中文摘要：

首先对一维应变平面冲击载荷下20#钢的动态拉伸断裂行为进行了实验研究，考察了加载应力和拉伸应变率影响；然后基于损伤度函数模型，对实验进行了数值模拟研究，结果表明：模型中定义的特征物理量一断裂临界损伤度与外载荷条件（加载应力和拉伸应变率）的无关性或不敏感性；最后，采用Ls-dyna动力有限元程序并嵌入损伤度函数模型，对滑移爆轰下20#钢柱壳内爆驱动层裂进行二维数值模拟研究，结果表明：一维应变平面层裂实验和模型计算确定的损伤模型参数，也适用于描述柱壳构形复杂应力环境下的动态拉伸断裂问题．从而初步证实了断裂临界损伤度可以看作是一个表征延性金属动态拉伸断裂的内禀物性参数．

英文摘要：

The influence of the impact stress and the tensile strain rate on the dynamic tensile fracture of 20# steel was investigated experimentally by plate impact spall tests. Based on the damage function model, numerical calculations about the spall tests were performed. The results indicated that the critical fracture damage Dr is independent on the impact stress and the tensile strain rate. By means of an explicit nonlinear dynamic finite element computer code Ls-dyna, spallation in cylindrical steel tube loaded by slid- ing-implosion had been studied with the introduction of damage function model. Results demonstrated that Ds determined by plate impact and numerical calculation is applicable to predict the dynamic tensile fracture behavior in metal cylinders under the complex loadings as well. Therefore, Ds may be regarded as a mate- rial constant to identify the intrinsic characteristic of the dynamic tensile fracture.