A Method to Predict the Modal Damping in a Braking System based on the Damping of the Pad in its Free-Free Condition

Damping plays an important role in controlling brake squeal caused by the coupling between the rotor and the pads. Since most of the damping in the system (during brake squeal conditions) is coming from the pads, it becomes important to understand the relationship between the damping of the pad by itself in its free-free condition and that of the system in terms of braking pressure, temperature, and frequency. This relationship will help in understanding the effects of optimizing the damping of the pad, whether the damping comes from the friction material, backing layer, or add-on damping treatments. The purpose of this paper is to show that the modal strain energy method can be used to arrive at such a relationship.

Results of measurements made on the pads and rotor in their free-free condition and when assembled in the system under typical operating conditions that cause brake squeal, will be presented as well as the effectiveness of the modal strain energy method in predicting the relationship.

This paper will only focus on one of the possible brake squeal mechanisms: the coupling between the pads and the rotor, when they exhibit similar frequencies and wavelength.