LY12铝合金在冲击绝热压缩下的泊松比

对泊松比的意义进行讨论，给出了单轴应变加载下线弹性区的泊松比与纵向应力和横向应力的关系，以及准弹性区的泊松比与声速的关系。通过实验测量LY12铝合金在冲击压缩下的纵波和体波声速，计算在20~131 GPa冲击压力范围内的泊松比。实验结果表明：LY12铝合金在发生冲击熔化前泊松比基本保持为常数，约为0.32左右；发生冲击熔化后混合相区的泊松比快速增加；当接近完全熔化时泊松比趋于理论极限值0.5. 泊松比测量为确定金属的冲击熔化压力区间提供了一种有用的方法。

Poisson's Ratio of LY12 Aluminum Alloy under Shock Compression

The physical meaning of Poisson’s ratio is discussed. The relationships among the Poisson’s ratio and the longitudinal and transverse stresses under uniaxial strain shock loadings, and the relationship between the Poisson’s ratio and the sound velocity in quasi-elastic deformation region are presented. Poisson’s ratios of LY12 aluminum alloy materials are calculated based on the sound velocities measured at shock pressures from 20 GPa to 131 GPa. It is found that, while the Poisson’s ratios keep almost constant, i.e., 0.32, before shock-melting happens, it increases rapidly in the shock-melting solid-liquid mixed phase region and approachs the theoretical limit of Poisson’s ratio, i.e., 0.5, as shock-melting completes, which may provide us a useful way for identifying the shock induced melting zone.