The mechanics of snow friction as revealed by micro-scale interface observations
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 furt...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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Cambridge University Press
2018-02-01
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| Series: | Journal of Glaciology |
| Subjects: | |
| Online Access: | https://www.cambridge.org/core/product/identifier/S0022143017000764/type/journal_article |
| _version_ | 1811155880510488576 |
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| author | JAMES H. LEVER SUSAN TAYLOR ARNOLD J. SONG ZOE R. COURVILLE ROSS LIEBLAPPEN JASON C. WEALE |
| author_facet | JAMES H. LEVER SUSAN TAYLOR ARNOLD J. SONG ZOE R. COURVILLE ROSS LIEBLAPPEN JASON C. WEALE |
| author_sort | JAMES H. LEVER |
| collection | DOAJ |
| description | 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. |
| first_indexed | 2024-04-10T04:41:03Z |
| format | Article |
| id | doaj.art-b4469c204e824db490e99c14cdcb14fc |
| institution | Directory Open Access Journal |
| issn | 0022-1430 1727-5652 |
| language | English |
| last_indexed | 2024-04-10T04:41:03Z |
| publishDate | 2018-02-01 |
| publisher | Cambridge University Press |
| record_format | Article |
| series | Journal of Glaciology |
| spelling | doaj.art-b4469c204e824db490e99c14cdcb14fc2023-03-09T12:40:29ZengCambridge University PressJournal of Glaciology0022-14301727-56522018-02-0164273610.1017/jog.2017.76The mechanics of snow friction as revealed by micro-scale interface observationsJAMES H. LEVER0SUSAN TAYLOR1ARNOLD J. SONG2ZOE R. COURVILLE3ROSS LIEBLAPPEN4https://orcid.org/0000-0002-5840-7538JASON C. WEALE5Cold Regions Research and Engineering Laboratory, US Army Engineer Research and Development Center, Hanover, New Hampshire, 03755, USACold Regions Research and Engineering Laboratory, US Army Engineer Research and Development Center, Hanover, New Hampshire, 03755, USACold Regions Research and Engineering Laboratory, US Army Engineer Research and Development Center, Hanover, New Hampshire, 03755, USACold Regions Research and Engineering Laboratory, US Army Engineer Research and Development Center, Hanover, New Hampshire, 03755, USAVermont Technical College, Randolph, Vermont, 05061, USACold Regions Research and Engineering Laboratory, US Army Engineer Research and Development Center, Hanover, New Hampshire, 03755, USAThe 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.https://www.cambridge.org/core/product/identifier/S0022143017000764/type/journal_articleabrasionhigh-resolution thermographyinter-granular bond failureself-lubricationsnow sliding frictionwear |
| spellingShingle | JAMES H. LEVER SUSAN TAYLOR ARNOLD J. SONG ZOE R. COURVILLE ROSS LIEBLAPPEN JASON C. WEALE The mechanics of snow friction as revealed by micro-scale interface observations Journal of Glaciology abrasion high-resolution thermography inter-granular bond failure self-lubrication snow sliding friction wear |
| title | The mechanics of snow friction as revealed by micro-scale interface observations |
| title_full | The mechanics of snow friction as revealed by micro-scale interface observations |
| title_fullStr | The mechanics of snow friction as revealed by micro-scale interface observations |
| title_full_unstemmed | The mechanics of snow friction as revealed by micro-scale interface observations |
| title_short | The mechanics of snow friction as revealed by micro-scale interface observations |
| title_sort | mechanics of snow friction as revealed by micro scale interface observations |
| topic | abrasion high-resolution thermography inter-granular bond failure self-lubrication snow sliding friction wear |
| url | https://www.cambridge.org/core/product/identifier/S0022143017000764/type/journal_article |
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