Cyclotetramethylene-Tetranitramine (HMX) is a secondary explosive used in military and civilian applications. Its plastic deformation is of importance in the initiation of the decomposition reaction, but the details of plasticity are not yet fully understood. It has been recently shown that both the elastic constants and the critical resolved shear stress for plastic deformation are pressure sensitive. Since initiation takes place during shock loading, the pressure sensitivity of plasticity is highly relevant. In this work, we examine the pressure-sensitivity of the dynamic mechanical behavior of HMX. To this end, we use an elastic–plastic continuum constitutive model of single crystal HMX in which the anisotropic elastic constants and direction-dependent yield stress are rendered pressure-sensitive. The pressure sensitivity is calibrated based on input from molecular models. We observe that accounting for pressure sensitivity changes significantly the profile of the elastic–plastic wave and the wave propagation speed upon impact. The accumulated dissipation profile and the total dissipation also exhibit profound differences between the simulations that take account of the pressure-dependence of the plastic deformation and the pressure independent counterpart.

环四亚甲基四硝胺 (HMX) 是一种用于军事和民用应用的二次炸药。它的塑性变形在分解反应的开始中很重要，但塑性的细节尚未完全了解。最近已经表明，塑性变形的弹性常数和临界解析剪切应力都是压力敏感的。由于引发发生在冲击载荷期间，塑性的压力敏感性是高度相关的。在这项工作中，我们检查了 HMX 动态机械行为的压力敏感性。为此，我们使用单晶 HMX 的弹塑性连续本构模型，其中各向异性弹性常数和方向相关的屈服应力对压力敏感。压力灵敏度根据分子模型的输入进行校准。我们观察到，考虑到压力敏感性，弹塑性波的轮廓和冲击时的波传播速度会发生显着变化。累积耗散分布和总耗散在考虑塑性变形的压力相关性和压力无关的对应物的模拟之间也表现出巨大的差异。