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The development process of automotive brakes is known to be challenging and time-consuming. It is an iterative process consisting of interplay between brake squeal simulation and extensive experimental investigations of the brake system at the test rig and in the vehicle. In this context, the complex eigenvalue analysis (CEA) of linearized FE models is a part of standard development process of brake systems. Nevertheless this linear analysis has not reached the status of a predictive tool yet, remaining a tool accompanying experimental investigations of the brake system only. Possible reasons may be inadequate simplifications of frictional contact, damping effects and friction material modeling on one hand and insufficiencies of the mathematical mechanical models themselves, i.e. linear vs. nonlinear stability analyses on the other hand. The extensive experimental investigations apply time consuming standard test procedures and need efficiency improvement.

Friction material properties influence brake squeal simulation results decisively. It is well known that friction materials exhibit nonlinear and transversely isotropic characteristics dependent on the type and direction of loading. In order to improve brake squeal prediction reliability, friction material properties identified under squeal loading conditions have to be introduced to the simulation models. Because of this fact, the development of a measurement and identification method for friction material properties in context of brake squeal simulation is in progress. The present paper presents the further developed Dynamic Compression Test Rig (DCTR) and the enhanced evaluation method for the estimation of the normal dynamic component stiffness of friction material specimens under typical squeal conditions. In general, the development of testing procedures implies a set of influence and uncertainty factors, which may influence measurement results decisively.

Considerable effort is spent in the design and testing of disk brakes of modern passenger cars. This effort can be reduced if refined mathematical-mechanical models and new experimental techniques are used for studying the dynamics of these brakes. The present paper is devoted to the modeling and experimental investigation of a floating caliper disk brake, special regard being given to the suppression of squeal using active elements. To actively suppress brake squeal, “smart pads” were designed and manufactured. These pads contain piezoceramic staple actuators, which can be independently driven at both pads and within the pads. In experiments they were successfully used for the active suppression of squeal via optimal control. As the piezoceramic elements can be used both as actuators as well as sensors, the “smart pads” are also useful in experimental investigations such as measuring transfer functions.

Industry and academia agree that brake squeal is a nonlinear phenomenon. Consequently, using solely linear finite-element (FE) models and assessing the tendency of a brake system to squeal exclusively on the stability of the trivial solution is not appropriate. However, the latter approach - in the brake community known as complex eigenvalue analysis (CEA) - is extensively used in industry. Until now, nonlinear simulation approaches considering existence and stability of periodic solutions are mostly limited to minimal models. Among the variety of reasons for this the complexity of large-scale nonlinear models as well as the identification of nonlinear material and system parameters are crucial. This contribution discusses the relevance of nonlinearities in friction brake noise, vibration, harshness (NVH) and presents a novel simulation approach for brake squeal.