Characterization of snow impact properties and comparison with synthetic surrogates for the correct implementation of helmet safety standards

Due to the high-speed values reached by the athletes, the most dangerous type of injury that can occur in alpine skiing competitions are head impacts. To reduce the risk of injury there are many regulations to verify the protective equipment for this discipline. This thesis project aims to characterize impact properties of snow and of possible surrogate materials, to improve the safety standards in ski helmet industry and to increase the level of safety for the athletes. In this regard, a first preliminary work of video analysis of accidents in alpine ski competitions was required to estimate the real impact speed of the head during the fall. The experimental characterization of the snow was done by using a sensorized drop tower with an impactor equipped with five different designs of tip. The tests were performed both with the free fall of the impactor and with a preloaded spring to achieve a meaningful simulation of the forces that occur during a ski impact. Different hardness of snow and five different foams were tested and through a comparative evaluation of the obtained data, we aim to find some correspondence between the snow and the possible surrogate materials.