Virtual Crack Closure as a Method for Calculating Stress Intensity Factor of Cracks in Metallic Specimens

Abstract

Stress intensity factor (SIF) is one of the most widely used parameters that characterize the behavior of structures that contain cracks. It can be used in static and fatigue analyses, and it is especially good for describing behavior of cracked structures when only small-scale yielding is present at the vicinity of the crack tip. Various crack growth models are based on this parameter, so it is of great importance to determine SIF accurately. Since more complex structures do not have standard analytical solutions for SIF, finite element analysis (FEA) is commonly used for this purpose. In this work, stress intensity factors calculated by the virtual crack closure technique (VCCT) using FEA results are compared to solutions calculated with the use of available analytical expressions from the literature. SIFs were calculated using a custom-programmed algorithm based on VCCT, which is independent from finite element (FE) code that is used to perform FE analyses. FE analyses were carried out for several standard metal specimen geometries, for a range of different relative crack sizes. Analysis of influence of FE size and type was also performed. Comments on the applicability of VCCT in static and fatigue FE analyses of cracked metallic specimens are given.