Application of Experimental Planning Techniques for Optimization of the Tribological and Thermal Behavior of Friction Materials During the Braking Process

<p></p><p>ABSTRACT Brake systems are employed to reduce or maintain the speed of a vehicle, take it to stillness or keep it motionless. The basic principle of friction brake systems is the conversion of the kinetic energy of the vehicle into thermal energy. This study aimed to analyze the operating parameters of a disc brake system for motorcycles using a test bench based on the Krauss procedure described by ABNT NBR 6143/1995. It was decided to conduct a complete 2³ factorial experiment, in which the three control factors considered (type of brake disc, type of pad and the value of brake lever drive pressure) were deliberately altered in two levels each. The properties of the new materials were analyzed and after a certain time of use, called seated materials. To evaluate the performance of the brake system during the braking process, two response variables were analyzed simultaneously: friction coefficient and final temperature. From the experiments, the most satisfactory tribological performance occurred for the constituent materials of the friction pair, disc and pads, set, and a lower value of brake lever drive pressure. As for the temperature, the best result occurred for the materials of the new friction pair and a lower pressure value. In order to find the best combination of levels of each factor that optimizes the overall performance of these two response variables, a multiple response optimization technique was proposed. As a result, the settling levels of the friction pair and the lowest pressure value were obtained as the ones able to optimize the two response variables simultaneously. Finally, the test bench was adapted with a higher power engine, which made it possible to highlight and clarify more about brake fade or brake reduction effect.</p><p></p>