Modeling, Analysis, and Simulation of Auxiliary Bearing for High-speed Rotating Machinery

Abstract

An active magnetic bearing (AMB) revolutionizes rotating machinery applications by eliminating the friction problem of conventional contact bearings and the need for lubrication. Supporting equipment is necessary as a countermeasure in case the AMB fails to operate or its magnetic field decreases in power, causing the rotor to fall, known as a dropdown event. An auxiliary bearing is necessary to prevent direct contact between the rotor and the AMB, as the AMB itself is not designed to be durable against impact or rotational friction. Therefore, the auxiliary bearing is designed to absorb and withstand the contact force. The aim of this study is to find the best design for the auxiliary bearing to decrease the erratic and whirling motion of the rotor after contact. The nonlubricated Hertzian contact model is used to analyze the rotor drop dynamics, and the finite element method is used as the basis of the flexible rotor model. A simulation is carried out using MATLAB software. The simulation reveals the rotor orbit, rotor response, and contact force, provides a comparison of the stiffness support and damping support effects, and also predicts the bearing life to provide a new approach for bearing selection. The results of this study provide the relevant information for selecting the material of the auxiliary bearing with the most appropriate damping and stiffness properties to disperse the contact force during a rotor drop event.

Dynamic Simulation of a 5 Degrees of Freedom Rotor Dropping on a Protective Bearing

“…where ρ is the principal curvature of the contact surface, e δ is the Hertzian contact coefficient related to the principal curvature of the contact surface, which can be calculated from reference [24], and Q is the normal load on the contact surface. Therefore, the contact coefficient between the rolling element and the raceway is k b = e δ −3/2 (∑ ρ) −1/2 , and the contact coefficient is 3/2 [25].…”