Avoidance of brake squeal by a separation of the brake disc’s eigenfrequencies: A structural optimization problem

Brake squeal is a high-pitched noise originating from self-excited vibrations caused by the frictional contact between brake pads and brake disc. It is known from experiments and has also been proved mathematically that splitting the eigenfrequencies of the brake rotor has a stabilizing effect and avoids brake squeal. In this work, this knowledge is used to derive design goals for asymmetric, squeal-free discs. It is necessary to split all eigenfrequencies of the brake disc in a pre-definable frequency band to guarantee stability, inhibit the onset of self-excited vibrations and thus avoid squeal completely. In order to achieve this goal, a structural optimization of automotive as well as bicycle brake discs is conducted. Optimized automotive and bicycle brake discs have been manufactured and tested to assess their squeal affinity, and it is shown that the optimized discs have a greatly improved squeal behavior. This demonstrates that splitting eigenfrequencies of the brake rotor is a passive, low-cost and effective squeal countermeasure applicable to a variety of brake systems.