Effect of surface roughness on hydrodynamic lubrication of slider bearings

The effect of surface roughness on the performance of hydrodynamic slider b earings is studied. A generalized form of surface roughness characterized b y a stochastic random variable with non-zero mean, variance and skewness is assumed to define the bearing surface tomography. Various film shapes such as: plane slider, exponential, secant and hyperbolic are considered. The r esults are obtained for the general lubricant film shape in integral form w hich are numerically computed for the shapes under consideration. The resul ts are presented both graphically as well as in tabular form. The performan ce of a rough heaving can be considered in terms of an identical smooth bea ring with an equivalent film thickness. It is observed, for the lubricant f ilm shapes under consideration, that the increasing positive values of alph a, sigma and epsilon decrease the load carrying capacity, frictional force and temperature rise while it increases the coefficient of friction. Increa sing positive values of sigma and epsilon shift the center of pressure towa rds the outlet edge. For negative values of alpha, the increasing value rev erses the trend of the effect on performance characteristics which is in co nformity with the physical aspects of the problem. A similar trend is obser ved in case of the effect of negative values of epsilon. Thus, a negatively skewed surface roughness modifies the performance of a bearing suffers on account of positively skewed surface roughness. Moreover, it is noticed tha t in the case of exponential and hyperbolic slider bearings the effect of i ncreasing values of sigma is more pronounced whereas in case of plant slide r and secant shaped slider this effect is marginal.