Issue 75

R. Ince et alii, Fracture and Structural Integrity, 75 (20YY) 435-462; DOI: 10.3221/IGF-ESIS.75.30





i

i

i

s

 i i CTOD a c CTODc Nc      , , K a K c I Nc Ic i



i

n

,

1, 2,...,

(28)

Here, n is the number of sets, i is the i th set and i

Nc  is the mean critical nominal strength of the i th set, which corresponds

to the mean critical notch depth ( i c a ) of the i th set. By employing Eqns. (1) and (2), the K s Ic and CTOD c curves of specimens are initially plotted for each different notch depth to apply the method to the specimens in sets. Subsequently, the mean K s Ic and CTOD c curves, along with the standard deviation curve based on Eqn. (6), are plotted. Consequently, the fracture quantities of the material can be determined from the abscissa and ordinate of the point corresponding to the minimum standard deviation on the mean curve. Fig. 11 illustrates the implementation of the peak load method for SNDB specimens with Ankara andesite. In these figures, the K s Ic and CTOD c plots of the SNDB specimens with s/D =0.6 are shown at the top, while those of the SNDB specimens with s/D =0.7 are at the bottom. The standard deviation plots based on Eqn. (6) are presented in the middle. In conclusion, the fracture quantities of the stone material were calculated from the s min values, which correspond to the minimum standard deviations, as depicted in Fig. 11. This figure demonstrates a strong correlation between both fracture quantities of Ankara andesite despite using SNDB specimens with two different s/D ratios. Note that the E value measured by Tutluoglu and Keles [14] was used in this analysis. In Tab. 4, the relative critical notch depths (  c ) and the crack extension values (  a c ) of the stone material are reported for each   and each s/D ratio. Using Eqns. (7), (8), and (23), the parameters of initiation fracture toughness of the double- K model, computed according to results of the peak load method, are also summarized in Tab. 4.

a 0 mm

D mm

r mm 50.9 50.3 50.5 50.9 50.9 50.8 50.9 50.8 50.8 50.8 50.7 50.9 50.8 50.8 50.9 50.9 50.9 50.8 50.9 50.9

d mm 50.1 49.6 50.1 48.1 47.8 50.1 48

s mm

P c N

CMOD c mm 0.0347 0.0299 0.0334 0.0414 0.0471 0.0443 0.0488 0.0532 0.0513 0.0341 0.0352 0.0419 0.0398 0.0488 0.0548 0.035 0.038 0.045

No

106-1 *106-2 106-3 206-1 206-2 206-3 306-1 306-2 406-1 406-2 406-3 107-1 107-2 207-1 207-2 207-3 307-2 307-3 407-2 407-3

6.5 5.5

101.74 101.02 100.98 101.83 101.71 101.68 101.68 101.65 101.68 101.43 101.85 101.48 101.67 101.81 101.8

61.76 60.62 61.02 61.82 61.78

26020 24549 21712 15882 16346 16535 15728 14456 10326 12250 12431 18337 20310 13649 15058 15568 12917 12150

5

10

9.75 9.75

61.7

15.63 15.25

61.72

50

61.7 61.6 61.7

20.5

50.5 50.9

20.25

20

50

61.32 71.84 71.52 71.68

5.5 5.5

50.4 50.2 49.7 50.2 50.4 51.1

10.5

10.75

71.8 71.8

9.75

101.8

15.38

101.77 101.68

71.78 71.66 71.74 71.76

15.5

50

20 21

101.7

51.3 51.2

9596

0.048

101.76

10377

0.0573

Table 2: Test Results of SNDB specimens by Alkilicgil [15].

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