冲击载荷下活性材料的动态破坏机理研究

Due to the mechanical strength and reaction performance when subjected to intensive impact loading, reactive materials can significantly improve the damage capacity of the warhead. The impact-induced reaction and energy release of reactive materials are tightly associated with their failure properties. Focusing on the dynamic failure properties, two typical reactive materials—metal/polymer and intermetallic compounds are investigated in this project, the details are shown in the following: (1) A series of experiments are performed in both quasi-static and dynamic state to investigate the dynamic behaviors and the failure properties of the reactive materials. As the result, some influence laws are obtained to describe the effects of particle size, type, porosity and the proportion of each component on the macroscopic failure properties and ignition reaction. (2) The microstructure of the specimens is observed after impact to analyze the damage mode of the two kinds of reactive materials. Based on the meso-damage mechanics, a thermo-mechanical constitutive model can be established by considering the evolution of microcracks and micropores. (3)A theoretical model of the heat source zone at crack tip is established and the effects of thermodynamic parameters and crack propagation velocity on temperature rise at crack tip are obtained, which reveals the hotspot formation mechanism of the reaction induced by deformation and failure of reactive materials. (4) A numerical method is applicable in the study to investigate the thermo-mechanical-chemical response of reactive materials combined with constitutive model, state equation as well as reaction kinetic equation. Achievements in this project provide an important theoretical basis and technical support to the application of high-efficiency damage technology in China.

活性材料具有一定的强度，爆炸与冲击载荷下迅速发生反应产生燃烧或爆炸效应，可显著提高战斗部对目标的毁伤能力。活性材料的冲击反应和能量释放与其冲击破坏特性紧密相关。本项目围绕金属/聚合物、金属间化合物两类活性材料的动态破坏开展研究：（一）通过静态和动态多种冲击实验测试技术，研究活性材料的动力学响应和破坏特点，获得颗粒尺寸、类型、孔隙率、组份比例对力学性能、破坏特性和点火反应的影响规律；（二）对冲击破坏后的试件进行细观结构观察，分析两类活性材料的损伤破坏模式；基于细观损伤力学，给出损伤演化方程，建立含损伤的热-力学本构模型；（三）建立裂纹尖端热源区的理论模型，获得材料热力学参数和裂纹扩展速度对裂尖温升的影响规律，揭示活性材料变形破坏诱导的冲击反应的热点形成机理；（四）结合材料本构模型、状态方程和反应动力学方程，数值计算活性材料的热-力-化学响应，为我国高效毁伤技术的应用提供理论基础和技术支撑。

活性材料具有一定的强度，爆炸与冲击载荷下迅速发生反应产生燃烧或爆炸效应，可显著提高战斗部对目标的毁伤能力。活性材料的冲击反应和能量释放与其冲击破坏特性紧密相关。 本项目围绕金属/聚合物、金属间化合物两类活性材料的动态破坏开展研究，为新型含能材料在战斗部设计、高效毁伤技术的应用方面提供理论基础和技术支撑。主要研究工作和成果有：.（1）通过模压烧结法制备了 Al/PTFE、纤维增强Al/PTFE、Zr/PTFE和Al/W、Zr/W多种活性材料，采用改进的分离式霍普金森压杆装置（SHPB），研究了上述活性材料在高应变率下的动力学性能和破坏特性。研究表明：Al/PTFE、Zr/PTFE动态应力应变曲线是典型的弹塑性变形特征，动态抗压强度随应变率(应变率103/s-1)增加而提高；纤维（纤维含量1%-4%）的加入显著提高了Al/PTFE活性材料动态抗压强度；W质量分数(44%，64%，83 %)较低时，Al/W活性材料呈现典型的弹塑性变形特点；而当W质量分数达到91%时，试件呈现脆性破坏的特点；Zr/W活性材料抗压强度显著高于聚合物基活性材料，其动态应力应变曲线呈现明显的弹脆性破坏特征。.（2）基于 SHPB 实验技术，采用“升降法”获得了Al/PTFE活性材料撞击反应阈值，并分析了活性材料的细观特征（孔隙率、铝粉粒径、初始损伤）及温度对反应特性的影响规律。研究表明，孔隙率 2.9%~4.8% 时，随孔隙率的降低,Al/PTFE 试件的比入射能量阈值缓慢升高；Al粉粒径对活性材料反应阈值有显著的影响， 200μmAl粉粒径的Al/PTFE试件更难发生反应；此外，活性材料的冲击反应阈值具有显著的损伤敏化现象；温度（22℃-205℃）范围内，温度增加Al/PTFE更容易变形和分解，从而使得其撞击反应阈值显著下降。.（3）基于孔洞塌缩模型和累计损伤模型，分析了不同孔隙率Al/PTFE 在多次脉冲载荷下的孔壁温升曲线以及 Al/PTFE 在撞击载荷下的损伤演化过程，揭示了活性材料热点形成机理；建立了Al/PTFE活性材料的粘弹性损伤本构模型，并将该模型嵌入到动力学有限元程序中，数值模拟了不同应变率下Al/PTFE的动力学响应，与实验结果有良好的一致性。