Portray rail head surface crack 3D contour through image analysis and morphology reconstruction

Abstract

Rail head spalling and fractures are strongly correlated with fatigue crack propagation. Fatigue cracks typically form along evolving surfaces, but their propagation paths are not accurately described by idealized semi-elliptical crack morphology. This study aims to capture the true three-dimensional shape of fatigue cracks during initiation and propagation. New mathematical and physical models, based on reconstructed 3D cracks, are proposed to predict rail crack propagation at various service stages. The analysis reveals that the crack propagation path in the 2D lateral rail section approximates a quadratic parabola or circular curve, and the 3D crack morphology is similar to a partial spherical surface with a curvature radius of approximately 18.5 mm. The three-dimensional crack morphology remains consistent within a small rail range. The reconstruction model proposed in this study can predict internal crack propagation on the rail head surface, assisting in track inspection, maintenance, and repair.