Scale and contact geometry effects on friction in thermal EHL: twin-disc versus ball-on-disc

Haichao Liu* (Corresponding Author), Binbin Zhang, Norbert Bader, Cornelis H. Venner, Gerhard Poll

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Plint (IMechE 182 (1):300–306,1967) reported a reduced coefficient of friction with increasing roller sizes in EHL traction measurements. In this study, a similar scale effect has been observed when comparing measured traction curves at the same operating conditions between a ball-on-disc rig and a twin-disc machine of different geometrical sizes. This scale effect has been studied numerically for point contacts of different radii of curvature Rx based on thermal EHL simulations. Results show that the reduced friction for large Rx is caused by an increase in film thickness and the enhanced thermal effects. The mechanisms are: (1) heat is hard to conduct across a thicker EHL film due to bad thermal conductivity; (2) shear is mainly localized in the middle film.
Original languageEnglish
Article number106694
JournalTribology international
Volume154
Early online date1 Oct 2020
DOIs
Publication statusE-pub ahead of print/First online - 1 Oct 2020

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