Study of railway curve squeal in the time domain using a high-frequency vehicle/track interaction model

Railway curve squeal is an intense tonal and annoying type of noise commonly attributed to self-excited vibrations during curving. The mechanisms for its generation remain unclear and it is still a subject of discussion among researchers. Most of them have considered the falling behaviour of the friction coefficient with the slip velocity essential for reenergising the system. Recently, some authors have found that squeal can also appear even for constant friction coefficient through the wheel modal coupling between the normal and tangential directions caused by the wheel/rail contact. This paper particularly evaluates whether the latter mechanism is sufficient to find squeal in curving conditions. The introduction of flexibility in the railway subsystems is required to widen the domain to the high-frequency range in which squeal occurs. One single flexible and rotatory wheelset is considered and suitable forces are prescribed at the primary suspension seats in the current investigation. The rails are modelled through the Moving Element Method (MEM), permitting to extend the range of validity of beam models usually utilised in the literature. This work extends the formulation to rails supported by a viscoelastic Winkler bedding. Both wheelset and track models are coupled by means of a non-linear and unsteady wheel/rail contact model based on Kalker's Variational Theory. Simulation results for different track curvatures and friction coefficients are presented and discussed, showing tonal peaks in the tangential contact forces of the inner wheel. These results can be associated with squeal according to the characterisation of this phenomenon, indicating that squeal can be found in curving conditions using advanced dynamic interaction models even with constant friction coefficient.