Analysis of Fatigue Crack Growth under Mixed Mode (I + II) Loading Conditions in Rail Steel Using CTS Specimen

The paper is focused on the investigation of fatigue crack growth in rail steel. Mode I and its combination with mode II are one of the frequent reason for rail failures. Therefore, mode I and mixed-mode (I + II) experiments were carried out in order to obtain the fatigue crack growth curves for typical rail steel. In experimental campaign were used CTS (Compact Tension Shear) specimens. The Stress Intensity Factors (SIF) were determined for all load cases using Finite Element Method (FEM) with developed and automated Authors' tool ABAQUS environment. During the experimental and numerical study, the impact of different elastic mixity level on fatigue crack growth rates and fatigue crack growth directions has been discussed. As it is noticeable the decrease of the mode I domination (under mixed-mode loading condition) caused an increase of the specimen fatigue lifetime. This observation was also discussed in the light of the detailed fatigue crack paths study using Scanning Electron Microscope (SEM).