Modeling and Analysis of the Eccentric-Load Resistance of Single Rectangular Hydrostatic Oil Pad Units

Hydrostatic bearings are extensively utilized in precision and ultra-precision machinery. Owing to the small oil film clearance of such bearings, they are prone to tilting under eccentric loads, which may ultimately lead to bearing failure. To investigate the eccentric load characteristics of hydrostatic bearings, a typical rectangular hydrostatic oil pad unit was selected as the research object. First, an analytical model for the eccentric load-carrying capacity of the rectangular oil pad was established. This model was then validated through computational fluid dynamics (CFD) simulations. On this basis, the static and dynamic characteristics of the rectangular hydrostatic oil pad were systematically studied. The results indicate that oil supply pressure, orifice diameter, and oil pad dimensions exert significant influences on the angular stiffness and angular damping of hydrostatic bearings. Specifically, increasing the oil supply pressure to above 3 MPa can facilitate the enhancement of anti-eccentric load capacity. Under the premise of ensuring static load-carrying capacity, a moderate increase in orifice diameter is conducive to improving anti-eccentric load capacity. When the oil pad area is fixed, adjusting the width-to-height ratio of the oil pad can modify the angular damping coefficient in the corresponding direction. However, the adjustment tends to reduce the angular damping coefficient in other directions, necessitating a comprehensive evaluation in practical applications.