Engineers “Tread” Toward Quieter Tyres

Engineers at Purdue University (Indiana/USA) have developed a new technique for analysing tyre vibrations that identifies which features produce the most noise, a step toward designing quieter tyres and reducing highway noise. A mathematical model is used to identify which parts of a tyre produce the most noise. The vibrations are characterised on a graph, a visual representation that’s like a fingerprint of each tyre’s vibration pattern.

“We’ve introduced a way of experimentally looking at tyre vibration in a way that identifies components that can generate the most sound,” said Stuart Bolton, professor at Purdue. The work will be presented August 27, during the 30th International Congress and Exhibition on Noise Control Engineering in The Hague (Netherlands) which is also known as “Internoise 2001”. A tyre’s tread contains block shapes that smack against the road surface like tiny hammers.

Those tread blocks and underlying reinforcing belts vibrate and radiate energy outward, producing sound much like the vibrating cones in stereo speakers. Different portions of the tyre vibrate faster than other portions, producing more noise. The work by Bolton and his collaborates represents an attempt to relate specifically how a tyre’s design, and its associated vibrations, produce noise.

“We created this numerical model that we can pretend is a tyre, giving it the properties of a tyre and running a ‘test’ in the computer as if we were doing a real experiment,” Bolton said. “This illustrates the fact that you can predict the vibration and noise differences related to various design features. Tyre noise and vibration are both a nuisance and a consumer issue because they account for much of the unwanted noise heard inside a car, as well as outside, Bolton said.

The engineers measure various vibrational waves that travel along a tyre’s treadband, which is the outer segment of a tyre that includes reinforcing belts and the tread pattern that meets the road’s surface. Specific vibrations are assigned “wave numbers,” and those numbers are then used to create graphs that illustrate which vibrations are coming from which portions of the tyre – and which vibrations are likely to produce the most noise. “I won’t claim to have totally succeeded in that,” Bolton said.

“This is the first attempt to form some simple theoretical models.” The analytical model represents the treadband as a flat belt connected at both ends to form a circle. However, to be more accurate, the entire tyre – not only the treadband – should be modelled in a three-dimensional cross section, Bolton said.

“We are working to make the model much more tyre-like,” he said, noting that engineers will use findings from such models to help design quieter tyres. The work is being conducted at Purdue’s Institute for Safe, Quiet and Durable Highways as part of a contract supported by the U.S.

Department of Transportation, Ford Motor Co., and tyre manufacturers Michelin Tyre Corp., Continental General Tyre Inc.

, Goodyear Tyre & Rubber Co., and Hankook Tyre Co. Ltd.