Analytical study of the spherical hydrostatic bearing dynamics through a unique technique

Because of their self-alignment property and design simplicity, the spherical hydrostatic bearings have the advantage over the other bearing configurations. Their static and dynamic performances have been intensively studied. Focusing on the bearing dynamic performance, it could be realized that the researchers used to mechanically excite the bearing in the experimental studies and perturb the rotor (spatial finite displacement) in the theoretical studies, observing its behavior and expressing it by dynamic stiffness and damping coefficient. Owing to a lack of information on bearing oscillation, this study adopts a new method to analyze this bearing behavior theoretically and grasp its nature. Unusually, the bearing vibration is studied hydro-dynamically rather than mechanically, showing the effect of eccentricity, inertia, restrictor type, seat configuration, and the supply pressure on the performance. New and unique formulas have been derived to predict the frequency, stiffness, and dampness, explaining how these parameters create the bearing self-alignment property. Some thrust bearings, designed with different techniques, have been examined where the results show vibration even in the bearing’s stationary state. Also, the newly derived formulas could precisely predict the rotation and rotational speed of the Kugel ball (recently proved and designed as a spherical hydrostatic bearing).