拉伸应变率对20钢层裂特性的影响

采用轻气炮加载技术和激光速度干涉(VISAR)测速技术相结合，对不同拉伸应变率条件下20钢的层裂特性进行了实验研究。通过改变飞片和样品的几何尺寸来调整拉伸应变率的大小，研究了拉伸应变率对20钢层裂强度的影响。实验的拉伸应变率的变化范围为104~106 s-1，最大拉伸应变率接近激光加载所能产生的拉伸应变率，相比激光加载，薄飞片技术容易保证一维应变条件。实验结果显示20钢的层裂特性明显依赖着拉伸应变率的大小，106 s-1条件下层裂强度比104 s-1时提高近70%。基于对数值计算结果的分析，讨论了影响层裂强度的主要外载荷因素。

Effect of tensile strain rate on spall fracture in 20 steel

Using a gas gun, a set of plate impact experiments were performed for 20 steel by measuring the rear free-surface velocity profiles with a velocity interferometer system for any reflector (VISAR). Experiments were arranged by adjusting the thicknesses of flyer and sample to change the tensile strain rate, in order to investigate the effect of the tensile strain rate on the spall strength. The maximum tensile strain rate approximately reaches 10⁶ s^-1, and approachs to the value determined by the laser irradiation. Compared with laser irradiation, the thin flyer technique is easy to satisfy the one-dimensional strain condition for spall fracture. The measured results show that an apparent increase of spall strength with tensile strain rate is evidenced, and 70% increase of spall strength is determined in the present tensile strain rate range of 10⁴~10⁶ s^-1. Based on the numerical simulation results, the influence of the loading conditions on the spall strength was discussed.