A novel free-gliding ski tribometer for quantification of ski-snow friction with high precision

Abstract

The nature of snow and the ever-changing environment make measurements of friction on snow and ice challenging. In addition, since this friction is low, the equipment utilised must be highly sensitive. Previous investigations of ski–snow friction have ranged from small-scale model experiments performed in the laboratory to experiments with full-sized skis outdoors. However, few have been conducted under conditions similar to those encountered during actual skiing. Here, we developed a novel sled tribometer which provides highly reproducible coefficient of friction (COF) values for full-sized skis gliding at relevant speeds (approximately 20 km/h) in a controlled indoor environment. The relative standard deviation (RSD) of COF is as low as 0.5 % enable differentiation between the structures and preparations of different ski bases. The continuous recording of speed enable novel investigations of COF variations when skis are allowed to free-glide to a full stop in a natural setting. Different methods of analysing the results are presented which shows that the precision is not a single number, but a function of the range of speeds over which the average COF is calculated.