Chang Lizhen, Yao Wenkai, Yu Yin, Ge Nina
State Key Laboratory of Environment-Friendly Energy Materials, Southwest University of Science and Technology, Mianyang, P. R. China.
Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang, 621900, China.
J Mol Model. 2025 Mar 18;31(4):122. doi: 10.1007/s00894-025-06337-4.
The formation of hot spots and chemical decomposition of explosives under shock loading are crucial for understanding the initiation of heterogeneous explosives. In this study, molecular dynamics simulations were employed to investigate the collapse of nanovoids, hotspot formation, and decomposition reactions of HMX under four typical stress wave loadings: long-pulse, short-pulse, triangular wave, and ramp wave. Different loading modes lead to varying critical transition velocities at which void collapse shifts from uniform to jetting collapse. For long-pulse loading, short-pulse and ramp wave loadings, and triangular wave loading were about 1.75 km/s, 2.25 km/s, 2 km/s and 2.5 km/s, respectively. Furthermore, it was found that under the uniform collapse mode, the hot spot temperature remains below 2000 K, and the initial decomposition pathway of HMX primarily involved the breaking of the N-NO₂ bond. In the jetting collapse mode, hydrogen transfer and the formation of HONO were observed. These findings contribute to a better understanding of the relationship between shock loading modes and void collapse patterns in explosives, revealing the initial reaction pathways of HMX under different collapse modes, and providing theoretical guidance for experimental investigations, to provide a theoretical basis for developing a new ignition model.
Based on the ReaxFF-MD method, Lammps software was used to simulate the shock process of the HMX system with circular holes, and the reaction force field files containing C, H, O, and N elements were used. The post-processing of the results was implemented using OVITO and self-programmed Python scripts.
热点的形成以及炸药在冲击载荷下的化学分解对于理解非均质炸药的起爆至关重要。在本研究中，采用分子动力学模拟研究了四种典型应力波载荷（长脉冲、短脉冲、三角波和斜坡波）作用下纳米孔洞的坍塌、热点形成以及HMX的分解反应。不同的加载模式导致孔洞坍塌从均匀坍塌转变为喷射坍塌的临界转变速度各不相同。对于长脉冲加载、短脉冲和斜坡波加载以及三角波加载，临界转变速度分别约为1.75 km/s、2.25 km/s、2 km/s和2.5 km/s。此外，研究发现，在均匀坍塌模式下，热点温度保持在2000 K以下，HMX的初始分解途径主要涉及N-NO₂键的断裂。在喷射坍塌模式下，观察到了氢转移和HONO的形成。这些发现有助于更好地理解炸药中冲击加载模式与孔洞坍塌模式之间的关系，揭示不同坍塌模式下HMX的初始反应途径，并为实验研究提供理论指导，为开发新的点火模型提供理论依据。
基于ReaxFF-MD方法，使用Lammps软件模拟含圆孔的HMX体系的冲击过程，并使用包含C、H、O和N元素的反应力场文件。结果的后处理使用OVITO和自编的Python脚本实现。
