Effects of surface defects on rolling contact fatigue of rail

Rolling contact fatigue damages on the surface of rail such as head check, squats are one of growing problems. Squats are originated from the white etching layer (WEL) or the dent on rail surface and accompanied with dark spots including cracks. Another form of rail surface damage, known as "Ballast imprint" has become apparent. This form of damage is associated with ballast particles becoming trapped between the wheel and the surface of rail. In this study, we have investigated whether the ballast imprint is an initiator of head check type cracks using the twin disc test and Finite element analysis. The tests were conducted using specimens with artificial defects. FE analysis were used to investigate stresses and strains in subsurface of defects. The test results show that cracks initiate and propagate in dents larger than a certain size. (C) 2011 Published by Elsevier Ltd. Selection and peer-review under responsibility of ICM11