Stability Analysis and Complex Dynamics of a Gear-Pair System Supported by a Squeeze Film Damper

1997 ◽  
Vol 119 (1) ◽  
pp. 85-88 ◽  
Author(s):  
Chin-Shong Chen ◽  
S. Natsiavas ◽  
H. D. Nelson
Keyword(s):  
Steady State ◽  
Periodic Solutions ◽  
Squeeze Film ◽  
Time Behavior ◽  
Steady State Response ◽  
Squeeze Film Damper ◽  
State Response ◽  
Mass Unbalance ◽  
Periodic Steady State ◽  
The Stability

The stability properties of periodic steady state response of a nonlinear geared rotordynamic system are investigated. The nonlinearity arises because one support of the system includes a cavitated squeeze film damper, while the excitation is caused by mass unbalance. The dynamical model and the procedure which leads to periodic steady state response of the system examined have been developed in an earlier paper. Here, the emphasis is placed on analyzing the stability characteristics of located periodic solutions. Also, within ranges of the excitation frequency where no stable periodic solutions are detected, the long time behavior of the system is investigated by direct integration of the equations of motion. It is shown that large order subharmonic, quasiperiodic and chaotic motions may coexist with unstable periodic response in these frequency ranges. Finally, attention is focused on practical consequences of these motions.

Effect of Thermal Growth on Vibration Behavior of Flexible Rotor System Mounted on MR Squeeze Film Damper

2010 ◽  
Author(s):  
Hamed Ghaednia ◽  
Abdolreza Ohadi
Keyword(s):  
Steady State ◽  
Rotation Velocity ◽  
Electrical Current ◽  
Frequency Domain Analysis ◽  
Squeeze Film ◽  
Fe Model ◽  
Steady State Response ◽  
Flexible Rotor ◽  
Squeeze Film Damper ◽  
State Response

In this paper a Magnetorheological squeeze film damper (MR-SFD) has been modeled using two governing equations. Firstly, considering Bingham model for MR fluid (MRF), a hydrodynamic model has been presented. Secondly, a thermal model for the system has been modeled and used to calculate the temperature rise in the squeeze film and different damper’s components. Time and frequency domain analysis has been performed over a system consists of an unbalanced flexible rotor (FE model) mounted on a pair of MR-SFDs. Results show that the amplitude of rotor’s vibration is not a simple function of electrical current such that, increase in the current cannot guaranty decrease in the value of amplitude. The steady state response of rotor versus rotation velocity is presented for different values of electrical current, which show the effects of temperature and current on the steady state response of rotor.

Closed-Form, Steady-State Solution for the Unbalance Response of a Rigid Rotor in Squeeze Film Damper

1983 ◽  
Vol 105 (3) ◽  
pp. 551-556 ◽  
Author(s):  
D. L. Taylor ◽  
B. R. K. Kumar
Keyword(s):  
Steady State ◽  
Closed Form ◽  
Closed Form Solution ◽  
Steady State Solution ◽  
State Solution ◽  
Squeeze Film ◽  
Steady State Response ◽  
Rigid Rotor ◽  
Squeeze Film Damper ◽  
State Response

This paper considers the steady-state response due to unbalance of a planar rigid rotor carried in a short squeeze film damper with linear centering spring. The damper fluid forces are determined from the short bearing, cavitated (π film) solution of Reynold’s equation. Assuming a circular centered orbit, a change of coordinates yields equations whose steady-state response are constant eccentricity and phase angle. Focusing on this steady-state solution results in reducing the problem to solutions of two simultaneous algebraic equations. A method for finding the closed-form solution is presented. The system is nondimensionalized, yielding response in terms of an unbalance parameter, a damper parameter, and a speed parameter. Several families of eccentricity-speed curves are presented. Additionally, transmissibility and power consumption solutions are present.

Periodic Steady State Response and Fatigue Analysis of a Nonlinear City Bus Model

2009 ◽  
Author(s):  
George Valsamos ◽  
Christos Theodosiou ◽  
Sotirios Natsiavas
Keyword(s):  
Steady State ◽  
Degrees Of Freedom ◽  
Nonlinear Models ◽  
Equations Of Motion ◽  
High Stress ◽  
Direct Determination ◽  
Accurate Information ◽  
Steady State Response ◽  
State Response ◽  
Periodic Steady State

Dynamic response related to fatigue prediction of an urban bus is investigated. First, a quite complete model subjected to road excitation is employed in order to extract sufficiently reliable and accurate information in a fast way. The bus model is set up by applying the finite element method, resulting to an excessive number of degrees of freedom. In addition, the bus suspension units involve nonlinear characterstics. A step towards alleviating this difficulty is the application of an appropriate coordinate transformation, causing a drastic reduction in the dimension of the final set of the equations of motion. This allows the application of a systematic numerical methodology leading to direct determination of periodic steady state response of nonlinear models subjected to periodic excitation. Next, typical results were obtained for excitation resulting from selected urban road profiles. These profiles have either a known form or known statistical properties, expressed by an appropriate spatial power spectral density function. In all cases examined, the emphasis was put on investigating ride response. The main attention was focused on identifying areas of the bus suspension and frame subsystems where high stress levels are developed. This information is based on the idea of a nonlinear transfer function and provides the basis for applying suitable criteria in order to perform analyses leading to prediction of fatigue failure.

The Steady-State Response of a Cantilevered Rotor With Skew and Mass Unbalances

1983 ◽  
Vol 105 (4) ◽  
pp. 456-460 ◽  
Author(s):  
R. C. Benson
Keyword(s):  
Steady State ◽  
Drive Shaft ◽  
Phase Lag ◽  
Steady State Response ◽  
Centrifugal Forces ◽  
Critical Speeds ◽  
State Response ◽  
Mass Unbalance ◽  
Rotor Balancing

The steady state response of a cantilevered rotor with skew and mass unbalances is studied, with special attention to the effects due to skew. A disk misaligned with its drive shaft receives active gyroscopic moments which force pitch changes in the disk, much as mass unbalance centrifugal forces induce disk translation. These active gyroscopic moments affect the rotor in ways unpredicted by passive gryoscopics; that is to say the moments acting on a perfectly aligned disk which changes pitch solely due to its precession. Under the combined influences of disk skew and mass unbalance the precessing rotor exhibits an unconventional phase lag response, and it need not be in line with the mass unbalance at low spin rates. This can significantly alter rotor balancing procedures. Rotor critical speeds are studied for their number and severity, with results presented in a compact nondimensional form.

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