Modelling the growth of rolling contact fatigue cracks in rails

A 2D FE analysis along with the fatigue tests results was used to predict growth rate and direction of a surface breaking rolling contact fatigue (RCF) crack in a rail head. The FE analysis was used to determine the LEFM crack tip stress intensity histories including the effects of residual stress, crack face friction and fluid entrapment. The new FE results for the longer cracks (a/b=2) as well as those of previous FE analyses are examined again with a view to identifying the enhancement of the SIF ranges by the fluid entrapment mechanism. The values determined are superposed on the other 2D solutions. Full solutions of the rolling contact history in the presence of fluid are both time consuming and laborious to perform. In the paper, an approximate method employing superposition is presented, which allows relatively rapid estimates of fatigue crack behaviour to be made.