Effect of damping on the propensity of squeal instability: A numerical investigation

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 and a general approach used by several authors to determine the system instabilities is the CEA: Complex Eigenvlues Analysis. This work presents a finite element modal analysis of a simplified brake system, addressed to identify the effect of damping on the squeal instability. The mode lock-in instability is reproduced by a parametrical numerical 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 the damping can increase the squeal propensity.