Squealing brakes cost auto manufacturers several hundred million dollars a year in warranty repairs and are among consumers’ top 20 vehicle complaints – even in luxury cars. Now, acoustics researchers at the Georgia Institute of Technology have developed a solution that could stop the problem of noisy brakes once and for all.
Professor Ken Cunefare (foreground) displays an actuator that would be part of an active control system to stop brake squeal in vehicles. Graduate Research Assistant Jeff Badertscher poses with brake dynamometer used to test the system.
Georgia Tech Photo: Gary Meek
Close-up of actuator that would be part of an active control system to stop brake squeal in vehicles. It includes a piezoceramic stack that generates a dithering frequency to control the squeal.
Georgia Tech Photo: Gary Meek
In disc brakes, squeal can occur when the brake pads contact the rotor while the vehicle is moving at low speeds, setting up a vibration that manifests itself as an annoying high-pitched squeal. The noise doesn’t affect brake operation, but the problem – which occurs in cars, trucks and buses – leads to needless replacement of brake pads and the addition of shims, damping materials and other parts designed to stop the noise.
“A squealing brake still works, and from an engineering perspective, there is no safety problem when the brakes are squealing,” said Kenneth Cunefare, an acoustics researcher in Georgia Tech’s School of Mechanical Engineering. “But it’s a perceived problem with the quality of the vehicle. If you’ve bought a new luxury car, you don’t want the brakes to squeal. So manufacturers must spend money on warranty repairs that shouldn’t be necessary.”
John Toon | Georgia Institute of Technology
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