Test method for objective evaluation of automotive friction-induced squeak noises regarding complete vehicle conditions on a laboratory scale

Due to the decreasing interior sound level in passenger cars, BSR noise (buzz, squeak, rattle) is perceived more and more intensely by the passengers. For car manufacturers, BSR noise is therefore one of the top quality issues. In particular, squeaking noises are generated by friction-induced vibrations between components in relative motion. State-of-the-art setups for experimental stick-slip testing only simulate a two-dimensional motion between two components, which, however, cannot reproduce the characteristics of the complete vehicle system. Moreover, an adequate measurement of acoustic properties cannot be conducted due to the transient background noise of the setups. The presented work introduces a new test method for the experimental simulation of automotive squeaking noise issues on a laboratory scale while incorporating the conditions present in real vehicles in order to predict stick-slip-risks in early development stages. The setup is based on a three-axis shaker system simulating the actual three-dimensional relative motion of two components in a vehicle. We show that a simultaneous measurement of acoustic and tribological properties is possible and distinct correlations between them can be found. A statistical study verifies the repeatability of the method with very high accuracy. Vibration characterization in the time and frequency domain suggests a four-group noise classification.