Effect of material elastic properties and surface roughness on grip performances of ski boot soles under wet and icy conditions

- Grip of ski-boot soles is studied by a coupled experimental-simulation approach.
- Soles friction is correlated to material chemical composition and surface morphology.
- High grip is associated to low material stiffness and surface roughness.
- The coefficient of friction represents a performance indicator of overall grip.
- Results have considerable application in the design of anti-slip sports equipment.

A set of thermoplastic materials employed in soles for alpine skiing boots were characterized in terms of chemical composition, cristallinity, hardness, surface roughness, and grip. The results of friction experiments on different substrates reproducing the real environmental scenarios point out that materials provide more grip as they become softer. Moreover, higher roughness results in lower dynamic coefficient of friction (COF). Finite element simulations corroborate the experimental measures of COF and let to rationalize the role of material elasticity and surface roughness on the frictional characteristics of soles. The measure of grip on an inclined wet surface provides analogous results, indicating that COF can be used as key performance indicator in the design of ski-boot soles and of other anti-slip equipments in wet and icy environments.