INFLUENCE OF RESIDUAL STRESS AND CRACK INITIATION LOCATION ON CRACK GROWTH RATE ON RAIL HEAD

Abstract

Rail breakage due to transverse crack originating from squats and gauge corner cracks has been occurring in the rail head, therefore it is required to research on crack propagation.

In this research, we carried out measurements of residual stress inside the rail head, and FEM analysis taking into account the rail shape and the singular field of the crack tip. Then we evaluated the influence of the residual stress and the crack initiation position on the transverse crack growth rate. It was shown that the residual stress inside the rail head which were changed due to annealing and usage affects the transverse crack growth rate. It was shown that the FEM analysis accuracy is good agreement by reflecting the measured residual stress and rail shape etc. The analysis result without taking into account the measured residual stress is about half of transverse crack growth rate where it is taken into account. It was clarified that the depth of transverse crack leading to the rail breakage is different by the position of transverse crack being different in the rail cross section direction.