| Nowadays, China has entered into the era of high-speed railway transportation, more and more people choose a high-speed electric multiple unit as the mean for travel. However, noise pollution is attracting people’s concern. Brake squeal noise generated by train braking will affect the comfort of passengers, destroy the living environments. The self-excited vibration generated during braking is also likely to cause fatigue damages of brake components, which will endanger the safety of passengers, too.Researchers have done numerous work to understand the mechanisms for brake squeal since the early20th century. Of the existing mechanisms, the modal coupling is accepted most generally. Based on the modal coupling theory, the author carried out a detailed analysis of brake squeal for a wheel-disc brake system. In the thesis, a model of a wheel-disc brake system was set up, which includes a wheel set, two wheel-disc brake units. True constraint conditions were taken into account in the model. The occurrence propensity of brake squeal for the wheel-disc brake system was analyzed using the complex eigenvalue analysis method and transient dynamics analysis. The following results were obtained.1. The friction coefficient between the brake disc and the brake pads has a significant impact on the brake squeal noise. The occurrence possibility of brake squeal will rise with the increase of the friction coefficient, and the squeal frequency is also increased.2. The Young’s modulus of the brake pad, brake pad seat and brake disc have a great impact on the brake squeal noise. A small Young’s modulus of them can lead to the increasing of possibility of brake squeal.3. The dominant vibration frequency of the contact force between the brake pad and disc is consistent with that of the normal vibration of brake pad. The dominant vibration frequency obtained by the transient analysis method is very closed to the unstable frequency obtained by the complex eigenvalue method. |
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