Instability Analysis in Curve Noise of Urban Railway Systems for Optimal Steering Bogie Development

This paper is primarily aimed at investigating the excitation related factors of curve noise in urban metro lines. This study is initiated within the scope of a project on the development of an active steering bogie, which has the purpose of reducing the wear and noise caused by curves. Noise and wheel profile monitoring tests were carried out four times in 2007–2008. In order to identify the excitation conditions, the frequencies are investigated which are related to the unstable dynamic behaviors of the wheel. In addition, the curve negotiation performance of a metro train was analyzed to investigate the time-domain characteristics of the creepages and creep forces caused by the curved sections. The frequency region, where the flexible dynamic behavior of a wheel is unstable and the occurrence time of the unstable dynamical behavior match well with the results of the noise measurements. The relationship between the noise generation related factors due to the lateral creepage in the contact region and the longitudinal creepage, the spin creepage could be also identified. As a new approach, the parameters related to the curve noise excitation caused by the dynamic instability of the wheel are predicted with consideration to the control concept of the active steering bogie, which is now in development. A calculation on the steering performance of an active steering bogie concept shows a promising reduction in and a stable dynamic condition of the lateral creep parameters of the inner front wheel.