On the need for new approaches for brake squeal prediction and suppression

Brake squeal is a dynamic instability of the mechanical system caused by friction forces at the contact interface. Notwithstanding several decades of investigations and an increased understanding of brake noise, commercial brake design is still not capable of avoiding squeal instability. The actual predictive tools employed by the designers, mostly based on complex eigenvalue analysis, appear inadequate for reliable squeal prediction. It is now time for investigating alternative approaches using the knowledge developed on squeal generation and its dependence on fundamental parameters (e.g. damping). In the example presented here, attention is no longer focused on the design of brakes with a view to avoid coincidence of natural frequencies, which is impossible in practice, but rather on the suppression of the squeal-causing vibrations during their generation. Structural alterations made to the rotor allow continuous modification of the system dynamics during disc rotation.