动态拉伸试验中试样应变测试的有效性分析  

Validity Analysis of Sample Strain Measurement in Dynamic Tensile Experiment

作　　者：田宏伟[1] 郭伟国[1] 

机构地区：[1]西北工业大学航空学院,陕西西安710072

出　　处：《实验力学》2008年第5期403-410,共8页Journal of Experimental Mechanics

基　　金：基金项目:国防科技民用直升机抗鸟撞结构设计和试验技术(2007-1414);国防科技民用固定翼飞机抗鸟撞设计;分析验证(N6BM)

摘　　要：为了评估将试样通过胶粘连接到加载杆的Hopkinson杆装置所获得试样应变的有效性,对四种强度刚度差异较大的纤维增强复合材料进行了动态拉伸试验。试验时,试样通过环氧胶和杆夹层粘接,试样的应变分别按照Hopkinson杆一维应力波理论计算和试样上应变计直接准确测量得到。结果证明:对小变形碳纤维复合材料,按一维应力波理论计算的应变与试样上直接所测应变值偏差超过100%;对较大变形的GFRP和KFRP层合板,两者偏差小于40%。说明采用Hopkinson杆一维应力波理论计算的试样应变不准确。为修正不准确性,一是通过大量数据分析建立按一维应力波理论计算值与直接测量应变之间的关系式,用此式可使此试验装置获得有效的试样应变;二是借助ABAQUS有限元模拟分析得出粘胶层以及试样过渡弧段的变形,用一维应力波理论计算的应变减去此变形,也可获得有效的试样应变。In order to evaluate the validity Hopkinson loading bars, the dynamic tensile of specimen strain measurement, which is glued to experiments were carried out using four types of fiber reinforced plastic with remarkable different strength and stiffness. Specimens were sandwiched and glued to the bars by epoxy resin before testing. The specimen strain was obtained respectively from the one-dimensional stress wave theory calculation of Hopkinson bar and the direct measurement by a strain gage. Results show that for CFRP materials with small deformation, the relative errors between these two methods are over 100%, while for GFRP and KFRP with larger failure strain, the relative strain errors of these two methods are less than 40%, which indicates that the calculated strain from the one-dimensional stress wave theory of Hopkinson bar is not accurate. In order to modify the error, one way is to establish a function between the calculated strain and the directly measured strain data through extensive experiment, therefore the valid sample strain can be obtained. The second way is to subtract the glue deformation and the specimen transition sections from the strain determined from waves in the bars based on the ABAQUS finite element analysis. The valid sample strain values can also be obtained.

关 键 词：HOPKINSON杆 应变 有效性 复合材料 有限元 

分 类 号：TB330.1[一般工业技术—材料科学与工程]