Vibration Analysis Of Rotor System Research Articles

Vibration analysis of rotor systems with bearing clearance using a novel conformal contact model

Vibration analysis of rotor systems with bearing clearance using a novel conformal contact model

A dynamic model considering the time-varying friction moment of a flexible rotor system

PurposeBearing friction moments are important factors that affect the vibrations of rotor systems. The bearing friction moments are related to the dimension parameters, lubrication conditions and manufacturing errors of support bearings. This work studies the effects of the bearing friction moments on the vibrations of rotor systems.Design/methodology/approachThe rotor is separated into several shaft elements for formulating a flexible rotor. The time-varying friction moment (TFM) is affected by the time-varying contact loads. The vibrations of FRS from the TFM and Palmgren's friction moment (PFM) calculation methods are compared. Moreover, the effects of the rotor offset and radial clearance on the frequency-amplitude characteristics of FRS are studied.FindingsThe TFM method is more consistent with the actual operation mechanisms. The rotor offset and radial clearance can significantly affect the nonlinear vibrations of FRS. This work provides a new reference and research method for the vibration analysis of rotor systems considering the friction effects.Originality/valueThe elastohydrodynamic lubrication (EHL), elastic hysteresis and differential sliding are considered. A flexible rotor system (FRS) dynamic model considering the TFM is proposed. The vibrations of FRS from the TFM calculation method and empirical calculation formula are compared. The effects of the rotor offset and radial clearance on the frequency–amplitude characteristics of FRS are studied.

Nonlinear Vibration and Stability Analysis of Flexible Rotor Supported on SFD by IHB Method

In this paper, the nonlinear vibration of a flexible rotor supported on squeeze-film dampers (SFDs) with centering springs is analyzed using the incremental harmonic balance (IHB) method, and bifurcation phenomena appeared in the resonance region are investigated. Complex nonlinear phenomena occur in this system due to the interaction of the fluid-film forces and the unbalance forces of the rotor in the SFD. Systems with these complex nonlinearities cannot be solved using the classical IHB methods. To overcome this problem, the classical IHB method and the alternating frequency/time (AFT) method are combined. The processing of linear matrices is performed in the same way as the classical IHB method, and only the processing of nonlinear force matrix caused by fluid–structure interaction is modified (application of transformation matrix). To prove the validity of the proposed method, the results calculated using the proposed method are compared with the results calculated using the Runge–Kutta method and the results presented in reference. Then, frequency response curves according to changes in bearing parameter [Formula: see text], gravity parameter [Formula: see text], stiffness ratio [Formula: see text], mass ratio [Formula: see text], and unbalance parameter [Formula: see text] are constructed. Stability and bifurcation analyses of the calculated solution are performed using the Floquet theory. The proposed method can be effectively applied to the nonlinear vibration analysis of rotor systems supported on fluid-film bearings.

Graphical User Interface (GUI) for Torsional Vibration Analysis of Rotor Systems Using Holzer and MatLab Techniques

In this study, a new approach for the torsional vibration analysis of rotor systems using Holzer and Matlab techniques, by developing a graphical user interface (GUI), has been introduced. The objective of the work is to show the usefulness and power of Matlab GUI in investigating and analyzing the effects of torsional vibration on rotor systems. Also to carry out an analysis using the developed GUI to simulate three different rotor configurations such as 2-Rotor, 3-Rotor, and 5-Rotor systems. Illustrated problems in the field of analysis of torsional vibration are carried out. The results show that the developed GUI is very useful for engineers, designers, and analysts of torsional vibration problems in rotor systems.

Coupled Bending-Torsional Vibration Analysis of Rotor System with Two Asymmetric Disks

The dynamic equations derived based on the actual rotor system with two asymmetric disks. In the analysis, the eccentric, rubbing fault characteristics and internal damping effects is considered, and all the analysis is established based on nonlinear oil film force model and coupled bending-torsional differential equations. The Rugge-Kutta method is used to solve numerical model, the torsional displacement response, torsion angle and Poincare map are obtained. The results show torsion amplitudes with initial phase difference π / 2 is larger than initial phase difference of π and 0. In order to eliminate the rigid rolling component the relative torsional angle must be considered.

Vibration Analysis of Rotor System by Combined Adaptive Time-Frequency Analysis and Independent Component Analysis

Traditional time-frequency analysis methods such as short-time Fourier transform (STFT) and Wigner-Ville distribution (WVD) cannot always work effectively for the complex rotor systems where the multiple faults are involved. A noise cancellation method for the rotor faults detection is proposed in this paper by combining the independent component analysis (ICA) scheme and the adaptive time-frequency analysis (ATFA) approach. In the proposed method, the raw picked data are first separated into different independent components (ICs) via the ICA according to the different vibration sources. Then the ICs are processed by the ATFA to obtain a clear vibration character for the fault diagnosis. Experiments on a rotor system with hybrid fault of the rotor imbalance and the bolt looseness are introduced to verify the feasibility and validity of the proposed scheme.

Nonlinear vibration analysis of a rotor system using component mode synthesis method

In this paper, an effective procedure using the component mode synthesis (CMS) and the method of multiple scales (MS) or the harmonic balance (HB) method for the nonlinear vibration analysis of rotor systems is proposed. In the procedure, the system is divided into components and the differential equation for the component for each perturbation order or frequency is derived. The equation of motion for the overall system is then obtained using the CMS method. The dynamic analysis of a rotor system is carried out using the MS or the HB method. The distinguishing feature of the proposed procedure is that the nonlinear restoring force term is expressed using modal coordinates in a convenient form. The order of the modal equation of motion and the calculation time, therefore, can be reduced. In the numerical example, it is shown that the analytical methods proposed in this paper are effective for the nonlinear vibration analysis of rotor systems.

Impact Vibration Analysis of Rotor Systems in Screw Compressor

Impact Vibration Analysis of Rotor Systems in Screw Compressor

The Study of Nonlinear Vibration Analysis of Rotor System Using Component Mode Synthesis Method

In this paper, an effective method for the nonlinear vibration analysis of rotor systems is proposed using the Component Mode Synthesis method and the harmonic balance method. In the method, the system is divided into components and the differential equations for each frequency and component is derived. The equation of motion for the whole system, then, is obtained using the Component Mode Synthesis method. The dynamic analysis of a rotor system is carried out using the harmonic balance method. The distinguishing feature of the proposed method is that the nonlinear restoring force term is expressed using modal coordinate system in a convenient form. The order of the modal equation of motion and calculation time, therefore, can be reduced. In the numerical example, it is shown that the analysis method proposed in this paper is effective for the nonlinear vibration analysis of rotor systems.

The Study of Nonlinear Vibration Analysis of Rotor System Using Component Mode Synthesis Method. Analysis using The Harmonic Balance Method.

In this paper, an effective method for the nonlinear vibration analysis of rotor system is proposed by using the Component Mode Synthesis method and the Harmonic Balance Method. In that method, the system is divided into some components and the differential equations for each frequency for every components are derived. The equation of motion for the whole system, then, is obtained by using the Component Mode Synthesis method. The dynamic analysis of rotor system is carried out by using the Harmonic Balance Method. The distinguished feature of the proposed method is that the nonlinear restoring force term is represented by using modal coordinates in the convenient form. The order of the modal equation of motion and calculation time, therefore, can be reduced. In the numerical example, it is shown that the analysis method proposed in this paper is effective for the nonlinear vibration analysis of rotor system.

Non-Linear Vibration Analysis of Rotor System Using Substructure Synthesis Method. Analysis with Consideration of Non-Linearity of Rotor.

In this paper, a method to solve a complex nonlinear vibration system is proposed by using both component mode synthesis method and perturbation method to save computation cost. That is, the system is divided into some components and these are approximately transformed to modal coordinate system with nonlinearity under the assumption that the modes shape does not change, then equations of every modes are solved by using a perturbation method. These solutions are synthesized to the whole system and the solution for the whole system is obtained for the modal coordinate system. Finally, it is translated to the physical coordinate system. This method is applied to a vibration analysis of nonlinear rotor and bearing-casing system. In order to illustrate the accuracy and computation time of the proposed method, the results obtained are compared with those obtained by the finite element method.

Vibration analysis of rotor systems using reduced subsystem models

A general impedance method using reduced submodels has been developed for the linear dynamic analysis of rotor systems. Formulated in terms of either modal or physical coordinates of the subsystems, the method enables imbalance responses at specific locations of the rotor systems to be efficiently determined from a small number of 'master' degrees of freedom. To demonstrate the capability of this impedance approach, the Space Shuttle Main Engine high-pressure oxygen turbopump has been investigated to determine the bearing loads due to imbalance. Based on the same formulation, an eigenvalue analysis has been performed to study the system stability. A small 5-DOF model has been utilized to illustrate the application of the method to eigenvalue analysis. Because of its inherent characteristics of allowing formulation of reduced submodels, the impedance method can significantly increase the computational speed.