Dynamic Analysis of the Rarefaction-Modified Reynolds Equation Considering Porosity of Thin Liquid Lubricant Film

Abstract

A rarefaction-modified Reynolds equation was derived to solve dynamic problems of a thin liquid lubricant film coated on a sliding surface. Applying the perturbation method, a calculation procedure based on FEM was formulated to obtain the stiffnesses and damping coefficients of gas lubricating films over a permeable liquid lubricant. Calculations were performed for a specified flying head slider. First, the effects of the permeability and porosity correction coefficients, which serve to increase the molecular mean free path, were presented focusing on landing on/off characteristics. Next, the effects of those on the stiffnesses and damping coefficients were demonstrated using the frequency domain. The results showed that the permeability and porosity correction coefficient increasingly had an influence on the landing on/off characteristics more in the higher velocity region, and that the permeability was effective in increasing the damping of lubricating films.