Car disc brake squeal: Theoretical and experimental study

International Journal for Numerical Methods in Engineering, 2004

This paper presents a numerical method to calculate the unstable frequencies of a car disc brake and suggests a suitable analysis procedure. The stationary components of the disc brake are modelled using finite elements and the disc as a thin plate. The separate treatments of the stationary components and the rotating disc facilitate the modelling of the disc brake squeal as a moving load problem. Some uncertain system parameters of the stationary components and the disc are tuned to fit experimental results. A linear, complex-valued, asymmetric eigenvalue formulation is derived for the friction-induced vibration of the disc brake. Predicted unstable frequencies are compared with experimentally established squeal frequencies of a real car disc brake.

Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, 2003

This paper presents a method for analysing the unstable vibration of a car disc brake, and numerical results are compared with squeal frequencies from an experimental test. The stationary components of the disc brake are modelled using many thousands of solid and special nite elements, and the contacts between the stationary components and between the pads and the disc are considered. The disc is modelled as a thin plate and its modes are obtained analytically. These two parts (stationary and rotating) of the disc brake are brought together with the contact conditions at the disc/pads interface in such a way that the friction-induced vibration of the disc brake is treated as a moving load problem. Predicted unstable frequencies are seen to be close to experimental squeal frequencies.

International Journal of Vehicle Noise and Vibration, 2005

This paper reviews numerical methods and analysis procedures used in the study of automotive disc brake squeal. It covers two major approaches used in the automotive industry, the complex eigenvalue analysis and the transient analysis. The advantages and limitations of each approach are examined. This review can help analysts to choose right methods and make decisions on new areas of method development. It points out some outstanding issues in modelling and analysis of disc brake squeal and proposes new research topics. It is found that the complex eigenvalue analysis is still the approach favoured by the automotive industry and the transient analysis is gaining increasing popularity.

2008

Friction-induced vibration and noise emanating from car disc brakes is a source of considerable discomfort and leads to customer dissatisfaction. The high frequency noise above 1 kHz, known as squeal, is very annoying and very difficult to eliminate. There are typically two methods available to study car disc brake squeal, namely complex eigenvalue analysis and dynamic transient analysis. Although complex eigenvalue analysis is the standard methodology used in the brake research community, transient analysis is gradually gaining popularity. In contrast with complex eigenvalues analysis for assessing only the stability of a system, transient analysis is capable of determining the vibration level and in theory may cover the influence of the temperature distribution due to heat transfer between brake components and into the environment, and other time-variant physical processes, and nonlinearities. Wear is another distinct aspect of a brake system that influences squeal generation and itself is affected by the surface roughness of the components in sliding contact. This chapter reports recent research into car disc brake squeal conducted at the University of Liverpool. The detailed and refined finite element model of a real disc brake considers the surface roughness of brake pads and allows the investigation into the contact pressure distribution affected by the surface roughness and wear. It also includes transient analysis of heat transfer and its influence on the contact pressure distribution. Finally transient analysis of the vibration of the brake with the thermal effect is presented. These studies represent recent advances in the numerical studies of car brake squeal.

2006

Passenger cars have become one of the main transportations for people travelling from one place to another. Indeed, vehicle quietness and passenger comfort issues are a major concern. One of vehicle components that occasionally generate unwanted vibration and unpleasant noise is the brake system. Brake squeal noise is the most troublesome and irritant one to both car passenger and the environment, and is expensive to brakes and carmakers in terms of warranty costs.

Disc brake squeal noise is a very complicated phenomenon, which automobile manufacturers have confronted for decades due to consistent customer complaints and high warranty costs. In recent years, the finite element method (FEM) has become the preferred method due to high hardware costs of experimental methods. In this study, a simplified model for the disc brake is presented using the ABAQUS/Standard finite element software. The analysis process uses a nonlinear static simulation sequence followed by a complex eigenvalue extraction to determine the squeal propensity. The effect of the main operational parameters (braking pressure, and friction coefficient) on the squeal propensity is performed. The influence of changing the rotor stiffness and back plates stiffness under different operation condition are investigated. The results of this analysis show that the squeal noise can be reduced by increasing the rotor stiffness and decreasing the back plate stiffness of the pads.

1995

Squeal analysis of disc brake system continues to be a challenging issue in both industrial and academia due to its complexity and frequent occurrence. Thanks to rapid development of computational device and commercial software, finite element analysis becomes much more efficient and dominates the methods of analysis. Currently, two major FEA approaches are used in general, the transient analysis and complex modal analysis. Complex modal analysis studies the stability of the steady state system under small perturbation; if the vibration amplitude blows up, squeal may occur. Transient analysis is capable to study the vibration of the system during whole braking process. Frequencies of squeal are then calculated from Fourier transform. Particularly, nonlinearity, such as thermodynamic and wear effects could be included. In our case, a disc brake system for passenger car is modelled and analysed using both approaches. We use ANSA/META as pre/postprocessor and ABAQUS as solver. Furthermore, thermal effect is included in transient analysis. Results are compared and analysed in detail.

fkm.utm.my

This paper presents prediction of disc brake squeal using the finite element method. A time domain nonlinear transient analysis approach in ABAQUS v6.4 is employed in order to assess instability of the disc brake assembly, which can be identified as an initially divergent vibration ...

International Journal of Vehicle Noise and Vibration, 2006

There are typically two different methodologies that can be used to predict squeal in a disc brake, i.e., complex eigenvalue analysis and dynamic transient analysis. The positive real parts of complex eigenvalues indicate the degree of instability of the disc brake and are thought to associate with squeal occurrence or noise intensity. On the other hand, instability in the disc brake can be identified as an initially divergent vibration response using transient analysis. From the literature it appears that the two approaches were performed separately, and their correlation was not much investigated. In addition, there is more than one way of dealing the frictional contact in a disc brake. This paper explores a proper way of conducting both types of analyses and investigates the correlation between them for a large degree-of-freedom disc brake model. A detailed three-dimensional finite element model of a real disc brake is developed. Three different contact regimes are examined in order to assess the best correlation between the two methodologies.