Numerical Generation of Mode I Stress Intensity Factors for Narrow Elliptical Cracks in Round Bars

Abstract

ABSTRACT Linear elastic fracture mechanics (LEFM) allows for the analysis of crack propagation by combining remote stress fields in the solid with stress intensity factors (SIFs) obtained for specific crack configurations. To date, the use of tabulated SIFs has greatly facilitated the calculation of crack propagation in various geometries and loading conditions. Focusing on the type of component studied in this work, the literature on round bars presents a wide range of crack geometries, including circular cracks, almond‐shaped and sickle‐shaped elliptical cracks, as well as straight cracks. These geometries are especially relevant for Mode I tension and bending loading conditions. However, the authors consider that there is still a lack of SIF solutions for narrow elliptical‐shaped cracks. Even if in more advanced stages of propagation, the typical shapes approximate circular forms, generating these SIF solutions for a certain range of crack geometries is of great interest for cases where the shape of the initial crack (the propagation of which usually consumes most of the fatigue life) may have great variability. Therefore, the work presents Mode I SIF solutions for “narrow” (high depth to surface length aspect ratio, commonly observed in pitting‐type damage) elliptical‐shaped cracks obtained through the finite element method (FEM).