Rail Fatigue Crack Initiation Life Prediction Under Wheelset Creep Condition

Abstract:

Multi body dynamics and three dimensional elastic bodies Non Hertz rolling contact theory were used to obtain wheel rail creep states in several tracks which include different rail cant, superelevation, coefficients of friction (COF) and radius. Pressure and tangential force distribution were loaded to the contact patch of rail finite element model. Then the fatigue parameters of all nodes in the railhead were obtained by stress/strain response analysis. Composition of fatigue parameter was analyzed to decide the prediction formula. If the share stress/strain part was dominating, the share type prediction formula should be used, otherwise the tensile type formula was used. Rolling contact fatigue (RCF) crack initiation life in the leading and trailing wheel was predicted separately. The result shows that the high rail RCF crack is caused by the leading wheel, the influence of the engaged wheel is little. High rail RCF crack initiation life increases with the augment of the curve radius or superelevations, and it decreases with the augment of COF. It can delay high rail RCF crack initiation to set the cant of 1∶20. When COF is over 0.3, the high rail RCF crack is initiated on the surface of railhead; when COF becomes smaller than 0.3, the location of RCF crack initiation transfers to the inside rail head gradually.

Key words:wheel rail creep; critical plane; fatigue parameter; stress strain analysis; crack initiation life