Calculation of minimum crack size for growth under RCF between wheel and rail

Surface initiated cracks in rails by repeated rolling contact between wheels and rails have been one of the growing problems in high speed rail. Estimation of a minimum crack size for growth and its growth rate are the most demanding work to develop a cost effective rail maintenance strategy and prevent rails from failure. In this study, we did a series of modelling runs to predict a minimum crack size for growth, which was defined as a crack that grew fast enough to ‘keep ahead’ of its removal by surface truncation in various contact conditions. For this purpose, we developed crack growth simulation software based on the F&B model suggested by Fletcher and Beynon, and calculated the minimum crack sizes for growth considering the effect of dominant contact contributors such as contact pressure, surface friction coefficient, surface wear rate and initial defect size. The minimum crack sizes for growth were calculated from 0.19 to 3.60mm.