Fatigue Strength Prediction of Corroded Rails with Reduced Thickness at the Bottom Using Stress and Stress Gradient

Abstract

 Corrosion is one factor in rail fracture. Due to corrosion, there is a noticeable loss in volume at the side of the rail bottom where the rails contact the components of rail fastening systems, particularly at the spot where leaked water drops onto the rails in a mountain tunnel. A high-accuracy prediction of the fatigue strength of corroded rails is required because the fatigue strength decreases according to the decrease in rail volume. This study attempts to evaluate the fatigue strength of rails, focusing on actual stress and a stress gradient derived from a calculation using the finite elements analysis model, which reproduces the accurate surface shape of the whole rail bottom using a three-dimensional measurement device. The result reveals that the rail strength prediction accuracy of the proposed method against the fatigue test is 0.7 to 2 times at the cycle number when a rail breaks due to a fatigue crack originating from the surface of the rail bottom.