Despite the fact that disk brakes are used on almost entire mass produced vehicle, drum brakes are still applied on light-, medium-, and heavy-duty vehicles. However, both exhibit a high level of brake noises in which squeal is the most uncomfortable and one of the reasons behind high warranty costs that concern the automotive industry. Hence, the development of prediction methods and models of brake noise have prompted significant efforts. This study intends to analyze two types of drum brakes of a commercial automotive application. Their parametric finite element model comprises drum, shoes, and frictional linings and are submitted to a computational process that includes static calculations of the system under the brake forces to get a pre-stress state around which is computed the complex eigenvalues of the system which characterize their stability. These calculations indicate the unstable frequencies of the entire system. After the design of experiments (DOE) process, the influence of drum brake parameters on system stability can be seen. The friction coefficient and Young’s modulus presented a strong correlation with squeal incidence. At the end is presented a comparison and the optimal material parameters to decrease squeal noise occurrence of these brakes.

A method for optimizing acoustical linings is described and applied to multilayered panels including solid, fluid, and porous components. This optimization is based on an analytical simulation of the insulation properties and a genetic algorithm. The objective function is defined by taking into account both the acoustical frequency response over a 1/3 octave spectrum and the total mass of the panel. The optimization process gives rise to an optimal choice for the number of layers as well as for the nature and the thickness of each layer that maximizes the transmission loss. A practical example of such an optimization is described.

The method presented in this work intends to analyze drum brake design parameters of a light duty automotive drum brake system. The main objective of this work is to correlate brake materials and unstability parameters to identify which condition will effectively reduce squeal propensity. The methodology involves (a) the finite-element method of the brake components, namely, drum, shoes, and frictional linings, (b) static calculations to get a pre-stress state around which (c) is computed the complex eigenvalues of the system. Hence, positive real parts indicate dynamic instabilities which are explored by varying parameters, namely, the modulus of elasticity of the materials and the friction coefficient at the contact of the shoes with the drum. According to calculations, it was observed that there exist a given range of values for Young’s modulus and friction coefficient that are favorable to reduce drum brake squeal occurrence. In addition, the method proposed delivered results that match with brake squeal literature.

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One of the factors of influence on driver comfort is undoubtedly the noise. The noise generated by the brake, in addition to causing discomfort, can cause uncertainty as to the existence of mechanical failure in the brake system. Among the types of noise related to disc brakes, what has been generating a greater interest of researchers is squeal noise. This research paper is concerned with the disc brake squeal problem for motorcycles. The aim of the present research is developing a finite element model of the motorcycle disc brake in order to improve the understanding of the influence of material and operational parameters on squeal generation. Stability analysis of the disc brake assembly was accomplished to find unstable frequencies. A parametric study was carried out to investigate the effect of changing Young's modulus of the disc, back plate, friction material and operational parameters, as rotational velocity of the disc, pressure and temperature, on squeal generation. The results of simulation indicated that material and operational parameters play a substantial role in generating the squeal noise.