摘要
泡沫金属在高速冲击下表现为变形局部化,采用传统的分离式Hopkinson杆技术进行动态实验测试可能存在问题。本文以动态、刚性-塑性硬化(D-R-PH)模型为理论基础,对闭孔泡沫铝开展Taylor-Hopkinson冲击实验,结合高速摄影技术和数字图像相关技术(DIC),获得了冲击速度的历史曲线。通过运用冲击波理论,提出了冲击速度与冲击时间的隐函数拟合方法,确定了动态初始压溃应力和应变硬化参数等两个动态材料参数。利用冲击端的应力历史曲线检验了结果的有效性,分析了动态材料参数对相对密度的敏感性,发现动态初始压溃应力和应变硬化参数均与相对密度近似呈幂函数关系。实验表明泡沫铝的应力-应变行为呈现明显的冲击速率敏感性。
Foam metal exhibits deformation localization under high speed impact.There may be some problems in dynamic experimental measurement of foam metal by using traditional split Hopkinson pressure bar(SHPB).Based on dynamic rigid-plastic hardening(DR-PH)model,Taylor-Hopkinson impact experiment for closed-cell aluminum foam with different relative densities was carried out.Combining with high speed photography and digital image correlation(DIC)technique,the timehistory curve of impact speed is obtained and presented in this paper.By applying shock wave theory,an implicit function fitting method of impact speed and impact time is proposed,and two dynamic material parameters,including dynamic initial crushing stress and the strain hardening parameter,are determined.The validity of this analysis method was verified by the stress time-history curve at the impact end of specimen.The sensitivity of dynamic material parameters to relative density was analyzed.It is found that the dynamic initial crushing stress and strain hardening parameter have an approximate power function relationship with relative density.Experimental results show that the stress-strain behavior of aluminum foam presents apparent impact rate sensitivity.
作者
黄苏南
丁圆圆
王士龙
何思渊
郑志军
虞吉林
HUANG Su-nan;DING Yuan-yuan;WANG Shi-long;HE Si-yuan;ZHENG Zhi-jun;YU Ji-lin(CAS Key Laboratory of Mechanical Behavior and Design of Materials,Department of Modern Mechanics,University of Science and Technology of China,Hefei 230026,China;State Key Laboratory of Bioeleetronics,Southeast University,Nanjing 210096,China)
出处
《实验力学》
CSCD
北大核心
2018年第6期851-861,共11页
Journal of Experimental Mechanics
基金
国家自然科学基金(11372308,11372307,11572087)资助
关键词
泡沫铝
泰勒冲击
高速摄影仪
隐函数拟合
相对密度
Aluminum foam
Taylor impact
high-speed camera
implicit function fitting
relative density
