Wheel–rail adhesion during torsional vibration of driven railway wheelsets

Abstract

Stability verification of railway wheelsets in Germany can currently become a process difficult to plan. Besides standardised calculations, expensive and often time-consuming test ride measurements have to be conducted. In particular, determining the maximum dynamic torsional stresses resulting from torsional vibration of wheelsets is a frequently discussed topic. Neither an analytical nor an empirical model has been found yet to predict the named stresses. Actually, they are determined experimentally and the representativeness of the recorded maximum dynamic torque is assured statistically. However, statistical evaluation only deals with axle stresses (torque and bending) itself. The origin of torsional vibration, which is the wheel–rail contact point, is not considered for evaluation. Its conditions are typically described by wheel–rail adhesion characteristics, but normally the necessary quantities describing these characteristics are not measured or not measured in sufficient precision. Therefore, this article analyses high-resolution wheel–rail adhesion data that have been recorded additionally on regular test ride measurements. The analysis of these measurement data leads to the following two correlations: (1) Torsional vibration events occur at a certain ratio of adhesion change and slippage change. (2) Dynamic torque swings up within a characteristic time span.