self-excited vibration matched the fluid average angular circumferential velocity in the balancing drum.

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