scholarly journals Modelling of Asymmetric Rotor and Cracked Shaft

2019 ◽  
Author(s):  
Tatsuro Ishibashi ◽  
Atsushi Yoshida ◽  
Tadao Kawai
Keyword(s):  
Asymmetric Rotor ◽  
Cracked Shaft

scholarly journals Multistage Asymmetric Rotors Coaxial Measurement Stacking Method Based on Minimization of Exciting Force

Symmetry ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 1054
Author(s):  
Yongmeng Liu ◽  
Yingjie Mei ◽  
Chuanzhi Sun ◽  
Pinghuan Xiao ◽  
Ruirui Li ◽  
...  
Keyword(s):  
Vibration Amplitude ◽  
High Speed ◽  
Geometric Error ◽  
Exciting Force ◽  
Propagation Model ◽  
Assembly Method ◽  
Geometric Center ◽  
Asymmetric Rotor ◽  
Rotor Equipment ◽  
Geometric Error Measurement

The unbalanced exciting force of high-speed rotary asymmetric rotor equipment is the main factor causing rotor vibration. In order to effectively suppress the vibration of the asymmetric rotor equipment, the paper establishes a multistage asymmetric rotor coaxial measurement stacking method that minimizes the exciting force. By analyzing the propagation process of the centroid of the multistage asymmetric rotor assembly and analyzing the relationship between the geometric center and the centroid of a single asymmetric rotor, a multistage asymmetric unbalanced rotor propagation model based on geometric center stacking is established. The genetic algorithm is used to optimize the unbalance of the multistage asymmetric rotors. Combined with the vibration principle under the exciting force, the vibration amplitude of the left bearing at different rotation speeds under the minimization of the exciting force and the random assembly phase is analyzed. Finally, the experimental asymmetric rotors are dynamically measured, combined with the asymmetric rotors’ geometric error measurement experiment. The experimental results confirm that the vibration amplitude of the assembly phase with the minimum exciting force is smaller than the vibration amplitude under the random assembly phase at three-speed modes, and the optimization rate reached 73.2% at 9000 rpm, which proves the effectiveness of the assembly method in minimizing the exciting force.

A Modified Transfer Matrix Method for Asymmetric Rotor-Bearing Systems

1994 ◽  
Vol 116 (3) ◽  
pp. 309-317 ◽  
Author(s):  
Yuan Kang ◽  
An-Chen Lee ◽  
Yuan-Pin Shih
Keyword(s):  
Transfer Matrix ◽  
Transfer Matrix Method ◽  
Matrix Method ◽  
Harmonic Balance Method ◽  
Continuous System ◽  
Euler Beam ◽  
Rotating Shaft ◽  
Rotor Bearing ◽  
Asymmetric Rotor ◽  
Steady State Responses

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.

Computer programs for the asymmetric rotor

1969 ◽  
Vol 4 (5-6) ◽  
pp. 470-472 ◽  
Author(s):  
K.-M. Marstokk ◽  
Harald Møllendal
Keyword(s):  
Computer Programs ◽  
Asymmetric Rotor

Application of Dry-Friction Whip and Whirl Solution Methods to Systems With Support Asymmetry

2018 ◽  
Author(s):  
Jason C. Wilkes
Keyword(s):  
Relative Motion ◽  
General Model ◽  
Dry Friction ◽  
Current Work ◽  
General Sense ◽  
Continuous Contact ◽  
Solution Methods ◽  
Asymmetric Rotor ◽  
Two Bodies

Dry-friction whip and whirl occurs when a rotor contacts a stator across a clearance annulus. In a general sense, the relative motion between the two bodies is described by a circular precessing motion. While this problem is generally well understood, the author is unaware of any papers that discuss the problem for systems having asymmetric rotor or stator supports. The current work will investigate a general model to describe dry-friction whip and whirl for the case of continuous contact between a rotor and stator in the presence of asymmetry. This paper will show that for light asymmetry, the rotor and stator motions are elliptical; however, the relative motion between the two bodies remains circular.

Vibration of Asymmetric Rotor through Critical Speed with Limited Power Supply

1972 ◽  
Vol 14 (3) ◽  
pp. 184-194 ◽  
Author(s):  
T. Iwatsubo ◽  
H. Kanki ◽  
R. Kawai
Keyword(s):  
Power Supply ◽  
Critical Speed ◽  
Damping Coefficients ◽  
Asymmetric Rotor ◽  
Acceleration And Deceleration ◽  
Stationary Vibration ◽  
Limited Power ◽  
Limited Power Supply ◽  
The Many ◽  
Driving Torque

The non-stationary vibration of an asymmetric rotor with limited power supply is studied using the asymptotic method. The many factors which affect the transient vibrating behaviour of the asymmetric rotor in passing through critical speed are studied in relation to the amplitude of motion, phase angle, energy, etc. by numerical calculation; that is, stiffness ratio of the asymmetric rotor, damping coefficients, driving torque (during both acceleration and deceleration) and so on. The experimental study using a simple model is added.

Stability analysis of rotor whirl under nonlinear internal friction by a general averaging approach

2016 ◽  
Vol 23 (5) ◽  
pp. 808-826 ◽  
Author(s):  
Francesco Sorge
Keyword(s):  
Internal Friction ◽  
Equations Of Motion ◽  
Translational Motion ◽  
Stable Limit ◽  
Rotor Shaft ◽  
Shaft System ◽  
Flexible Supports ◽  
Asymmetric Rotor ◽  
Nonlinear Equations Of Motion ◽  
Shrink Fit

The two main sources of internal friction in a rotor-shaft system are the shaft structural hysteresis and the possible shrink-fit release of the assembly. The internal friction tends to destabilize the over-critical rotor running, but a remedy against this effect may be provided by a proper combination of some external damping in the supports and an anisotropic arrangement of the support stiffness, or at most by the support damping alone, depending on the system geometry. The present analysis reported here considers a general asymmetric rotor-shaft system, where the rotor is perfectly rigid and is constrained by viscous–flexible supports having different stiffnesses on two orthogonal planes. The internal friction is modelled by nonlinear Coulombian forces, which counteract the translational motion of the rotor relative to a frame rotating with the shaft ends. The nonlinear equations of motion are dealt with using an averaging approach based on the Krylov-Bogoliubov method with some adaptation to address the multi-degree-of-freedom nature of the problem. Stable limit cycles may be attained by the overcritical whirling motions, whose amplitudes are inversely proportional to the external dissipation applied by the supports. A noteworthy result is that the stiffness anisotropy of the supports is recognized as beneficial in reducing the natural whirl amplitudes, albeit mainly in the symmetric configuration of the rotor at the mid span and, to a rather lesser extent, in the asymmetric configuration, which then requires a stronger damping action in the supports.

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