Experiments and Numerical Results for Varying Compliance Contact Resonance in a Rigid Rotor–Ball Bearing System

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Yulin Jin ◽  
Rui Yang ◽  
Lei Hou ◽  
Yushu Chen ◽  
Zhiyong Zhang
Keyword(s):  
Vertical Direction ◽  
Numerical Results ◽  
Hertzian Contact ◽  
Radial Clearance ◽  
Rigid Rotor ◽  
Rolling Element ◽  
Run Up ◽  
Varying Compliance ◽  
Bearing System ◽  
Contact Resonance

This paper investigates the nonlinear characteristics of varying compliance contact resonance in a rotor–bearing system and takes into consideration the Hertzian contact deformation and internal radial clearance. We created an experimental rig of a rigid rotor supported by rolling element bearings. In the course of the rotational speed run up and down, the frequency–amplitude curves of the varying compliance vibrations were observed during experiments using different radial loads and compared with the results of our numerical simulations. The experimental and numerical results indicate that the varying compliance contact resonance in the vertical direction presents the soft spring characteristic, while the soft and hard spring characteristics coexist for the horizontal resonance.

Nonlinear Modeling of a Rigid Rotor Supported on Rolling Element Bearings With Localized Defects

2010 ◽  
Author(s):  
Karthik Kappaganthu ◽  
C. Nataraj
Keyword(s):  
Nonlinear Model ◽  
Nonlinear Models ◽  
Nonlinear Modeling ◽  
Rolling Element Bearings ◽  
Rigid Rotor ◽  
Rolling Element ◽  
Localized Defects ◽  
Bearing Race ◽  
Overall Performance ◽  
Bearing System

In this paper a nonlinear model for defects in rolling element bearings is developed. Detailed nonlinear models are useful to detect, estimate and predict failure in rotating machines. Also, accurate modeling of the defect provides parameters that can be estimated to determine the health of the machine. In this paper the rotor-bearing system is modeled as a rigid rotor and the defects are modeled as pits in the bearing race. Unlike the previous models, the motion of the rolling element thorough the defect is not modeled as a predetermined function; instead, it is dynamically determined since it depends on the clearance and the position of the shaft. Using this nonlinear model, the motion of the shaft is simulated and the effect of the rolling element passing through the defect is studied. The effect of shaft parameters and the defect parameters on the precision of the shaft and the overall performance of the system is studied. Finally, suitable measures for health monitoring and defect tracking are suggested.

Stabilizing Effects of Speed Fluctuations on the Dynamic Response of Rolling Element Bearings With Radial Clearances

2005 ◽  
Author(s):  
A. N. Lioulios ◽  
I. A. Antoniadis
Keyword(s):  
Theory Of Elasticity ◽  
Contact Forces ◽  
Radial Clearance ◽  
Rolling Element Bearings ◽  
Governing Parameter ◽  
Frequency Distributions ◽  
Rolling Element ◽  
Stabilization Effect ◽  
Speed Fluctuations ◽  
Varying Compliance

A horizontal balanced rotor supported on ball bearings with radial internal clearance, subjected to rotational speed fluctuations is modeled. The dynamic model takes under consideration contact forces derived by the hertzian theory of elasticity between the balls and the races, the effect of varying compliance, the internal radial clearance and the rotor’s speed fluctuations. The effect of variation in speed fluctuations is examined for periodic, unstable periodic and chaotic responses with the use of frequency distributions, higher order Poincare maps, and Lyapunov exponents. All results presented show a dominant stabilization effect of the speed fluctuations to the system behavior. From the analysis performed, it is concluded that even a minimum fluctuation of the rotor speed may result to major changes of the system dynamics, indicating that speed fluctuations of the rotor are a governing parameter to the dynamic behavior of the system.

Study on Bifurcation of Rigid Rotor Roller Bearings System Considering Nonlinear Dynamic Behavior

2010 ◽  
Vol 34-35 ◽  
pp. 467-471
Author(s):  
Li Cui ◽  
Jian Rong Zheng
Keyword(s):  
Dynamic Behavior ◽  
Nonlinear Dynamic ◽  
Roller Bearing ◽  
Radial Clearance ◽  
Rigid Rotor ◽  
Rotating Speed ◽  
Rotor Bearing ◽  
Nonlinear Dynamic Behavior ◽  
Bifurcation And Stability ◽  
Bearing System

Rigid rotor roller bearing system displays complicated nonlinear dynamic behavior due to nonlinear Hertzian force of bearing. Nonlinear bearing forces of roller bearing and dynamic equations of rotor bearing system are established. The bifurcation and stability of the periodic motion of the system in radial clearance-rotating speed and ellipticity-rotating speed parametric domains are studied by use of continuation-shooting algorithm for periodic solutions of nonlinear non-autonomous dynamics system. Results show that the parameters of rotor bearing system should be designed carefully in order to obtain period-1 motion.

Contact Dynamic Response With Misalignment in a Flexible Rotor/Magnetic Bearing System

2004 ◽  
Author(s):  
Patrick S. Keogh ◽  
Matthew O. T. Cole
Keyword(s):  
Dynamic Behavior ◽  
Experimental System ◽  
Magnetic Bearing ◽  
Contact Dynamics ◽  
Radial Clearance ◽  
Flexural Mode ◽  
Non Linear ◽  
Auxiliary Bearing ◽  
Run Up ◽  
Bearing System

This paper investigates the vibration characteristics of rotor displacement signals in a magnetic bearing system under conditions when rotor contact with auxiliary bearings is possible. Since these signals may be used for feedback control, it is necessary to determine how they may affect the ability of the controller to regain rotor levitation. An experimental system is used to demonstrate the sensitivity of the rotor non-linear dynamic behavior to unbalance, which is sufficient to cause contact during rotor run up through rigid body and flexural mode critical speeds. Complex rotor dynamics may involve contact with more than one auxiliary bearing or bush. Application of appropriate rotating forces to the rotor through a magnetic bearing is also shown to induce similar contact dynamics. Thus an alternative procedure for assessing the non-linear rotor dynamic behavior is established with the potential for identification of appropriate control forces. The contact dynamics are also considered in the presence of auxiliary bearing misalignment. Misalignment may arise through physical translation of a housing or through steady state offset errors in sensor measurements. A misalignment of 50% of the nominal radial clearance is applied at an auxiliary bearing. Various contact modes are evident as the rotor is run up in speed. During run down different contact dynamics may be encountered and the level of such hysteresis is assessed.

Nonlinear Vibration Analysis of an Unbalanced Flexible Rotor Supported by Ball Bearings With Radial Internal Clearance

2008 ◽  
Author(s):  
T. C. Gupta ◽  
K. Gupta ◽  
D. K. Sehgal
Keyword(s):  
Ball Bearing ◽  
Natural Frequencies ◽  
Power Spectra ◽  
Hertzian Contact ◽  
Phase Portraits ◽  
Integration Scheme ◽  
Flexible Rotor ◽  
Deep Groove ◽  
Varying Compliance ◽  
Bearing System

In the present work, the nonlinear dynamic response of an unbalanced horizontal flexible rotor supported by deep groove ball bearing is studied. Nonlinearity effects in rolling element bearings arise from Hertzian contact force deformation relationship and clearance between rolling elements and races. The system is bi-periodically excited due to varying compliance of ball bearing and rotating unbalance. The flexible rotor bearing system is modeled by finite element method, taking into account the gyroscopic moments, rotary inertia, shear deformation, proportional damping, nonlinear stiffness and radial internal clearance of ball bearing. The implicit type numerical time integration scheme Newmark-β and Newton-Raphson methods are used to numerically solve the nonlinear equations of motion. The mathematical model is validated for the natural frequencies of the flexible shaft and whirl frequencies. On account of variation in the ball bearing stiffness, the variation in natural frequencies of the rotor ball bearing system is estimated. The influence of ball bearing nonlinearity on dynamic behavior is analyzed by time histories of steady state response, phase portraits and power spectra. Effect of radial internal clearance and varying compliance on the unbalance response of flexible rotor is studied in detail.

Contact Dynamic Response With Misalignment in a Flexible Rotor/Magnetic Bearing System

2004 ◽  
Vol 128 (2) ◽  
pp. 362-369 ◽  
Author(s):  
P. S. Keogh ◽  
M. O. T. Cole
Keyword(s):  
Dynamic Behavior ◽  
Experimental System ◽  
Magnetic Bearing ◽  
Contact Dynamics ◽  
Radial Clearance ◽  
Flexural Mode ◽  
Auxiliary Bearing ◽  
Run Up ◽  
Control Forces ◽  
Bearing System

This paper investigates the vibration characteristics of rotor displacement signals in a magnetic bearing system under conditions when rotor contact with auxiliary bearings is possible. Since these signals may be used for feedback control, it is necessary to determine how they may affect the ability of the controller to regain rotor levitation. An experimental system is used to demonstrate the sensitivity of the rotor nonlinear dynamic behavior to unbalance, which is sufficient to cause contact during rotor run-up through rigid-body and flexural mode critical speeds. Complex rotor dynamics may involve contact with more than one auxiliary bearing or bush. Application of appropriate rotating forces to the rotor through a magnetic bearing is also shown to induce similar contact dynamics. Thus, an alternative procedure for assessing the nonlinear rotor dynamic behavior is established with the potential for identification of appropriate control forces. The contact dynamics are also considered in the presence of auxiliary bearing misalignment. Misalignment may arise through physical translation of a housing or through steady-state offset errors in sensor measurements. A misalignment of 50% of the nominal radial clearance is applied at an auxiliary bearing. Various contact modes are evident as the rotor is run up in speed. During rundown, different contact dynamics may be encountered and the level of such hysteresis is assessed.

Comparison study of misalignment effect along two perpendicular directions on the stability of rigid rotor-aerostatic journal bearing system

2020 ◽  
Vol 234 (10) ◽  
pp. 1618-1634
Author(s):  
Jianbo Zhang ◽  
Han Zhao ◽  
Donglin Zou ◽  
Na Ta ◽  
Zhushi Rao
Keyword(s):  
Journal Bearing ◽  
Thickness Distribution ◽  
Vertical Direction ◽  
Inertial Force ◽  
Journal Bearings ◽  
Rigid Rotor ◽  
Stability Threshold ◽  
Dynamic Coefficients ◽  
The Stability ◽  
Bearing System

Under misalignment condition, the film thickness distribution of aerostatic journal bearings is changed comparing with condition without misalignment, which results in the change of performances of aerostatic journal bearings. In the paper, the effects of misalignment along two perpendicular directions (along the vertical direction θ y and along the horizontal direction θ x) on the dynamic coefficients and stability thresholds of both critical whirl ratio and critical inertial force calculated by the motion equation of rigid rotor-aerostatic journal bearing system are studied comparatively. The results indicate that the dynamic coefficients, critical whirl ratio, and critical inertial force are more sensitive to θ x compared with θ y. Moreover, the stability threshold of whirl ratio reduces with increasing the misalignment degree, while stability threshold of inertial force increases with increasing the misalignment degree.

scholarly journals A Simplified Mathematical Model for the Analysis of Varying Compliance Vibrations of a Rolling Bearing

2020 ◽  
Vol 10 (2) ◽  
pp. 670 ◽  
Author(s):  
Radoslav Tomović
Keyword(s):  
Mathematical Model ◽  
Parametric Analysis ◽  
Rolling Bearing ◽  
Influential Factors ◽  
Radial Clearance ◽  
Radial Load ◽  
Simplified Approach ◽  
Rolling Element ◽  
Rolling Elements ◽  
Varying Compliance

In this paper, a simplified approach in the analysis of the varying compliance vibrations of a rolling bearing is presented. This approach analyses the generation of vibrations in relation to two boundary positions of the inner ring support on an even and an odd number of the rolling element of a bearing. In this paper, a mathematical model for the calculation of amplitude and frequency of vibrations of a rigid rotor in a rolling bearing is presented. The model is characterized by a big simplicity which makes it very convenient for a practical application. Based on the presented mathematical model a parametric analysis of the influence of the internal radial clearance, external radial load and the total number of rolling elements on the varying compliance vibrations of rolling bearing was conducted. These parameters are the most influential factors for generating varying compliance vibrations. The results of the parametric analysis demonstrate that with the proper choice of the size of the internal radial clearance and external radial load, the level of the varying compliance vibrations in a rolling bearing can be theoretically reduced to zero. This result opposes the opinion that varying compliance vibrations of rolling bearing cannot be avoided, even for geometrically ideally produced bearing.

Applications of vibro-acoustic measurement and analysis in conjunction with tribological parameters to assess surface fatigue wear developed in the roller-bearing system

2021 ◽  
pp. 135065012098246
Author(s):  
Shashikant Pandey ◽  
Muniyappa Amarnath
Keyword(s):  
Roller Bearing ◽  
Operating Conditions ◽  
Rolling Contact ◽  
Stribeck Curve ◽  
Fatigue Wear ◽  
Surface Fatigue ◽  
Rolling Element ◽  
Measurement And Analysis ◽  
Contact Surfaces ◽  
Bearing System

Rolling-element bearings are the most commonly used components in all rotating machinery. The variations in the operating conditions such as an increase in the number of operating cycles, load, speed, service temperature, and lubricant degradation result in the development of various defects such as pitting, spalling, scuffing, scoring, etc. The defects that appeared on rolling contact surfaces cause surface deterioration and change in the vibration and sound levels of the bearing system. The present experimental investigations are aimed at assessing the surface fatigue wear that appears on the contact surfaces of roller bearings. The studies considered the estimation of specific film thickness, analysis of surface fatigue wear developed on the rolling-element surfaces, surface roughness analysis, grease degradation analysis using Fourier transform infrared radiation, and vibration and sound signal measurement and analysis. The results obtained from the experimental investigation provide a good correlation between surface wear, vibration, and sound signals with a transition in the lubrication regimes in the Stribeck curve.

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