Experimental investigation into the initiation of head check damage using v-track

Abstract

Rolling contact fatigue (RCF) has been a persistent type of damage in rails. To guarantee the safety of railway operation and reduce the maintenance cost, various tests have been conducted to study the RCF damage. In this research, a state-of-the-art downscaled V-Track test rig at TU Delft was used to investigate the initiation of the head check (HC), a typical type of RCF damage. The V-Track test was designed to simulate the wheel-rail contact conditions with the stress state and spin creepage as similar as that in the field. The test rig ran up to 60, 000 load cycles, after which significant surface damage in the form of surface irregularity and cracks was observed in two different zones on the rails. The test results demonstrated that the V-Track is capable of maintaining steady-state loading conditions after a high number of load cycles. Using the same loading condition, a contact stress analysis was subsequently performed to identify the surface stress distribution and predict the pattern of plastic flow inside the contact patch. The plastic flow prediction was then confirmed by a microscopic analysis of the samples cut from the V-Track rails. Furthermore, the microscopic analysis indicated an opposite orientation of the plastic flow in the zone outside contact patch, which will be investigated in further studies.