Nonlinear Dynamic Behavior Effect of Magnetorheological Damper on a Rotor System with Axial and Radial Rub-Impacts

In this article, we study the problem of axial and radial coupling rub-impact faults based on a full degree-of-freedom rotor system, which has not been extensively discussed in previous literature. An improved magnetorheological (MR) damper configuration is proposed in order to study its effect on the inhibition of coupling rub-impact faults. The Lagrange method is used to establish the finite element model of a rotor-bearing system under radial, axial, and radial-axial coupling rub-impact. At the same time, based on the bilinear constitutive equation of the MR fluid, the dynamic model of the MR damper is established. Through using the Newmark-β method to present a numerical solution, the nonlinear dynamic behaviors of the rotor system under different rub-impact faults are studied; also, the influence of the MR damper on the rub-impact fault dynamic behavior is investigated. The results show that the radial rub-impact makes the system produce rich dynamic behaviors such as period-2 and quasi-periodic. In comparison with the dynamic responses of the radial rub-impact, the axial rub-impact causes the system to produce multiple frequencies, in which the 1X frequency is the most evident. Additionally, it has a certain impact on the radial rub-impact fault, which creates a multiple period interval under the radial rub-impact delay. Consequently, MR dampers have effective mitigation on single radial rub-impact faults, but they have no obvious effect on the radial-axial coupling rub-impact.