Evaluation of mode-I SIF, T-stress and J-integral using displacement data from digital image correlation – Revisited

Experimental determination of mode I fracture parameters in orthotropic materials by means of Digital Image Correlation

“…Both displacement components, 1 and 2 , were considered when using the Over Deterministic Least Squares Fitting procedure for determining the SIF. As reported by Subramanyam et al [2] this approach should lead to more stable and accurate results.…”

“…Their studies proved the accuracy and effectiveness of the LSF method. Moreover, they demonstrated that 2D DIC provided results comparable to the ones obtained using more sophisticated methods, as 3D DIC [2] or FEM-based calibration [1,2], provided that a judicious choice of the fitting and the DIC parameters is made, and the location of the crack tip is calculated with sufficient approximation [2,5,6]. Other authors [7] showed that the DIC technique, combined with high-speed digital cameras, is able to study the crack growth behaviour of a polymeric beam subjected to impact loading, managing to extract the SIF for both mode I and II using a LSF procedure.…”

“…Subramanyam et al [2] evaluated the influence of the angular extent, showing that angular values higher than 130° allow to obtain more stable results. Since the formulation of the displacement used is a power series, also the effect of the number of terms has to be evaluated.…”

“…Subramanyam et al [2], Yates et al [3] and Harilal et al [4] employed the Least Squares Fitting (LSF) method on DIC data to determine the SIF in isotropic materials. Their studies proved the accuracy and effectiveness of the LSF method.…”

“…Long before the diffusion of the DIC, authors such as Dadkhah et al [12], starting from the crack tip displacement fields determined by Moire interferometry, evaluated the J-Integral, studying its path independency and the existence of a HRR field. Subramanyam et al [2] compared both the area and contour approaches for the evaluation of the J-Integral and concluded that the use of the Energy Domain Integral approach provides more accurate predictions. Similar conclusions were obtained by other authors [8][9][10][11].…”