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Yu. G. Matvienko et alii, Frattura ed Integrità Strutturale, 25 (2013) 20-26; DOI: 10.3221/IGF-ESIS.25.04 26 #015 ( K I =14.3 MPa·m 0.5 ) differ by 20 per cent. A difference in maximal values of T-stress for specimen #016 ( T = –188 MPa) and specimen #015 ( T = –120 MPa) reaches 30 per cent. Distributions of K I in Fig. 5a are constructed by using formula (6). T-stresses shown in Fig. 5b are derived on a base of relations (9)-(11). It should be specially noted that formula (12) gives T = 0 for both specimens and any notch length increment. C ONCLUSIONS ew technique for a determination of fracture mechanics parameters is developed. Its essence resides in a measurement of local deformation response on small crack length increment by electronic speckle-pattern interferometry. Obtained experimental information is capable of deriving the first four coefficients of Williams’ asymptotic series and further calculations of stress intensity factor and T-stress values. Developed approach allows estimating dependencies of fracture mechanics parameters from a real width of the U-notch and/or notch radius. A CKNOWLEDGEMENT resented study is performed in the framework of RFBR Grant #10-08-00393-а and the Program of joint investigations of Central Aero-Hydrodynamics Institute and Mechanical Engineering Research Institute of the Russian Academy of Science. R EFERENCES [1] Maleski, M.J., Kirugulige, M.S., H.V. Tippur, H.V., A method for measuring mode I crack tip constraint under static and dynamic loading conditions, Exp. Mech., 44 (2004) 522-532. [2] Hild, F., Roux, S., Measuring stress intensity factors with a camera: Integrated digital image correlation (I-DIC), C. R. Mecanique, 334 (2006) 8-12. [3] Yoneyama, S., Morimoto, Y., Takashi, M., Automatic evaluation of mixed-mode stress intensity factors utilizing digital image correlation, Strain, 42(2006) 21-29. [4] Yoneyama, S., Ogawa, T., Kobayashi, Y., Evaluating mixed-mode stress intensity factors from full-field displacement fields obtained by optical methods, Eng. Fracture Mech., 74(2007) 1399-1412. [5] Réthoré, J., Roux, S., Hild, F., Noise-robust stress intensity factor determination from kinematic field measurements, Eng. Fracture Mech., 75(2008) 3763-3781. [6] López-Crespo, P., Burguete, R.L., Patterson, E.A., Shterenlikht, A., Withers, P.J., Yates, J.R., Study of a crack at a fastener hole by digital image correlation. Exp. Mech., 49(2009) 551–559. [7] Yates, J.R., Zanganeh, M., Tai, Y.H., Quantifying crack tip displacement fields with DIC, Eng. Fracture Mech., 77(2010) 2063-2076. [8] Hadj Meliani, M., Azari, Z., Pluvinage, G., Matvienko, Yu.G., The effective T-stress estimation and crack paths emanating from U-notches, Eng. Fracture Mech., 77(2010) 1682–1692. [9] Schindler, H.-J., Determination of residual stress distributions from measured stress intensity factors. Int. J. of Fracture, 74(1995) R23-R30. [10] Schindler, H.-J., Cheng, W., Finnie, I., Experimental determination of stress intensity factors due to residual stresses. Exp. Mech., 37(1997) 272-277. [11] Rastogi, P., Digital speckle pattern interferometry and related techniques. Wiley, West Sussex, (2001). [12] Williams, M.L., On the stress distribution at the base of a stationary crack. ASME J. of Applied Mech., 24(1957) 109– 114. N P