Linear-Elastic and Elastoplastic Mode II and III Crack Tip Stress-Strain Fields in Cylindrical Specimens with Circumferential Crack

摘要

A numerical analysis by means of the ANSYS code was performed in order to identify the ratio of both stress intensity factors and crack tip opening displacements for a cylindrical specimen with circumferential V-notch loaded by remote pure shear stress. This kind of loading produces pure mode II and III loading in four points on the circumferential crack front while the mix-mode II+III exists in all other crack front points. In the linear-elastic range, the ratio of maximum values of mode III and mode II stress intensity factors was found to be K_(max.III)/K_(max,II) =1-37. On the other hand, the ratio of crack tip opening displacements in the elastoplastic range approaches δ_(t max, III)/δ_(t max, II) =2.7. These results can be used for the construction of fatigue crack growth rate curves in austenitic and ferritic steels measured in the near-threshold and near-fracture regions by means of a special testing device.