Characteristics of a Brake Disc’s Nonuniform Thermomechanical Responses to an Emergency Braking

Brake discs in service are subjected to the combined thermal and mechanical loadings. Due to the complex interactions of different parts in operating brake systems and various thermal and mechanical boundary conditions, the thermomechanical responses of brake discs are highly nonuniformly distributed across the brake discs. In this paper, a detailed finite element analysis model was developed to understand the thermomechanical responses of a solid brake disc to an emergency braking. The temperature and the stress in the brake disc were then characterized thoroughly in the radial, circumferential and thickness direction of the disc, and it was found that they were all nonuniformly distributed in the three directions. Furthermore, the stress responses of the disc due to the combined thermal and mechanical loadings were separated into thermal stress and mechanical stress, and their particular characteristics to the individual thermal or mechanical loading were identified. That is: the amplitude of the total stress in the disc was predominately determined by the thermal loading; however the high cycle fluctuations were mainly due to the mechanical loading. All these findings will help us to understand the behaviors of brake discs under the emergency braking, particularly their responses to the separated thermal or mechanical loading, and allow us to optimize the brake disc design and the material usage for the specific applications.