Rechnerische und experimentelle Untersuchung der Schmierfilmbildung in geschmierten Tribokontakten

Research output: ThesisDiploma Thesis

Abstract

In many fields of mechanical engineering highly stressed contacts between surfaces which move relatively to each other occur. For the purpose of increasing the surfaces life-time, lubrication is used. Such contacts are exposed to a number of influences, e.g. oil containing wear debris, high contact temperatures or breakdown of the lubricating film that separates the surfaces. Beside these influences also the pressure distribution in the contact area due to external forces has to be considered. For a reliable estimation of a highly stressed and lubricated contacts life-time, the knowledge of only the Hertzian pressure is insufficient. It is required to understand the pressure in the lubricating film between the contacting surfaces. This pressure can exceed the maximum Hertzian pressure significantly. In the context of this study, commercial software packages were evaluated on their ability of solving the elastohydrodynamic problem. Furthermore, the hydrodynamic pressure distribution and shear stress in the lubricating film in rolling and sliding contacts were calculated analytically. This analytical solution helped in building up a profound knowledge about the flow phenomena occuring when deformation of the involved surfaces is neglectible. Maps for pressure distribution, load capacity and friction torque in dependency on shear are additionally computed by simulation technique. The results of simulation are in high consistency with the analytical solutions. For an experimental validation of the simulated results, a test setup was developed. This setup allows to measure the pressure in the gap between a thrust bearing sample and its counter sample. The values for pressure and friction torque measured with this test setup enable to estimate the minimal film thickness using the maps from simulation. The estimated values for the minimal film thickness show a good consistency between the simulated maps.

Details

Translated title of the contributionAnalytical and experimental analysis of lubrication tribological contacts
Original languageGerman
QualificationDipl.-Ing.
Supervisors/Advisors
Award date26 Mar 2010
Publication statusPublished - 2010