含不同张开角度裂纹结构的动态断裂试验研究  

Dynamic fracture experiment on the structures with open cracks with different open angles

作　　者：梁欣桐 肖成龙[2] 范嘉宾 郭啸 陈文 丁晨曦 LIANG Xintong;XIAO Chenglong;FAN Jiabin;GUO Xiao;CHEN Wen;DING Chenxi(School of Civil and Resource Engineering,University of Science and Technology Beijing,Beijing 100083,China;School of Mechanics and Civil Engineering,China University of Mining and Technology(Beijing),Beijing 100083,China;China Railway Construction Group Company,Beijing 100040,China;School of Mathematics and Physics,University of Scienceand Technology Beijing,Beijing 100083,China)

机构地区：[1]北京科技大学土木与资源工程学院,北京100083 [2]中国矿业大学(北京)力学与建筑工程学院,北京100083 [3]中铁建设集团有限公司,北京100040 [4]北京科技大学数理学院,北京100083

出　　处：《振动与冲击》2023年第18期130-137,共8页Journal of Vibration and Shock

基　　金：国家自然科学基金(52204085);北京科技大学青年教师学科交叉研究项目(FRF-IDRY-21-006);北京科技大学青年教师国际交流成长计划(QNXM20220010);金属矿山安全与健康国家重点实验室开放课题(2021-JSKSSYS-03)。

摘　　要：不同结构的动态断裂行为受多个因素影响,其中裂纹缺陷对其影响最为显著。张开型裂纹是工程结构中十分常见的缺陷,而且张开角度往往并不固定。为研究结构的运动裂纹与不同预制角度裂纹相互作用的规律,以张开角度为单一变量,采用动态焦散线试验系统,在冲击荷载下对含不同张开角度裂纹的有机玻璃试件进行三点弯试验。研究发现:裂纹扩展经过不同张开角度的预制裂纹时,都会先扩展至预制裂纹夹角尖端,再从预制裂纹其中一端重新蓄能起裂,然后偏向落锤点方向扩展,最终贯穿整个试件;开口向上的预制裂纹会增加运动裂纹的扩展时长,而且预制裂纹的开口角度越大,对裂纹扩展产生的迟滞效应越大,裂纹贯穿试件的总时长越大;与预制裂纹相互作用阶段,动态裂纹都会先减速后增速至峰值,预制裂纹角度越大,裂纹扩展速度峰值越小,且当预制裂纹角度为180°时的峰值与无预制裂缝试件的峰值非常接近;运动裂纹再次从预制裂纹尖端处起裂时裂纹尖端应力强度因子迅速大幅增加后又迅速减小直至试件完全断裂。Open crack is quite common in engineering structures,while its open angle is usually uncertain.The existence of crack defects has a significant effect on the dynamic fracture behavior of structures.To study the interaction between the running crack and the prefabricated crack with different open angles,the open angle was set as a single variable in the experiments.A dynamic caustics experiment system was used to conduct the three-point bending experiments on PMMA specimens under impact load.The results show that:when the crack propagates through the prefabricated crack,it always propagates first to one of the ends of the prefabricated crack,then propagates from the end toward the drop hammer point,and finally penetrates through the whole specimen;the prefabricated crack with upward opencrack will increase the propagation time of the running crack,the larger the open angle of the prefabricated crack,the larger the hysteresis effect on the crack propagation,and the longer the total duration of the crack penetration;during the period of interaction with the prefabricated crack,the dynamic crack propagation velocityfirstly slows down and then increases to the peak,the larger the prefabricated crackangle,the smaller the peak of crack propagation velocity,meanwhile,the peak value of the specimen with180°open crack is very close to that of the specimen without prefabricated crack;when the running crack initiates again from the end of the prefabricated crack,the stress intensity factor at the crack tip increases rapidly and then decreases rapidly until the specimen completely breaks.

关 键 词：动态断裂 裂纹夹角 裂纹缺陷 动态应力强度因子 裂纹扩展速度 

分 类 号：TH212[机械工程—机械制造及自动化] TH213.3