A numerical investigation into the squeal instability: Effect of damping

Between the NVH issues, brake squeal is a harmonic acoustic emission (between 1 and 20 kHz) caused by friction induced vibrations. The onset of squeal is due to an unstable behaviour of the system leading to limit cycle vibrations. A general approach used by several authors to determine the system instabilities is the CEA: Complex Eigenvalues Analysis. This work presents a numerical investigation into the squeal instability on a simplified disc-brake system addressed to analyse the effect of damping on the squeal instability. The mode lock-in instability is reproduced by a parametrical analysis. The relationship between the distribution of damping on the system components and the propensity of the brake to develop squeal is investigated. The numerical results are validated by the experimental ones, presented in a previous work. The behaviour of the system eigenvalues highlights that, while a homogenous distribution of damping stabilizes the system, a non-uniform repartition of damping can increase the squeal propensity.