Surface roughness effect on the dynamic stiffness and damping characteristics of compensated hydrostatic thrust bearings

On the basis of Christensen's stochastic model of rough surfaces, this stud y theoretically analyzes the effect of surface roughness on the dynamic sti ffness and damping characteristics of compensated hydrostatic circular step thrust bearings. Both the stochastic Reynolds equation with rotational ine rtia effect and the recess flow continuity equation with recess volume flui d compressibility effect are derived to take into account the presence of r oughness on the bearing surfaces. Using a small perturbation method, the dy namic coefficients of bearings are evaluated. According to the results, the mean stiffness and damping behaviours are significantly affected by the ro ughness pattern and the height of roughness. The effect of circumferential roughness provides an increase in the mean bearing stiffness and damping ch aracteristics as compared to the smooth-bearing case. However, these trends are reversed for the bearing having radial roughness structure. An illustr ation of a design example is also included for industrial practice. (C) 200 0 Elsevier Science Ltd. All rights reserved.