Effect of Different Bearing Ratios on the Friction between Ultrahigh Molecular Weight Polyethylene Ski Bases and Snow

Abstract

The purpose of this study was to analyze the effect of surfaces with different bearing ratios, but similar roughness heights, on the friction between ultrahigh molecular weight polyethylene (UHMWPE) and snow. On a linear tribometer positioned inside a cold chamber, the different samples were tested over a wide range of velocities and snow temperatures. The surface roughness was measured with a focus variation microscope and analyzed using the bearing ratio curve and its parameters. The surface energy was investigated by measuring the contact angles of a polar (water) and nonpolar (diiodmethane) liquid. The friction tests showed that the bearing ratio had a major effect on the friction between UHMWPE and snow. For temperatures close to the melting point a surface with wide grooves and narrow plateaus (nonbearing surface) performed well. For cold conditions, the friction was less for a surface with narrow grooves and wide plateaus (bearing surface). Interpretations of the results are given on the basis of mixed friction, with lubricated friction being dominant at higher snow temperatures and solid-solid interaction at lower ones.

Characterisation of the Contact between Cross-Country Skis and Snow: A Micro-Scale Study Considering the Ski-Base Texture

“…In connection to this, it was also hypothesised that a surface with both a high S pk -value and a S a -value exhibit a low average reciprocal interfacial separation 1/h n . Hence, since the Ski 2 surface (with broad plateaus and narrow grooves), which in [18] was found to perform better "on warm snow", it also ought to exhibit a lower 1/h n than Ski 1. In turn, this suggests it would be possible to use the present results (Fig.…”

“…Table 2: Surface roughness parameters for two ski-base textures Ski 1 ("bearing surface") and Ski 2 ("nonbearing surface") considered in [18]. Rounded values for the six previously analysed ski-base surfaces have been appended to facilitate the comparison.…”

“…Textures S a (µm) S pk (µm) S k (µm) S vk (µm) The reduced peak height (R pk ), core roughness height (R k ), valley depth (R vk ) relative to the peak-to-valley height, represented by Σ k = S pk + S k + S vk , the ratio S vk /S k and Σ k , for the two ski-base surfaces analysed in[18]. The corresponding values for the six previously analysed ski-base surfaces have been appended to facilitate the comparison.Textures S pk /Σ k S k /Σ k S vk /Σ k S vk /S k Σ k (µm)…”

Video Analysis Techniques for Calculating the Coefficient of Friction of Ski Wax and Ski Base Treatments Using Miniature Ski Sleds

“…Furthermore, ski conditions, including snow structure, snow surface temperature, air temperature, water content, and others, greatly impact the performance of skis and ski bases. [1][2][3][4][5][6][7][8][9][10] To mitigate some of the temperature-dependent properties of ski waxes, manufacturers have included additives into their wax compositions that enhance glide performance, and some have even specialized their waxes to speci c temperature conditions, including low temperature waxes, high temperature waxes, and all-temperature waxes. [1][2][3][4][11][12][13] The characterization of ski waxes and ski base treatments includes several limitations.…”

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

“…For skiing, friction-reducing efforts have focussed on structuring the UHMWPE base material by grinding (Rohm et al, 2015 , 2016 ), imprinting (Breitschädel et al, 2010 ; Nordin and Styring, 2014 ), and sanding (Giesbrecht et al, 2010 ). The development of glide waxes has been industry-driven, and little has reached the scientific literature.…”