Objective

To visualize the location on the disc brake assembly where brake squeal is generated.

Test Procedure

1. The disc brake assembly was driven by a brake dynamometer.
2. A circular 48-microphone array was used to capture acoustic pressure data close to the disc brake assembly surface.
3. The disc was operated and proper conditions were applied for the brake to squeal.
4. Data was captured for 6 seconds.
5. Data for a loud squeal instant was used for further processing.
6. Acoustic pressure, normal acoustic intensity and surface velocity were reconstructed on the disc brake assembly surface.

Results

The following screenshot shows the 6-sec time history of the recorded acoustic pressure.

The following screenshot shows the frequency spectrum at a loud squeal instant. The major squeal was found at 2649Hz and its second harmonic was found at 5296Hz.

The following screenshot shows the acoustic pressure distribution at the major squeal frequency 2649Hz.

The following screenshot shows the normal surface velocity at the major squeal frequency 2649Hz.

The following screenshot shows the normal acoustic intensity on the disc surface at the major squeal frequency 2649Hz. High acoustic intensity (red) indicates the location where sequeal occurs.