Characterization of the High Frequency Squeal on the Laboratory Brake Set-up

Brake squeal is one of the major issues in the design process of an automotive brake and the development of a robust procedure of a squeal-free design is still under investigation. The high frequency squeal is the most frequent noise generated by automotive brakes and is characterized by a wavelength of the disc mode comparable to the length of the brake pad. In 2002 one of the authors presented a new experimental set-up called "laboratory brake" that is a good compromise between simple test rigs, such as the beam-on-disc, and the experimental set-ups that use real brakes. The beam-on-disc set-up is a useful tool to understand the mechanism leading to instability, but it does not simulate appropriately a real brake. On the other hand, real brakes are too complex for fundamental investigation and for efficient modeling. The laboratory brake has now been modified and used to understand the behavior of the high frequency squeal and the relations between the squeal characteristics and the modal interaction of disc and caliper.