Model based investigations of the NVH behaviour of bogie brakes

"In the development of new train components, many development goals are in conflict with each other. For example, reducing the weight of the bogie and its components usually results in these components becoming more sensitive to vibrations. The bogie brake is a particularly critical component. The nonlinear frictional contact between the brake pad and the brake disc can lead to self-excited vibration phenomena caused by various excitation mechanisms that can result in NVH. These NVH phenomena can have a significant impact on component life and passenger comfort. To better assess the conflict between weight reduction and comfort or component lifetime due to NVH phenomena, simulations are often performed in addition to bench tests and field tests. By using appropriate simulation models and methods, problematic NVH phenomena can be addressed at an early stage of product development, which saves costs. Experience shows that the simulation models used often do not describe the dynamic problems accurately enough and certain NVH phenomena cannot be reproduced by simulation. Previous work has already shown that the model boundary conditions used usually represent the boundary conditions of test benches and do not consider the installation situation in the train. However, these boundary conditions have a considerable influence on the simulation results of unstable vibrations with complex eigenvalue analysis (CEA). For example, by selectively extending the system limits of the brake disc in the simulation, it was possible to show that the system becomes significantly more sensitive to self-excited vibrations. The models developed for CEA are now to be extended to include a speed-dependent friction value to investigate the nonlinear influence of a falling friction characteristic on the system dynamics of the bogie brake. In addition, the influence of different brake components and different operating conditions on the dynamic behaviour of the entire brake unit will be investigated The main objective is to demonstrate the influence generated by lightweight construction on the brake's dynamic stability behaviour. "