Laboratory of Machine Elements and Machine Design




Author: Drivakos Nikolaos
Title: Investigation of reological parameters of liquid lubricants
Abstract: The determination of reological characteristics of liquid fluids was conducted using measured values of the friction coefficient. for the above reason a new two disk test rig has been constructed, able for measuring the friction coefficient, by measuring the friction force, the disks temperature field, the contact time percentage, the wear of the disks and it is capable of performing fatique and scuff experiments. The results derived from the new test rig were compared with results from other test rigs and found to be similar. A new method was developed, for the fast calculation of the mean temperature of the oil film, using the finite elements method of the block theory as well as the oil height and is independent of the reological law of the lubricant. The results were copmared with other methods and the validity was very high. Using this method in congunction with measured values of the friction coefficient, the relationship of the Eyring stress over the mean temperature of the oil film was derived for the lubricant under investigation. Finally, from this relationship the friction coefficient was calculated and was compared with the measured values of the friction coefficient, for ellipticities from 1 to 12 showing very satisfactory results


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