Two-Sided Texture Effects on Ultra-Thin Wide Wedge Gas Bearings

Abstract

This work seeks to determine the effects of two-sided surface roughness amplitude on ultra-thin, compressible, isothermal, infinitely wide gas bearings. The transient Reynolds equation of lubrication is solved using a finite difference scheme that is second order accurate in space and time. Solutions of the Reynolds equation are presented for bearing numbers spanning seven orders of magnitude, including those experienced in magnetic hard disk recording. The results presented here show that introducing roughness on either bearing surface causes an increase in the load carrying capacity as compared to the smooth bearing case. However, when roughness is introduced on the stationary surface, the gas bearing generates higher loads which also exhibit a peak at finite bearing numbers. The load peaks increase quadratically with increasing stationary roughness amplitude. It is also demonstrated that at very high values of the bearing number, the load becomes dependent on the amplitude of the surface roughness and not its location. This suggests that a closer look at the possibility of roughening the head surface instead of the larger disk surface in order to cause a more rapid separation is warranted. Stiction resistance would still be achieved, but perhaps more economically, and wear to both surfaces would be minimized.