基于Hopkinson杆的材料高应变率拉伸实验技术

分离式霍普金森杆(Split Hopkinson Bar)是测试材料在高应变率加载下力学行为的一种有效的实验手段.本文基于霍普金森杆测试原理,设计和研制了气枪式变截面间接杆杆型高应变率拉伸实验装置.该装置具有完备的、高精度的水平和轴向基准,采用等高的固定支撑,保证了杆-杆型实验系统具有良好的共轴度；入射杆与撞击套筒之间设有导向管,避免了撞击套筒直接与入射杆接触而产生的相互干扰；在导向管内设有支撑圈,以减小入射杆与导向管直接接触而产生的摩擦,并消除入射杆的径向跳动；采用前置金属短杆来获得光滑、平稳且幅值和宽度可调的拉伸入射加载脉冲.对LY12CZ铝合金在两种应变率下初步的验证性实验表明,该高应变率拉伸实验装置的设计是合理的,实验获得的应力—应变结果是可靠、有效的.

Experimental Technique of High Strain-Rate Tension Based on Hopkinson Bar

Split Hopkinson bar has been widely used to measure the mechanical behavior of materials at high strain rates. A new air-gun and indirect bar-bar type of high strain-rate tensile experimental device with a variable cross-section input bar was designed and manufactured by authors. A self-contained and high-precision level and axial benchmark is established, and fixed equal-height supports are adopted to ensure the reliable coaxality of the bar-bar experimental system. A lined guide tube between the projectile bar and the input bar was designed to avoid mutual interference due to direct contact of the projectile bar with the input bar. Furthermore, the support rings assembled in guide tube is used to decrease the friction between the input bar and the guide tube and to eliminate input bar radial jump. A smooth and stable incident tensile loading pulse with adjustable amplitude and duration can be obtained by changing the diameter and length of prefixed short metal bar. Elementary validation experiments for LY12CZ aluminum alloy at two strain-rates indicate that the design of this high strain-rate tensile experimental device is reasonable; the experimentally obtained stress-strain results are reliable and effective.