The behaviour of the Jeffcott rotor under a vibrating base of fluid film bearing

The whirl motion of the Jeffcott rotor was investigated. The system was analyzed by setting up the kinetic, potential, and dissipation energy equations, and the excitation was assumed as a random vibration on the base of the fluid film bearing of the rotor. Lagrangian was used to derive the equations of motion in the Y and Z directions and the Simulink under Matlab software was used to simulate the current system. The simulation was carried out under a constant rotational speed and different masses for the shaft and the disk. In addition, the effect of changing the stiffness and the damping coefficients is also investigated. The responses of the two coordinates (Z and Y) were also observed as well as the whirl orbits of the shaft for different mass ratios. Furthermore, the stability of the system was investigated mathematically. The results show that the whirl motion is stable when the rotor speed is 8,000 rpm, while the mass ratio of the disk and the shaft is 0.4