scholarly journals Study on response characteristics of rotor-bearing system under sudden base excitation load

2020 ◽  
Vol 33 ◽  
pp. 1-5
Author(s):  
Guihuo Luo ◽  
Zhaojun Feng ◽  
Zedong Yang ◽  
Nan Zheng ◽  
Wei Chen
Keyword(s):  
Base Excitation ◽  
Response Characteristics ◽  
Rotor Bearing ◽  
Bearing System

Numerical Simulation of a Bending-Torsion Coupling Gear Transmission System

2013 ◽  
Vol 448-453 ◽  
pp. 3403-3407
Author(s):  
Chao Feng Li ◽  
Shi Hua Zhou ◽  
Jie Liu
Keyword(s):  
Rotation Frequency ◽  
Variable Stiffness ◽  
Rolling Bearing ◽  
Rotational Frequency ◽  
Helical Gear ◽  
Angular Contact Ball Bearing ◽  
Rotating Speed ◽  
Response Characteristics ◽  
Rotor Bearing ◽  
Bearing System

Based on the establishment of angular contact ball bearing mechanical model, a nonlinear coupled lateral, torsional and axial dynamic model of helical gear-rotor-bearing system is established, and the dynamic differential equations of the coupled lateral-torsional-axial nonlinear vibration are deduced for imbalance rotors. The investigations are systematically carried out by oscillograms and spectrograms with rotating speed, taking into account eccentricity and nonlinear supporting by rolling bearing. The results show that the rotation frequency of the driven shaft appears in the driving shaft. In addition, the rotation frequencies and meshing frequency appear obviously in torsional direction. It can be seen that the lateral, torsional and axial response characteristics of driving and driven shafts obvious differences are due to the effects of the gear assembly characteristic, gear geometry parameters and the angular contact ball bearings characteristics. As a result, not only appear the rotational frequency and stiffness frequency, but also yield the bearing variable stiffness frequency and conbined frequency in lateral directions. However, the theory of the helical gear-rotor-bearing system still needs further research.

Unbalanced Response of Cracked Rotor-Bearing System Under Time-Dependent Base Movements

2013 ◽  
Author(s):  
Qinkai Han ◽  
Fulei Chu
Keyword(s):  
Harmonic Balance Method ◽  
Response Spectra ◽  
Element Model ◽  
Time Dependent ◽  
Cracked Rotor ◽  
Transverse Cracks ◽  
Response Characteristics ◽  
Equivalent Time ◽  
Rotor Bearing ◽  
Bearing System

Unbalanced response of cracked rotor-bearing system under time-dependent base movements is studied in this paper. Three base angular motions, including the rolling, pitching and yawing motions, are assumed to be sinusoidal perturbations superimposed upon constant terms. Both the open and breathing transverse cracks are considered in the analysis. The finite element model is established for the base excited rotor-bearing system with open or breathing cracks. Considering the time-varying base movements and transverse cracks, the second order differential equations of the system will not only have time-periodic gyroscopic and stiffness coefficients, but also the multi-frequency external excitations. An improved harmonic balance method is introduced to obtain the steady-state response of the system under both base and unbalance excitations. The whirling frequencies of the equivalent time-invariant system, orbits of shaft center, response spectra and frequency response characteristics, are analyzed accordingly. The effects of various base angular motions, frequency and amplitude of base excitations, and crack depths on the system dynamic behaviors are considered in the discussions.

Suppression of Rotor-Bearing System Vibrations Through Flexible Bearing Support Damping

1976 ◽  
Vol 98 (3) ◽  
pp. 1053-1061
Author(s):  
J. M. Tessarzik ◽  
T. Chiang ◽  
R. H. Badgley
Keyword(s):  
High Speed ◽  
Journal Bearing ◽  
Amplitude Distribution ◽  
Random Vibrations ◽  
Response Characteristics ◽  
Response Data ◽  
Power Spectral ◽  
Tilting Pad ◽  
Rotor Bearing ◽  
Bearing System

A bearing damper, operating on the support flexure of a pivoted pad in a tilting-pad type gas-lubricated journal bearing, has been designed, built, and tested under externally applied random vibrations. A 36,000 rpm, 10 Kwe turbogenerator had previously been subjected to external random vibrations, and vibration response data had been recorded and analyzed for amplitude distribution and frequency content at a number of locations in the machine. Based upon data from that evaluation, a piston-type damper was designed and developed for each of the two flexibly-supported journal bearing pads (one in each of the two three-pad bearings). A modified turbogenerator, with dampers installed, has been retested under random vibration conditions. Root-mean-square vibration amplitudes were determined from the test data, and displacement power spectral density analyses have been performed. Results of these data reduction efforts have been compared with vibration tolerance limits and previously reported response characteristics of the unmodified machine. Results of the tests indicate significant reductions in vibration levels in the bearing gas-lubricant films, particularly in the rigidly mounted pads. The utility of the gas-lubricated damper for limiting rotor-bearing system vibrations in high-speed turbomachinery has thus been demonstrated.

Analysis of faults in rotor-bearing system using three-level full factorial design and response surface methodology

2021 ◽  
pp. 095745652110307
Author(s):  
Hara P Mishra ◽  
Arun Jalan
Keyword(s):  
Response Surface Methodology ◽  
Response Surface ◽  
Fault Analysis ◽  
Vibration Response ◽  
Effect Analysis ◽  
Outer Race ◽  
Surface Plot ◽  
Rotor Bearing ◽  
Full Factorial ◽  
Bearing System

This article presents the experimental and statistical methodology for localized fault analysis in the rotor-bearing system. These defects on outer race, on inner race, and on a combination of ball and outer race are considered. In this study speed, load and defects were considered as the essential process variables to understand their significance and effects on vibration response for the rotor-bearing system. Three factors at three levels were considered for experimentation, and the experiment was designed for L27 based on design of experiments (DOE) methodology. From the experiments, the vibration response results are recorded in terms of root mean square value for the analysis. Response surface methodology (RSM) is used for identifying the interaction effect of varying process parameters upon the response of vibrations by response surface plot. The rotor-bearing test setup is used for experimentation and is analyzed by using DOE. This study establishes the prediction of fault in the rotor-bearing system in combined parametric effect analysis and its influence with DOE and RSM.

Natural frequency analysis of a functionally graded rotor-bearing system with a slant crack subjected to thermal gradients

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Arnab Bose ◽  
Prabhakar Sathujoda ◽  
Giacomo Canale
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Power Law ◽  
Beam Theory ◽  
Functionally Graded ◽  
Thermal Gradients ◽  
Element Analysis ◽  
Rotor Bearing ◽  
Natural Frequency Analysis ◽  
Bearing System

Abstract The present work aims to analyze the natural and whirl frequencies of a slant-cracked functionally graded rotor-bearing system using finite element analysis for the flexural vibrations. The functionally graded shaft is modelled using two nodded beam elements formulated using the Timoshenko beam theory. The flexibility matrix of a slant-cracked functionally graded shaft element has been derived using fracture mechanics concepts, which is further used to develop the stiffness matrix of a cracked element. Material properties are temperature and position-dependent and graded in a radial direction following power-law gradation. A Python code has been developed to carry out the complete finite element analysis to determine the Eigenvalues and Eigenvectors of a slant-cracked rotor subjected to different thermal gradients. The analysis investigates and further reveals significant effect of the power-law index and thermal gradients on the local flexibility coefficients of slant-cracked element and whirl natural frequencies of the cracked functionally graded rotor system.

Stability of periodic motion on the rotor-bearing system with coupling faults of crack and rub-impact

2007 ◽  
Vol 21 (6) ◽  
pp. 860-864 ◽  
Author(s):  
Yue-Gang Luo ◽  
Zhao-Hui Ren ◽  
Hui Ma ◽  
Tao Yu ◽  
Bang-chun Wen
Keyword(s):  
Periodic Motion ◽  
Coupling Faults ◽  
Rotor Bearing ◽  
Bearing System
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