含预制圆孔半圆盘的冲击动态断裂过程试验研究  

Experimental Study on Impact Dynamic Fracture Process of Semi-disk with Prefabricated Circular Hole

作　　者：李清[1] 田策[1] 徐文龙[1] 高正华 马润东 李海涛[1] 周睿 LI Qing;TIAN Ce;XU Wen-long;GAO Zheng-hua;MA Run-dong;LI Hai-tao;ZHOU Rui(School of Mechanics&Civil Engineering,China University of Mining&Technology(Beijing),Beijing 100083,China)

机构地区：[1]中国矿业大学(北京)力学与建筑工程学院,北京100083

出　　处：《科学技术与工程》2021年第3期878-884,共7页Science Technology and Engineering

基　　金：国家自然科学基金(51374212);中国矿业大学(北京)大学生创新训练项目(C201906274)。

摘　　要：为研究预制孔洞缺陷对I型裂纹扩展过程的影响与作用机制,利用数字激光动态焦散线方法对预制I型边裂纹和孔洞缺陷的巴西半圆盘进行三点弯动态冲击实验。实验得到以下结论:受到冲击荷载后,与预制的试件内部孔洞相比,预制边裂纹尖端应力集中程度更高,因此内部的缺陷对冲击荷载敏感度较弱;当I型裂纹扩展接近预制圆孔时,预制圆孔会使裂纹扩展的速度和强度因子产生波动变化,且孔洞越大,影响作用越强;当裂纹与圆孔贯通后,由于圆孔钝化作用会抑制裂纹继续扩展,钝化裂纹再次起裂后其裂纹尖强度因子比贯通前最大值提高了124.56%~190.60%,扩展速度上升了47.06%~57.89%;预制孔洞尺寸存在一最优值,对裂纹再起裂抑制作用和钝化作用最为明显,起裂时的起裂韧度最高,产生这一现象的原因是加载速率和试件缺陷特征共同作用的结果。In order to study the effect of prefabricated hole defects on type I crack propagation and the mechanism of action,a three-point bending dynamic impact experiment was conducted on the Brazilian semi-disk prefabricated with type I edge crack and hole defects by the digital laser dynamic caustic line method.The following results are got from the research.Under impact loading,after being subjected to the impact load,the stress concentration of the prefabricated edge crack tip is higher than that of the prefabricated internal holes,so the internal defects are less sensitive to the impact load.When the crack I grows close to the prefabricated hole,the prefabricated hole will cause the fluctuation of crack growth velocity and stress intensity factor,and the larger the hole,the stronger the influence.When the crack is connected with the prefabricated hole,the passivation effect of the circular hole will restrain the further development of crack.After the passivation crack starts again,the crack tip stress intensity factor increases by 124.56%~190.60%compared with the maximum value before the connection,and the growth velocity increases by 47.06%~57.89%.The size of the prefabricated hole has an optimal solution,which has the most obvious inhibition and passivation effect on the re-crack of the crack,and the highest crack initiation toughness.The reason for this phenomenon is the combination of loading rate and specimen defect characteristics.

关 键 词：焦散线 冲击荷载 动态应力强度因子 预制孔洞 裂纹扩展速度 

分 类 号：O347.3[理学—固体力学]