The friction that occurs between ski and snow is affected by a large number of factors. Partly those connected to the ski's grain curve, coating material, surface structure and grazing, partly those connected to the snow surface's properties such as temperature, water content and grain size. In addition, the friction is affected by the temperature and humidity of the air as well as the skill of the rider. A friction test is being developed at the new Ski and Snow Lab at Lindbäcksstadion in Piteå, in order to be able to study with high accuracy how the various factors affect the glide.
Virtual test bench for ski technology
The function of the ski is controlled by a large number of parameters. It is therefore difficult to use only experimental methods to be able to determine the impact of the various parameters and how they can be optimized to give the ski the best possible properties. A multi-scale model of the ski describes the ski from macro level (the whole ski) to nanometer level (in contact with the snow) with intermediate levels that describe the surface structure of the ski. The model can be used to optimize texture, grinding structure and grazing for a particular ski condition.
Skiing requires a lot of equipment beside the skis for a successful ski trip or a successful competition at the ultimate elite level. Some examples are bindings, poles, ski gloves, alpine ski helmets and clothes. In ski sports such as biathlon and ski orienteering, weapons, ammunition, harnesses and map racks are added. We look at how it is possible to optimize equipment in terms of weight, function and environmental impact, and make a comparison between expensive competition ammunition, cheap training ammunition and lead-free ammunition for biathlon.
Fluorine compounds such as fluorinated hydrocarbons have been very successful in the waxing industry. The fluorine compounds have made the surfaces more water-repellent (hydrophobic), which has significantly reduced friction, not least in humid conditions. Unfortunately, fluoride compounds have a negative environmental effect and create major work environment problems for the wax technicians. Therefore, fluoride will be banned. Finding good replacement for these fluorinated hydrocarbons is an important and urgent matter.
Snow – a prerequisite for skiing
Friction occurs when two surfaces are brought into contact with each other. It is therefore not possible to study ski friction without also understanding the snow surface. Ski-snow is an unusual tribological system because one surface (the snow) is close to its melting point. The water supply in the contact between ski and snow is crucial. Both too little and too much water gives rise to high friction. It is therefore important to understand the water content of the snow and how the snow melts when the ski passes. A large number of parameters are important to understand and characterize, including grain size and shape as well as the hardness and shear strength of the snow surface.