含预制裂纹的悬臂梁-柱试件冲击断裂实验

Experimental study on impact fracture of cantilever beam-column specimen with prefabricated crack

采用数字动态焦散线试验系统,对柱端含有不同倾斜角度(0°、30°、60°)预制裂纹的悬臂梁-柱试件进行落锤冲击实验,研究其冲击断裂力学特征。结果表明,预制裂纹倾斜角度为0°的试件最先达到断裂韧度;随着预制裂纹倾斜角度的增加,裂纹起裂能量在裂纹尖端处越不易积累,起裂所需时间延长;预制裂纹倾斜角对裂纹扩展轨迹有较大影响,倾斜角越大,扩展轨迹曲裂程度越大;裂纹倾斜角的增加导致裂纹扩展速度振荡幅度变大,裂纹扩展的平均速度增加,说明斜裂纹对裂纹扩展速度有较大影响;预制裂纹倾斜角度增加,试件动态断裂韧度K_(Ⅰc)~d逐渐减小,K_(ⅡC)~d逐渐增加,断裂时复合特征更加明显。研究结果可为裂纹扩展轨迹的预测和研究含裂纹结构的动态响应问题提供理论参考。

The impact fracture mechanics of the cantilever beam-column specimens with different inclination angles( 0°,30°,60°) prefabricated cracks subjected to hammer impact loading were studied by using digital dynamic caustic test system. The results show that the specimen with prefabricated crack of 0° reaches the fracture toughness first and starts to crack. Along with inclination angle increases,the energy accumulated at the crack tip becomes difficult,result in the initiation time is longer; The angle of crack has a great influence on the crack propagation trajectory,the bigger the angle is,the bigger the crack curving is. The increase of crack inclination leads to the vibration amplitude of the crack propagate rate increase and the average crack propagation rate increase,which indicates the influence of slanting crack on the velocity is larger than that of straight crack; With the inclination angle of prefabricated crack increases,the dynamic fracture toughness K_(Ⅰc)~d gradually decreases,K_(ⅡC)~d gradually increases and the composite characteristic becomes more obvious. The results provide a guidance for the prediction of crack propagating trajectory and the dynamic response of structure with cracks.