Surface roughness effects on the oscillating squeeze-film behavior of long partial journal bearings

The surface roughness effects on the pure squeeze-film behavior of a long partial journal bearing operating under a time-dependent oscillating load is analyzed. Based upon the Christensenʹs stochastic model, the stochastic Reynolds-type equation governing the film pressure is derived to take account of the presence of roughness on bearing surfaces. The nonlinear equation of squeezing motion is then formulated by applying the hydrodynamic film force. According to the results evaluated, the mean squeeze-film characteristics are significantly affected by the roughness pattern and the height of roughness. The effect of circumferential roughness provides a reduction in the mean bearing eccentricity ratio as compared to the smooth-bearing case. However, the squeeze-film bearing with longitudinal roughness structure results in a reversed trend. Furthermore, the quantitative effects of surface roughness on the oscillating squeeze-film characteristics are more pronounced for small values of Sommerfeld number and large values of roughness parameter.