Fracture Analysis for Angled Surface, Corner and Edge Cracks in Rails Subjected to Bending Loads

Abstract

In this study, three-dimensional stress intensity factor (SIF) solutions for inclined and deflected surface, corner and edge cracks in rails subjected to bending loads are presented. Fracture analyses are performed using FRAC3D, which is part of Fracture and Crack Propagation Analysis System (FCPAS), employing fully unstructured tetrahedral elements along the crack front and in the whole model. The results of the analyses declare how the SIF distributions along the crack front having with different configurations variate with the change of the crack orientations and which crack type is critical in rails. It is observed that increasing the inclination or deflection angle results in a decrease in mode-I SIFs and increases in mode -II and mode -III SIFs. The decrease in mod-I SIF ranges from about 6.3-6.4 MPa root m to about 1.4-1.5 MPa root m with increasing the inclination or deflection angle from 0 to 75 for the edge or surface cracks while it changes from about 4.48 MPa root m to about 0.5 MPa root m for the corner crack under constant design load conditions. It is shown that the distributions and magnitudes of mixed mode SIFs for the edge and the surface cracks are very similar for both crack orientations. The results also show that the corner crack is a less risky damage type compared to the edge and the surface cracks for rails subjected to bending load since the dominant mode-I SIFs obtained for the corner crack are generally much smaller than other cases for both crack orientations.