A minimal model to study self-excited vibrations of a tram wheelset in curves with small radius of curvature

Abstract

A wheelset of a rail vehicle may experience stability issues in curves with a small radius of curvature, which are typical for tramway networks. Accompanied self-excited vibrations of the wheelset might be a potential mechanism of adverse wheel polygonization, although a possible relationship between the two phenomena is not addressed here. A basic 2-DOF model, representing a wheelset with non-driven, independently rotating resilient wheels, has been derived from the analysis of simulation results with a more detailed system model to understand the reasons for a possibly unstable motion in a uniform curve. It has been found that a dominating motion in the regime with a negative gradient of the lateral creep force–creepage characteristics is necessary for possible self-excitation but is not sufficient for the considered parameter range. The combination and interaction of the lateral oscillations of the resilient wheel and laterally elastic wheelset axle is essential for amplification. Resulting stable limit cycles can be observed, and influences on corresponding amplitudes are discussed. The lateral flexibility of the wheelset axle appears as an important influence.