Bewertung des Einflusses von Wellen-Oberflächenstrukturen auf das tribologische Verhalten von Gleitlagern

Translated title of the contribution: Evaluation of the influence of shaft surface structures on the tribological behavior of journal bearings

Research output: ThesisMaster's Thesis


The current development of combustion engines drives the reduction of fuel consumption and pollutant emissions with approaches in the area of lightweight design and friction reduction. The crankshaft as an important engine component is also subject of this optimization process. For example, the use of crankshafts made of cast iron offers certain weight and cost advantages. However, the robustness during operation of the hydrodynamic journal bearings, especially for higher loaded engines, is weakly pronounced, compared to steel crankshafts, according to the surface structure of such cast iron crankshafts. The optimization of the cast-iron sliding surfaces by different surface machining processes would enable the use of crankshafts made of cast iron, even in higher loaded engines. In the present work a screening of different material and machining variants of crankshafts is carried out. This includes a polished steel crankshaft, cast iron crankshafts with various surface treatments, as well as a grinded steel crankshaft. The application-oriented test in a rotary tribometer with journal bearing configuration is characterized by the sampling from the finished crankshafts, as well as the use of the original bearing shells and lubricants. The focus of the evaluation of the start-stop tests accomplished is on bearing wear and friction energy. In addition to the experiments, a simulation of the hydrodynamic bearing in the test rig is carried out. The hydrodynamic effects of the different surface structures are taken into account by the integration of flow factors which are derived directly from the real microtopography of shaft and bearing. With the methodology implemented, the wear and friction differences can be well resolved. The polished steel shaft shows the lowest mixed and fluid friction losses and the lowest bearing wear in the ranking of the tested crankshaft variants. A grinded steel shaft as well as the different cast iron crankshafts exhibit a more detrimental friction and wear behavior, whereby the behavior of the cast iron shafts can be influenced by special surface treatment. The comparison of the test and simulation results shows a good agreement, which was used to check and adjust the simulation methodology as well as to verify the friction measurements on the test rig. Furthermore, key findings on the behavior of different surface structures on flow, pressure formation and friction losses were obtained.
Translated title of the contributionEvaluation of the influence of shaft surface structures on the tribological behavior of journal bearings
Original languageGerman
  • Grün, Florian, Supervisor (internal)
  • Summer, Florian, Co-Supervisor (internal)
  • Bergmann, Philipp, Co-Supervisor (internal)
Award date7 Apr 2017
Publication statusPublished - 2017

Bibliographical note

embargoed until 01-10-2021


  • journal bearing
  • crankshaft
  • tribology

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