Experimental study of central and minimum elastohydrodynamic film thickness by colorimetric interferometry technique

Recently developed colorimetric interferometry technique was used for the s tudy of both minimum and central film thicknesses for a wide range of opera ting parameters. Over 300 film thickness maps were obtained for the combina tion of four values of the materials parameter Gt five values of the load p arameter W and many values of the speed parameter U. The use of a spacer la yer extended the range of film thickness measurement down to 5 nm. An excel lent agreement was found between experimental values and data obtained from numerical solution presented by Venner and ten Napel, especially for thin lubrication films. An increase in a speed exponent with increasing material parameter G was observed for both central and minimum film thicknesses. Th e minimum film thickness and, thereby, the ratio between central and minimu m film thickness was confirmed to be of a stronger dependence on material a nd load dimensionless parameters than Hamrock and Dowson equations predict.