Safety Assessment Method of Railway Vehicle under Oscillatory Wheel Load Fluctuation

Abstract

Oscillatory wheel load fluctuation of considerable amplitude is observed on high speed railway vehicles such as the Shinkansen. It is considered to be generated through very small irregularity with short wave length on the rail surface, and the frequency of this fluctuation is estimated to be approximately 50 to 60 Hz. Due to off-loading caused by this oscillation, when lateral forces by curve negotiation act on the wheel flange, derailment quotients in excess of conventional safety criterion, which is set at 0.8, are often observed. In order to study the influence of such oscillatory wheel load fluctuation on the derailment, a computer simulation was carried out using single wheelset model, and then the evaluation method of running safety was investigated. From the results of this calculation, it is found that the external forces and moments to cause derailment are little affected by existence of such high frequency wheel load fluctuation, and that the time duration while the derailment quotient continuously exceeds the limit value relates to the height of flange climbing and jumping. This paper proposed a method of safety assessment which is applicable to such conditions.