Mittwoch, 22.01.2025, 08:15-09:30 im Raum N1147

Im Rahmen des Lehrstuhlseminars wird der Doktorand Christoph Dietz seine aktuellen Forschungsergebnisse zum Bremsenknarzen vorstellen.

Der Vortrag ist hochschulöffentlich und findet in Präsenz im Raum N1147 (TUM Stammgelände) und via Zoom statt. TUM-weite Intressierte sind herzlich eingeladen, dem Vortrag und der anschließenden Diskussion zu folgen.

Um eine kurze Anmeldung der Teilnahme bei Herrn Dietz wird gebeten.

Abstract:

Experimental Analysis and Numerical Simulation of Brake Creep Groan

 Presenter: Christoph Dietz, PhD-student at Technical University of Munich

The shift to Battery Electric Vehicles (BEVs) generates new requirements for the NVH (Noise, Vibration, and Harshness) design of vehicles. Brake noises are particularly affected by this transition in two ways: the overall quieter electric powertrain increases acoustic perception of other disturbing noises in the passenger cabin. Secondly, regenerative braking reduces the use of mechanical brakes, making them more prone to noise issues in principle. A common example is brake creep groan, a low-frequency brake noise originating from a stick-slip in the braking system at velocities close to standstill. The stick-slip excites vibrations in the axle system, that are audible to the passengers as a grumbling sound. To ensure customers a noise-free driving experience, the industry is currently working on solutions to mitigate brake creep groan. It is well known from other industrial application that changes in friction material as well as optimizations of mechanical parameters can reduce or even suppress stick-slip excitations at all. To tackle the noise issue in passenger vehicles, a better understanding of the stick-slip dynamics is required.

In this contribution, brake creep groan is investigated in a McPherson front axle of a mid-class passenger vehicle. The axle system is measured under different operating conditions in vehicle driving tests. Furthermore, the eigen-dynamics of the axle system are analyzed using experimental modal analysis. The results indicate a complex interplay between the stick-slip excitation and the eigen-dynamics of the axle system. A similar phenomenon has been known in literature as mode locking, in which one or multiple eigen-modes of the system can synchronize with the stick-slip to form a self-excited vibration. To gain more insight into this phenomenon, a theoretical 2-DOF minimal model under stick-slip excitation is considered. With the help of nonlinear transient simulations, the effects of mechanical parameters on the stick-slip dynamics are investigated. Finally, a high-fidelity finite element model of the axle system and a simplified version of it is presented. These models should serve as a basis to study the effects of mechanical parameters of the real axle system on brake creep groan in future investigations.