冲击荷载下深梁动态断裂行为的光弹性实验

Photoelastic experiments on deep beam fracture behaviors under impact load

采用动态光弹性实验方法,对简支深梁进行冲击实验,研究其冲击动态断裂行为。实验得到了冲击断裂过程中深梁的等差条纹变化图片,分析了冲击荷载下裂纹尖端的动态应力强度因子和裂纹扩展速度的变化规律。研究结果表明:由于应力波的作用,在试件开裂前,预制裂纹尖端应力强度因子KdI始终呈波动上升的趋势,最大值为1.995MPa·m^(1/2);试件起裂后,裂尖动态应力强度因子KdI先迅速下降,然后保持在1.222~1.677 MPa·m^(1/2)内震荡,平均值为1.458 MPa·m^(1/2);裂纹起裂后,扩展速度先迅速增大,后保持在310~380 m/s,动态裂纹基本呈匀速扩展,平均扩展速度为345.703 m/s。

By using dynamic photoelastic method, the impact experiments were performed to study the dynamic fracture behaviors of simply supported deep beams. The isochromatic fringe patterns of the deep beams were obtained during the fracture process. The dynamic stress intensity factors （DSIF） and propagation velocities of the crack tips were calculated and analyzed in this paper. The results are shown as follows： the DSIF of the crack tip keeps increasing with fluctuation before the initiation as a consequence of stress waves, reaching the maximum value of 1.995 ; after the initiation, the DSIF decreases rapidly at first, and then stays oscillating within a range from 1.222 to 1.677 . The mean value of DSIF is 1.458 . The propagation velocity of crack after the initiation rises drastically at the beginning, and retains between 310m/s and 380m/s afterwards. The dynamic crack keeps a constant extension basically, and the average velocity is 345.703m/s.