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

Highlights

• 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.

Abstract

In this paper, the plastic component of the crack-tip opening displacement (CTOD_p) 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 CTOD_p and fatigue crack growth rates, suggesting the independence of this relationship to load-interaction effects. Therefore, this study demonstrates that the CTOD_p 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.