Issue 35

Chunjiang et alii, Frattura ed Integrità Strutturale, 35 (2016) 500-508; DOI: 10.3221/IGF-ESIS.35.56 503 Unilateral opening specimen is affected by bending moments only, and SIF is:   2 2 6 / L M K a g a D tD   (2) where, 1/ 2 1/ 2 h v M P D P e   and           2 3 4 / 1.122 1.4 / 7.33 / 13.08 / 14 / g a D a D a D a D a D      Overlapping formula (1) and (2), SIF expression of crack tip in any load time with wedge splitting geometry is obtained: 1 2 I L L K K K   (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) Categories Size [mm] P [kN] CMOD [mm] E [GPa] a c [mm] c a  [ mm] K 1 K 2 K I PC 300 4.91 141.1 19.45 166.4 46.5 0.432 0.872 1.304 PC 300 5.08 170.3 16.04 165.4 45.3 0.438 0.881 1.319 PC 300 4.61 130.4 18.02 160.5 40.4 0.381 0.771 1.152 PC 300 5.03 133.3 15.77 161.4 41.3 0.416 0.840 1.256 PC 300 4.52 118.0 21.36 165.5 45.3 0.399 0.804 1.203 PC 300 5.03 138.3 17.58 158.4 38.5 0.400 0.810 1.210 PC 400 5.55 183.9 16.53 234.4 74.5 0.466 0.913 1.379 PC 400 5.76 222.1 15.45 240.3 80.2 0.509 0.991 1.500 PC 400 6.60 245.5 16.02 241.6 81.6 0.582 1.131 1.713 PC 400 6.49 252.4 16.89 240.7 80.8 0.569 1.104 1.673 PC 400 6.44 266.9 15.32 245.2 85.3 0.592 1.145 1.737 PC 500 8.16 180.2 16.33 275.4 75.5 0.510 0.997 1.507 PC 500 8.31 210.2 15.78 298.5 98.4 0.615 1.183 1.798 PC 500 7.68 252.4 15.58 300.4 100.7 0.534 1.124 1.658 PC 500 8.26 208.6 20.00 300.1 100.4 0.621 1.193 1.814 RCC 300 4.53 155.0 15.51 174.0 54.2 0.444 0.887 1.331 RCC 300 5.37 226.3 14.91 176.2 56.0 0.525 0.903 1.428 RCC 400 5.58 221.1 16.19 245.0 85.3 0.521 1.010 1.531 RCC 400 5.76 216.3 14.38 248.1 88.1 0.554 1.070 1.624 RCC 400 4.78 200.7 15.33 243.0 83.0 0.457 0.890 1.347 RCC 500 8.30 239.8 15.02 314.2 114.2 0.705 1.039 1.744 RCC 500 6.92 246.4 15.00 309.8 109.9 0.604 1.154 1.758 RCC 500 6.37 257.5 15.09 311.9 112.0 0.546 1.043 1.589 Table 3 : Trial results of various working conditions.