Simulation Model and Testing of a Formula SAE Brake System

In order to have a detailed insight of a vehicle dynamics and performance of a car and its influencing parameters, it is common to use simulation programs to get this job done. The purpose of this work is to model the longitudinal dynamics of a Formula SAE prototype in Matlab/Simulink® environment, focusing on the braking dynamics and on the incorporation of collected data from the brake lining materials. The model was designed to receive data from a Formula SAE prototype, which are used in the interaction of subsystems, such as, brakes, sprung mass, aerodynamics and tires. The implementation of the three degrees of freedom for the sprung mass and the non-linear model used for the tires assure a better precision in the model. The brake bench tests were made in a machine that simulates the braking process and was defined as a Krauss testing procedure, which could be used to evaluate the coefficient of friction variation versus temperature. This data was implemented in the model, and through it the reliability and the precision could be improved. Besides the implementation of the real data from the parts and the interaction between the systems, it is crucial the validation of such tool compared to the real behavior of the car. The validation of the model results was made comparing the real test data of the ES09 prototype from the Formula Cefast Team in a straight-line braking carried out in the competition of this category. The data compared between the model and the test validation were the rear wheel speed, the longitudinal acceleration, the prototype speed, the braking distance and the the braking time. The results could represent the car braking behavior precisely, with low values of errors and little discrepancies, such as the percentage error of longitudinal acceleration as 4,8%, the braking distance percentage error as 2,5% and the braking time percentage error as 8%.