Modification of Doublet Modes in a Circular Disc Constrained by Cyclic Symmetric Features

From design perspective, structural modification including material modification and geometry modification in a brake system is the most common approach in reducing the brake squeal. Research of this paper will focus on the modification of the largest noise-generating part in motorcycle’s brake system-the circular disc rotor, based on an existing product available in Taiwan. To reach the best geometry design of a circular disc rotor for specific vibration reduction criteria, parametric studies will be carried out in understanding effects of two evenly distributed modifications in the disc — the bolts and ribs. This paper aims to find a criterion in dealing with the design of a pattern on a disk through finite element analyses and experimental modal analyses. From which results, a new criterion for frequency splitting is developed and a mode-veering phenomenon is observed. The outcome has engineering application in reducing specific squeal noise caused by split doublet modes and shifting natural frequencies of a brake disc without creating a new one.