In order to solve the problem of insufficient load capacity and rotor vibration, an active fluid-film bearing lubricated with magnetorheological fluid (MRF) is proposed. Firstly, the geometry of the MRF fluid-film bearing is designed and its intelligent lubrication mechanism is analyzed. In addition, mathematical model of MRF fluid-film bearing-rotor system is derived, and FEM model is utilized to obtain stiffness and damping coefficients to supplement mathematical model. Moreover, an improved grey wolf optimization (IGWO) algorithm is developed to tune the PID parameters. The validity of the proposed method is verified by numerical simulation. Furthermore, the simulation results show that with the increasing of current magnitude, the orbit of shaft center is smaller. The shaft center orbits under the presence of magnetic field converges to a point, and therefore the active MRF bearing has better stability and ability to suppress fluid uncertainty, which could attribute to oil whirl and whip phenomena. Finally, IGWO-PID controller parameters has better response characteristics than GWO, PSO and GA algorithms, and hence the IGWO algorithm can find the appropriate PID controller parameters, that the validity of this algorithm is further proved. Therefore, this new active bearing and its insightful research fundings provide new understanding for MRF vibration control in the field of journal bearing lubrication.
 

Magnetorheological fluid (MRF), fluid-film bearing, intelligent lubrication, improved gray wolf optimizer, multi-physics field simulation, PID controller