scholarly journals An Identification Method for the Unbalance Parameters of a Rotor-Bearing System

2016 ◽  
Vol 2016 ◽  
pp. 1-9
Author(s):  
Wengui Mao ◽  
Guiping Liu ◽  
Jianhua Li ◽  
Jie Liu
Keyword(s):  
Identification Problem ◽  
Convolution Integral ◽  
Test Rig ◽  
Identification Method ◽  
Rotor Bearing ◽  
Force Reconstruction ◽  
Deconvolution Problem ◽  
Unbalance Force ◽  
The Time Domain ◽  
Bearing System

This paper is to be submitting an identification method for the unbalance parameters of a rotor-bearing system. In the method, the unbalance parameters identification problem is formulated as the unbalance force reconstruction which belongs to solving deconvolution problem, in which the unbalance force is expressed in the time domain. The unbalance response is expressed by the convolution integral of Green’s function and the unbalance force. In order to avoid the unstable solution arising from the noisy responses and the deconvolution, a regularization method is adopted to stabilize the solution. Meanwhile, a searching of the sensitive measured point has also been carried out to confirm the robustness of the method. Numerical example and a test rig have been used to illustrate the proposed method.

Analysis and Experimental Study on Stability of Nonlinear Rotor-Bearing System

2011 ◽  
Vol 236-238 ◽  
pp. 2626-2629
Author(s):  
Wei Dong Gu ◽  
Yong Liang Wang ◽  
Bo Fang ◽  
Zhan Sheng Liu ◽  
Wen Hu Huang
Keyword(s):  
Finite Element Method ◽  
Experimental Study ◽  
Test Rig ◽  
Model Simulations ◽  
Oil Whip ◽  
Film Instability ◽  
Oil Whirl ◽  
Rotor Bearing ◽  
Practical Model ◽  
Bearing System

The paper established the model of the practical Model test rig rotor-bearing system using finite element method, and discusses the phenomena of oil whirl and oil whip occurred in fluid lubricated bearing. The characteristics of stability of the nonlinear rotor-bearing system were numerically studied under different unbalance and different parameter of bearings, the model simulations are compared with measurements at the test rig, which can provide the theoretical reference for forecasting malfunction of oil film instability.

Transverse Vibrations of a General Cracked-Rotor Bearing System

1982 ◽  
Vol 104 (2) ◽  
pp. 345-355 ◽  
Author(s):  
T. Inagaki ◽  
H. Kanki ◽  
K. Shiraki
Keyword(s):  
Bending Moment ◽  
Step Function ◽  
Analysis Model ◽  
State Response ◽  
Expansion Technique ◽  
Rotor Bearing ◽  
Small Test ◽  
Unbalance Force ◽  
Numerical Calculation Method ◽  
Bearing System

In this study, the steady state response to the gravity and the unbalance force, and the major natural vibration of a general rotor bearing system with the open or open-close type crack, is analyzed along the iterative numerical calculation method (the transfer matrix method). The open-close type crack is idealized as a step function of the bending moment. The nonlinear equations are linearized by using the Fourier expansion technique, and its solutions are given approximately with the static deflection, the once/rev. vibration, and the twice/rev. vibration. The analyzed calculated method is confirmed by comparing the calculations with the experiments for a small test rotor. The rotor bearing system model in this method is as accurate as the usual numerical rotor dynamic analysis model, and also the required procedures for the calculation are almost the same.

Time-Varying Modal Analysis by SDOF Wavelets

2000 ◽  
Author(s):  
Arata Masuda ◽  
Akira Sone
Keyword(s):  
Matching Pursuit ◽  
Damping Ratio ◽  
Identification Problem ◽  
Mode Shapes ◽  
Time Varying ◽  
Identification Method ◽  
Time Varying Systems ◽  
Single Input ◽  
Expansion Coefficients ◽  
The Time Domain

Abstract The purpose of this paper is to provide a modal expression of a time-varying MDOF system and to develop an identification method for it. The single-input-multi-output relation of a time-varying N-DOF system is expressed as a superposition of N time-varying SDOF subsystems in the time domain, where the expansion coefficients represent the time-varying mode-shapes, and the natural frequency and the damping ratio of each subsystem represent the time-varying modal parameters of each mode. Then we define the SDOF wavelets, which correspond to the time-varying impulse responses of SDOF subsystems and show that the output of the entire system can be expressed by a superposition of SDOF wavelets. Then, the identification problem is reduced to an atomic decomposition problem of choosing the nearly best set of SDOF wavelets and determining the expansion coefficients. We develop a modified matching pursuit algorithm, called modal pursuit, to solve the problem. Basic examples are numerically examined to show that the proposed modal representation and the identification method are applicable to track the modal characteristics of time-varying systems.

Dynamic Response of a Rotor-Hybrid Gas Bearing System Due to Base Induced Periodic Motions

2010 ◽  
Author(s):  
Luis San Andre´s ◽  
Keun Ryu ◽  
Yaying Niu
Keyword(s):  
Natural Frequency ◽  
Excitation Frequency ◽  
Base Plate ◽  
Transportation Systems ◽  
Test Rig ◽  
Periodic Load ◽  
Gas Bearings ◽  
Rotor Bearing ◽  
Gas Bearing ◽  
Bearing System

Rotating machinery in transportation systems experiences intermittent excitation from road conditions. Internal combustion (IC) engines exert (multiple) periodic load excitations into passenger vehicle turbochargers, for example. Too large base motions can produce severe rotor-bearing system damage, even failure. The paper shows the reliability of a rotor-hybrid gas bearing system to withstand intermittent base foundation motions induced by a shaker. The test rig consists of a rigid rotor, 190mm in length, 0.825 kg in mass, and 28.6 mm in diameter, supported on two hybrid, flexure pivot tilting pad type, gas bearings. The whole system, weighing 48 kg, is supported on two soft coil springs and its lowest natural frequency is just ∼5 Hz. The rod connecting the shaker to the base plate is not affixed rigidly to the test rig base. The rod merely pushes on the base plate and hence the induced based motions are intermittent with multiple impacts and frequencies. The base induced motions are at a low main frequency (5–12 Hz) relative to the operating speed of the rotor-bearing system (max. 35 krpm). The recorded rotor responses, relative to the bearing housings, also contain the main excitation frequency and its super harmonics; and because of the intermittency of the base motions, it also excites the rotor-bearing system natural frequency, in particular when the gas bearings are supplied with a low feed pressure. Predicted rotor dynamic displacements induced by the base excitations show reasonable agreement with the test data.

scholarly journals Transmissibility Analysis of a Regenerated Rotor System

2021 ◽  
Vol 9 (8) ◽  
pp. 1102-1107
Author(s):  
Akanksha Dhurvey
Keyword(s):  
High Speed ◽  
Critical Speed ◽  
Rotor System ◽  
Jet Engines ◽  
Simply Supported ◽  
Rotor Bearing ◽  
Unbalance Force ◽  
Force Transmissibility ◽  
Very High ◽  
Bearing System

Abstract: The aim of this paper is to represents a dynamic behavior of rotor bearing system wirth simply supported beam for three different position disc. rotating machinery such as compressors, turbines, pumps, jet engines, turtobo chargers, etc. are subject to vibrations. rotating machines are operated in very high speed and they are subjected to some unbalance force due to vibration from that machine pass to the foundation of machine.so the analysis of the dynamics parameter of rotor it is important to determine force transmissibility, natural frequency, critical speed and amplitudes of rotor system. Keywords: force transmissibility, vibration, critical speed, rotor bearing system etc.

The Effect of the 150-Degree Partial Bearing on Rotor-Unbalance Vibration

1964 ◽  
Vol 86 (2) ◽  
pp. 337-345 ◽  
Author(s):  
P. C. Warner ◽  
R. J. Thoman
Keyword(s):  
Force Transmission ◽  
Oil Whip ◽  
Rotor Bearing ◽  
Unbalance Force ◽  
Stability Limits ◽  
Dynamic Unbalance ◽  
Bearing System

The effect of a centrally loaded 150-deg partial bearing on the transmission of unbalance force is determined for a simple, symmetrical rotor-bearing system considering both static and dynamic unbalance. Design curves giving force transmission, mass and journal vibration, and oil-whip stability limits are included.

Evolutionary system identification in the time domain

1997 ◽  
Vol 211 (5) ◽  
pp. 319-323 ◽  
Author(s):  
K C Tan ◽  
Y Li
Keyword(s):  
System Identification ◽  
Identification Problem ◽  
Step Response ◽  
Multivariable System ◽  
Test Rig ◽  
Response Data ◽  
Discrete Time Systems ◽  
Non Linear Systems ◽  
The Time Domain ◽  
Time Systems

This paper develops a genetic algorithm based technique that may be used to identify multivariable system identification directly from plant step response data. Using this technique, globally optimized models for linear and non-linear systems can be identified without the need for a differentiable cost function or linearly separable parameters. Results are validated against a benchmark identification problem and a laboratory test-rig for continuous and discrete-time systems.

Application of Finite Element Method in Time Domain to a Rotor System With Nonlinear Supports

2001 ◽  
Author(s):  
Liguo Wang ◽  
Wenhu Huang ◽  
Chao Hu
Keyword(s):  
Finite Element ◽  
Time Domain ◽  
Nonlinear Differential Equations ◽  
Element Formulation ◽  
Algebraic Equations ◽  
Periodic Response ◽  
Jeffcott Rotor ◽  
Rotor Bearing ◽  
The Time Domain ◽  
Bearing System

Abstract A new method for analyzing periodic response of rotor dynamic system with nonlinear supports is presented in this paper. Based on a finite element formulation in the time domain, this method transforms nonlinear differential equations governing the dynamic behavior of rotor-bearing system into a set of nonlinear algebraic equations that can be reduced and calculated by the characteristic set of Wu elimination method. The analytic solution of the nodal displacement has been obtained finally. According to this result the behavior of periodic response is analyzed. The feasibility and advantage of the proposed method are illustrated with an example of flexible Jeffcott rotor-bearing system with nonlinear supports.

Experiment Research of Two-Span Rotor-Bearing System with Rub-Impact and Crack Faults

2013 ◽  
Vol 706-708 ◽  
pp. 1335-1338
Author(s):  
Yue Gang Luo ◽  
Song He Zhang ◽  
Bin Wu ◽  
Hui Ma
Keyword(s):  
Dynamic Characteristics ◽  
Frequency Component ◽  
Rotor System ◽  
Test Rig ◽  
Experiment Research ◽  
Coupling Faults ◽  
Rotor Bearing ◽  
Frequency Components ◽  
Bearing System

The test rig of two-span rotor-bearing system with rub-impact and crack faults was constructed. The vibration of the rotor-bearing system was observed for different conditions, such as single rub-impact fault, double rub-impact faults and coupling faults of rubbing and crack. The 3D-waterfall spectrum of rotor system was used to analyze the dynamic characteristics of the system during faults. The results indicate there appears 6-superharmonic frequency component on double rub-impact faults. The amplitudes of subharmonic frequencies decrease obviously and it of superharmonic frequencies increases on coupling faults of rubbing and crack, and the superharmonic frequency components are different obviously in different span.

One-Shot Balancing of Rigid Rotors: A Closed Form Solution

2009 ◽  
Author(s):  
Enrique S. Gutie´rrez-Wing ◽  
Jorge E. Aguirre-Romano
Keyword(s):  
Closed Form ◽  
Experimental Test ◽  
Total Mass ◽  
Closed Form Solution ◽  
Form Solution ◽  
Modal Parameters ◽  
Test Rig ◽  
Rotor Bearing ◽  
Rigid Rotors ◽  
Bearing System

This article presents a closed-form solution to the computation of unbalance correction masses for rigid rotors mounted on flexible bearings. The solution requires measurements of the response of the rotor-bearing system to the unbalance that is to be corrected, as well as knowledge of its total mass or other stiffness or damping parameters that are readily deducible from the mounting configuration. No detailed mathematical models or information from previous balancing runs are required. The computation is based on the relationships that exist between some spatial and modal parameters of rotor-bearing systems. Such relationships are derived in this article, and their use in the computation of balancing masses is presented and verified with results from an experimental test rig. This work demonstrates the feasibility of balancing rigid rotors without trial runs, detailed models or historical balancing records.

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