Vehicle noise, vibration and harshness (NVH) is usually among the top five attributes in terms of its priority in the design of automotive vehicles. Its priority in other types of vehicles (e.g., aerospace) is also important. Like other attributes of safety, performance, dynamics, fuel economy, NVH has to be considered closely in the design process. This manuscript presents a summary of recent research in the general area of NVH with an emphasis in the automotive field. It follows up on a previous review and classifies the phenomena by the main sources of NVH into powertrain, road and tyre, wind and other NVH. The last includes brake and chassis, squeak and rattle, electromechanical NVH, exterior (or drive-by) NVH and others. The paper provides a review of some of the recent literature in this field.

Recent Research on Vehicle Noise and Vibration

Brake squeal reduction of vehicle disc brake system with interval parameters by uncertain optimization

Experimental and numerical studies of friction-induced vibration and noise and the effects of groove-textured surfaces

In the last few decades, a considerable amount of research has been done by many researchers around the world on the possibility of understanding mechanisms of brake squeal noise in order to improve vehicle users' comfort and reduce the overall environmental noise level. Despite these efforts, still no general solution exists. Therefore, it is one of the most significant issues that require a detailed and in-depth study for realizing mechanisms of squeal generation in order to design silent brakes. The aim of this review paper is to gain insight into the disc brake squeal mechanisms that lead to audible noise. The principal mechanisms will be introduced to explain the brake squeal phenomenon namely; stick-slip, sprag-slip, modal coupling and hammering excitation mechanism. As more experimental evidence and simulation results become available, it is found that none of the above mechanisms alone can explain all events related to the squeal noise.

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A Review of Automotive Brake Squeal Mechanisms

Development of multiple linear regression-based models for fatigue life evaluation of automotive coil springs

* Corresponding authors) Abstract This paper proposes an approach to investigate the influencing factors of the brake pad on the disc brake squeal by integrating finite element simulations with statistical regression techniques. Complex eigenvalue analysis (CEA) has been widely used to predict unstable frequencies in brake systems models. The finite element model is correlated with experimental modal test. The 'input-output' relationship between the brake squeal and the brake pad geometry is constructed for possible prediction of the squeal using various geometrical configurations of the disc brake. Influences of the various factors namely; Young's modulus of back plate, back plate thickness, chamfer, distance between two slots, slot width and angle of slot are investigated using design of experiments (DOE) technique. A mathematical prediction model has been developed based on the most influencing factors and the validation simulation experiments proved its adequacy. The predicted results show that brake squeal propensity can be reduced by increasing Young's modulus of the back plate and modifying the shape of friction material by adding chamfer on both sides of friction material and by introducing slot configurations. The combined approach of modeling brake squeal using CEA and DOE is found to be statistically adequate through verification trials. This combined approach will be useful in the design stage of the disc brake.

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A combined approach of complex eigenvalue analysis and design of experiments (DOE) to study disc brake squeal

This paper presents a novel approach to understand the influencing factors of the brake pad on the disc brake squeal by integrating finite element simulations with statistical regression techniques. The complex eigenvalue analysis has been widely used to predict unstable frequencies in brake system models and to provide design guidance. The 'input-output' relationships between the brake squeal and the brake pad geometry is constructed for possible prediction of the squeal using various geometrical configurations of the disc brake. Influences of the various factors, namely back plate Young's modulus, back plate thickness, chamfer, distance between two slots, slots width and angle of slots, are investigated using design of experiments technique. The proposed approach is aimed towards prediction of optimal pad design to reduce the damping ratio of the dominant unstable modes through the various factors of the brake pad geometrical construction. The damping ratio is analysed and a non-linear mathematical prediction model is developed based on the most influencing factors.

Reducing disc brake squeal through FEM approach and experimental design technique

A nontraditional evaluation tool is introduced to examine the effects of different materials, in practical applications, that are used in fabricating disc brake components for commonly used or special requirements such as heavy-duty performance and racing cars. As an extension to earlier finite element (FE) disc brake models, a detailed FE model of the whole disc brake corner that incorporates the wheel hub and steering knuckle is developed and validated using experimental modal analysis. Stability analysis of the disc brake corner using the finite element software ABAQUS is carried out to predict squeal occurrence also taking into account the negative and positive damping effects and friction material real surface to increase the accuracy of prediction. A Taguchi method–based design of experiment is used to better assess the contributions of different materials and its interaction effects for effective reduction of brake squeal. The results showed that the pad friction material contributes 56% to the tot...

D. Mathivanan

Papers

A combined approach of complex eigenvalue analysis and design of experiments (DOE) to study disc brake squeal

Reducing disc brake squeal through FEM approach and experimental design technique

Evaluation of disc brake materials for squeal reduction