LUBRICANT PRESSURE RIPPLING IN DYNAMIC HERTZIAN CONTACTS INDUCED BY SURFACE ROUGHNESS

BECAUSE OF SURFACE ROUGHNESS, THE PRESSURE DINTRIBUTION IS A LUBRICATED HERTZIAN CONTACT WILL BE SUBJECT TO RANDOM FLUCTUATIONS IN TIME EVEN THOUGH THERE MAY BE NO DIRECT CONTACT OF THE ROUGH SURFACES.THE MAGNITUTDE OF THESE PRESSURE FLUCTUATIONS AS MEASURED BY THEIR RMS VALUE FOR THE CONTACT OF TWO-DIMENSIONAL (LONG) CYLINDERS IS FOUND TO VARY WITH 1) THE LOCATION IN THE CONTACT 2) THE SPECTRUM OR FREQUENCY CONTENT OF THE SURFACE ROUGHNESS 3) THE MEAN PLATEAU FILM THICKNESS AND 4) THE RMS VALUE OF THE SURFACE ROUGHNESS.RIPPLE PRESSURES CALCULATED ACCORDING TO THE ANALYSIS PRESENTED HERE ARE COMPARABLE WITH THE MAXIMUM HERTZ PRESSURE.