Multi-Disciplinary Analyses for Brake Fluid Temperature Evaluation 2013-01-0635

During braking events, a brake corner sustains high brake torque, generating a large amount of heat in the process. This is most significant during mountain descent events and vehicle race track events. The brake thermal events not only reduce brake friction coefficient and lining life, but also produce elevated brake fluid temperature.

Traditionally, brake hardware testing is warranted to evaluate brake fluid temperature for high speed flat track and mountain descent. These tests are costly and time-consuming. A CAE process to predict brake fluid temperature early in the vehicle development process before hardware exists, and to reduce and to replace testing will greatly benefit the vehicle development process. To this end, multiple analyses can be run. The heat transfer coefficients and cooling coefficients were evaluated from relevant CFD analyses. Then BrakePro and CarSim were run to evaluate appropriate brake flat track temperature profiles and simulated mountain schedule temperatures of rotors. Finally brake fluid temperatures were evaluated with ABAQUS analyses.

In this paper, the process of CFD calculation with Fluent, flat track temperature profile evaluation and simulated mountain descent temperature with BrakePro and CarSim, and brake fluid temperature prediction with ABAQUS is discussed. Examples are included to further illustrate the process and the results, and testing data is compared whenever appropriate. ABAQUS's brake fluid temperature and brake corner temperature distribution predictions show good correlation with the hardware test results for various events. Also the numerical simulation reveals the impacts of lining, caliper and piston materials, gap conductance properties between parts, caliper design, as well as the role that the caliper convective heat transfer coefficient plays in dissipating heat from the brake system and keeping the brake fluid temperature from rising.