Abstract
KEYWORDS – High Speed Train, Friction Pair, Scale Testing, Friction and Wear, Wear Debris
ABSTRACT
The development and optimization of friction pairs usually goes hand in hand with extensive series of bench tests, since the complex nature of friction and wear cannot be gathered just by means of theoretical considerations or simulations.
Full scale tests provide proper information about the macroscopic behaviour of the friction pair, since the real components and load spectra can be applied. Macroscopic parameters of the tribosystem are the coefficient of friction, the temperature field and deformation of the brake disc.
Besides commercial issues of high costs for the operation of a full scale test bench and supply of full-scale specimen as well as long testing durations due to supply and handling of real-life specimen, tests in full scale are not suitable when it comes to the examination of microscopic processes at the interface between disc and pad.
However, for the optimization and development of friction pairs, knowledge about those processes is essential, since they are determining the system in terms of friction and wear. The most important microscopic processes are the formation and degeneration of friction layers and the generation of wear by micro wear mechanisms.
To be able to gain data on the microscopic processes, tests need to be carried out on lab scale. For this, the load spectrum and geometry of the full scale needs to be proper transferred to the reduced scale to obtain equal macroscopic and microscopic behaviour of the tribosystem in both scales. With the knowledge on microscopic processes and the assurance, that the results achieved in reduced scale tests are also valid in full scale, reduced scale tests can be used to significantly reduce the time and costs for the development of new friction pairs.
The purpose of this work is to introduce an advanced method to verify scaling of full to reduced scales and vice versa. In addition to the macroscopic parameters coefficient of friction and temperature distribution, microscopic wear mechanisms and friction layers are examined. For this, tests have been carried out in two different scales with massive steel brake discs, combined with a sinter-metal brake pad for high speed trains. The dimensions of the discs are Ø 640 mm × 45 mm thickness (Full Scale) and Ø 460 mm × 20 mm thickness (Reduced Scale). The examinations are focused on the brake disc.