利用VISAR测量LY12铝在冲击压缩下的声速

 介绍了利用VISAR技术测量受冲击压缩LY12铝的高压声速的方法。平板对称碰撞实验在冲击波物理与爆轰物理实验室的二级轻气炮上进行，峰值应力约为20、32、55和71 GPa。每发实验中，VISAR同时使用三种条纹常数测量LY12铝和单晶LiF窗口的界面粒子速度剖面。从三种条纹常数计算的界面粒子速度剖面相互符合，完全一致。实验信号具有很高的信噪比，表明样品与窗口之间的界面连结和处理技术非常成功。这种测量技术不仅能够得到初始加载应力下的纵波声速，而且能够得到声速沿着卸载路径的变化。将声速的塑性段外推到初始冲击加载压力即得到该压力下的体积声速。LY12铝的声速测量结果与假定ργ为常数条件下用Mie-Grüneisen状态方程计算的结果符合得很好。

Sound Velocity Measurements for Shock-Compressed LY12 Aluminum Alloy by Using VISAR Technique

The experimental method to measure the high-pressure sound velocity of shock-compressed LY12 aluminum alloy by VISAR technique is described. Symmetrical plate impact experiments were conducted with the two-stage light-gas gun and at peak stresses about 20, 32, 55 and 71 GPa, respectively. In each shot, a VISAR system with three different fringe-constants was used to measure the particle-velocity profile at the interface between the test sample and the single crystal LiF window. The particle velocity histories deduced from three fringe numbers in each shot coincided with each other excellently. The high signal to noise experimental records also demonstrated that the joint and the treatment of the interface between the sample and the window were very successful. Beside the longitudinal sound velocities at the initial shock stresses, also produced were the sound velocity histories along the release paths, from which the bulk sound velocities at the initial shock stresses were determined by extrapolating the plastic portion of the sound velocity history. These results were consistent with the calculations obtained through Mie-Grüneisen equation of state under the assumption that ργ=constant.