Development of a Small-scale Test Bench for Investigating the Tribology and Emission Behaviour of Novel Brake Friction Couples

Abstract

The brake industry is currently on the search for lighter, corrosion-resistant and more eco-friendly brake systems. Apart from health and environmental issues, the main drivers for this development are the changing load profiles arising from the megatrends of electrification and autonomous driving. As the brake disc and brake pad together represent a tribological system, both components must be adjusted in order to achieve optimal functionality. Testing of brake friction couples, however, is usually a very costly, energy and time-consuming process, that only allows for a very limited range of material concepts to be considered. This is where testing friction materials on a small-scale level has great advantages because much time and money can potentially be saved in sample generation, testing and post-test analysis compared with full-scale testing. A novel small-scale test bench has been developed at the University of Leeds which aims to screen friction materials under realistic braking conditions. The foundation of the setup is the Bruker UMT TriboLab tribometer operating in a modified pin-on-disc type configuration. Popular full-scale cycles such as the WLTP based real-world driving cycle have been implemented to replicate current everyday driving scenarios as well as custom cycles that aim to simulate possible future load profiles. A full enclosure around the friction couple has been designed using CFD to allow for controlled airflow and subsequent wear debris capture and analysis. The wear particles generated during braking operation are sampled under isokinetic conditions using the well-known Dekati ELPI+ instrument. The paper will report on the scaling approach used to design the test bench and the conversion of the WLTP based real-world driving cycle to a non-inertial system. Details of the CFD analysis as well as preliminary test results will also be presented.