Article ID Journal Published Year Pages File Type
1703106 Applied Mathematical Modelling 2016 19 Pages PDF
Abstract

•A new nonlinear dynamic model of an asymmetric rotor-bearing system is established.•The model considers the interaction of nonlinear oil-film force and rub-impact force.•The motions of system are studied upon the changes of unbalanced force or rub-impact force.•Oil-whirl could be restrained or even removed in different fault states.•Self-healed phenomenon is discovered in the system with multi faults.

The nonlinear dynamic behavior of an asymmetric double-disc rotor-bearing system with interaction between rub-impact and oil-film forces is addressed in this paper. Using dynamics theory, the mathematical model of an asymmetric double-disc rotor-bearing system is established, considering nonlinear oil-film force and rub-impact force. The nonlinear oil-film force model is presented in Reynolds equation, and the rub-impact is assumed with a Hertz contact and a Coulomb friction. The dynamic equations with coupled rub-impact and oil-film forces are numerically solved using the Runge–Kutta method. Bifurcation diagrams, largest Lyapunov exponent, Poincaré maps, and three-dimension spectral plots are employed to analyze the dynamic behavior of the system. The sub-harmonic, multiple periodic, quasi-periodic and chaotic motions are observed in this study. A special phenomenon is occurring that the motion of system becomes simple and the oil-whirl is restrained or even removed with an increasing imbalance by magnifying the eccentricity. Another special phenomenon is also occurring that the oil-whirl gets diminished or even disappeared with increasing stator stiffness, but the oil-whip is uninfluenced. The discoveries will have a considerable value as diagnostic tools in settling oil-film instability. The numerical results show that the nonlinear dynamic behavior of the system varies with the rotational speed and model parameters.

Related Topics
Physical Sciences and Engineering Engineering Computational Mechanics
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