Under uniaxial shock compression, the steepness of the plastic shock front usually exhibits power law characteristics with the Hugoniot pressure, also known as the “Swegle-Grady law.” In this Letter, we show that the Swegle-Grady law can be described better by a third power law rather than the classical fourth power law at the strain rate between ${10}^5–{10}^7{\mathrm{s}}^{-1}$. A simple dislocation-based continuum model is developed, which reproduced the third power law and revealed very good agreement with recent experiments of multiple types of metals quantitatively. New insights into this unusual macroscopic phenomenon are presented through quantifying the connection between the macroscopic mechanical response and the collective dynamics of dislocation assembles. It is found that the Swegle-Grady law results from the particular stress dependence of the plasticity behaviors, and that the difference between the third power scaling and the classical fourth power scaling results from different shock dissipative actions.

中文翻译：

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再谈冲击载荷下塑性冲击前沿的幂律特性

在单轴冲击压缩下，塑性冲击前沿的陡度通常具有Hugoniot压力的幂律特征，也称为“ Swegle-Grady定律”。在这封信中，我们表明，在应变率之间，Swegle-Grady定律可以用第三幂定律而不是经典的第四幂定律更好地描述。${10}^5–{10}^7{\mathrm{s}}^{-\mathrm{1个}}$。建立了一个简单的基于位错的连续体模型，该模型重现了第三幂定律，并且与多种金属的近期定量实验结果非常吻合。通过量化宏观机械响应与位错集合体的集体动力学之间的联系，提出了对这种异常宏观现象的新见解。结果发现，Swegle-Grady定律是由可塑性行为的特定应力依赖性引起的，而第三幂定标和经典第四幂定标之间的差异是由不同的耗散作用引起的。