冲击荷载下运动裂纹与空孔相互作用的焦散线试验研究

Caustics experimental study on the interaction between moving cracks and voids under impact loading

为了研究含有圆形缺陷的半圆盘试件在不同冲击速度下的断裂特征,采用霍普金森杆加载系统和动态焦散线试验系统,对半圆盘试件进行了试验研究。结果表明:裂纹起裂前,焦散斑半径出现跳跃情况,是入射杆的反复加载造成的;随着冲击速度的增加,裂纹穿过圆形缺陷的应力强度因子峰值有所增加,裂纹穿过圆形缺陷的扩展速度也增加明显;随着圆形缺陷半径的增大,裂纹在圆形缺陷处发生二次起裂时的应力强度因子变大。

In order to study the fracture characteristics of semi-disc specimens with circular defects under different impact speeds,Hopkinson rod is used to dynamically load the semi-disc specimen,and the fracture process of the semi-disc specimen is observed by the dynamic caustics test system,Through the combination of the two test systems,the fracture characteristics of the semi-disc specimens are studied,the research results show that:before the crack initiation,the focal speckle radius jumps,which is caused by the repeated loading of the incident rod.With the increase of the impact velocity,the peak stress intensity factor of the crack passing through the circular defect increases,and the propagation speed of the crack passing through the circular defect also increases significantly,which shows that the impact velocity contributes to the crack propagation.With the increase of the radius of the circular defect,the stress intensity factor of the second crack initiation at the circular defect becomes larger.