Issue 41

S. Beretta et alii, Frattura ed Integrità Strutturale, 41 (2017) 269-276; DOI: 10.3221/IGF-ESIS.41.36 276 F INAL REMARKS his work focused on the analysis of the field-of-view influence in the SIF calculation from displacement fields measured using the DIC technique. In the first part of the work, numerical analyses on CCT and SENT geometries were designed aiming to reproduce the displacement fields in the crack tip area. The results of the FE simulations enabled to study the influence of the number of terms in the regression of the displacement fields based on the area investigated (field-of-view). This study provides a guideline to properly select the field-of-view dimension and the number of terms in the Williams expansion to obtain accurate SIF evaluation from DIC measurements. Experimentally, a crack was grown in a notched dog-bone specimen (SENT geometry), and the displacement fields were measured with real-time DIC acquisitions for specific crack advancements. The SIFs were determined using 2-terms and 3-terms regressions and compared. Following the first part of the work, two different field-of-views were selected depending on the number of terms selected in the Williams expansion giving a difference in the SIFs estimations within 5%. R EFERENCES [1] Mokhtari, M., Lopez-Crespo, P., Moreno, B., Zanganeh, M., Some experimental observations of crack-tip mechanics with displacement data, Frattura ed Integrit [2] Hild, F., Roux, S., Measuring stress intensity factors with a camera: Integrated digital image correlation (I-DIC), Comptes Rendus Mécanique 334(1) (2006) 8-12. [3] Réthoré, J., Gravouil, A., Morestin, F., Combescure, A., Estimation of mixed-mode stress intensity factors using digital image correlation and an interaction integral, International Journal of Fracture, 132(1) (2005) 65-79. [4] Sutton, M.A., Orteu, J.-J., Schreier, H. W., Image Correlation for Shape, Motion and Deformation Measurements: Basic Concepts, Theory and Applications, (2009). [5] Pan, B., Qian, K., Xie, H., Asundi, A., Two-dimensional digital image correlation for in-plane displacement and strain measurement: a review, Measurement science and technology, 20(6) (2009) 062001. [6] Williams, M., On stress distribution at base of stationary crack., Journal of Applied Mechanics 24 (1957) 109. [7] Carroll, J., Efstathiou, C., Lambros, J., Sehitoglu, H., Hauber, B., Spottswood, S., Chona, R., Investigation of fatigue crack closure using multiscale image correlation experiments, Engineering Fracture Mechanics, 76(15) (2009) 2384- 2398. T