Experimental and Numerical Studies on Nonlinear Dynamic Behavior of Rotor System Supported by Ball Bearings

2010 ◽  
Vol 132 (8) ◽  
Author(s):  
Changqing Bai ◽  
Hongyan Zhang ◽  
Qingyu Xu
Keyword(s):  
Finite Element ◽  
Dynamic Behavior ◽  
Nonlinear Dynamic ◽  
High Speed ◽  
Ball Bearing ◽  
Rotor System ◽  
Hertzian Contact ◽  
Ball Bearings ◽  
Flexible Rotor ◽  
Nonlinear Dynamic Behavior

Ball bearings are important mechanical components in high-speed turbomachinery that is liable for severe vibration and noise due to the inherent nonlinearity of ball bearings. Using experiments and the numerical approach, the nonlinear dynamic behavior of a flexible rotor supported by ball bearings is investigated in this paper. An experimental ball bearing-rotor test rig is presented in order to investigate the nonlinear dynamic performance of the rotor systems, as the speed is beyond the first synchroresonance frequency. The finite element method and two-degree-of-freedom dynamic model of a ball bearing are employed for modeling the flexible rotor system. The discrete model of a shaft is built with the aid of the finite element technique, and the ball bearing model includes the nonlinear effects of the Hertzian contact force, bearing internal clearance, and so on. The nonlinear unbalance response is observed by experimental and numerical analysis. All of the predicted results are in good agreement with experimental data, thus validating the proposed model. Numerical and experimental results show that the resonance frequency is provoked when the speed is about twice the synchroresonance frequency, while the subharmonic resonance occurs due to the nonlinearity of ball bearings and causes severe vibration and strong noise. The results show that the effect of a ball bearing on the dynamic behavior is noticeable in optimum design and failure diagnosis of high-speed turbomachinery.

scholarly journals Nonlinear Dynamic Behavior of Double-Disk Isotropic Rotor System with Axial Rub-Impact

2011 ◽  
Vol 2-3 ◽  
pp. 678-682
Author(s):  
Y. Zhang ◽  
W.M. Wang ◽  
J.F. Yao
Keyword(s):  
Dynamic Behavior ◽  
Nonlinear Dynamic ◽  
High Speed ◽  
Element Model ◽  
Rotor System ◽  
Self Healing ◽  
Rotor Bearing ◽  
Nonlinear Dynamic Behavior ◽  
Operation Stability ◽  
Bearing System

In the case of considering the shear effect and gyroscopic effect, a finite element model is developed to study the nonlinear dynamic behavior of a double-disk isotropic rotor- bearing system with axial rub-impact in this paper. The influences of rotational speed and initial phase difference on the operation stability of the rotor-bearing system are discussed. It transpires that the response of the rotor system with axial rub- impact is mainly synchronous periodic motion. The vibration signals of axial rub-impact include such as the synchronous signal and the multiple frequencies, in which the synchronous signal is dominating signal. There is no weakening wave phenomenon in time wave plot. All the results are in reasonable good agreement with those observed in engineering. The results of this paper could provide certain reference for fault diagnosis and self-healing of large high-speed rotating machinery system, thus ensuring the safe operation of the system.

Nonlinear Dynamic Study on Effects of Rub-Impact Caused by Oil-Rupture in a Multi-Shafts Turbine With a Squeeze Film Damper

2014 ◽  
Author(s):  
T. N. Shiau ◽  
C. R. Wang ◽  
D. S. Liu ◽  
W. C. Hsu ◽  
T. H. Young
Keyword(s):  
Dynamic Behavior ◽  
Nonlinear Dynamic ◽  
Equations Of Motion ◽  
Rotor System ◽  
Squeeze Film ◽  
Speed Ratio ◽  
Frequency Spectra ◽  
Squeeze Film Damper ◽  
Assumed Mode Method ◽  
Nonlinear Dynamic Behavior

An investigation is carried out the analysis of nonlinear dynamic behavior on effects of rub-impact caused by oil-rupture in a multi-shafts turbine system with a squeeze film damper. Main components of a multi-shafts turbine system includes an outer shaft, an inner shaft, an impeller shaft, ball bearings and a squeeze film damper. In the squeeze film damper, oil forces can be derived from the short bearing approximation and cavitated film assumption. The system equations of motion are formulated by the global assumed mode method (GAMM) and Lagrange’s approach. The nonlinear behavior of a multi-shafts turbine system which includes the trajectories in time domain, frequency spectra, Poincaré maps, and bifurcation diagrams are investigated. Numerical results show that large vibration amplitude is observed in steady state at rotating speed ratio adjacent to the first natural frequency when there is no squeeze film damper. The nonlinear dynamic behavior of a multi-shafts turbine system goes in its way into aperiodic motion due to oil-rupture and it is unlike the usual way (1T = >2T = >4T = >8T etc) as compared to one shaft rotor system. The typical routes of bifurcation to aperiodic motion are observed in a multi-shafts turbine rotor system and they suddenly turn into aperiodic motion from the periodic motion without any transition. Consequently, the increasing of geometric or oil parameters such as clearance or lubricant viscosity will improve the performance of SFD bearing.

Nonlinear Dynamic Behavior of Angular Contact Ball Bearings under Microgravity and Gravity

2020 ◽  
Vol 183 ◽  
pp. 105782
Author(s):  
Yuanqing Liu ◽  
Wenzhong Wang ◽  
He Liang ◽  
Tao Qing ◽  
Yunlong Wang ◽  
...  
Keyword(s):  
Dynamic Behavior ◽  
Nonlinear Dynamic ◽  
Ball Bearings ◽  
Nonlinear Dynamic Behavior

Reduced Weight Design of a Flexible Rotor with Ball Bearing Stiffness Characteristics Varying with Rotational Speed and Load

2000 ◽  
Vol 122 (3) ◽  
pp. 203-208 ◽  
Author(s):  
Dong-Soo Lee ◽  
Dong-Hoon Choi
Keyword(s):  
Dynamic Behavior ◽  
Rotational Speed ◽  
High Speed ◽  
Optimization Technique ◽  
System Dynamic ◽  
Design Approach ◽  
Ball Bearings ◽  
Flexible Rotor ◽  
Augmented Lagrange Multiplier ◽  
Stiffness Characteristics

This paper presents an effective design approach for reducing the weight of a flexible rotor in ball bearings with rotational speed and load dependent stiffness characteristics under constraints on the system eigenvalues and bearing fatigue life. Design variables are chosen to be the inner radii of shaft elements, the positions of ball bearings, and the preloads on the bearings. The stiffness characteristics of high speed ball bearings are completely described as functions of applied loads and spin speed, and applied to the dynamic behavior analysis of a rotor-bearing system. A transfer matrix method is used to obtain eigenvalues of the system and an augmented Lagrange multiplier (ALM) method is employed as an optimization technique. A multi-stepped rotor supported by two angular contact ball bearings is analyzed and designed to show the speed and load dependent stiffness effect on the system dynamic behavior and to demonstrate the effectiveness of the proposed optimum design approach. The results show that the effect of the stiffness on the system dynamic behavior is noticeable and that the suggested design approach is effective. [S0739-3717(00)00803-5]

Nonlinear Dynamic Behavior of Rotor-Bearing Systems Involving Two Hydrodynamic Oil Films in Series: Prediction and Test Application to High-Speed Turbochargers

2006 ◽  
Author(s):  
Kostandin Gjika ◽  
Chris Groves
Keyword(s):  
Dynamic Behavior ◽  
Nonlinear Dynamic ◽  
High Speed ◽  
High Performance ◽  
Maximum Speed ◽  
Inlet Temperature ◽  
Oil Viscosity ◽  
Rotor Bearing ◽  
Nonlinear Dynamic Behavior ◽  
Bearing System

In recent years, the desire for increased engine performance has led to technology that increasingly relies on robust and reliable turbocharging solutions. The rotor-bearing system (RBS) operates under extreme oil conditions of low viscosity, high temperatures, low HTHS (high temperature high shear) value and low pressure, while the demand for maximum turbocharger speed and variable geometry technology continues to increase. The rotordynamics instability is a potential issue and the development of RBS is becoming a challenge for design optimization at the development stage. It is further complicated by a lack of industrial standards to guide design practices related to the dynamics and the effort to combine high performance with low cost. This paper concerns the progress on nonlinear dynamic behavior modeling of turbocharger rotor-radial bearing system with fully floating bearing design. A developed fluid dynamics code predicts bearing rotational speed, operating inner and outer bearing clearances, effective oil viscosity taking into account the shear effect and hydrostatic load. The data are input to a rotordynamics code which predicts nonlinear lateral response (total shaft motion) of the rotor-bearing system. The model is validated with a high speed turbocharger RBS of 7.9 mm journal diameter running up to 160,000 rpm (maximum speed) with oil 0W30, 100 °C oil inlet temperature and 4 bar oil feed pressure. The test is conducted on a rotordynamics technology cell. An advanced data acquisition system is implanted and a powerful code is developed for automated data reduction. Prediction/test data show good correlation with the respect of synchronous response and total motion. The predictive model helps the development of high performance RBS with faster development cycle times and increased reliability.

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