Analysis of automobile brake creep groan vibrations: Test rig experiments in comparison to finite element simulations

Vibro-acoustic brake emissions impaira vehicles comfort and quality. In this context, self-excited brake creep groan phenomena gain in relevance. The non-linear low-frequency vibrations of creep groan potentially appear during an overlap of moderate brake pressures with slow velocities near standstill. Electrified cars with semi-autonomous driving functionalities are especially prone. To treat creep groan already at early stages of the brake development process, reliable investigation and evaluation methods must be available. On that account, this paper deals with test rig experiments and equivalent transient simulations. Both approaches are considered at vehicle corner level which involves axle and suspension components, brake assembly and wheel of one front side of a passenger car. The observed creep groan phenomena have fundamental stick-slip intervals at approximately 90 or 20 Hz. To analyse measured and/or computed time series data in a deterministic way, different rating criteria are specified. These relate to physically reasonable, purely synthetic or statistical metrics. Thereby obtained abstract number values allow the identification, categorisation and validation of brake creep groan vibrations in experiment and/or simulation.