Goodyear Manages Tire Stress Before It Hits the Road
17 October 2000
Goodyear Manages Tire Stress Before It Hits the Road AKRON, Ohio Working tirelessly to invent the next-generation tire for Goodyear, design engineers need to manage stress tire stress, that is. Tire stress is the cornering, stopping, accelerating, rolling and weight-bearing forces that a tire undergoes on the family automobile. With motorists taking unprecedented notice of their tires these days, the need to deal with stresses on the internal components of a tire is growing in importance, according to Mike Trinko, tire-vehicle engineer for Goodyear. "All structures that carry loads are stressed in some way, tires included," Trinko said. "We can't make stress disappear completely, so we're learning new ways to manage it. In fact, we're designing it into today's tires on our terms." The benefits are evident to motorists, Trinko added. How a tire reacts to stress contributes to vehicle ride, tire durability and fuel efficiency. "Consumers want tires that offer security, dependability and a certain toughness." Engineers use computer models to evaluate stress between tire components, the reinforcing belts, cords and rubber that give it strength. The results are telling. "How a tire reacts to stress and strains is a difficult problem to solve," Trinko said. "We have to account for the forces from the road, plus the pressure distributed across the tire 'footprint,' the handsized patch of rubber in contact with the road. "To add to that complexity, a rolling tire's rubber converts mechanical energy into heat, which contributes to rolling resistance and reduced fuel economy." Before the computer, "We used experimental methods in the laboratory to detect stress with questionable success," he said. When Goodyear performed the first finite element analysis or stress test of a loaded tire on a computer, a monumental change in tire engineering followed. Laboratory tests now validate results of computer modeling. Durability tests and three-dimensional holographic laser images screen test tires and look for variations in internal stresses in new constructions. "New technology in our computer model is giving us a leap forward before those tires ever reach the lab. We're now able to predict cornering properties of an actual rolling tire in a matter of a few hours, instead of weeks in actually having to build and test tires. "This approach enables us to look beyond tire durability into actual tire performance tailored for special vehicles. As vehicles are getting lighter and more flexible, they're also sensitive to more subtle vibrations. The computer helps us solve these stress-induced challenges," Trinko said. It also reduces the time it takes to get a new tire to market, he said. For example, the new Aquatred 3 family-car tire was brought to market in half the time previously required to introduce a new passenger car tire. "What took us perhaps three years to design, build and test, we now can do in 18 months or less with the assistance of the computer," Trinko said. "That time and money savings allows us to deliver tires with the latest technology to the consumer more quickly at a fair price." -0-