高温下炸药晶体尺度冲击细微观力学-点火响应研究

Polymer bonded explosive (PBX) is the key energy component in warhead of weapon system. During the manufacturing, transportation and utilizing processes, the high localized energy directly affects the structural reliability and safety of the weapon system. Subjected to complex thermal and shock loading, the key to establishing relationships between the ignition response of heterogeneous energetic materials and their microstructures (formulation) is to obtain the mesoscale mechanical-ignition mechanisms of explosive single crystal under shock loading at elevated temperatures. In the present work, we set up a mesoscale test platform for explosive single crystals under shock loading at elevated temperatures to obtain the anisotropic mechanical responses of HMX and RDX single crystals. Based on the tests results, a temperature and pressure dependent mesoscopic reactive model is developed to analyze the mesoscale thermal-mechanical-chemical responses of HMX and RDX single crystals. Moreover, an algorithm for the generation of polycrystal microstructures with prescribed grain sizes, shapes, and size distributions is established and a mesoscale simulation framework is developed to quantify the effect of microstructure on ignition sensitivity of PBX under shock at elevated temperatures, which helps to better understand the ignition mechanisms, to guide the formulation and structural design of energetic materials and to predict the ignition sensitivity of PBX at the macroscale.

塑性粘结炸药(PBX)作为武器系统战斗部中的关键能量部件材料，其在加工、运输、使用过程中的能量高度局部化，直接影响武器系统的安全性和结构可靠性。受复杂热和冲击环境的影响，量化PBX微观结构与点火感度关系的重点在于获取高温下炸药单晶的冲击细微观变形-点火机制。本项目从细观晶体尺度出发，发展高温下炸药单晶冲击试验测试方法，研究高温下不同取向HMX和RDX单晶的冲击细观力学响应，建立温度和压力相关的晶体细微观力-化学耦合本构模型。通过开发微观结构生成算法构建PBX微观结构几何计算模型，量化微观结构对高温下PBX冲击细观力学-点火响应的影响。研究结果对从细观尺度深入理解炸药点火机制、预测和评价安全性和安定性、指导炸药配方和结构设计以及搭建细微观力学响应与宏观点火感度的桥梁具有十分重要的意义。

深入理解炸药在热和冲击作用下的点火机制对炸药的安全性研究具有重要意义，本项目首先建立了热力刺激共同作用下炸药单晶多物理场耦合测试方法，获取并揭示了高温下炸药单晶的冲击响应特性规律；建立了热刺激下炸药宏细观点火响应特性计算方法，在获取宏观热-点火响应的基础上，揭示了炸药细观相变-点火响应规律；发展了单晶多物理场力-热-化学耦合模型，构建了三维PBX炸药的细观计算框架，得到了温度、加载压力对PBX炸药力-热-点火响应的影响规律。以上结果对从细观尺度深入理解炸药在热力复合刺激下的点火机制、预测复杂环境下炸药的安全性和安定性具有重要意义。