Issue 42

S. Seitl et alii, Frattura ed Integrità Strutturale, 42 (2017) 56-65; DOI: 10.3221/IGF-ESIS.42.07 63 The tendency line of NSC and HSC, for dimensionless SIF and T -stress, are plotted in Fig. 8. As it can be seen the two curves are practically the same, as it can be proved from their linear equation shown in Fig. 8. The coefficient of correlation reveal that the data are significantly scattered because they are used to obtain the linear tendency MCT and TPB tests. In spite of this, the results show reliable and useful behaviour. The dominant role for evaluation of data is played by geometry [35]. (a) (b) Figure 6 : Tendency curve of evolution of T -stress/ f t related to K I on NSC. The T-stress value for MCT specimen is positive for relative crack length 0.5 and we could recommend this test for obtaining fracture toughness from core drill specimen. (a) (b) Figure 7 : Tendency curve of evolution of T -stress/ f t related to K I on HSC. Figure 8 : Comparison of tendency curve of evolution of T -stress/ f t related to K I (dimensionless) on NSC and HSC.