By means of experimental method of dynamic caustics, this study compared the dynamic fracture behaviors such as stress intensity factor and the extension tracks, velocity and acceleration of cracks between precast beams with single crack and double cracks under the impact load. The experiment results indicate the following findings. When the impact point is directly upon the main crack, the double-crack beam cracks the earliest, with a extension track of the main crack slightly deviates to the secondary crack in the late stage of cracking extension; Latter comes the single-crack beam of I-type, with a straight extension track of the main crack; the double-crack beam cracks the latest with bending fracture obviously, when the impact point are upon neither of the cracks. The more serious of bending fracture phenomenon during the process of crack extension, the smallest of the maximum velocity. During the whole cracking process which is between the tacking places of the impact load and the fracture of the precast beams, the stress intensity factors vary with time in oscillation. The stress intensity factors of the secondary crack on the double-crack beam decrease dramatically in the middle stage of cracking extension.
Li Qing;Zhang Di;Yang Yang;Hao Jian-wei;Xue Yao-dong;Wang Qiang-xun;Li Jin-yu.
DYNAMIC FRACTURE EXPERIMENTAL STUDY ON A BEAM CONTAINING UNILATERAL PRE-EXISTING CRACKS UNDER IMPACT LOADS[J]. Journal of Vibration and Shock, 2015, 34(4): 205-210
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