岩石SHPB试验中子弹形状对加载波形的数值模拟

利用有限元分析软件LS-DYNA对几种不同几何形状入射子弹在霍普金森压杆试验实验中产生的加载波形进行了数值模拟,在入射杆尺寸与撞击速度恒定的情况下,重点探讨入射子弹的几何形状对于加载波形的影响,为设计能打出近似理想半正弦波(或钟形波)的子弹提供理论依据。模拟研究发现:等截面子弹长度与加载波持续时间成正相关;锥形子弹末端截面直径越小,加载波上升沿时与脉冲持续时间越长,同时波形也越趋向于钟形波,但应力峰值则降低;对于本文设计的变截面子弹,其等截面段越长,加载波形越趋向于半正弦波。

Numerical Simulation on the Influence of Projectile Shape on Loading Waveform in SHPB Tests of Rocks

The loading waveforms produced by projectiles of several different geometric shapes in SHPB (Split Hopkinson Pressure Bar)tests of rocks were simulated by the finite element analysis software LS-DYNA. As the size of incident bar and the impact velocity were constant, we emphasized in discussing the influence of geometric shapes of projectiles on the loading waveform in order to provide basis for developing some nice projectile shapes which can produce a waveform similar to half-sine wave(or bell-shaped wave). The simulation results were: 1) for the projectiles with uniform cross section, the longer the length was, the longer the duration of incident wave would be; 2)for the cone projectiles, the smaller the end section diameter was, the longer the duration of the rising stage and the whole incident wave would be, meanwhile, the peak stress decreased and the waveforms were more and more approximate to the bell-shaped wave; 3) for the projectiles with variable cross section given in this paper, the longer the part of uniform cross section was, the incident waveform was closer to half-sine wave.