Ⅰ型裂纹中低速冲击荷载下起裂韧度测试新方法  

A new testing method for mode Ⅰ crack initiation fracture toughness under middle-low speed impacts

作　　者：施泽彬 朱哲明 汪小梦 王雄 SHI Zebin;ZHU Zheming;WANG Xiaomeng;WANG Xiong(Key Laboratory of Energy Engineering Safety and Disaster Mechanics,School of Architecture and Environment,Sichuan University,Chengdu 610065,Sichuan,China)

机构地区：[1]四川大学建筑与环境学院能源工程安全与灾害力学教育部重点实验室,四川成都610065

出　　处：《爆炸与冲击》2018年第6期1247-1254,共8页Explosion and Shock Waves

基　　金：国家自然科学基金项目(11672194;11702181);四川省安全监管局安全生产科技项目(aj20170515161307)

摘　　要：为了探寻更加合理的构型试件来研究纯Ⅰ型裂纹在冲击荷载下的起裂及扩展行为,提出一种新构型试件,即双倾斜底边中心裂纹试件(double inclined bottom central cracked,DIBCC)。借助于中低速落锤式冲击实验装置进行冲击实验,通过应力波来使试件内预制裂纹起裂并扩展,同时利用应变片测试系统监测裂纹起裂时刻,并采用AUTODYN有限差分软件对实验过程进行数值模拟,最后计算裂纹的动态应力强度因子,利用实验测得的起裂时刻,确定试件的起裂韧度。结果表明:(1)在反射拉伸波作用下,预制裂纹两侧会产生垂直于裂纹面向外的位移,使预制裂纹扩张,从而使裂纹起裂。(2)数值模拟结果与实验结果在裂纹扩展路径上具有一致性,说明本文中提出的DIBCC构型试件有效,可以用来测试裂纹在冲击载荷下的断裂韧度。In this work,we proposed a specimen with a new configuration specimen,i.e.double inclined bottom central cracked specimen(DIBCC)to explore a more suitable configuration specimen for the study of the behavior of Mode I crack under impacts,by conducting tests using a middle-low speed drop hammer impact test device,and by driving the initiation and propagation of the prefabricated crack inside the DIBCC specimens using stress waves.Meanwhile,we measured the crack initiation time using a strain gauge test system and carried out the corresponding numerical simulation using the AUTODYN finite difference code.Then we calculated the dynamic stress intensity factors and determined the initiation toughness of the specimens using the initiation time measured from the experiments.The results show that,under the action of the reflected tensile waves,the prefabricated crack surfaces have outward displacements perpendicular to the crack surface,making the prefabricated crack expand and thus induce the crack to initiate,and that the numerical result of the crack propagation path agrees well with the test result,indicating that the DIBCC configuration specimen proposed is effective and can be used to test the fracture toughness under impacts.

关 键 词：纯Ⅰ型裂纹 双倾斜底边中心裂纹(DIBCC) 应力波 冲击荷载 AUTODYN 起裂韧度 

分 类 号：O346[理学—固体力学] TU45[理学—力学]