Reliability analysis of fatigue crack initiation of railhead in bolted rail joint

Mechanical fracture of rail can have devastating and long-lasting effects on this industry included: death, injury, costs and loss of public confidence. Today the rate of fatigue failure was increased due to high axle load, velocity and volume traffic. Bolted rail joint is more vulnerable area in railway track. In this study is tried to provide a comprehensive probability model of fatigue crack initiation prediction in railhead of joint area by using of FEM, response surface method, probability theory and reliability analysis. In parametric study, axle load, velocity, number of wagons, number of passing trains during a day and mechanical properties were considered as stochastic variables. The contact of wheel/rail is analyzed quasi static, and the results of FEM are validated by Hertz’s theory. Combined energy–density based and critical plane based fatigue concept is used for fatigue crack prediction. The results show that axle load and yield stress are more sensitive parameters while Poisson’s ratio is less sensitive parameter to fatigue crack initiation life. Also the reliability index reduced rapidly, due to the low cycle fatigue regime in this area.