A Scientific Perspective on Reducing Ski-Snow Friction to Improve Performance in Olympic Cross-Country Skiing, the Biathlon and Nordic Combined

Almqvist, Andreas; Pellegrini, Barbara; Lintzén, Nina; Emami, Nazanin; Holmberg, Hans‐Christer; Larsson, Roland

doi:10.3389/fspor.2022.844883

Cited by 25 publications

(17 citation statements)

References 34 publications

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“…In order to explain what governs the friction on snow and ice, a substantial amount of research has also been produced to explore and understand the mechanisms involved. See the research of Lever et al [11], Scherge et al [12] and Almqvist et al [13] for some recent work in this direction. The different friction mechanisms, i.e., snow compaction, micro-ploughing, adhesion, viscous shearing and water bridging, see [13], have been modelled by assorted equations based on different assumptions.…”

Section: Introductionmentioning

confidence: 99%

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Characterisation of the Contact between Cross-Country Skis and Snow: A Macro-Scale Investigation of the Apparent Contact

et al. 2022

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In a cross-country skiing competition, the time difference between the winner and the skier coming in at second place is typically very small. Since the skier spends much of the energy on overcoming resistive forces, a relatively small reduction in these forces can have a significant impact on the results. The resistive forces come partly from the friction, at the tribological interface between the ski and the snow, and as with many tribological processes, the characterisation of its origin plays an important role in determining the frictional properties. Furthermore, in cross-country ski friction, there are several scales impacting the frictional performance, with the major contributors being the ski-camber profile and ski-base structure. Macro-scale measurements of the ski-camber profile under loading are often used to determine how adequate the ski is for use under specific conditions. The characteristic properties usually assessed are the force required to collapse the ski in order to obtain a certain camber height, the topography of the kick-wax zone, and the length (determined by simple means) of the frictional interfaces associated with the rear- and front glide zones, i.e., the apparent contact length. These measurements are, however, commonly performed by loading the ski against a much stiffer counter surface than snow and this affects the quantification of the characteristic properties. To date, some mathematical models have been proposed, but there is no reliable approach for determining the macro-scale properties of the contact between a cross-country ski and a counter surface using simulations. In the present paper, an Artificial Neural Network (ANN) has been trained to predict the ski-camber profile for various loads applied at different positions. A well-established deterministic approach has been employed to simulate the contact between the ANN-predicted ski-camber profile and a linearly elastic body with a flat upper surface, representing the snow. Our findings indicate that this method is feasible for the determination of relevant macro-scale contact characteristics of different skis with snow. Moreover, we show that the apparent contact area does not linearly depend on the load and that the material properties of the counter surface also exert a large impact when quantifying the apparent contact area and the average apparent contact pressure.

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Section: Introductionmentioning

confidence: 99%

“…See the research of Lever et al [11], Scherge et al [12] and Almqvist et al [13] for some recent work in this direction. The different friction mechanisms, i.e., snow compaction, micro-ploughing, adhesion, viscous shearing and water bridging, see [13], have been modelled by assorted equations based on different assumptions.…”

Section: Introductionmentioning

confidence: 99%

Characterisation of the Contact between Cross-Country Skis and Snow: A Macro-Scale Investigation of the Apparent Contact

et al. 2022

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“…Therefore, fluorinated glide products are currently being banned from ski waxes by the International Ski Federation (FIS), and their production is increasingly tightly regulated by the European Union and other authorities. Needless to say, the skiing community is in dire need of fluorine-free glide products with competitive performance (Almqvist et al, 2022 ).…”

Section: Introductionmentioning

confidence: 99%

Effect of Polydimethylsiloxane Oil Lubrication on the Friction of Cross-Country UHMWPE Ski Bases on Snow

Buene

Auganæs

Klein-Paste

2022

Front. Sports Act. Living

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Silicone oils are known for their excellent lubricating properties, low toxicity and are ice-, snow-, and hydrophobic. With the upcoming ban on fluorine-containing glide products imposed by the International Ski Federation (FIS), novel glide enhancers for skis are desperately needed. Here, the effect of four silicone oil viscosities (10, 20, 50, and 100 cSt) have been evaluated at three temperatures and snow conditions ranging from −10 °C dry snow to +5 °C wet snow. In dry snow conditions, the shear forces introduced by the silicone oil film increased friction significantly compared to a ski without any treatment. On wet snow, the increased hydrophobicity from the silicone oils reduced the friction by 10%. While commercial glide wax outperformed the silicone oils, this study reports the silicone oils do have desirable friction reducing properties for wet conditions.

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“…During the years, there have been quite many theoretical studies [4][5][6][7][8][9][10] that present various equations to model the friction between the ski and the snow. In order to explain what governs the friction on snow and ice, a substantial amount of research has also been committed to explore and understand the mechanisms involved, see e.g., Lever et al [11], Scherge et al [12] and Almqvist et al [13] for some recent work in this direction. The different friction mechanisms, i.e., snow compaction, micro-ploughing, adhesion, viscous shearing and water bridging, see [13], have been modelled by assorted equations based on different assumptions.…”

mentioning

confidence: 99%

“…In order to explain what governs the friction on snow and ice, a substantial amount of research has also been committed to explore and understand the mechanisms involved, see e.g., Lever et al [11], Scherge et al [12] and Almqvist et al [13] for some recent work in this direction. The different friction mechanisms, i.e., snow compaction, micro-ploughing, adhesion, viscous shearing and water bridging, see [13], have been modelled by assorted equations based on different assumptions. In most of the models available, the apparent contact pressure is assumed to be uniformly distributed over the apparent contact area.…”

mentioning

confidence: 99%

Snow contact characterisation of cross-country skis: A macro-scale study of the apparent contact

Kalliorinne¹,

Sandberg²,

Hindér³

et al. 2022

Preprint

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In cross-country skiing the time difference between a race winner and the person coming second is typically very small. Since much of the energy is spent on overcoming resistive forces, a relatively small reduction of these can have a significant impact on the results. The resistive forces come partly from the friction in the tribological interface, between the ski and the snow, and as with many tribological applications the characterisation of its origin, plays an important role in determining the frictional properties. Also in cross-country ski friction, there are several scales impacting the frictional performance, with the major contributors being the ski-camber profile and ski-base structure. Macro-scale measurements of the ski's camber profile under load, are often used to determine how adequate the ski is for a specific condition. The characteristic properties usually obtained are, the force required to collapse the ski to a certain camber height, the topography of the kick-wax zone, and by simple means a determined lengths of the frictional interface, i.e., the apparent contact length. To this date, there are some mathematical models, but there is no robust way of determining the macro-scale contact properties between a cross-country ski and a counter surface using simulations. In the present paper an Artificial neural networks (ANN) is trained to predict the ski-camber profile for various loads placed at different positions, and a well established deterministic approach is used to simulate the contact between the ANN-predicted ski-camber profile and a linearly elastic body with a flat surface, representing the snow. The results suggest that this method is feasible for the determination of the apparent contact characteristics of different skis. Moreover, we show that the apparent contact area does not linearly depend on the load, and that the elastic properties of the counter surface also has a large impact on the apparent contact area and the average apparent contact pressure.

show abstract

A Scientific Perspective on Reducing Ski-Snow Friction to Improve Performance in Olympic Cross-Country Skiing, the Biathlon and Nordic Combined

Cited by 25 publications

References 34 publications

Characterisation of the Contact between Cross-Country Skis and Snow: A Macro-Scale Investigation of the Apparent Contact

Characterisation of the Contact between Cross-Country Skis and Snow: A Macro-Scale Investigation of the Apparent Contact

Effect of Polydimethylsiloxane Oil Lubrication on the Friction of Cross-Country UHMWPE Ski Bases on Snow

Snow contact characterisation of cross-country skis: A macro-scale study of the apparent contact

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