Wear of snow due to sliding friction

Abstract

Whilst studies of the wear of ski bases and wax coatings are available, few is known about the change of the snow due to sliding ski. In this study, ski-friction-induced changes of snow were investigated. The structure of the snow was scanned using X-ray computed tomography (CT) before and after 1, 10, and 20 recurring runs of a cross country ski at snow temperatures of −1.3, −10.7, and −19.1 °C. Concurrently, friction was measured. The volume fraction of ice as function of the vertical distance from the snow surface was derived from the CT data. Superficial snow was compacted and surface roughness was reduced by the ski passage. The volume fraction of ice in snow had maximum values of 0.58–0.93 at 0.02–0.3 mm below the snow surface. Below the depth of 1.0 mm, snow was not altered at all. Friction increased after the first run with subsequent runs at −1.3 °C and −10.7 °C whereas it decreased at −19.1 °C. In the first run of a ski, brittle deformation of the snow due to vertical force and ploughing was dominant. In the following runs, abrasive wear and/or melting appeared. Estimates for the available relative contact area varied between 0.02 and 0.27.