Experimental investigation on polygonization of railway wheels using a scaled test rig

• Applicant: Professor Dr. Christian Schindler
• Subject Area: Engineering Design, Machine Elements, Product Development
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 546297431

The term polygonization in rail vehicles refers to periodic out-ofroundness of the tread surface of railway wheels: a wave-shaped wear pattern with a constant wavelength arises on the wheel tread along the entire perimeter. Polygonization causes a high-frequency fluctuation of the normal force in the wheel-rail contact, which leads to severe loading of the wheel, wheelset, bogie and track. Polygonization has been studied predominantly using computer simulations. However, the accuracy of the simulation results depends on the correctness of the input data, especially the material parameters. Experimental investigation by bench testing offers the possibility of generating meaningful and reproducible results compared to computer simulations. Based on an existing single-wheel roller rig, a scaled test setup has already been fabricated and comissioned. The set up consists of a test specimen with a diameter of 50 mm which rolls on a larger drive wheel. A special mechanism attached to the specimen causes its angle of attack to oscillate at a high-frequency. With the aid of this test setup, it is possible to produce the characteristic wear pattern of polygonization on the test specimen within a short period of time. However, the results are not yet clearly reproducible. In addition, the experimentally generated polygonization deviates from the expected wear pattern derived from generally accepted theories. Therefore, there is a need for an experimental investigation of the existing theories. As part of the proposed research project, various improvements to the drivetrain as well as the electrical and electronic systems will be implemented on the test rig. The variables influencing polygonization are determined and quantified in series of tests. Then, a simulation model of the test rig will be developed in which existing wear models will be implemented. The experiments are backed by simulations so that the underlying models can be improved and validated. The findings contribute to a better understanding of how polygonization occurs. In addition, the simulation model can be used to reduce the risk of polygonization formation in new vehicle designs and to make better predictions about the development of polygonization in existing vehicles.

• DFG Programme: Research Grants