"Uniaxial compressive tests were carried out on cylindrical samples at different deformation rates. Creep deformation, bending strength and ultimate load were evaluated. The deformation rate is crucial whether the snow will deform plastically or brittle. The grain size and structure of the snow had a strong in influence on the strength properties", says Nina Lintzén, PhD Student in Soil Mechanics at Luleå University of Technology.
Photo: Richard Renberg
Properties of snow is constantly changing with time and temperature. Classification of snow is thus important. In this thesis a non-contact detection method is used to quantify liquid water content in snow i.e. spectral reflectance measurements. A spectrometer and an optical sensor called Road Eye were used. The Road Eye sensor was also used to classify snow in cross-country ski tracks. This method enables a fast classification of a complete track and different snow types can be distinguished.
Ski track and the snow determine type of skis for optimum sliding. Cross-country skis have different mechanical properties, related to the ski span curve. Due to the skier's style, skills, terrain and track, different ski properties/span curves are required. Span curves were measured by a new digital instrument “Skiselector” and results show that skis within the same pair may have very different properties and the influence of temperature is considerable.
"Skis with similar span curves but different ski base topography were tested during wet and cold snow conditions showing that different topographies are preferable for different snow conditions", says Nina Lintzén
Due to climate change, ski resorts produce an increasing amount of machine-made snow. This is often stored in insulated piles over summer. In Nina Lintzén´s work it is shown that surface area of the pile should be minimized in order to reduce the melt rate. Due to melting, big piles will have smaller relative losses than a small pile. Piles should be covered with an insulating layer having good evaporation properties. A theoretical model is presented to estimate snow melting and to assess the efficiency of thermal insulation materials. Calculations and measured values were in good agreement for tests in northern Sweden.
At the conference Frozen earlier this year, researchers from around the world met to discuss the challenges that less snow will mean.
In connection with the defense of Nina Lintzén´s dissertation Dec. 20 the opponent Dr. Meinhard Breiling will give a lecture on new methods for making snow.