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The noise and vibration are directly related to the perceived quality of a vehicle and it is crucial that the manufacturers focus their efforts to reduce that. When an unusual noise appears, it is a great challenge to define an approach for understanding the phenomenon, identifying the cause and then defining a solution to reduce its effect. A “knocking noise” coming from the brake rigid pipes is perceived while driving the vehicle in a cobbled pavement at low speed and it coincides with the closure of brake system module inlet valves. When a valve closes quickly, there is a sudden change in the flow velocity, which generates a pressure transient in the brake fluid inducing vibrations in the rigid pipes. The pressure transient can be minimized by reducing the speed at which the pressure waves travel in the pipe. The bulk modulus, the density of the fluid, the velocity of valve closing, the Young’s modulus and the dimensions of the pipes, determine the wave speed.

The static coefficient of friction between lining and shoe plays a fundamental role in the lining fixing project, which is the most important parameter for the riveted joint calculation. For the lining riveting, the rivet needs to ensure that friction material and shoe remain in contact through the normal force applied on the surfaces, but the rivet should not be exposed to shear forces. Thus, the brake torque transmission must occur through the static coefficient of friction between lining and shoe, not allowing relative slips or movements between the pair in contact. Therefore, the present study aims to understand the influence of the static friction coefficient between lining and shoe as a function of the lining internal superficial roughness, from the evaluation of different roughness conditions - contact area with shoe -.

Pedal feeling for race cars is a subject of great uncertainties, due to singularities of this type of system and the large amount of components that may influence it. High performance friction materials are developed considering different requirements, aiming to establish a commitment relationship, among different characteristics - for example, compressibility, friction and wear - for critical conditions of use, such as high temperatures and pressure applications. The purpose of this study is to analyze the brake system strain through the fluid displacement measurements and analysis, during brake events, applying different brake pressures for static tests performed on an inertial dynamometer. Test procedures applied aim to simulate automobile race laps, according measurements previously done. Two high performance friction materials, specifically developed for this application, with similar compositions - around 5% different and some physical properties improved - were analyzed.

This study aims at analyzing the causes of noise in a heavy vehicle brake system (6x2 tractor) and proposing solutions to improve comfort during braking as it is known that, during the activation of the automotive brakes, noise can be generated in different frequency bands that can cause discomfort to the user and the study of how to reduce it is considerably important to bring more comfort in its use. As a working methodology, firstly, comparative analysis of dimension and material were performed between the axle assembly that presented noise and another axle assembly of a vehicle with no noise adopted as reference. This information was used as the basis for the frequency and acceleration virtual analysis that were validated with vehicle instrumentation and data acquisition. In parallel, vehicle tests with different brake friction materials were conducted.

Analytical models used to design most of drum brake systems assume rigid body behavior of shoes and drum, resulting in sinusoidal pressure distribution in the friction interface. This approach leads to various limitations and sometimes incoherent results at typical applications since brake components are highly deformable and the contact pressure distribution plays an important role on the brake system efficiency. This study addresses a numerical analysis of drum brake pressure distribution, using Finite Element Method and considering shoes and drum as flexible bodies. The model validation from experimental procedure, where brake components were instrumented in an inertial dynamometer test. Once the pressure distribution can not be accurately measured, this research uses strain field measurements to calibrate the numerical model. This model is nonlinear, implying in convergence difficulties.