A Virtual Bearing Method for Optimal Bearing Placement of Flexible Rotor Systems

2017 ◽  
Author(s):  
Shibing Liu ◽  
Bingen Yang
Keyword(s):  
Optimization Problem ◽  
Optimization Method ◽  
Rotor System ◽  
Problem Solution ◽  
Flexible Rotor ◽  
Rotor Systems ◽  
Real Coded Genetic Algorithm ◽  
Minimum Number ◽  
Distributed Transfer Function ◽  
Flexible Rotor Systems

Flexible multistage rotor systems have a variety of engineering applications. Vibration optimization is important to the improvement of performance and reliability for this type of rotor systems. Filling a technical gap in the literature, this paper presents a virtual bearing method for optimal bearing placement that minimizes the vibration amplitude of a flexible rotor system with a minimum number of bearings. In the development, a distributed transfer function formulation is used to define the optimization problem. Solution of the optimization problem by a real-coded genetic algorithm yields the locations and dynamic coefficients of bearings, by which the prescribed operational requirements for the rotor system are satisfied. A numerical example shows that the proposed optimization method is efficient and accurate, and is useful in preliminary design of a new rotor system with the number of bearings unforeknown.

Optimal Vibration Reduction of Flexible Rotor Systems by the Virtual Bearing Method

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Shibing Liu ◽  
Bingen Yang
Keyword(s):  
Optimization Problem ◽  
Rotor System ◽  
Flexible Rotor ◽  
Rotor Systems ◽  
Rotor Design ◽  
Design Variables ◽  
Real Coded Genetic Algorithm ◽  
Minimum Number ◽  
Unique Method ◽  
Distributed Transfer Function

This paper presents a new approach to optimal bearing placement that minimizes the vibration amplitude of a flexible rotor system with a minimum number of bearings. The thrust of the effort is the introduction of a virtual bearing method (VBM), by which a minimum number of bearings can be automatically determined in a rotor design without trial and error. This unique method is useful in dealing with the issue of undetermined number of bearings. In the development, the VBM and a distributed transfer function method (DTFM) for closed-form analytical solutions are integrated to formulate an optimization problem of mixed continuous-and-integer type, in which bearing locations and bearing index numbers (BINs) (specially defined integer variables representing the sizes and properties of all available bearings) are selected as design variables. Solution of the optimization problem by a real-coded genetic algorithm yields an optimal design that satisfies all the rotor design requirements with a minimum number of bearings. Filling a technical gap in the literature, the proposed optimal bearing placement approach is applicable to either redesign of an existing rotor system for improvement of system performance or preliminary design of a new rotor system with the number of bearings to be installed being unforeknown.

Distributed Transfer Function Synthesis of Multi-Body Flexible Rotor Systems

1997 ◽  
Author(s):  
Bingen Yang ◽  
Houfei Fang
Keyword(s):  
Transfer Function ◽  
Analytical Solutions ◽  
General Boundary Conditions ◽  
Flexible Rotor ◽  
Modeling And Analysis ◽  
Numerical Examples ◽  
Rotor Systems ◽  
Distributed Transfer Function ◽  
Multi Body ◽  
Flexible Rotor Systems

Abstract A distributed transfer function synthesis is proposed for modeling and analysis of rotor systems assembled from multiple flexible and rigid components. The method is capable of treating non-self-adjoint effects, general boundary conditions and multi-body coupling, and delivers exact and closed-form analytical solutions for various problems. The proposed method is illustrated in two numerical examples.

Dynamics of a Mechatronic System with Flexible Vertical Rotor

2006 ◽  
Vol 113 ◽  
pp. 223-228 ◽  
Author(s):  
Vytautas Barzdaitis ◽  
Vytautas Žemaitis ◽  
R. Jonušas ◽  
Vytautas Kazimieras Augustaitis ◽  
Vytautas Bučinskas
Keyword(s):  
Angular Speed ◽  
Technical Condition ◽  
Theoretical Modeling ◽  
Rotor System ◽  
Flexible Rotor ◽  
Mechatronic System ◽  
Rotor Systems ◽  
Fatigue Development ◽  
Resonance Frequencies ◽  
Flexible Rotor Systems

The paper is dedicated to research on flexible rotor systems with anisotropic rotor material properties. In addition, the anisotropy of rotor supports alters the rotor system resonance frequencies and the machine has to pass till it attains the operating angular speed. This phenomenon of rotor vibration is observed in vertical rotors. The aim of this work is to compare experimental vibration measurements and results of theoretical modeling. In the paper theoretical model, created from physical one of really existing rotor system is described. Collected experimental data of rotor vibrations in bearings are compared with results of theoretically derived equations. The results of theoretical modeling and research enables for estimation of a more precise technical condition of the rotor system both after the overhaul and during the maintenance and thus to avoid unexpected breakdowns, especially concerning the fatigue development in ball bearing elements.

scholarly journals An analytical investigation for optimizing the support stiffness and positions of the bearings of a flexible rotor system

2020 ◽  
Author(s):  
Jing Liu ◽  
Changke Tang
Keyword(s):  
Optimization Design ◽  
Rotor System ◽  
Mode Shapes ◽  
Rotational Inertia ◽  
Fe Model ◽  
Flexible Rotor ◽  
Fe Method ◽  
Critical Speeds ◽  
Rotor Systems ◽  
Flexible Rotor Systems

Abstract The support stiffness and positions of the bearings can greatly affect the vibrations of flexible rotor systems. However, most previous works only focused on the effect of the support stiffness of the bearings on the critical speeds of the rigid rotor systems or modal characteristics including natural frequencies and mode shapes, which missed the combine effects of the support stiffness and positions of the bearings. To overcome this issue, an analytical dynamic model of a flexible rotor system based on the finite element (FE) method is proposed. The model considers the support stiffness of the bearings and rotational inertia of the rotor system. The frequency equation of the rotor system is established for solving the critical speeds. The critical speeds and modal deformations of the system from the presented model and the numerical model based on a commercial software are compared to verify the effectiveness of the proposed FE model. The effects of the support stiffness and positions of the bearings on the critical speeds of the flexible rotor system are analyzed. The results show that the critical speeds are positively correlated with the support stiffness. The critical speeds of the flexible rotor system are also greatly affected by the support positions of the bearing. This study can provide some guidance for the optimization design method of the support stiffness and positions of the bearings in the flexible rotor systems.

An Electroviscous Damper for Rotor Applications

1990 ◽  
Vol 112 (4) ◽  
pp. 440-443 ◽  
Author(s):  
J. L. Nikolajsen ◽  
M. S. Hoque
Keyword(s):  
Rotor System ◽  
Damping Capacity ◽  
Flexible Rotor ◽  
Vibration Damper ◽  
Friction Damping ◽  
Electric Voltage ◽  
Rotor Systems ◽  
Oil Supply ◽  
Coulomb Type ◽  
New Type

A new type of vibration damper for rotor systems has been developed and tested. The damper contains electroviscous fluid which solidifies and provides Coulomb-type friction damping when an electric voltage is imposed across the fluid. The damping capacity is controlled by the voltage. The damper has been incorporated in a flexible rotor system and found to be able to reduce high levels of unbalance excited vibrations. Other proven advantages include controllability, simplicity, and no requirement for oil supply. The anticipated capabilities to circumvent the critical speeds and to suppress rotor instabilities are still unconfirmed.

Robust Optimization of Flexible Rotor Systems With Uncertain Parameters via Interval Analysis Method

2019 ◽  
Author(s):  
Jie Hong ◽  
ZheFu Yang ◽  
YaoYu Ni ◽  
YanHong Ma
Keyword(s):  
Interval Analysis ◽  
High Speed ◽  
Dynamic Performance ◽  
Practical Significance ◽  
Analysis Method ◽  
Flexible Rotor ◽  
Parameter Uncertainties ◽  
Rotor Systems ◽  
Interval Analysis Method ◽  
Flexible Rotor Systems

Abstract Uncertainties in the input parameters are inevitable in any design process. Along with the demands for higher rotational speed and higher efficiency of rotating machinery, parameter uncertainties (e.g. support stiffness, the effective bending stiffness of connecting structures) resulted from the increasing load on rotor systems lead to significant scatter of its dynamic performance. These parameters are “uncertain but bounded” which means the distributions are unknown, but the intervals are always got easier. This paper presents a method to robustly optimize the dynamic performance of flexible rotor systems taking into account parameter uncertainties via interval analysis method. Interval analysis methods for modal properties and dynamic response behavior of rotor systems are developed with the interval variables introduced into the equation of motion. The aim of the robust design method is to optimize the critical speed margins and dynamic load on bearings, in the meanwhile, minimizing the variability of the objective items by the means of reducing their sensitivity to parameter uncertainties. A numerical example is presented, results show that, for the high-speed flexible rotor systems, the optimal choices of design variables could reduce of sensitivity to rotor parameter uncertainties, thus optimizing the variability of dynamic performance, which has important practical significance in engineering.

Period-1 Motion to Chaos in a Nonlinear Flexible Rotor System

2020 ◽  
Vol 30 (05) ◽  
pp. 2050077 ◽  
Author(s):  
Yeyin Xu ◽  
Zhaobo Chen ◽  
Albert C. J. Luo
Keyword(s):  
Period Doubling ◽  
Rotor System ◽  
Harmonic Amplitude ◽  
Flexible Rotor ◽  
Periodic Motions ◽  
Bifurcation Tree ◽  
Rotor Systems ◽  
Saddle Node ◽  
Jeffcott Rotor ◽  
And Control

In this paper, a bifurcation tree of period-1 motion to chaos in a flexible nonlinear rotor system is presented through period-1 to period-8 motions. Stable and unstable periodic motions on the bifurcation tree in the flexible rotor system are achieved semi-analytically, and the corresponding stability and bifurcation of the periodic motions are analyzed by eigenvalue analysis. On the bifurcation tree, the appearance and vanishing of jumping phenomena of periodic motions are generated by saddle-node bifurcations, and quasi-periodic motions are induced by Neimark bifurcations. Period-doubling bifurcations of periodic motions are for developing cascaded bifurcation trees, however, the birth of new periodic motions are based on the saddle-node bifurcation. For a better understanding of periodic motions on the bifurcation tree, nonlinear harmonic amplitude characteristics of periodic motions are presented. Numerical simulations of periodic motions are performed for the verification of semi-analytical predictions. From such a study, nonlinear Jeffcott rotor possesses complex periodic motions. Such results can help one detect and control complex motions in rotor systems for industry.

Optimization Design and Experimental Study of a Two-disk Rotor System Based on Multi-Island Genetic Algorithm

2019 ◽  
Vol 36 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Jingjing Huang ◽  
Longxi Zheng ◽  
Chris K Mechefske ◽  
Bingbing Han
Keyword(s):  
Genetic Algorithm ◽  
Vibration Amplitude ◽  
High Speed ◽  
Optimization Design ◽  
Critical Speed ◽  
Optimization Method ◽  
Rotor System ◽  
Flexible Rotor ◽  
Optimum Position ◽  
Transient Experiments

Abstract Based on rotor dynamics theory, a two-disk flexible rotor system representing an aero-engine with freely supported structure was established with commercial software ANSYS. The physical model of the two-disk rotor system was then integrated to the multidisciplinary design optimization software ISIGHT and the maximum vibration amplitudes experienced by the two disks when crossing the first critical speed were optimized using a multi-island genetic algorithm (MIGA). The optimization objective was to minimize the vibration amplitudes of the two disks when crossing the first critical speed. The position of disk 1 was selected as the optimization variable. The optimum position of disk 1 was obtained at the specified constraint that the variation of the first critical speed could not exceed the range of ±10 %. In order to validate the performance of the optimization design, the proof-of-transient experiments were conducted based on a high-speed flexible two-disk rotor system. Experimental results indicated that the maximum vibration amplitude of disk 1 when crossing the first critical speed declined by 60.9 % and the maximum vibration amplitude of disk 2 fell by 63.48 % after optimization. The optimization method found the optimum rotor positions of the flexible rotor system which resulted in minimum vibration amplitudes.

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