20.500.12556/RUL-152882 In-situ micro-asperity investigation of real contact area formation during sliding with the effects of roughness and normal load considered 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). real contact area sliding contact realistic engineering surfaces real-time in-situ measurement realna kontaktna površina drsni kontakt realistične inženirske površine in-situ meritev v realnem času true false true Angleški jezik Slovenski jezik Članek v reviji 2023-12-11 08:16:23 2023-12-11 08:16:25 2024-02-08 03:54:38 0000-00-00 00:00:00 2024 0 0 9 str. Vol. 191, art. 109171 Mar. 2024 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 539.92 1879-2464 10.1016/j.triboint.2023.109171 176779779 1-s2.0-S0301679X23009623-main.pdf 1-s2.0-S0301679X23009623-main.pdf 1 250BD409245EF5C1C9AF107941DC9EC3 b240c52192c874805748523c4a2e6a6ff8c2e72da350f37f26b705ace7835afe 9be0d527-c4f6-11ee-a2a3-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=180652 https://www.sciencedirect.com/science/article/pii/S0301679X23009623 1 32a29428-97f5-11ee-bb90-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=178582 Fakulteta za strojništvo 0 0 0