Frequency and time domain prediction of railway curve squeal including multiple wheel/rail contact points

Curve squeal is a high-frequency tonal noise produced by rail vehicles on tight curves, with its occurrence subject to various uncertainties. The generation mechanism is typically attributed to self-excited vibration within the wheel/rail system, with the leading inner wheel of the vehicle often being the most prone to squeal. However, loud and tonal noise is also found to be generated by the outer wheel or for trams when the leading inner wheel is in contact with the grooved rail head. This article presents a wheel/rail interaction model accounting for the presence of multiple contact points between the wheel and the rail. It is used to study the squeal noise generated by a modern low-floor tramcar equipped with resilient wheels. Time-domain simulations are carried out in the case of contact between the flange back of the inner leading wheel and the grooved head. The simulations also reveal that the outer wheel in flange contact can be involved in curve squeal. Variation in the lateral contact point position and the activation of a second contact point on the flange back are found to potentially alter the frequencies involved in the squealing mechanism and the wheel vibration amplitude. A comparison of time-domain simulation results for multiple contact points with full-scale on-track measurements is presented, analysing the inner and outer wheel squeal generated by the tramcar. The squeal is predicted at the same frequencies observed during experiments. Furthermore, the wheel vibration levels in the axial and radial directions are aligned with those measured by accelerometers mounted on the wheels.