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Brake squeal from either disc brakes or drum brakes has been one of the major concerns in the automotive industry due to the persistent complaint that reduces customers' satisfaction with their vehicle. In order to understand, predict and prevent brake squeal, experimental and numerical approaches have been used. Whilst the experimental approach is expensive due to hardware costs and long turnaround time, the numerical approach seems to offer many advantages over experimental approach. In predicting brake squeal using numerical approach, there are typically two methods available, namely, complex eigenvalue analysis and dynamic transient analysis. In this paper both methods are applied on a drum brake assembly using a single commercial finite element software package, ABAQUS. Predicted results from both analyses will then be compared and discussed.

Due to the friction forces acting at the rotor and pads interface, the pressure distribution at the interface is asymmetric in a disc brake system of normal floating-type caliper design. The asymmetry and the high unevenness of the interface pressure distribution cause uneven wear and shorten life of pads. It has been speculated that these undesirable features promote disc brake squeal. This paper investigates the contact (interface) pressure distributions at the rotor and piston-pad interface in response to several ideas of simulated structural (geometric or material) modifications. These modifications are made on the pads and/or at the interface between the piston and the back plate or at the pad guide. A detailed finite element model is constructed taking into account all significant contact interfaces between disc brake components. Sliding frictional contact is analyzed to obtain the interface pressure distributions.

A simple finite element model for the pads, caliper and mounting of a car disc brake system is built and its dynamic influence to the disc is established. The disc is modeled as a thin plate in sliding contact with the pads. Through the contact conditions, the dynamics of the whole disc brake system is formulated. The friction-induced instability of the disc brake system is analyzed for different system parameters and operating conditions so that their influences on the dynamic instability and squeal are understood. Numerical simulation indicates that in the specific cases considered reasonably stiff pads tend to reduce the likelihood of squeal.