子弹撞击Hopkinson杆的应力误差分析

Stress error analysis of bullet impacting Hopkinson bar

针对在Hopkinson杆的中间对称位置放两片应变片测得时间-应力曲线不同的问题,采用ANSYS/LS-DYNA有限元分析软件建立子弹撞击小杆的实验模型;通过仿真得到沿着杆轴向不同位置的时间-应力曲线,该曲线的变化趋势和平头弹撞击Hopkinson杆实验数据得到的实测时间-应力曲线变化趋势一致,得出压力变化越快,应变率越大,导致应变快,相应的应力增大快的结论。由于应力波的衰减与弥散,前应变片测得的应力总是大于后应变片。

Two strain gauges put on the symmetrical position in the middle of a Hopkinson bar were measured to obtain different time-stress curves. As a result, the ANSYS/LS-DYNA finite element analysis software was used to build an experimental model for bullets hitting the bar. The time-stress curves in different positions along the stem direction were gained through simulation tests. The variation trend of these curves was consistent with that of the time-stress curves obtained through the experiment of head bullets hitting the Hopkinson bar. In conclusion, the faster the pressure changes, the greater the strain rate and the stress become. The measured stress of the former strain gauge is always larger than that of the latter one due to the attenuation and dispersion of the stress wave.