Customized Sit Skis for Athletes with Disability

Photo: Athlete with prototype

German biathlete Martin Fleig helped designing the sit skis; © Fraunhofer IWM

Given the avalanche of sponsorship deals offered to Olympic ski stars, it comes as no surprise that they compete using highly customized equipment. But up to now, the situation has been very different for even the top disabled athletes. Indeed, the development of equipment tailored to disabled competitors is still in its infancy. Scientists from the Fraunhofer Institute for Mechanics of Materials IWM and their research and industry partners are working to change that in the Snowstorm project, which customizes sit skis for disabled biathletes.

Top sportsman and biathlete Martin Fleig volunteered to have a sit ski designed to meet his particular needs. A biathlon combines shooting and cross-country skiing; disabled athletes compete using specially designed sit skis, which have a seat mounted on at least one skating ski.

Until now, sit skis have tended to be one-offs, manufactured mostly by technically gifted athletes or their assistants. The challenge for the Snowstorm partners is to come up with a lightweight and yet stable design specifically tailored to Mr. Fleig.

During a biathlon, sit skis have to weather a variety of stresses. Obviously, they have to perform well over uneven cross-country snow, but they also have to withstand extreme pivotal motion, such as when a biathlete lies down on the mat to shoot and then quickly and powerfully rises back up. The first phase of Snowstorm measures equipment stress encountered during typical use. 3D biometric data of the athlete’s movements help ascertain the optimum seating position. Then the sit ski’s lightweight design is determined using a variety of computer simulations. At Fraunhofer IWM, scientists calculate the design data by evaluating stress readings and various computer simulations.

“Our aim for the project is to find ways to design sit skis that can be tailored to any athlete while also making the process as cost-effective as possible,” explains Fraunhofer scientist Matthias Scherge. As the extent and nature of physical impairment is unique to each individual, athletes must be able to achieve the very specific position in which they can unleash their full potential.

Simulation software developed at Fraunhofer IWM supplies the data for a computer-aided design that provides the roadmap for additive manufacturing. Using selective laser sintering, the sit ski is formed from layers of powder; the resulting made-to-measure sporting equipment can be produced at a reasonable cost.

The Snowstorm project produced its first prototype from the polyamide 12 high-performance polymer and fitted it with sensors to measure stresses occurring during use. Even the ski poles included built-in sensors to register the force transferred when poling. The data collected provided the basis for the second prototype, allowing the researchers to add channels at the points subjected to the highest stresses; these channels could then be fitted with steel wires to provide additional strength. The new sit ski has already passed its first round of endurance tests: Fleig had plenty of opportunities to push the sit ski to its limits at the Notschrei Nordic Center in Germany’s Black Forest and the altitude training camp in Livigno, Italy.

The project partners hope the Winter Paralympics will stimulate wider interest in the sport among amateurs: “We’d be thrilled if the Games gave disabled people new ideas about how to get involved in sport by showing just what’s possible with help from the right technology,” says Scherge.; Fraunhofer Institute for Mechanics of Materials IWM

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