Integrated Digital Image Correlation for experimental Generalized Stress Intensity Factors determination

Generalized Stress Intensity Factors (GSIFs) at 30 deg. V-notch tips in epoxy Arcan specimens under shear and opening mixed-mode loading are experimentally estimated using Integrated Digital Image Correlation (IDIC). The approach is based on asymptotic displacement fields and implemented with the open-source code pyFEDIC, for which a minimal working example is provided. Analysis of gray level and displacement residuals is used to improve the selection of the region of interest for IDIC, taking a classical finite element-based DIC as reference. The proposed approach, which is compared to the common fitting DIC data in analytical fields, enables the measurement of opening and shear GSIF variations prior to crack initiation, the corresponding mode mixities for several Arcan specimen positions, as well as non-singular terms that helps reducing gray level residuals. Dual mode GSIFs are also included in the analysis, enabling the characterization of local nonlinearity development such as a process zone at the V-notch tip, quantified either directly from the dual mode GSIF magnitude, or from a shift in the equivalent V-notch tip position within the IDIC formulation.