Issue 27

L. Marsavina et alii, Frattura ed Integrità Strutturale, 27 (2014) 13-20; DOI: 10.3221/IGF-ESIS.27.02 19 including minimal specimen preparation, equipment relatively unaffected by test environment, and perhaps most importantly it is able to provide a direct measurement of the crack driving force  K . This will undoubtedly mean that the technique will be beneficial in studying crack closure effects, mixed-mode and propagating cracks. N OMENCLATURE A Calibration constant [MPa/signal] K I , K II Mode I, II stress intensity factors [MPa  m] r Polar coordinate [mm] R Stress ratio [ - ] S Thermoelastic signal [signal]  Variation (maximum - minimum)  Mode mixity [rad]  Polar angle [rad]     Principal stresses [MPa] R EFERENCES [1] Harwood, N., Cummings W. M., Thermoelastic Stress Analysis, edited by, Adam Hilger, New York, (1991). [2] Tomlinson, R.A., Olden, E.J., Thermoelasticity for the analysis of crack tip stress fields – a review, Strain, (1999) 49 – 55. [3] Risitano, A., Fargione, G., Experimental method for the determination of the under-stress first-plasticization process parameters. Proc. of IGF XXII, Rome, Italy, (2013) 370-382. [4] Stanley, P., Chan, W. K., The determination of stress intensity factors and crack tip velocities from thermoelastic infra-red emissions, Proc. of International Conference on Fatigue of Engineering Materials and Structures, C262, IMechE, (1986) 105-114. [5] Stanley, P., Dulieu-Smith, J. M., Progress in the thermoelastic evaluation of mixed-mode stress intensity factors, Proc. of the SEM Spring Conference on Experimental Mechanics, Dearborn, USA, (1993) 617-626. [6] Lesniak, J. R., Differential thermography for extreme-environmental structural integrity measurements, ASC/NAF Report F33657-93-C-2230, (1994). [7] Tomlinson, R. A, Nurse, A. D., Patterson, E. A., On determining stress intensity factors for mixed-mode cracks from thermoelastic data, Fatigue Fract. Engng. Mater. Struct., 20 (1997) 217-226. [8] Lin, S. T., Feng, Z., Rowlands, R. E., Thermoelastic determination of stress intensity factors in orthotropic composites using the J-integral, Engng. Fract. Mech . , 56 (1997) 579-592. [9] Stanley, P., Chan, W. K., Mode II crack studies using the ‘SPATE’ technique, Proc. of SEM Spring Conference on Experimental Mechanics, New Orleans, (1986) 916-923. [10] Stanley, P., Dulieu-Smith, J. M., The determination of crack tip parameters from thermoelastic data, Exp. Techniques, 20, (1996), 21-23. [11] Fulton, M. C., Dulieu-Barton, J. M., Stanley, P., Improved evaluation of stress intensity factors from SPATE data, Proc. of the 11 th International Conference in Experimental Mechanics, Oxford, (1998) 1211-1216. [12] Dulieu–Barton, J.M., Fulton, M.C., Stanley, P., The analysis of thermoelastic isopachic data from crack tip stress fields, Fatigue Fract. Engng. Mater. Struct . , 23 (2000) 301-313. [13] Dulieu- Barton, J M, Worden, K, Genetic identification of crack-tip parameters using thermoelastic isopachics, Meas. Sci. & Tech., 14 (2003) 176-183. [14] Lesniak, J.R., Bazile, D. J., Boyce, B. R., Zickel, M. J., Cramer, K. E., Welch, C. S., Stress intensity measurement via infra-red focal plane array, Proc. of ASTM Non-traditional Methods of Sensing Stress, Strain and Damage in Materials and Structures, Orlando, (1996) STP 1318. [15] Diaz, F.A., Yates, J. R., Patterson, E.A., Some improvements in the analysis of fatigue cracks using thermoelasticity, Int. J. Fatigue, 26 (2004) 365–376. [16] Shiratori, M., Miyoshi, T., Nakanishi, T., Noda, Hanada, T., Detection of cracks and measurement of stress intensity factors by infrared video system, JSME International Journal, Series I, 33 (1990) 400-408.