The Dynamic Stiffness of Controlled Hydrostatic Bearings

The first part of this paper is concerned with the theoretical analysis of the dynamic behavior of externally pressurized bearings compensated by constant resistance as well as controlled restrictors. The response of the bearing to harmonic and step function loads is considered and perturbation solutions are obtained. The effect of the different bearing design parameters on its dynamic stiffness is studied and recommendations are suggested. The second part of the paper includes a description of an experimental investigation supporting the theoretical analysis. Experiments were conducted on a single bearing as well as on a scale-model machine table supported on four bearings. Results obtained for different types of bearing compensation and loading are described and discussed. Moreover, the effect of oil aeration on the dynamic stiffness of hydrostatic bearings is investigated.