The mechanics of snow friction as revealed by micro-scale interface observations
| Autor: | JAMES H. LEVER, SUSAN TAYLOR, ARNOLD J. SONG, ZOE R. COURVILLE, ROSS LIEBLAPPEN, JASON C. WEALE |
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| Jazyk: | angličtina |
| Rok vydání: | 2018 |
| Předmět: | |
| Zdroj: | Journal of Glaciology, Vol 64, Pp 27-36 (2018) |
| Druh dokumentu: | article |
| ISSN: | 0022-1430 1727-5652 |
| DOI: | 10.1017/jog.2017.76 |
| Popis: | The mechanics of snow friction are central to competitive skiing, safe winter driving and efficient polar sleds. For nearly 80 years, prevailing theory has postulated that self-lubrication accounts for low kinetic friction on snow: dry-contact sliding warms snow grains to the melting point, and further sliding produces meltwater layers that lubricate the interface. We sought to verify that self-lubrication occurs at the grain scale and to quantify the evolution of real contact area to aid modeling. We used high-resolution (15 µm) infrared thermography to observe the warming of stationary snow under a rotating polyethylene slider. Surprisingly, we did not observe melting at contacting snow grains despite low friction values. In some cases, slider shear failed inter-granular bonds and produced widespread snow movement with no persistent contacts to melt (μ < 0.03). When the snow grains did not move and persistent contacts evolved, the slider abraded rather than melted the grains at low resistance (μ < 0.05). Optical microscopy revealed that the abraded particles deposited in air pockets between grains and thereby carried heat away from the interface, a process not included in current models. Overall, our results challenge whether self-lubrication is indeed the dominant mechanism underlying low snow kinetic friction. |
| Databáze: | Directory of Open Access Journals |
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