Steps towards Predictive Simulation and Faster Experimental Investigation of Automotive Brake Systems with Respect to Squeal

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. This paper introduces several steps towards improvement of brake development process efficiency with respect to brake squeal and gives an overview on corresponding research at the chair of Mechatronics and Machine Dynamics at TU Berlin. First it describes the refinement of friction material parameter acquisition with respect to squeal relevant loading conditions using the DCTR (dynamic compression test rig) technology. Based on this experimental identification of dynamic friction material parameters, linear as well as nonlinear stability analyses of multibody - disk brake models are performed. Pointing out limits and potentials of the particular analysis methods, the nonlinear stability analysis explains basic phenomena known from the operating experience of brake systems. Finally an experimental method for rapid identification of squeal suspicious states is introduced. The time efficiency of this method allows a fast overview on the usefulness of constructive countermeasures to avoid squeal and might contain potentials towards efficiency improvement with respect to time consuming standardized experimental investigations.