Airless tire project may prove a lifesaver
in military combat
An ambitious company is trying to reinvent the wheel—literally—with a project to develop tires that can withstand the kind of punishment vehicles face in combat zones.
Resilient Technologies is working on a four-year, $18 million project with the U.S. Department of Defense and faculty and students in the Polymer Engineering Center (PEC) to research and develop a non-pneumatic tire for use on heavy-grade military vehicles. The project could be a lifesaver for the military: In many situations in Iraq, tires have proven to be weak links in Humvees that enemies target with improvised explosive devices (IEDs). “You see reports all the time of troops who were injured by an IED or their convoys got stranded because their tires were shot out,” says Mike Veihl,Resilient general manager. “There’s all sorts of armor on the vehicle, but if you’re running in the theater and get your tire shot out, what have you got? You’ve got a bunch of armor in the middle of a field.”
In April 2008, Resilient installed its tires on a Wausau-based National Guard Humvee for rigorous on- and off-road tests. The project challenged PEC faculty and students, given the completely new tire design and high-performance levels the tire must meet, says Kuo K. and Cindy F. Wang Professor of Mechanical Engineering Tim Osswald, center co-director.
The design breakthrough, first developed by Resilient’s in-house design and development team, takes a page from nature. “The goal was to reduce the variation in the stiffness of the tire, to make it transmit loads uniformly and become more homogeneous,” says Osswald. “And the best design, as nature gives it to us, is really the honeycomb.”
He and graduate students Nick Newman and Eric Foltz ran tests that helped Resilient confirm the quality of its unique design concept. The patent-pending design relies on a precise pattern of six-sided cells that are arranged, like a honeycomb, in a way that best mimics the “ride feel” of pneumatic tires. The honeycomb geometry also reduces noise levels and heat generated during usage—two common problems with past applications. “It’s amazing to think that we were going from literally sketching designs on a piece of paper in June 2006 to having actual Humvees riding around on prototype tires in April 2008,” says Newman. “In under two years, really functional tires were created.”
Veihl says Resilient has evolved into a full-service operation, with in-house facilities that can develop new materials and run them through a battery of physical and environmental tests. He says the UW-Madison experience is vital to continuing the project. The group holds weekly teleconferences, and Osswald has spent time at the company providing high-level polymer coursework for Resilient’s engineers. Many of the same tests done in Wausau were done in parallel at UW–Madison to further validate outcomes. “Osswald has given us the ability to dive into a lot of things much more quickly, because he’s seen so many things that we haven’t in working with these materials,” says Viehl.
Osswald will continue the partnership this fall with two new graduate students. One project will be to evaluate sidewall designs, which will give the tire a more conventional look.
Although military application is the most urgent primary market, Veihl says the tire has potential for virtually any vehicle— including ATVs, mining or construction equipment and farm machinery— where a flat tire causes significant headaches.
But right now, Veihl is concentrating on his customers at the National Guard, many of whom have seen tours of duty in Iraq and offer invaluable advice. “They will tell you the real deal, and they’re not shy about it. If we can develop a product that satisfies their requirements, then we’ve done our job.”