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.

The dynamic response of a rotor supported by two foil-air bearings with an enhanced model of foil structure

2020 ◽  
Vol 34 (22n24) ◽  
pp. 2040160
Author(s):  
Nguyen Minh Quan ◽  
Pham Minh Hai ◽  
Dinh Van Phong
Keyword(s):  
Dynamic Response ◽  
Dynamic Model ◽  
Bending Moment ◽  
Equation System ◽  
Nonlinear Characteristic ◽  
Air Bearings ◽  
Rotor Bearing ◽  
The Stability ◽  
Rotor Bearings ◽  
Bearing System

Foil-air bearings have presented their advantageous performance due to their different structures when compared to traditional air bearings. However, it is the nonlinear characteristic of this kind of bearing that has drawn studies on dynamic response of the rotor-bearing system, especially rotor stability. In this paper, an improved foil dynamic model with internal bending moment included has been proposed to determine the nominal stiffness of the foil structure. Based on that, the nominal stiffness of the foil structure has been investigated with different geometry parameters of the foil structure. By such means, the stability of the rotor-bearings system has been theoretically studied through an equation system in a common turbocharger structure. The results can be effectively used for designing and suitably selecting some geometry parameters of foil-air bearings to have a good rotor performance in this case.

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.

Dynamic Response of a Geared Rotor-Bearing System Under Residual Shaft Bow Effect

2006 ◽  
Author(s):  
T. N. Shiau ◽  
E. K. Lee ◽  
Y. C. Chen ◽  
T. H. Young
Keyword(s):  
Steady State ◽  
Natural Frequencies ◽  
Coupling Effect ◽  
Equations Of Motion ◽  
Transmission Error ◽  
Mode Shapes ◽  
Steady State Response ◽  
State Response ◽  
Rotor Bearing ◽  
Bearing System

The paper presents the dynamic behaviors of a geared rotor-bearing system under the effects of the residual shaft bow, the gear eccentricity and excitation of gear’s transmission error. The coupling effect of lateral and torsional motions is considered in the dynamic analysis of the geared rotor-bearing system. The finite element method is used to model the system and Lagrangian approach is applied to derive the system equations of motion. The dynamic characteristics including system natural frequencies, mode shapes and steady-state response are investigated. The results show that the magnitude of the residual shaft bow, the phase angle between gear eccentricity and residual shaft bow will significantly affect system natural frequencies and steady-state response. When the spin speed closes to the second critical speed, the system steady state response will be dramatically increased by the residual shaft bow for the in-phase case. Moreover the zero response can be obtained when the system is set on special conditions.

Study of Nonlinear Dynamics of Rotor-Bearing System Coupled with a Floating Raft Isolation Device

2014 ◽  
Vol 598 ◽  
pp. 202-205 ◽  
Author(s):  
Wen Zhao ◽  
Ming Li
Keyword(s):  
Periodic Motion ◽  
Nonlinear Dynamic ◽  
Basic Assumption ◽  
Mathematic Model ◽  
State Response ◽  
Floating Raft ◽  
Nonlinear Dynamic Characteristics ◽  
Rotor Bearing ◽  
Isolation Device ◽  
Bearing System

The mathematic model of rotor-bearing system coupled with floating raft isolation device is developed and its nonlinear dynamic characteristics are mainly discussed in this paper. First, on the basic assumption theory of short bearing, the nonlinear dynamic motions of the system with 4 DOF is deduced after considering the vertical and horizontal deformation and the nonlinear vibrating behaviors are analyzed such as the steady state response and its spectrum, orbit and its Poincaré map. The results show that the responses at a low speed appear single periodic motion, with increasing the speed it indicates the doubling and quasi periodic motion, etc.

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.

Dynamic Analysis of a Geared Rotor-Bearing System With Viscoelastic Supports Under the Bow Effect

2007 ◽  
Author(s):  
T. N. Shiau ◽  
E. K. Lee ◽  
T. H. Young ◽  
W. C. Hsu
Keyword(s):  
Steady State ◽  
Dynamic Analysis ◽  
Loss Factor ◽  
Critical Speed ◽  
Transmission Error ◽  
Steady State Response ◽  
Critical Speeds ◽  
State Response ◽  
Rotor Bearing ◽  
Bearing System

This paper investigates the dynamic behaviors of a geared rotor-bearing system mounted on viscoelastic supports under considerations of the gear eccentricity, excitation of the gear’s transmission error and the residual shaft bow. The finite element method is used to model the system and Lagrangian approach is applied to derive the system equations of motion. The coupling effect of lateral and torsional motions is considered in the system dynamic analysis. The investigated dynamic characteristics include system natural frequencies and steady-state response. The results show that the mass, the stiffness and the loss factor of the viscoelastic support will significantly affect system critical speeds and steady-state response. Larger loss factor and more rigid stiffness of the viscoelastic supports will suppress the systematic amplitude of resonance. Parameters, which include magnitude of the residual bow and phase angle, are also considered in the investigation of their effects on system critical speeds and steady-state response. Results show that they have tremendous influence on first critical speed when the geared system mounted on stiff viscoelastic supports. The transmission error of the gear mesh is assumed to be sinusoidal with tooth passing frequency and it will induce multiple low resonant frequencies in the system response. It is observed that the excited critical speed equals to the original critical speed divided by gear tooth number.

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.

An FE Transient Response Analysis Model of a Flexible Rotor-Bearing System With Mount System to Base Shock Excitation

2007 ◽  
Author(s):  
An Sung Lee ◽  
Byung Ok Kim
Keyword(s):  
Transient Response ◽  
Transportation Systems ◽  
Integration Scheme ◽  
Response Analysis ◽  
Flexible Rotor ◽  
Analysis Model ◽  
Transient Responses ◽  
Transient Response Analysis ◽  
Rotor Bearing ◽  
Bearing System

Turbomachinery such as turbines, pumps and compressors, which are installed in transportation systems such as warships, submarines and space vehicles, etc., often perform crucial missions and are exposed to potential dangerous impact environments such as base-transferred shock forces. To protect turbomachinery from excessive shock forces, it may be needed to accurately analyze transient responses of rotors, considering the dynamics of mount designs to be applied with. In this study a generalized FE transient response analysis model, introducing relative displacements, is firstly proposed to accurately predict transient responses of a flexible rotor-bearing system with mount systems to base-transferred shock forces. In the transient analyses the state-space Newmark method of a direct time integration scheme is utilized, which is based on the average velocity concept. Results show that for the identical mount systems considered, the proposed FE-based detailed flexible rotor model yields more reduced transient vibration responses to the same shocks than a conventional simple model or a Jeffcott rotor. Hence, in order to design a rotor-bearing system with a more compact light-weighted mount system, preparing against any potential excessive shock, the proposed FE transient response analysis model herein is recommended.

scholarly journals Nonlinear Dynamic Behaviors of a Marine Rotor-Bearing System Coupled with Air Bag and Floating-Raft

2015 ◽  
Vol 2015 ◽  
pp. 1-18 ◽  
Author(s):  
W. Zhao ◽  
M. Li ◽  
L. Xiao
Keyword(s):  
Nonlinear Dynamic ◽  
Largest Lyapunov Exponent ◽  
Steady State Response ◽  
Dynamic Effects ◽  
State Response ◽  
Floating Raft ◽  
Rotor Bearing ◽  
Vibration Mechanism ◽  
Air Bag ◽  
Bearing System

To understand the nonlinear dynamic mechanism of a rotor-bearing system coupled with air bag and floating-raft, the dynamic characteristics of the system are investigated. This work has two key objectives. First, the vibration mechanism of rotor-bearing system coupled with air bag and floating-raft is investigated by developing a numerical model. Then, the nonlinear dynamics of the system and the effect of several parameters are studied, which includes the steady-state response and its spectrum, the orbit and its Poincaré map, the bifurcation diagram, and largest Lyapunov exponent (LLE). The results show that at low speed the dynamic behavior appears in a single periodic motion, and, with the increase of the speed, the motion becomes quasi-periodic and chaotic. These performances indicate that the air bag and floating-raft introduce some dynamic effects of marine rotor-bearing system.

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