Browsing by Author "KANG, Y"

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A MODIFIED TRANSFER-MATRIX METHOD FOR ASYMMETRIC ROTOR-BEARING SYSTEMS
(1994-07-01)
KANG, Y
;
LEE, AC
;
SHIH, YP
;
交大名義發表
;
機械工程學系
A modified transfer matrix method (MTMM) is developed to analyze rotor-bearing systems with an asymmetric shaft and asymmetric disks. The rotating shaft is modeled by a Rayleigh-Euler beam considering the effects of the rotary inertia and gyroscopic moments. Specifically, a transfer matrix of the asymmetric shaft segments is derived in a continuous-system sense to give accurate solutions. The harmonic balance method is incorporated in the transfer matrix equations, so that steady-state responses of synchronous and superharmonic whirls can be determined. A numerical example is presented to demonstrate the effectiveness of this approach.
A MODIFIED TRANSFER-MATRIX METHOD FOR LINEAR ROTOR-BEARING SYSTEMS
(1991-09-01)
LEE, AC
;
KANG, Y
;
LIU, SL
;
機械工程學系
;
Department of Mechanical Engineering
The steady-state responses of linear flexible rotor-bearing systems are analyzed by the modified transfer matrix method. The transfer matrix has the advantage of solving the problems in frequency domain with fixed matrix size. This makes the method more economical in analyzing a large degree-of-freedom rotor system than many time-marching integrating methods. In this paper, the modifications of transfer matrix method include that the transfer matrix of shaft is derived from the "continuous system" concept instead of conventional "lumped system" concept, and the paper tries to extend the transfer matrix method to fit synchronous elliptical orbit and nonsynchronous multi-lobed whirling orbit. To demonstrate the applications of the method, three examples are presented; two synchronous and one nonsynchronous.
INVESTIGATION ON THE STEADY-STATE RESPONSES OF ASYMMETRIC ROTORS
(1992-04-01)
KANG, Y
;
SHIH, YP
;
LEE, AC
;
交大名義發表
;
機械工程學系
This paper is to generalize the previous work by utilizing finite element formulation to accommodate the effects of both deviatoric inertia and stiffness due to asymmetry of flexible shaft and disk. A Timoshenko beam element is employed to simulate rotor-bearing systems by taking the gyroscopic moment, rotary inertia, shear deformation of shaft and, asymmetry of disk and shaft into account. Internal damping is not included but the extension is straightforward. Eulerian angles are used to describe the orientations of shaft element and disk, by which, in opposite to the vectorial approach, the mathematical formulation will be symmetric for angular displacements in two directions. The effects of the angle between the major axes of shaft and disk, deviatoric inertia of the asymmetric shaft, and characteristics of bearing on synchronous critical and subcritical speeds are estimated in conjunction with the harmonic balance method. Numerical examples show that the resonant speeds, at which peak responses occur, change due to various angles between major axes, asymmetry of shaft, stiffness, and damping of bearing.
STEADY-STATE ANALYSIS OF A ROTOR MOUNTED ON NONLINEAR BEARINGS BY THE TRANSFER-MATRIX METHOD
(1993-06-01)
LEE, AC
;
KANG, Y
;
LIU, SL
;
機械工程學系
;
Department of Mechanical Engineering
The steady-state responses of subharmonic, superharmonic and synchronous vibrations of a flexible rotor supported by bearings of power nonlinearity (i.e. the bearing force satisfies a power law of the deflection) are studied. The transfer matrix method is applied to formulate the transfer matrices of nonlinear rotor-bearing systems with MDOF (multi-degree of freedom) and in conjunction with the harmonic balance method to obtain the steady-state responses. Two examples of rotor-bearing systems with cubic nonlinearity spring characteristics are given to investigate the effects of nonlinearity on frequency response and the whirling orbits.
THE ANALYSIS OF LINEAR ROTOR-BEARING SYSTEMS - A GENERAL TRANSFER-MATRIX METHOD
(1993-10-01)
LEE, AC
;
SHIH, YP
;
KANG, Y
;
交大名義發表
;
機械工程學系
A general transfer matrix method (GTMM) is developed in the present work for analyzing the steady-state responses of rotor-bearing systems with an unbalancing shaft. Specifically, we derived the transfer matrix of shaft segments by considering the state variables of shaft in a continuous system sense to give the most general formulation. The shaft unbalance, axial force, and axial torque are all taken into consideration so that the completeness of transfer matrix method for steady-state analysis of linear rotor-bearing systems is reached. To demonstrate the effectiveness of this approach, a numerical example is presented to estimate the effect of three-dimensional distribution of shaft unbalance on the steady-state responses by GTMM and finite element method (FEM).
TRANSIENT ANALYSIS OF AN ASYMMETRIC ROTOR-BEARING SYSTEM DURING ACCELERATION
(1992-11-01)
LEE, AC
;
KANG, Y
;
TSAI, KL
;
HSIAO, KM
;
交大名義發表
This paper deals with the transient vibration of asymmetric rotor systems during acceleration passing through several critical speeds at which synchronous or super-harmonic resonance occurs. The dynamic equations of the rotor-bearing system are formulated by the finite element model and the resulting dynamic equations are time-varying due to the effects of acceleration and asymmetry. In the formulation, a Timoshenko beam element is employed to simulate the rotating shaft and Eulerian angles are used to describe the orientations of the shaft element and disk. The numerical integration scheme for transient analysis is generated from the finite element model. Numerical examples are presented to illustrate (1) the effects of acceleration on peak amplitude and speed at which the peak occurs as the system passes through critical speeds, (2) the optimal acceleration process, which can be obtained by minimizing the peak response and the period of acceleration, (3) the speed regions where the transient instability exists.