Corrugation wavelength fixing mechanism and its relationship to train and track geometry parameters

M.Tech.Abstract: The wavelength fixing mechanism is studied by correlating natural frequencies of a locomotive wheelset to rail corrugation frequency. The bending natural frequencies of a locomotive wheelset are found to be related to a corrugation frequency at the Belfast to Steelpoort track. Modal analysis was conducted to determine the natural frequencies of the wheelset, and a corrugation frequency was calculated using captured train speeds and measured wavelengths. Due to severe curving forces, corrugation is only on curved track, particularly on the inner (low) rail of the track with wavelengths of 58 mm - 90 mm. Corrugation is understood to have occurred due to wear because there is no discernible metal flow on it at all curves. Concrete sleepers have an influence on the formation and sustaining of corrugation on rails - given the fact that corrugation was only found on curved track supported on concrete sleepers. There is a strong discernible relationship between corrugation wavelengths and train speeds; this is true especially for loaded trains. The train speeds are directly proportional to the wavelengths, whereas the tractive efforts are inversely proportional. This makes sense given the fact that in general, tractive efforts are inversely proportional to train speeds. Reference [1] states that amongst most researches that have been conducted over a century, an increase in corrugation wavelength with increasing train speed is observed. The greater the curve radius, the longer the wavelengths. In order to avoid long-pitch corrugation, the track curve radius should be reduced to less than 400 m, this means smaller radius curves have mostly short-pitch corrugation (wavelength 80 mm) [2]. There seems to be no discernible relationship between the track gauge deviation and the degree of severity of corrugation. All corrugated curves were found on curves with track gauge deviation, either narrowed or widened. Track curves with corrugation were compared with those that have no corrugation present. Track gauge deviations for curves with no corrugation are significantly less than those of curves with corrugation. This research study also looked at answering some of the common questions, regarding corrugation and its relationship with the environment and terrain