Abstract
Brakes system design is a complex process involving multiple performance attribute targets to be achieved simultaneously. The task of designer in such cases is to target design which optimizes a few set of attributes which in turn are decided by subjective user rating to objective measurement correlation metrics. In such cases, model based simulation serves the purpose of designer in making correct design decision at initial stages of design. This paper presents a detailed 1d model for automotive brakes system which will help the designer in brakes system design, brakes performance optimization and study the effect of interface systems on brakes performance. Validation of the model for an existing vehicle is also presented. A detailed physics based model of brakes is developed in LMS AMESim software. The builtin libraries of AMESim are leveraged to develop a full vehicle model which consist of the brakes, chassis, suspension, transmission, engine and tires. The brakes model is detailed one which consist of all the components of brakes system viz. brakes pedal, vacuum booster, master cylinder, front caliper, rear caliper, parking brakes and captures all the major design parameters. The remaining systems are modeled in low to medium detail. In order to validate the model for vehicle level FIA (Functional Image Attribute) test cases are considered. The FIA test cases consist of subjective user rating to objective measurement correlation activity. The test cases consist of 11 tests spreading across test conditions of low vehicle speed to high speed, low ramp rates to high ramp rates. Data captured in these tests consist of speed, pedal force, pedal travel, deceleration, master cylinder pressure and few other parameters. The captured data is converted into objective ratings which in turn is a measure of brake performance attributes viz. free travel, preload, deceleration deadband, bite etc. The time history for pedal force is fed into the model as input and required values as per FIA test cases are extracted from the model as output. This work finds its usability in simulation based prediction of brakes FI attributes, study effect of changes in interface systems on brakes performance, DOE study on brakes for selection of best design among available configurations.