A Study on the Characteristics of Curving Noise and Wheel Wear in Subway System

초록

Because of many curves in metropolitan subway system, the noise from subway system in curve gives displeasure to passenger very much. The subway noise in curve is affected not only by rail condition but also wheel condition and dynamic characteristics. The relationship between curving noise and the wheel dynamic characteristics was reviewed. Generally the curving noise is formed by combination of rolling noise and squeal noise. In this study, the main focus is a squeal noise except rolling noise. There are 3 types of squeal noise in curving noise ?the stick-slip noise due to lateral direction contact force, the stick-slip noise due to longitudinal direction contact force and the flange squeal noise. For finding the relationship between the curving noise and wheel dynamic mode, the squeal noise test by using subway EMU under commercial operation speed. The microphones were attached to the axle box by using connecting jig beside of wheel/rail contact point. The squeal noise was analyzed by using waterfall and power spectrum for curved line with very short radius, 300m. Each component of peaks in waterfall and power spectrum was compared to the natural frequency of wheel by FE analysis. From this analysis, it was found that the causes of squeal noise are directly related to the natural frequencies and dynamic modes of wheel. The other hand, the damage by fatigue according to the contact point was analyzed on wheel by experiment. The area of main damage on wheel could be identified from this analysis. This area was compared to the measurement data of wheel wear. The measurement data could be obtained 4 times in a year. By comparing the wheel wear data and the area of main damage on wheel tread, the contact phenomena between wheel and rail could be found.