Modifying the brake drum geometry to avoid self-excited vibrations and noise

A squealing noise of 50 dB was measured on a vehicle homologation test at around 900 Hz on the existing brake drum design, mounted on the rear axle of the mid-sized passenger automobile. Therefore, analysis of eigenfrequencies of the original drum design was performed using the impact hammer test and numerical analysis. It was established that a critical mode shape 0/2 exists at around 900 Hz, exactly where the squeal noise was recorded at the brake road noise evaluation vehicle test. The analysis was carried out with the intention to eliminate the possibility of the squealing noise by increasing the critical mode above 900 Hz. The relation between different brake drum modifications parameters and the eigenfrequencies was determined and the best solution was obtained. The first eigenfrequency of the proposed drum design was increased by 58 Hz and the difference between the in-plane and out-of plane mode shape was sufficient. We can conclude that the modified drum design will not have squeal issues at 900 Hz as there are no eigenfrequencies of the brake drum in that range and therefore the problem of the loud brake is solved.