Issue34

X. Zhengbing et alii, Frattura ed Integrità Strutturale, 34 (2015) 574-579; DOI: 10.3221/IGF-ESIS.34.63 576 25~180 mm as well as original rock with a size of 180 mm×180 mm×350 mm, while double blade (diameter 450 mm) can cut square (50 mm×50 mm) or rectangle (50 mm×120 mm); power of main motor: 2.2 kilowatt; power of longitudinal motor: 0.75 kilowatt) and finally polished by SHM-200 double-end face stone mill. After sampling, a cylinder (diameter 100 mm×50 mm, length-diameter ratio 1:2) is used for experiment combining with literatures related to dynamic compression test performed with SHPB. Five different levels of impact load are designed for two materials. Every impact load is corresponding to one strain rate and every experiment is repeated thrice under the same strain rate. The most reasonable group of data is selected for analysis after comparing experimental data in every group. Experimental results Tab. 3 and 4 are impact test results of concrete and sandstone obtained under five different strain rates respectively. Dynamic damage forms corresponding to two materials is shown in Fig. 1 and 2 respectively and they rank based on the strain ratio from low to high. Number of samples Diameter of reshaper (mm) Blow speed (m/s) Strain rate   , s -1 Dynamic compressive strength , c d f MPa Peak strain p  , 10 -3 Specific energy absorption (KJ/m 3 ) Damage form of sample A1 20 5.29 40.95 76.60 6.30 555.89 Blocky fragmentation B1 22 6.40 60.79 84.08 6.45 827.55 Blocky fragmentation C1 25 7.53 86.42 95.82 7.14 1174.38 Severe fragmentation D1 27 8.29 95.01 107.57 7.21 1344.52 Severe fragmentation E1 30 9.99 125.70 130.75 8.60 1558.67 Severe fragmentation Table 3: SHPB test results of concrete. Number of samples Diameter of reshaper (mm) Blow speed (m/s) Strain rate   , s -1 Dynamic compressive strength , c d f MPa Peak strain p  , 10 -3 Specific energy absorption (KJ/m 3 ) damage form of sample A2 30 11.0 93.1 173.5 18.32 1059.87 Large block B2 33 12.58 123.5 179.4 19.02 2490.25 Medium block C2 35 13.49 135.2 203.7 19.48 2830.33 Small block D2 40 14.39 154.9 218.9 20.37 3050.47 Blocky fragmentation E2 45 15.53 166.0 226.8 21.70 3320.12 Severe fragmentation Table 4: SHPB experiment results of sandstone. (a1) (b1) (c1) (d1) (e1) Figure 1: Damage form of concrete samples.