Swiss researchers have developed an innovative ski design, inspired by the interlocking scales on a turtle, that allows the device to flex and stiffen based on the skier's position to afford greater grip on the snow during turns.

The ideal ski can withstand high levels of pressure in turns, yet also be easy to maneuver. These two features usually require two different types of skis: the rigid skis preferred by expert skiers and the flexible ones that intermediate skiers typically choose.

The ideal ski can withstand high levels of pressure in turns, yet also be easy to maneuver. Image credit: Pixabay.The ideal ski can withstand high levels of pressure in turns, yet also be easy to maneuver. Image credit: Pixabay.But a new type of ski offers a two-in-one solution thanks to a design based on the movement of turtle scales. The skis are easy to maneuver while entering and exiting turns but stiffen up in the middle of turns to improve the skis’ control in the snow. This "turtle shell" design is the result of a joint effort of École Polytechnique Fédérale de Lausanne (EPFL), the Institute for Snow and Avalanche Research (SLF), in Davos and the Swiss ski manufacturer Stöckli.

The idea of mimicking the morphology of turtles occurred to Véronique Michaud, a researcher at EPFL's Laboratory of Polymer and Composite Technology, while she was attending a seminar on bioinspired materials. “The scales of a turtle interlock, like a jigsaw puzzle, and are connected by a polymer,” she says. “When turtles breathe, the scales separate slightly and the shell becomes flexible. But when an external shock occurs, the shell tightens and stiffens. It struck me immediately that we could build these features into skis.”

Michaud’s idea took form during a yearlong Commission for Technology and Innovation project in partnership with Stöckli, in which project team members ran a number of studies in an effort to replicate the natural phenomenon in skis. The best results were achieved by embedding aluminum plates with a snake-shaped fissure in both ends of the skis.

When the skis bend in a turn, the plates on each side of the gap come together and the ski stiffens, allowing the skier to execute stable and precise turns. As the skier comes out of the turn, the gap reopens, making the ski flexible again and easy to handle. “The aluminum plates work like the scales,” says Michaud, “and a special type of rubber between the plates is like the polymer in the turtle shell.”

Former professional speed skier Michl Leitner and double Olympic ski champion Tina Maze tested the skis for a day. “We were pleasantly surprised,” says Leitner. “It was easier to start the turn. And as the pressure on the skis’ edges rose gradually during the turn, the skis really gripped the snow and were very stable. I was impressed by the ease with which the plates come together and separate.”

The skis, which went on sale in early March, are designed for both average skiers and experts alike.

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