含缺陷结构的冲击断裂试验研究  

Tests for structures with flaws under impact loading

作　　者：杨仁树[1,2] 丁晨曦[1] 杨立云[1] 陈程[1] 孙金超[1] 

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 [2]深部岩土力学与地下工程国家重点试验室,北京100083

出　　处：《振动与冲击》2016年第15期103-108,121,共7页Journal of Vibration and Shock

基　　金：国家自然科学基金-煤炭联合基金重点项目(51134025);深部岩土力学与地下工程国家重点实验室自主重点课题(GDUEZB201401)

摘　　要：利用新型数字激光动态焦散线试验系统和落锤冲击加载平台,以缺陷端部曲率为单一变量,将孔状缺陷和裂纹缺陷纳入同一个试验研究体系。研究了冲击荷载下,含不同端部曲率中央缺陷的PMMA条形试件的三点弯曲动态断裂过程,断裂破坏经历三个阶段:前期为冲击应力波作用下,试件下边界裂纹的起裂与扩展;中期为裂纹在缺陷处的应力释放和停滞;后期为落锤自重作用下,缺陷端部的起裂与试件贯穿。在相同的试验条件下,不同端部曲率的缺陷对前期裂纹起裂与扩展基本没有影响;缺陷端部曲率越大,中期缺陷处停滞时间越短,并得出二者之间的近似函数关系;后期缺陷端部起裂时的应力强度因子随着缺陷端部曲率的增大呈现出先减小后增大的变化趋势。Using the test system of digital laser dynamic caustics（DLDC）and the impact loading platform of drop hammer,hole and crack flaws were introduced into the same test study system with a single variable of flaw tips curvature. Dynamic three-point bending tests of PMMA strip specimens with different tips curvatures of flaws under impact loading were studied.It was shwon that fracture failure experiences three stages including crack initiation and propagation at bottom border of specimens duo to impact stress wave action during initial stage,stress release and crack stagnation at flaws during medium stage,and crack initiation at top tips of flaws and specimens penetration duo to the weight of drop hammer during ultimate stage;under the same test conditions,changes of curvature at flaw tips almost have no effect on crack initiation and propagation during initial stage;stagnation time is shortened with increase in curvature at flaw tips during medium stage,the approxinate function relation between them is obtained;the stress intensity factors of crack initiation at flaw tips decreases firstly and then increases with increase in curvature during ultimate stage.

关 键 词：动态焦散线 冲击荷载 缺陷 曲率 应力强度因子 

分 类 号：O348.1[理学—固体力学]