Popular Science welcomes non-pneumatic tires to the market
Tim Osswald and his students in the University of Wisconsin-Madison Polymer Engineering Center began developing airless tires for the military in 2006. Their initial task was to save American soldiers the deadly predicament of having their tires shot out or pierced by shrapnel in the deserts of Iraq.
Eight years later, their design is getting its first test on the consumer market.
Polaris Industries recently debuted a new ATV model that uses tires based on Osswald and his students’ design and made by the Wausau-based Resilient Technologies.
The ATV recently topped the Popular Science magazine list of “The 10 best things from February 2014.” Meet the first consumer ATV with airless tires,” the article proclaimed.
Osswald, the Kuo K. and Cindy F. Wang professor of mechanical engineering at UW-Madison, says the project’s success required more than just his expertise in polymers. What drew Resilient to his lab, he says, was a holistic design process that takes into account what Osswald calls “the six P’s”: polymer, product, process, performance, post-consumer life, and the profit.
“You can’t do any of them without looking at all of them,” Osswald says. “We hit stumbling blocks if one of the aspects was neglected.”
Non-pneumatic tires have existed for more than a century, from solid rubber models to the more recent development of Michelin’s Tweel. But solid rubber makes for a rough ride, and the Tweel begins to vibrate and flap at speeds above 40 miles per hour, which results in a lot of noise.
Back in 2006, the military wanted to improve on the limited range and speed of the run-flat tires on its Humvee. Osswald set about trying to make a tire that can handle full speed even after a roadside bomb takes out 30 percent of its hexagonal polymer web—not to mention handle the heat and rough terrain that abuse military vehicles even on a good day.
Along with graduate students Erik Foltz and Nick Newman and visiting German students Daniel Urban, Levente Bokur and Maximilian Schöngart, Osswald developed a striking honeycomb structure for the tires. Prototypes and molds in Osswald’s lab show how the design evolved, gradually varying the size of the honeycombs and eventually arriving at progressively larger rings of hexagons.
“It was a really beautiful process,” Osswald says. “The students aren’t tainted with, ‘Oh, this is how it’s supposed to be done,’ so sometimes they are much more open-minded than I am.”
The team used rapid prototyping and computer simulations to test varying designs for resistance to heat, speed, vibration and stresses. Osswald proudly notes that the simulations took into account four of the six P’s, helping to keep practicality in view at all stages of the design process.
The UW-Madison researchers actually finished working on the project in 2008—and their two years of intense work yielded an airless tire that feels like it’s inflated. After that, Resilient continued working with the military to develop a manufacturing process for the tire, and the idea attracted attention from publications ranging from Scientific American to Jalopnik. Osswald says he’d like to further develop the tires, noting that they still don’t have sidewalls. (That said, a CNET writer proclaimed in 2008 that the crucial honeycomb structure is “so cool-looking there’s no need for hubcaps.”)
Now, the new Polaris ATV has Osswald thinking about saving other passenger vehicles from the hassle and danger of flat tires. “I still want to continue working with it, because we have ideas to eventually get cars and bicycles riding on these,” he says. “The market would be there.”