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Abstract: This study performs a systematic analysis of the dynamic behavior of a gear-bearing system with the turbulent flow effect, nonlinear suspension, nonlinear oil-film force and nonlinear gear mesh force. The dynamic orbits of the system are observed using bifurcation diagrams plotted using the dimensionless damping coefficient, unbalance coefficient and the dimensionless rotational speed ratio as control parameters. The onset of chaotic motion is identified from the phase diagrams, power spectra, Poincaré maps, Lyapunov exponents and fractal dimension of the gear system. The numerical results reveal that the system exhibits a diverse range of periodic, sub-harmonic and chaotic behaviors. The results presented in this study provide a detailed understanding of the operating conditions under which undesirable dynamic motion takes place in gear-bearing system and therefore offer a useful source of reference for engineers in designing and controlling such systems. [Copyright &y& Elsevier]

Asystematic analysis of the dynamic behavior of a gear-bearing systemwith nonlinear suspension, couple-stress fluid flow effect, nonlinear oil-film force, and nonlinear gear mesh force is performed in the present study. The dynamic orbits of the system are observed using bifurcation diagrams plotted using the dimensionless rotational speed ratio as a control parameter. The onset of chaotic motion is identified from the phase diagrams, power spectra, Poincar'e maps, Lyapunov exponents and fractal dimension of the gear-bearing system. The numerical results reveal that the system exhibits a diverse range of periodic, subharmonic, quasiperiodic, and chaotic behaviors. The couple-stress fluid would be a useful lubricating fluid to suppress nonlinear dynamic responses and improve the steady of the systems. The results presented in this study provide some useful insights into the design and development of a gear-bearing system for rotating machinery that operates in highly rotational speed and highly nonlinear regimes. [ABSTRACT FROM AUTHOR]

Abstract: This study aims to analyze the dynamic behavior of bevel-geared rotor system supported on a thrust bearing and journal bearings under nonlinear suspension. The dynamic orbits of the system are observed using bifurcation diagrams plotted with both the dimensionless unbalance coefficient and the dimensionless rotational speed ratio as control parameters. The onset of chaotic motion is identified from the phase diagrams, power spectra, Poincaré maps, Lyapunov exponents, and fractal dimensions of the gear-bearing system. The numerical results reveal that the system exhibits a diverse range of periodic, sub-harmonic, and chaotic behaviors. The results presented in this study provide an understanding of the operating conditions under which undesirable dynamic motion takes place in a gear-bearing system and therefore serves as a useful source of reference for engineers in designing and controlling such systems. [Copyright &y& Elsevier]

Abstract: This study performs a systematic analysis of the dynamic behavior of a single degree-of-freedom spur gear system with and without nonlinear suspension. The dynamic orbits of the system are observed using bifurcation diagrams plotted using the dimensionless damping coefficient and the dimensionless rotational speed ratio as control parameters. The onset of chaotic motion is identified from the phase diagrams, power spectra, Poincaré maps, Lyapunov exponents and fractal dimension of the gear system. The numerical results reveal that the system exhibits a diverse range of periodic, sub-harmonic and chaotic behaviors. The results presented in this study provide an understanding of the operating conditions under which undesirable dynamic motion takes place in a spur gear system and therefore serve as a useful source of reference for engineers in designing and controlling such systems. [ABSTRACT FROM AUTHOR]

Abstract: Vibration characteristics of two rotors equipped with long journal bearings placed at both ends were investigated. Besides the non-linear forces of the lubricated pairs, a non-linear elastic, damped coupling was assumed between the bearings and the rotor pedestal. Rotating speed is used as the control parameter to observe various forms of periodic, quasi-periodic and chaotic vibrations. Different cross section and length of shafts, mass of bearings and even different bearing approximations are presented to analyze and discuss the difference of dynamic responses. Dynamic trajectories, Poincaré maps, bifurcation diagrams, and maximum Lyapunov exponent are used to analyze the behavior of the bearing center in the horizontal and vertical directions under different operating conditions. It is shown that the system can exhibit very rich types of periodic, quasi-periodic, and chaotic vibrations. These forms of vibrations and relevant phenomena can be effectively used to diagnose the undesired vibration in rotor–bearing systems. [Copyright &y& Elsevier]

Abstract: This study performs a systematic analysis of the dynamic behavior of a gear-bearing system with nonlinear suspension, nonlinear oil-film force, and nonlinear gear mesh force. The dynamic orbits of the system are observed using bifurcation diagrams plotted with both the dimensionless unbalance coefficient and the dimensionless rotational speed ratio as control parameters. The onset of chaotic motion is identified from the phase diagrams, power spectra, Poincaré maps, Lyapunov exponents, and fractal dimensions of the gear-bearing system. The numerical results reveal that the system exhibits a diverse range of periodic, sub-harmonic, and chaotic behaviors. The results presented in this study provide an understanding of the operating conditions under which undesirable dynamic motion takes place in a gear-bearing system and therefore serves as a useful source of reference for engineers in designing and controlling such systems. [Copyright &y& Elsevier]

Abstract: A systematic analysis of the dynamics of a gear pair system supported by journal bearings is performed in this study. Nonlinear suspension effect, nonlinear oil-film force and nonlinear gear mesh force are all also considered in this study. The dynamic orbits of the system are observed using bifurcation diagrams plotted using the dimensionless damping ratios and the dimensionless rotational speed ratio as control parameters. The onset of chaotic motion is identified from the phase diagrams, power spectra, Poincaré maps, and Lyapunov exponents of the gear-bearing system. The numerical results reveal that the system exhibits a diverse range of periodic, sub-harmonic and chaotic behaviors. The results presented in this study provide an understanding of the operating conditions under which undesirable dynamic motion takes place in a gear-bearing system and therefore serve as a useful source of reference for engineers in designing and controlling such systems. [Copyright &y& Elsevier]

Abstract: This study presents numerical work investigating the dynamic responses of a flexible rotor supported by porous journal bearings. Both porous and non-porous bearing types are taken into consideration in this study. The rotating speed ratios and imbalance parameters are also presented and proved to be important control parameters. Many non-periodic responses to chaotic and quasi-periodic motions are found, too. From the bifurcation diagrams in this paper, it is also evidenced that the vibration behaviors would be improved by porous bearings. The modeling result obtained here can be employed to predict the dynamics of bearing–rotor systems, and undesirable behavior of the rotor and bearing orbits can be avoided. Also, this could help engineers and researchers in designing and studying bearing–rotor systems or some turbo-machinery in the future. [Copyright &y& Elsevier]

Abstract: The nonlinear dynamic analysis of the rotor–bearing system is studied in this paper and is supported by oil-film short bearings with nonlinear suspension. An observation of a nonlinearly supported model and the rub–impact between rotor and stator is needed. Therefore for more precise analysis of rotor-bearing systems, the rub–impact between rotor and stator is also proposed in this paper. The displacements in the horizontal and the vertical directions charactering the theoretical model of the system are considered with non-dimensional speed ratio. Inclusive of the analysis methods of the dynamic trajectory, the power spectrum, the Poincaré maps and the bifurcation diagrams are used to analyze the behavior of the rotor centre and bearing centre in the horizontal and vertical directions under different operating conditions. The maximum Lyapunov exponent analysis is also used in this study to identify the chaotic motion. It is concluded that the trajectory of rotor centre and bearing centre have undesirable vibrations. Especially at s=5.6, the rotor centre is at chaotic motion but the bearing centre is still at quasi-periodic motion. With the analysis of the dynamic behavior of these operating conditions, the theoretical and practical idea for controlling rotor–bearing systems and optimizing their operation can be more precise. [Copyright &y& Elsevier]

Abstract: The dynamic analysis of the rotor-bearing system is studied in this paper and is supported by oil film journal bearings. An observation of a nonlinearly supported model and the rub-impact between rotor and stator is needed for more precise analysis of rotor-bearing systems. Inclusive of the analysis methods of the dynamic trajectory, the power spectra, the Poincaré maps, the bifurcation diagrams and the Lyapunov exponent are used to analyze the behavior of the rotor centre and bearing centre in the horizontal and vertical directions under different operating conditions. The periodic, quasi-periodic, sub-harmonic and chaotic motion are demonstrated in this study. A special phenomenon is occurring at s =2.27, the motions of the bearing centre and the rotor centre in the horizontal direction are still at chaotic motions but the motions of the bearing centre and the rotor centre in the vertical direction are at 3T-periodic motions. It is concluded that the trajectory of rotor centre and bearing centre have undesirable vibrations. With the analysis of the dynamic behavior of these operating conditions, the theoretical and practical idea for controlling rotor-bearing systems with rub-impact condition can be more precise. [Copyright &y& Elsevier]