In international competition, the difference between a gold medal and missing the podium is often measured in split seconds. A team of UBC engineers is developing solutions to trim milliseconds from finishing times with the goal of providing a competitive edge for Canadian athletes.
The research is funded by Own the Podium (OTP), a technical sport program that is a partnership of Canada’s 13 winter national sport organizations, the Canadian Olympic Committee, the Canadian Paralympic Committee, Sport Canada and the Vancouver Organizing Committee for the 2010 Olympic and Paralympic Winter Games (VANOC). Research being done for the OTP program is providing innovative new performance tools and knowledge to Canada’s winter sports teams to help improve performance during the 2010 Games, although some of the technology will be implemented looking toward the 2014 Games.
The UBC engineering research focuses on improving speed on snow and ice by minimizing friction — the force that causes an object in motion to slow or stop.
Working closely with Canada’s snow and ice sport national teams — alpine skiing, cross-country skiing, snowboard, biathlon, speed skating and luge — the UBC experts have been investigating ways to reduce friction at both the microscopic and macroscopic levels.
Inspired by the lotus-leaf: creating super low-friction surfaces
Taking a lesson from nature, UBC engineers have mimicked the structure of the lotus leaf to create an edge for our athletes.
When a drop of water falls on a lotus leaf, it beads and rolls off the superhydrophobic — or super water-repellent — surface. The lotus’ surface structure, composed of a unique nanopattern that under an electron microscope looks like a field of cone-shaped pom pom balls [see slide 3], creates minimal friction and allows the droplet of water to maintain a perfect bevel or roundness. With minimal friction, optimal glide exists, allowing the bead of water to roll off.
“We have mimicked nature to create a low-friction surface on various metals and polymers,” says Prof. Savvas Hatzikiriakos. “We’ve copied the nanopatterns of the lotus leaf to engineer materials that reduce friction on both snow and ice.”
Led by Hatzikiriakos, the microscopic friction team includes co-investigator Prof. Peter Englezos and PhD students Anne Kietzig — who specializes in metals — and Christos Stamboulides — who focuses on polymers — all from the Department of Chemical and Biological Engineering.
In the case of metals, the team engineered a new material, laser-structured stainless steel, using the laser facilities in the UBC Department of Physics. “We were extremely surprised to find out that the laser-irradiated metallic surfaces turn superhydrophobic after a few days,” says Hatzikiriakos.
Compared to the traditional steel used in skates, the new material has a much greater contact angle, which means that a bead of water stays more rounded on the surface and rolls off more easily. The new material drastically reduces friction and essentially repels water; the surface structure of the traditional material absorbs a bit of each droplet, creating friction that slows motion.
“The greatly increased hydrophobicity of the laser-structured steel increases the slider’s ability to ‘float’ upon the ice, rather than become wetted into it,” explains Hatzikiriakos. “This research enables the development of new skate bases with smaller friction coefficients, compared with the existing bases. With less friction, they simply go faster.”
Hatzikiriakos and his team have also been developing ways to reduce friction of polymers — used for ski bases — on snow.
Using a plasma (ionized gas) treatment method to increase the level of water repellency, the researchers developed a new base modification for skis. With the plasma treatment, low-friction molecules attach to the exposed surface of the ski base, which renders the material nearly superhydrophobic.
Like the newly engineered steel, the plasma treatment for skis also increases the contact angle of a droplet of water, reducing friction by up to 25 per cent from previously used polymers.
Beyond the Olympics, these innovative materials can have broader applications. Essentially self-cleaning, superhydrophobic metals could improve surgical instruments and implants. The extreme water-repellent properties can also be applied to paper, offering a sustainable alternative to plastics.
Reducing friction by understanding snow conditions
In-depth knowledge of local snow and weather conditions at the venues could prove a home-field advantage for Canada in the upcoming Olympics. Mechanical engineering Professor Sheldon Green and research engineer Dan Dressler (MASc ’06) have studied drag-reduction at the macro (snow-surface) level, creating tools to assist athletes and ski technicians in making the most informed decisions when selecting which materials — skis, snowboards, waxes and grinds (base structure of skis) — will perform best.
Through their comprehensive analysis of snow properties and conditions, the engineers have discovered ways to minimize friction at the ski-snow interface, enabling athletes to go faster.
Green and Dressler have worked extensively with Canada’s Olympic-bound teams at the Olympic venues — Whistler Blackcomb, Callaghan Valley and Cypress Mountain Resort — to implement various tools for the teams to use for selecting the best materials.
One such tool is a database that includes variable conditions like air and snow temperature, wind speed and humidity. By entering the race-day conditions into the database, technicians and coaches will be able to obtain information on which materials will work best. For example, if the current snow is old and crystal-like, a hard wax will best reduce friction, helping to overcome the abrasiveness and slowing properties of this type of snow.
The team’s research has also led to the development of a new approach for measuring the hydrophobicity of skis. Through the use of a portable high-resolution imaging system combined with image processing software, tests can be done on site at a fraction of the cost of other systems. The test includes measuring the contact angles of a water droplet on a ski surface. The greater the contact angle, the less friction. This information is especially useful for selecting materials for distance racers who depend on the longevity of a wax for optimal performance.
“Snow is an incredibly complex substance whose structure is dependent on temperature, relative humidity, stresses and a host of other factors. It is amazing how little was, and still is, known about the fundamental science of snow friction,” says Green, an expert in fluid mechanics.
Many are hopeful the Own The Podium research will help Canada’s athletes shine during the Winter 2010 Games and beyond.
“Our friction research and new materials could have a significant impact in the years a head in racing that measures in split seconds,” explains Hatzikiriakos. “It could be the difference between fourth and first place for Canadian athletes in the years ahead.”