Experimental analysis of the plastic CTOD to characterize the variable amplitude fatigue crack growth in Grade 2 titanium samples

•Experimental analysis of the plastic CTOD using the DIC technique.•Study of the plastic CTOD behavior under single overload with constant amplitude loading conditions.•Observations of the plastic behavior in the crack tip region.•Experimental data for understanding the mechanisms governing the fatigue crack growth process. In this paper, the plastic component of the crack-tip opening displacement (CTODp) is experimentally evaluated to characterize the fatigue crack growth behavior in a Grade 2 titanium sample under single overload with constant amplitude loading conditions. The CTOD measurements were performed with the 2D-Digital Image Correlation (DIC) technique. The experimental results show a linear correlation between CTODp and fatigue crack growth rates, suggesting the independence of this relationship to load-interaction effects. Therefore, this study demonstrates that the CTODp can be a suitable crack-driving parameter to study crack propagation behavior under variable amplitude loading. Furthermore, it suggests that the fatigue crack growth process is primarily caused by cyclic plastic deformation.