Assessment of Mode I and Mode II Stress Intensity Factors Obtained by Displacement Extrapolation and Interaction Integral Methods

Abstract

A numerical study of the parameters influencing the accuracy of computed stress intensity factor (SIF) values is presented in this article. Mode I SIFs of a through-thickness center crack are calculated by employing the displacement extrapolation method (DEM) of near-tip field extrapolation and the energy-based interaction integral method (IIM). The results are compared with an analytical solution, and some recommendations are provided to increase the accuracy of the calculated mode I SIFs. Optimized influencing parameters can minimize the errors obtained with DEM, whereas the errors obtained with IIM are negligible for a variety of crack lengths. Based on the recommendations made for the mode I SIF calculation, assessment of the mode I and mode II SIFs is performed at the weld root crack tip of a load-carrying cruciform fillet welded joint loaded under a three-point bending condition. The accuracy of the mode I SIF calculated with DEM is independent of the crack length, whereas that of mode II is highly dependent. The IIM provides accurate SIFs for both modes for various crack lengths.