Experimentální studium tloušťky mazacího filmu v okolí reálných nerovností procházejících kontaktem

Experimental study of lubricant film thickness behavior in the vicinity of real asperities passing through lubricated contact

journal article - other

en

This paper presents an experimental study of the influence of real surface micro-geometry on the film thickness in a circular elastohydrodynamic (EHD) contact formed between a real, random, rough surface of steel ball and smooth glass disc. The Phase Shifting Interferometry has been used to measure in situ initial undeformed rough surface profiles whereas Thin Film Colorimetric Interferometry has provided accurate information about micro EHD film thickness behavior over a wide range of rolling speed. Two real roughness features were studied in detail 56 nm high ridge and 90 nm deep groove, both transversely oriented to the direction of surface motion. It has been shown that ridge is heavily deformed in a loaded contact and its height increases with increasing rolling speed. The asperity tip film thickness behavior is quite similar to the contact average film thickness when the film thickness is higher than the undeformed ridge height. However below this limit the film is thicker than what the EHD theory predicts. For the groove, a local reduction in film thickness at the leading edge has been observed. When the groove is passing through the EHD conjunction, it maintains its undeformed shape. The behavior of both roughness features studied shows good agreement with previous experimental observations conducted using artificially-produced ridge and groove.

V článku jsou uvedeny výsledky výzkumu tenkých mazacích filmů v okolí povrchových nerovností. Při studiu tenkých mazacích filmů byly užity dvě měřicí metody – kolorimetrická interferometrie a interferometrie s řízenou změnou fáze. To umožnilo stanovit topografii nedeformovaného třecího povrchu a následně pozorovat její změnu v mazaném kontaktu v závislosti na provozních podmínkách. Pro podrobné studium byly vybrány dvě nerovnosti, příčná rýha o hloubce 90 nm a příčný práh o výšce 56 nm.

This paper presents an experimental study of the influence of real surface micro-geometry on the film thickness in a circular elastohydrodynamic (EHD) contact formed between a real, random, rough surface of steel ball and smooth glass disc. The Phase Shifting Interferometry has been used to measure in situ initial undeformed rough surface profiles whereas Thin Film Colorimetric Interferometry has provided accurate information about micro EHD film thickness behavior over a wide range of rolling speed. Two real roughness features were studied in detail 56 nm high ridge and 90 nm deep groove, both transversely oriented to the direction of surface motion. It has been shown that ridge is heavily deformed in a loaded contact and its height increases with increasing rolling speed. The asperity tip film thickness behavior is quite similar to the contact average film thickness when the film thickness is higher than the undeformed ridge height. However below this limit the film is thicker than what the EHD theory predicts. For the groove, a local reduction in film thickness at the leading edge has been observed. When the groove is passing through the EHD conjunction, it maintains its undeformed shape. The behavior of both roughness features studied shows good agreement with previous experimental observations conducted using artificially-produced ridge and groove.

tloušťka filmu; elastohydrodynamický film

film thickness; elastohydrodynamic

2004

01.09.2004

0569-8197

Tribology Transactions

47

3

10