Friction-induced noise in drum brakes: finite-element modeling and experiments with special focus on damping

Abstract

Brake squeal in friction brakes is a typical audible noise phenomenon in vehicles leading to high development and sometimes warranty costs for the suppliers. The friction forces generated during braking are responsible for self-excited vibrations in the audible frequency range starting from $$1\hbox { kHz}$$ 1 kHz . In the past countermeasures against friction-induced vibrations are mostly investigated for disk brakes while the present study focuses on drum brakes. Damping is in the context of self-excited vibrations often one of the key measures. Nowadays recuperative braking in electric vehicles relieves the conventional friction brake. Due to safety reasons, electric vehicles need to possess at least a second independent brake system. Therefore, simpler drum brakes are on the rise again when developing brake systems. Compared to brake disks, where damping elements can hardly be implemented, the freely accessible drum surface and the brake shoes offer so far unused potential for applying passive damping measures. The present paper focuses on how damping measures influence the noise behavior of drum brakes. Industrial and non-industrial brake components are investigated in detail. Experimental as well as numerical procedures are used to assess damping and noise characteristics.

On Drum Brake Squeal—Assessment of Damping Measures by Time Series Data Analysis of Dynamometer Tests and Complex Eigenvalue Analyses

“…For this purpose, a steel drum has been manufactured at the chair of Machine Dynamics and Mechatronics. This "academic" steel drum possesses a lower material damping than the commonly used cast iron drums, see investigations in [27]. The aim is to assess the effectiveness of certain damping measures in order to reduce squealing events.…”

“…The aim is to assess the effectiveness of certain damping measures in order to reduce squealing events. The Finite Element (FE) model of a drum brake shown in Figure 1 is a modified version of the model used in [27]. However, the focus there was basic testing of the CEA with regard to drum brakes and modeling of the applied damping devices.…”

“…However, the focus there was basic testing of the CEA with regard to drum brakes and modeling of the applied damping devices. Since the objective is now focused on test rig results to be analyzed by time series data analysis to be compared with the FE model, the general model from [27] is adapted to the actual drum brake on the test rig. One of the main changes is that a simplex brake (bearing and actuation of shoes both on top and bottom of the brake) is used here and not a duplex brake (one shoe with bearing on top and actuation on bottom and the other vice versa) as before in [27].…”

“…In one paper [27], applying passive damping structures on drum brake components showed a significant improvement in noise behavior. Usually, thin composites, called shims in the automotive industry, are applied on pad back plates of disk brakes.…”

“…In the case of disc brakes, this is often realized by attaching so-called shims to the backplate, of the brake pads [5]. With drum brakes, on the other hand, the outside of the drum which is the main source of sound radiation [22], offers a great additional potential for the application of damping [18,27].…”