Finite element prediction of the stress state of a rail underhead radius under high axle load conditions

The stress state at the rail underhead radius (UHR) has been parametrically analysed in this paper under high axle load conditions. A finite element method (FEM) was used to undertake the analyses with respect to head wear (HW) and the operational/track support conditions. The wheel load was simulated as a Hertizan contact pressure applied to an elliptical patch to the rail head, assuming fully slipping conditions. The results reveal that the longitudinal tensile stress at the rail underhead radius is highly dependent on the rail head wear (HW), the wheel contact load eccentricity, and the L/V ration of lateral (L) to verical (V) loads. The magnitude of tension spike increases, as a result of an increase in the contact patch offset, the L/V ratio, and HW. This stress is further enhanced by residual and thermally induced stresses. This may result in fatigue cracking and risk of material failure at the underhead radius (UHR)