Characterisation of alpine skis

Sammanfattning: Skiing is a fast and competitive sport where skiers must push their performance limit to win medals, the di↵erence can be within hundreds of a second. Therefore, technical improvements are essential for assisting in the skier’s improvement. This thesis project is a joint project between KTH and the Swedish Ski Association and Swedish Ski Team with the purpose of obtaining a better understanding of the structural properties of alpine skis, aiming to improve the individual selection process of skis for the Swedish World Cup Skiers. The goal of the project is to develop and evaluate a method to characterize alpine skis in form of two main structural properties related to the ski characteristics, bending and torsion sti↵ness. An optical measurement device and image post-processing and analysis is used to determine the deflection and twist of skis, which are used to determine the bending and torsional sti↵ness. The method provides, a structural property variation over the whole ski length compared to the existing ISO standard where only a spring coefficient of the skis main parts is determined, which is insufficient for a good over all comparison. The method could be further used in several aspects to help the Swedish World Cup skiers win more medals. It can be used to help in the selection process of new skis for the next season where an objective comparison between models can be done, as oppose to today when the selection process is highly subjective. Skiers usually vary the ski plate constellation and the method could help skiers with their race preparations, like changing the constellation of the ski plate to optimize the sti↵ness for a specific race condition with engineering knowledge rather than just trusting the feeling. The use of this method can reduce the number of ski tests performed by the skier, thus leaving more time for practice. Testing skis in a laboratory environment also increases objectivity in testing and can therefore give the Swedish Ski Association and Swedish skiers a competitive advantage in upcoming competitions.