冲击载荷作用下含孔洞缺陷介质断裂行为研究

采用新型数字激光动态焦散线试验系统,对含孔洞缺陷和预制边裂纹的半圆盘试件进行了三点弯曲动态冲击实验。实验结果表明:在动态冲击载荷作用下,试件边裂纹处的应力集中程度较试件内部的孔洞缺陷处的应力集中程度更加显著;当孔洞位于裂纹前方时,孔洞对裂纹的扩展速度有抑制作用,且这种抑制作用随着孔洞与边裂纹尖端距离的增加有所减弱;当裂纹再次从孔洞处起裂时,裂纹的扩展速度和应力强度因子和裂纹与孔洞贯通前相比,均出现较大的上升,试件S1、S2中,裂纹扩展速度分别上升了1070%、138%,相应的裂纹尖端应力强度因子分别上升了61%、67%;裂纹的扩展速度与裂纹尖端的应力强度因子呈一定的正相关性,但受裂纹前方附近孔洞周围应力场的影响,裂纹尖端的应力强度因子有一定提高。

Study on Dynamic Fracture Behavior of Specimen Containing Empty Holes Flaws under Impact Loading

Using new digital lazar dynamic caustics system, the dynamic fracture behavior of semi-circular specimen containing empty holes subjected to impact loading was studied. The results show that, under dynamic impact loading, the stress concentration at the tip of edge cracks was greater than that at empty holes; when the empty holes were in front of running crack, the empty holes made the crack propagating velocity decreased, which decreased with the displacement between empty holes and the tip of edge cracks increasing; when the crack propagated again, compared to the crack propagating velocity and stress intensity factor at coalescence time, the crack propagating velocity for specimen S1, S2 increased by 1070%, 138%, respectively, stress intensity factor for specimen S1, S2 increased by 61%, 67% respectively; the dynamic stress intensity factor was positively correlated with the crack propagating velocity, but the stress intensity factor increased before coalescence time because of the empty holes.