Abstract
Brake squeal noise is a mid-high frequency noise enhanced by vibrations of the brake system, and moreover by a mode lock-in of each components. It is also assumed that the interface between the pad and the disc and its properties are also playing a part in the appearance of squeal noise. Coupling between these scales are still to be identified.
In the automotive industry, noise remains a major issue. This is why there is a study on squeal noise at Robert Bosch France to understand the physic behind. An experimental set-up, a simplified disc brake system, has been designed. The particularity of this system is that the “fixed” caliper is a rigid body mass made in a U-shape and the contact is arranged by two opposite pistons at each sides of the rotor. Besides the experimental brake system, a complete finite element model has been developed. The model is a complex eigenvalue analysis that provides the dynamic response of the brake system. The final aim of this FE model is to obtain accurate numerical results and furthermore, to have an evaluation of the impact of modifying the design or the functional parameters of the brake system.
In this paper, a methodology about correlating the numerical model to the experimental set-up is described for different purposes: determining the natural frequencies of each component, evaluating the material properties of the pads according to compressibility and shearing tests, determining the contact stiffness between each component pair, and finally analyzing the dynamic response of the whole system (unstable frequencies).
The originality of this paper is the methodology of validation step by step of the dynamical model of the test bench. It provides elements of understanding the mechanisms of squeal occurrence. This model coupled with testing allows the analysis of multi-scale effects involved in squeal noise. Some results will also be illustrated.
KEYWORDS – disc brake squeal, mode lock-in, contact stiffness, experimental set-up, modeling