In-situ micro-asperity investigation of real contact area formation during sliding with the effects of roughness and normal load considered

Jan, Petra (author), Brodnik Žugelj, Blaž (author), Kalin, Mitjan (author)

Real contact area is a challenging phenomenon in tribology, where despite established theoretical models, detailed experimental studies are still lacking. This work is focused on the evolution of the real contact area of multi-asperity steel contacts during sliding, by using sub-micron characterisation of entire multi-asperity contact area and simultaneous measurement of the friction force. Steel-sapphire contact was monitored by using an in-situ optical system in real time during 5 mm of unidirectional sliding in surface roughness range R$_a$ = 0.1–1.0 µm and normal loads up to the nominal contact pressure equal to steel yield strength (Y). The results showed that the initial real contact area caused by static loading increased during sliding. At low nominal contact pressure of 0.3Y, the increase in real contact area was the largest: for R$_a$ = 0.1 µm it went from 9.5% of the nominal area under static conditions to 15.0% after sliding, a 56% relative increase, and for R$_a$ = 1.0 µm it went from 5.0% to 11.5% after sliding, a 106% increase. The increase in real contact area was smaller at higher nominal contact pressures of 0.6Y and 1.0Y. At 1.0Y for R$_a$ = 0.1 µm the real contact area went from 18.0% to 21.8% after sliding and for R$_a$ = 1.0 µm it went from 9.4% to 12.9% after sliding. The coefficient of friction increased with roughness at the lowest nominal contact pressure 0.3Y (for R$_a$ = 0.1 µm it was 0.24 and for R$_a$ = 1.0 µm it was 0.29) but became independent of roughness at higher contact pressures (on average 0.18).

• Language: English
• Keywords: real contact area, sliding contact, realistic engineering surfaces, real-time in-situ measurement
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FS - Faculty of Mechanical Engineering
• Publication status: Published
• Publication version: Version of Record
• Year: 2024
• Number of pages: 9 str.
• Numbering: Vol. 191, art. 109171
• PID: 20.500.12556/RUL-152882
• UDC: 539.92
• ISSN on article: 1879-2464
• DOI: 10.1016/j.triboint.2023.109171
• COBISS.SI-ID: 176779779
• Publication date in RUL: 11.12.2023

Record is a part of a journal

• Title: Tribology international
• Shortened title: Tribol. int.
• Publisher: Elsevier
• ISSN: 1879-2464
• COBISS.SI-ID: 62108419

Licences

• License: CC BY-NC 4.0, Creative Commons Attribution-NonCommercial 4.0 International
• Link: http://creativecommons.org/licenses/by-nc/4.0/
• Description: A creative commons license that bans commercial use, but the users don’t have to license their derivative works on the same terms.

Secondary language

• Language: Slovenian
• Keywords: realna kontaktna površina, drsni kontakt, realistične inženirske površine, in-situ meritev v realnem času

Projects

• Funder: ARRS - Slovenian Research Agency
• Project number: P2-0231
• Name: Tribologija