Abstract A multiscale modeling strategy is used to quantify factors governing the temperature rise in hot spots formed by pore collapse from supported and unsupported shock waves in the high explosive HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine). Two physical aspects are examined in detail, namely the melting temperature and liquid shear viscosity. All-atom molecular dynamics simulations of phase coexistence are used to predict the pressure-dependent melting temperature up to 5 GPa. Equilibrium simulations and the Green–Kubo formalism are used to obtain the temperature- and pressure-dependent liquid shear viscosity. Starting from a simplified continuum-based grain-scale model of HMX, we systematically increase the complexity of treatments for the solid–liquid phase transition and liquid shear viscosity in simulations of pore collapse. Using a realistic pressure-dependent melting temperature completely suppresses melting for supported shocks, which is otherwise predicted when treating it as a constant determined at atmospheric pressure. Alternatively, melt pools form around collapsed pores when the pressure (and melting temperature) are reduced during the release stage of unsupported shocks. Capturing the pressure dependence of the shear viscosity increases the peak temperature of melt pools by hundreds of Kelvin through viscous work. The complicated interplay of the solid-phase plastic work, solid–liquid phase transition, and liquid-phase viscous work identified here motivate taking a systematic approach to building increasingly complex grain-scale models.

中文翻译：

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孔隙塌陷加热对 HMX 熔融温度和剪切粘度的敏感性

摘要 使用多尺度建模策略来量化控制高爆 HMX (octahydro-1,3,5,7-tetranitro-1,3,5 ,7-四唑嗪)。详细检查了两个物理方面，即熔融温度和液体剪切粘度。相共存的全原子分子动力学模拟用于预测高达 5 GPa 的与压力相关的熔化温度。平衡模拟和 Green-Kubo 形式用于获得与温度和压力相关的液体剪切粘度。从简化的基于连续介质的 HMX 晶粒尺度模型开始，我们系统地增加了在模拟孔隙坍塌时固液相变和液体剪切粘度处理的复杂性。使用与压力相关的实际熔化温度可以完全抑制受支持冲击的熔化，否则在将其视为在大气压下确定的常数时会预测到这种情况。或者，在无支撑冲击的释放阶段，当压力（和熔化温度）降低时，会在坍塌的孔隙周围形成熔池。捕捉剪切粘度的压力依赖性通过粘性功将熔池的峰值温度提高了数百开尔文。此处确定的固相塑性功、固液相变和液相粘性功之间复杂的相互作用促使采用系统方法来构建日益复杂的颗粒尺度模型。当将其视为在大气压下确定的常数时，否则会预测到这一点。或者，在无支撑冲击的释放阶段，当压力（和熔化温度）降低时，会在坍塌的孔隙周围形成熔池。捕捉剪切粘度的压力依赖性通过粘性功将熔池的峰值温度提高了数百开尔文。此处确定的固相塑性功、固液相变和液相粘性功之间复杂的相互作用促使采用系统方法来构建日益复杂的颗粒尺度模型。当将其视为在大气压下确定的常数时，否则会预测到这一点。或者，在无支撑冲击的释放阶段，当压力（和熔化温度）降低时，会在坍塌的孔隙周围形成熔池。捕捉剪切粘度的压力依赖性通过粘性功将熔池的峰值温度提高了数百开尔文。此处确定的固相塑性功、固液相变和液相粘性功之间复杂的相互作用促使采用系统方法来构建日益复杂的颗粒尺度模型。在无支撑冲击的释放阶段，当压力（和熔化温度）降低时，会在坍塌的孔隙周围形成熔池。捕捉剪切粘度的压力依赖性通过粘性功将熔池的峰值温度提高了数百开尔文。此处确定的固相塑性功、固液相变和液相粘性功之间复杂的相互作用促使采用系统方法来构建日益复杂的颗粒尺度模型。在无支撑冲击的释放阶段，当压力（和熔化温度）降低时，会在坍塌的孔隙周围形成熔池。捕捉剪切粘度的压力依赖性通过粘性功将熔池的峰值温度提高了数百开尔文。此处确定的固相塑性功、固液相变和液相粘性功之间复杂的相互作用促使采用系统方法来构建日益复杂的颗粒尺度模型。