A Finite Element Study On Curve Squeal Based On A Wheelset-Track Model

Railway noise is a public's main concern because of its negative influence on the environment, and it restricts further developments of high-speed railway and urban rail transit. A sharp curve is usually unavoidable in some railway lines, and the consequent curve squeal is one of main components of railway noise. Curve squeal is a complicated problem due to the many physical interactions of dynamical, tribological and acoustical behaviour.The main research purpose of this paper is to estimate the dynamic stability of wheelset-track system during curve negotiation. According to the relationship between the noise and the unstable vibration, the formation mechanism of curve squeal and the modal characteristics of the unstable vibration are investigated. Specially, the effect of frictional behaviour on the mode-merging of the system is described in detail. A 3D solid finite element model of a wheelset-track system is established, which includes a wheelset, two rails and a series of track support elements. The investigation leads to the following conclusions:(1) Unstable vibration of wheels and rails radiates the curve squeal, which is induced by the coupling effect of lateral saturated creep forces. The squealing noise source is attributed to the vibration of the inner wheel in the axial direction and the vibration of the low rail in the normal direction.(2) Curve squeal is generated as a result of self-exited vibration. The formation mechanism of curve squeal is the occurrence of mode-merging between the axial mode of the inner wheel and vertical mode of the low rail.(3) The friction coefficient has a significant influence on the stability of the wheelset-track system. There is a critical friction coefficient for each unstable mode. When the friction coefficient is larger than the critical value, a self-excited vibration of the wheelset-track system associated with the unstable modal frequency will occur.(4) The support spring stiffness is very influential on the stability of the system. The vertical support spring stiffness is essential but the lateral support spring stiffness only has a small influence. Different vertical support spring stiffness may suppress, enhance or slightly influence unstable vibration of the wheelset-track system. There is an optimal vertical support stiffness, applying which can largely suppress or eliminate the curve squeal. (5) The stability of the wheelset-track system does not have an obvious change for different axle loads. The magnitude of the friction forces between wheels and rails are not crucial for the instability of the wheelset-track system in some degree.