冲击荷载作用下的I/II复合型裂纹扩展规律研究

 为了研究纯I和I/II复合型裂纹在冲击荷载作用下的动态断裂行为，基于提出的单裂纹半孔板(SCSC)构型和大直径分离式霍普金森压杆设备，使用2种石材进行岩石的纯I和I/II复合型的动态断裂实验；同时，实验中使用新装置(裂纹扩展计和高速摄影系统)来监测裂纹的扩展速度。为了检验实验结论，基于Drucker-Prager强度模型和累积损伤失效准则，建立针对纯I和I/II复合型裂纹的数值模型，并使用AUTODYN软件来模拟裂纹的扩展行为。总体上，由数值模拟得到的裂纹扩展路径和实验结果十分吻合。研究结果表明，在裂纹扩展的过程中，其扩展速度是一个变化量，甚至有可能停滞，也就是说可能出现止裂现象；同时，CPG和高速摄影系统都可以很好的反映出此现象，并且高速摄影系统更加直观，说明在动态断裂研究中是适用的，同时给出纯I型动态断裂实验裂纹扩展速度特征，供工程参考。

The growth of mixed-mode I/II crack under impacting loads

The dynamic fracture experiments to a single cleavage semi-circle(SCSC) specimen with the split Hopkinson pressure bar(SHPB) equipment were conducted in order to study the fracture behavior of pure mode I and mixed-model I/II cracks under dynamic loads. The crack propagation speed was measured with a crack propagation gauge system and a high speed photography system respectively. Several numerical models for the pure mode I and mixed mode I/II were established based on Drucker-Prager strength model and cumulative damage(CD) failure criterion. The crack propagation behavior was simulated with the code AUTODYN. The crack propagation paths predicated with the numerical simulation agreed well with the experimental results. The propagation speed was found not to be a constant. The crack propagation may stop，i.e. the phenomenon of crack arrest happened. The phenomenon was captured by the crack propagation gauge system and the high speed photography system. The results of the high speed photography system are visualized easily.