铝的动态屈服强度测量及再加载弹性前驱波的形成机理分析

利用激光干涉测速技术(VISAR)测量LY12铝合金在20—34 GPa冲击压力下经历加载-卸载和加载-再加载过程的样品/窗口界面粒子速度剖面，采用AC方法确定了具有较高精度的动态屈服强度值.实验结果和文献发表的数据具有较好的一致性.通过以平面焊接方式制作组合飞片，克服了组合飞片在气炮发射过程中可能发生分离的技术困难，使铝的动态屈服强度测量压力范围从22 GPa扩展到了34 GPa.同时，根据对不同实验条件下的加载-再加载过程的比较，对再加载弹性前驱波的形成机理进行了讨论，认为位错是形成该现象的主要原因. 关键词： 动态屈服强度 AC方法 弹性前驱波 VISAR

Measurements of dynamic yield strength of aluminum alloy and mechanism analysis of elastic precursor during reloading

Dynamic yield strength is one of the key variables in construction of the constitutive relationship for solids under shock loading. This paper reports the yield strength of LY12 aluminum alloy which was measured experimentally on the basis of the method proposed by J. R. Asay and L. C. Chhibildas, in which the test sample underwent a load-reload process and a load-unload process, and the particle velocity history at the LY12 Al sample/LiF transparent window interface was observed by velocity interferometer system for any reflecting surface (VISAR). Improvement in fabrication of the layered flyer plate made these experiments successful. The measured yield strength data at shock stresses of 22GPa and 34GPa are consistent with the reported data at relatively lower pressures. Moreover, physical mechanism of the elastic precursor emerging in the reloading-process was discussed briefly. It is concluded that dislocations is the principal factor resulting in the elastic precursor.