Issue 41

S. Seitl et alii, Frattura ed Integrità Strutturale, 41 (2017) 323-331; DOI: 10.3221/IGF-ESIS.41.43 329 N = 1 N = 2 a) Knésl & Bednář [5] b) experiment + ODM Figure 5 : σ HMH crack tip stress approximation considering one and two initial terms of the Williams expansion on specimen denoted as YX9 a19_im30 ( P = 7.060 kN, a = 28.62 mm): a) stress values calculated from the coefficients determined theoretically [5]; b) stress values calculated from the coefficients obtained by means of the ODM from the experimental measurements. C ONCLUSIONS n the paper, the crack tip stress distribution is investigated in an Al 2024-T351 body. The standardised CT test was carried out and the displacements data measured optically by means of DIC. These data were used for calculation of the coefficients of the Williams expansion and the stress distribution was reconstructed. The results were compared to the theoretical values of the stress distribution determined from the Williams expansion with the coefficients obtained numerically by means of the hybrid elements. A very good agreement between the both kinds of results was found out. Thus, it can be concluded that the experimental measurement by means of DIC enables precise results to be obtained. These can be used for further fracture mechanics analysis on other types of specimens. A CKNOWLEDGEMENTS inancial support from the Czech Science Foundation (projects No. 15-19865Y and 15-07210S), from Junta de Andalucía through Proyectos de Excelencia grant reference TEP-3244 and from the University of Malaga through Lineas Emergentes of Campus de Excelencia International del Mar (CEIMAR) is gratefully acknowledged. This work is dedicated to the memory of our wonderful colleague, Dr. Vaclav Veselý, who recently passed away. R EFERENCES [1] Stepanova, L., Roslyakov, P. Multi-parameter description of the crack-tip stress field: Analytic determination of coefficients of crack-tip stress expansions in the vicinity of the crack tips of two finite cracks in an infinite plane medium, Int. J. Solids Struct., 100 (2016) 11–28. [2] Ramesh, K., Gupta, S., Kelkar, A. A., Evaluation of stress field parameters in fracture mechanics by photoelasticity— I F