Influence of Structural Vibrations on Polygonization on Tramways

Polygonization is one type of periodic wheel out-of-roundness that can diminish riding comfort and generate rolling and impact noises. Additionally, it may lead to the failure of various components, resulting in increased costs and compromising driving safety. Polygonization has been observed in several train operations. One proposed cause is the excitation of structural vibrations within the wheelset, which was, for example, observed when navigating tight curves. The objective of this paper is to enhance the understanding of the relationship between structural vibrations and the development of polygonization. To achieve this, a tram model with flexible wheelsets is established and simulated under tight curves with varying errors. A suitable wear model is implemented to assess wear across different scenarios. Ultimately, the correlation between worn wheels and structural vibrations is analyzed. A relationship between structural vibrations and the development of wheel polygonization could not be established. When negotiating tight curves, low velocities must be maintained due to limited lateral acceleration. With respect to the rather high frequencies of the examined structural modes, high polygon orders would be expected due to the relationship between the velocity, polygon order, and frequency. It was observed that factors such as constant curvature, an initial polygon shape, or rail corrugation play significant roles for polygon development.