A simulation of the vertical split head failure in rails

Abstract A two-dimensional analysis is presented to assess a possible mechanism to account for the axial cracking behavior in rails which is usually called a vertical split head failure. This failure is potentially damaging and may eventually lead to derailment. The vertical split head is simulated in the present analysis as a vertical crack in an eccentrically loaded infinite strip, representing the head, loaded on its upper surface and constrained on its lower surface, approximating the web constraint. The vertical crack is modeled as distributed dislocations. By using Fourier tarnsforms, the interior stress field and stress intensity factors at the crack tip are determined from the derived coupled integral equations. The calculated stress field indicates that the initiation of a vertical defect is more likely to be caused by the influence of residual stresses upon an existing rail defect, such as an inclusion. Moreover, the growth of the crack is constrained to within the rail head by the high magnitudes of compressive stresses that occur beneath the contact loading and the head-web juncture.