Stuart Bolton wants to quiet things down on our highways and roads. He and colleagues at Purdue University are trying to help tire manufacturers design tires that don't make so much noise. Bolton says that the way tires are made now, especially the shape of the treads, is what makes some tires more prone to noise generation than others. When they interact or smack onto the pavement, the blocky shapes act like hammers, he explains. Underlying reinforcement belts in the tire vibrate and radiate energy outward, producing sound resembling the cones in stereo speakers. Bolton is one of several Purdue University researchers who developed a mathematical model that helps designers identify the portions of the tire that produce the noise. "We've introduced a way of experimentally looking at tire vibration in a way that identifies components that generate the most noise," says Bolton. He measures various vibration waves that travel along the tire's tread band—the outer segment of the tire that includes the reinforcing belts. Specific vibrations are assigned wave numbers. These modes are used for creating graphs that illustrate which vibration is coming from specific portions of the tire. The graphs also indicate which vibrations are likely to produce the most noise. Purdue's Institute for Safe, Quiet, and Durable Highways is working with the U.S. Department of Transportation, Michelin Tire, Continental General Tire Inc., Goodyear Tire and Rubber Co., and Hancock Tire Co. Ltd.
For more information, go to www.internoise2001.tudelft.ni.