Análise estatística das características superficiais de materiais de atrito, parâmetros de operação e desempenho na frenagem de um veículo automotivo por meio de ensaios experimentais

Abstract

This work aims to characterize the plateaus formed on the surface of brake friction materials, correlating them with the tribological and thermal properties achieved in different vehicle braking conditions. For that, experiments were carried out both in vehicle, under real conditions of braking operation, and in the test bench of brake systems. Characteristics of the plateaus formed on the friction material surfaces, submitted to different operating conditions in a real vehicle, were analyzed in the laboratory and correlated with performance variables during braking, characterized by the friction coefficient at the interface of the tribological pair and the temperature. The tests carried out on the bench were performed to analyze the performance of the brake system in relation to the variables of temperature, friction and wear. For that, an optimization technique was used to select the levels of the parameters that optimize the performance of the analyzed brake system and two models to predict the behavior of these variables. As a result, it was found, through tests in a real vehicle, that there is a significant statistical correlation between the characteristics of the plateaus formed on the surface of the friction material, parameters of surface roughness of the friction material and performance variables during braking. There were no differences in the chemical compositions of the plateaus between the two types of vehicle tests. For tests conducted on bench, it was observed that the proposed experimental planning, combined with an optimization technique, made it possible to select the best levels of the factors involved during the braking process. In addition, it was observed that both the multiple regression prediction model (MRM) and artificial neural networks (RNA) are feasible for predicting the behavior of the braking performance variables, which can contribute to improving the project, the performance, reliability and maintenance of brake systems.