Nonlinear analysis of herringbone gear rotor system based on the surface waviness excitation of journal bearing

Cyclostationarity has been widely used as a useful signal processing technique to extract the hidden periodicity of the energy flow of the mechanical vibration signature. However, the conventional cyclostationarity is restricted to analyzing the real-valued signal, which is incapable of processing the constructed complex-valued signal obtained from the journal bearing supported rotor system operating with oil film instability. In this work, the directional cyclostationary parameters, such as directional cyclic mean, directional cyclic autocorrelation, and directional spectral correlation density, are defined based on the principle of directional Wigner distribution. Practical experiment has demonstrated the effectiveness and superiority of the proposed method in the investigation of the instantaneous planar motion of the journal bearing supported rotor system.

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Numerical and Experimental Research on Periodic Solution Stability of Inclined Rotor Journal Bearing System

Volume 6: Structures and Dynamics, Parts A and B ◽

10.1115/gt2011-45632 ◽

2011 ◽

Cited By ~ 1

Author(s):

Dashuai Qian ◽

Zhansheng Liu ◽

Jiajia Yan ◽

Liquan Sun ◽

Yongliang Wang

Keyword(s):

Periodic Solution ◽

Journal Bearing ◽

Rotor System ◽

Experimental Results ◽

System Stability ◽

Response Analysis ◽

Solution Stability ◽

Special Cases ◽

Rotor Journal ◽

Bearing System

Rotor bearing systems on ships usually work in inclined states when ships are swaying in wave and wind. The inclined status will affect the lubricant condition of journal bearing and bring about changes of the dynamic characteristics of the rotor system. To study the periodic solution stability of inclined rotor journal bearing system, Capone’s short bearing model is employed to describe the journal bearing support properties. Considering the inclination induced change of bearing radial load, the dynamic equation of inclined rotor system is established by using finite element method. The periodic solution stability is discussed based on bifurcation and response analysis. With the increase of rotating speed, instability of period-1 motion happens and oil whirl occurs. The motion then develops into a kind of quasi-periodic motion. Two special cases of inclined rotor system, the horizontal and the vertical cases, are compared and discussed. Both of the numerical and the experimental results show that the periodic solution unstable threshold decreases with the increase of rotor inclination angle. At last, some experimental results about influences of experiments conditions on rotor system stability are given.

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Pneumatic hammer instability in the aerostatic journal bearing–rotor system: A theoretical and experimental analyses

Proceedings of the Institution of Mechanical Engineers Part J Journal of Engineering Tribology ◽

10.1177/1350650120908100 ◽

2020 ◽

pp. 135065012090810

Author(s):

Abdurrahim Dal ◽

Tuncay Karaçay

Keyword(s):

Dynamic Response ◽

Journal Bearing ◽

Instability Region ◽

Rotor System ◽

Pneumatic Hammer ◽

Nonlinear Dynamic Response ◽

System A ◽

Differential Transform ◽

Hole Configuration ◽

Aerostatic Bearings

In this study, the pneumatic hammer instability phenomena in the aerostatic journal bearing–rotor system is analysed and discussed for different feeding hole configurations theoretically and experimentally. The influences of the configuration of the feeding holes on the nonlinear dynamics of the system are also investigated. The air flow between the surfaces is modelled with Reynold’s equation and it is numerically solved with differential transform and finite difference hybrid method. Three different aerostatic bearings are modelled and simulated to investigate the ınfluences of the configuration of the holes for different angular speeds. An experimental test rig is designed and tested for different rotor speeds to validate the obtained numerical results. The dynamic response of the system is analysed using waterfall plots, bifurcation diagrams, orbit plots, phase portrait and Poincaré map, which are drawn to determine the pneumatic hammer instability region of the modelled system. The results reveal a nonlinear dynamic response of the rotor centre. In addition, the analysis shows that the feeding hole configuration affects the rotor dynamics and the pneumatic hammer instability region.

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Nonlinear Dynamics Analysis of Tilting Pad Journal Bearing-Rotor System

Shock and Vibration ◽

10.1155/2011/213742 ◽

2011 ◽

Vol 18 (1-2) ◽

pp. 45-52 ◽

Cited By ~ 3

Author(s):

Jiayang Ying ◽

Yinghou Jiao ◽

Zhaobo Chen

Keyword(s):

Nonlinear Dynamics ◽

System Dynamics ◽

Journal Bearing ◽

Rotor System ◽

Moment Of Inertia ◽

Dynamics Analysis ◽

Tilting Pad ◽

Rotor Bearing ◽

Tilting Pad Journal Bearing ◽

Bearing System

The nonlinear dynamics theory is increasingly applied in the dynamics analysis of tilting pad journal bearing-rotor system. However, extensive work on system dynamics done previously neglects the influence caused by the moment of inertia of the pad. In this paper, a comparison is made between the responses of the rotor in the bearings with and without pad inertia effect. Taking the Jeffcott rotor system as an example, the characteristics of bearing-rotor system, such as bifurcation diagram, cycle response, frequency spectrum, phase trajectories, and Poincaré maps, were attained within a certain rotation rate range. The pivotal oil-film force of tilting pad journal bearing was calculated by database method. The results directly demonstrate that considering the influence of the pad moment of inertia, system dynamics characteristics are found more complicated when rotor-bearing system works around natural frequency and system bifurcation is observed forward when rotor-bearing system works on high-speed range.

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Nonlinear Dynamic of a Geared Rotor System With Nonlinear Oil Film Force and Nonlinear Mesh Force

Journal of Vibration and Acoustics ◽

10.1115/1.4005032 ◽

2012 ◽

Vol 134 (4) ◽

Cited By ~ 14

Author(s):

Yahui Cui ◽

Zhansheng Liu ◽

Yongliang Wang ◽

Jianhuai Ye

Keyword(s):

Numerical Integration ◽

Dynamic Model ◽

Rotational Speed ◽

Nonlinear Dynamic ◽

Journal Bearing ◽

Rotational Frequency ◽

Rotor System ◽

Dynamic Responses ◽

Oil Film ◽

Gear Mesh

To investigate the effect of oil film force on a geared rotor system, a short journal bearing model was applied to represent nonlinear oil film force. A dynamic model of the geared rotor oil journal bearing system was presented. The nonlinear gear mesh force and nonlinear oil film force were considered in the model. The nonlinear dynamic responses of the system were investigated by numerical integration method. This article shows that when the rotational speed is relatively low, the vibration of the system is mainly affected by nonlinear mesh force. With the increase of rotational speed, the influence of nonlinear oil film force also increases gradually, and the subsynchronous forward precession phenomena appear. When the speed increases to a certain value, the amplitude of the subsynchronous forward precession exceeds the amplitude of the rotational frequency, and the nonlinear mesh force is greatly affected by the nonlinear oil film force. However, the linear oil film force does not affect the nonlinear mesh force. The subsynchronous forward precession is difficult to be predicted by linear oil film force which was previously applied. This experiment is performed to validate the correctness of the dynamic model presented, and the numerical integration results of low speeds are validated by the experimental data.

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