Nonlinear Dynamics of Two-span Rotor-bearing System with Flexible Coupling Misalignment

doi:10.3901/JME.2020.16.109

Abstract

Abstract: At present, the high-speed direct-drive rotor system has become an important development trend. In order to research the dynamic model of a multi-span rotor system with a multi-disc bearing and a two-span rotor that contains misalignment faults under the coupling of an elastic coupling, the coupling mass matrix and stiffness matrix are used as part of the overall mass and stiffness matrix. Considering the effects of gravity, unbalanced force, oil film force, and misalignment force, taking Newmark-β method to solve the differential equation of motion, and obtaining the vibration response of the two-span rotor system. The dynamic characteristics of the systems with or without misalignment are compared and discussed. The effects of parallel misalignment, angular misalignment and coupling stiffness on the response of the system are studied with orbit plot, bifurcation diagram, Poincare section and spectrum diagram. Results suggest that the misalignment will make the nonlinear characteristics of the system more complicated, but it will not have a significant effect on the instability speed of the rotor system. After the radial stiffness of the diaphragm coupling increases, the rotor system produces strong 2×vibration response and 4×, 6×even frequency components, the increase of the angular stiffness of the coupling increases the instability speed and 2×vibration response. The research results can provide a theoretical reference for the structural design and fault diagnosis of the rotor system.

Key words: flexible coupling, parallel misalignment, angular misalignment, coupling stiffness

CLC Number:

TG156

ZHEN Man, TIAN Yongsheng, SUN Tao, ZHANG Hualiang, TAN Chunqing. Nonlinear Dynamics of Two-span Rotor-bearing System with Flexible Coupling Misalignment[J]. Journal of Mechanical Engineering, 2020, 56(16): 109-117.

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