Notch effect on the stress intensity factor in tension-loaded circumferentially cracked bars

This paper analyzes the influence of the presence of notches on the stress intensity factor (SIF)of round bars with circumferential cracks subjected to tension loading. The finite element method (FEM) together with the computation of the J-integral were used to calculate the SIF in both the circumferentially-cracked round bar (CCRB) and the circumferentially-cracked round notched bar (CCRNB). Results show how the SIF in notched bars (CCRNB) converges to that associated with unnotched bars (CCRB) as the depth of the circumferential (annular) crack increases (thus making the presence of the notch more negligible). Both SIF values (for notched and unnotched specimens) approach each other more quickly (faster convergence) when the notch depth is lower and the notch radius is smaller, so that a characteristic relative crack depth can be defined (depending on both parameters) from which the SIF of the notched bar is that corresponding to a smooth (unnotched) bar. In addition, the SIF was also calculated in similar geometries with a cylindrical hole, i.e. circumferentially-cracked round bar with a cylindrical hole (CCRBch) and circumferentially-cracked round notched bar with a cylindrical hole (CCRNBch), showing a more important effect in the case of deeper cracks and a negligible influence in the matter of the characteristic relative crack depth.