Issue 35

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Chunjiang et alii, Frattura ed Integrità Strutturale, 35 (2016) 500-508; DOI: 10.3221/IGF-ESIS.35.56

Unilateral opening specimen is affected by bending moments only, and SIF is:

 M K a g a D tD  2 6 /





(2)

where,  Overlapping formula (1) and (2), SIF expression of crack tip in any load time with wedge splitting geometry is obtained: 1/ 2 v M P D P e   and  1/ 2 h         14 / a D a D  2 3 4 / 1.122 1.4 / 7.33 / a D a D    13.08 / g a D 

1 L L K K K   2 I

(3)

As some problems may exist in part of specimen making and maintenance, here, the quantity of several effective specimens with good surface, basically complete trial curve, small deviation and calculative in double-K fracture parameter is listed in Tab. 3. Arithmetic mean value of initial fracture of 4~6 specimens from each group is taken as trial results. When the difference between single value and average value is over 15% of the average value, this value is excluded, and mean value of the rest of values is considered as trial result. Trial result is:   1 n IC ICj j K K MPa m    (4)

c a  [ mm] 46.5 45.3 40.4 41.3 45.3 38.5 74.5 80.2 81.6 80.8 85.3 75.5 98.4 54.2 56.0 85.3 88.1 83.0 100.7 100.4 114.2 109.9 112.0

a c [mm] 166.4 165.4 160.5 161.4 165.5 158.4 234.4 240.3 241.6 240.7 245.2 275.4 298.5 300.4 300.1 174.0 176.2 245.0 248.1 243.0 314.2 309.8 311.9

Size [mm]

P [kN] 4.91 5.08 4.61 5.03 4.52 5.03 5.55 5.76 6.60 6.49 6.44 8.16 8.31 7.68 8.26 4.53 5.37 5.58 5.76 4.78 8.30 6.92 6.37

CMOD [mm]

E [GPa] 19.45 16.04 18.02 15.77 21.36 17.58 16.53 15.45 16.02 16.89 15.32 16.33 15.78 15.58 20.00 15.51 14.91 16.19 14.38 15.33 15.02 15.00 15.09