A Numerical Study for the Effect of Ski Vibration on Friction

In ski jump, minimizing the energy loss when sliding down the track is crucial for improving jump performance. In particular, it is essential to reduce the friction between the ice track and the jumping ski, which is typically achieved by properly waxing the ski base according to weather and ice conditions. Additionally, it might be possible to reduce the friction by controlling the vibration of jumping skis as many experiments and numerical analyses have reported that vibration can reduce the friction in both dry and wet conditions. However, they have been done mostly for small, rigid specimens and therefore the results may not be directly applicable to jumping skis because they have unique vibrational modes due to their slenderness and structural flexibilities. Here, we investigate a potential effect of ski vibration on friction using finite element analysis. Finite element beam models for jumping skis are constructed by measuring the geometry and bending stiffness experimentally. We employ a pressure-dependent friction model between the ski base and the ice track derived from the reported experimental data. Various vibration conditions are tested for four jumping ski models with different bending stiffness profiles. Results demonstrate the possibility of friction reduction by designing the bending stiffness profile of a jumping ski that controls its vibrational modes.