广义机械刺激下高能炸药结构演化与反应级别的多尺度表征

The key to control the explosive energy output of a weapon system lies in the delicate understanding of mechanical and chemical coupling mechanism at multi-scale and multi-level. Various types of mechanical stimulation environment covers a wide strength range of mechanical stimulus for explosive materials during the preparation, transportation, storage and application of weapons. Current concepts of "shock" and "non-shock" detonations have no clear physical definition and quantitative criteria. At present, there is still a lack of explosives safety prediction theory accounting for structure-dependent chemical reaction violence with extensive stimulation range, which brings great confusion to the performance evaluation tests and theoretical model development. Aiming at above problems, this project is intended to address explosive charge filled in ammunition warheads subjected to mechanical and thermal stimulus. The concept of "generalized mechanical stimulation" is introduced according to the characteristics of stress-strain state, strain rate, pressure, failure mechanism, thermal deposition and wave structure. The intrinsic mechanical parameters caused by various thermal and mechanical surroundings are provided as the criterion for stimulus. A multi-physics test system for small-scale explosives will be designed for characterizing different reaction violence such as decomposition, ignition, combustion, explosion, detonation. The dependence of different levels of reaction rates on microstructure will be proposed. The project can promote the physical modeling of explosives safety in a more scientific direction and narrow the gap with advanced countries.

控制武器系统炸药能量输出的关键，在于对炸药多尺度多层次力-化学耦合机理的细腻理解。高能炸药在制备、运输、存储及在武器系统应用中，会遇到类型多样、强弱范围广的机械刺激环境。目前的“冲击”和“非冲击”起爆概念，并没有明确物理概念和定量判据去界定，缺乏宽广刺激范围、兼顾化学反应烈度对结构依赖关系的炸药安全性预测理论。给性能评估试验和理论模型的发展带来很大困惑。针对以上问题，本项目拟针对武器战斗部装药所受复杂力-热学环境，引入“广义机械刺激”的概念，根据热和机械作用所致应力-应变状态、应变率、压力、破坏机理、热能沉积、波结构的特点，给出各种刺激所对应的本征力学物理参量，通过小尺度炸药多物理量测试系统，对炸药分解-点火-燃烧-爆炸-爆轰等不同烈度反应进行测试表征，提出反应等级对结构变化的依赖关系。项目的研究可促进炸药安全领域物理建模朝更科学方向发展，缩小与先进国家的差距。

本项目针对战斗部装药所受复杂力-热学环境，引入“广义机械刺激”概念，根据热和机械作用所导致的力学变形、温升点火和反应等特点，系统给出各种刺激所对应的本征力学物理参量，通过机理试验并结合多物理量测试手段，对炸药分解-点火-燃烧-爆炸-爆轰等不同烈度反应进行测试表征，提出反应等级对结构变化依赖关系。研究内容及成果：①以炸药在不同加载条件下的力学性能为出发点，研究炸药在大温度范围下的准静态以及动态加载下力学性能，对单质炸药以及复合炸药的动态力学响应下的安全性影响。并基于炸药受到机械刺激时会发生复杂力热化学耦合响应，建立宏观力热化学耦合模型预测撞击条件下点火响应与随后化学反应级别；②发展炸药微裂纹-微孔洞力热化耦合细观模型，模型能预测炸药在机械刺激作用下两种不同的微缺陷导致的温升点火机理，且具有较好扩展性，可适应不同初始温度及高温下材料的力热化响应特性，同时可以预测注装高能炸药在冲击载荷作用下粘性剪切流动加热引起的热点点火现象；③发展炸药宏观力热化学耦合模型，采用弹塑性模型描述炸药的力学变形行为，采用塑性功率与有效塑性功相关的双点火准则预测炸药点火响应，点火后燃烧反应由化学反应流模型进行描述，同时考虑未反应物与气体产物的温度计算方法。④建立RDX单晶力-热-相变-反应本构模型，利用模型可模拟RDX单晶在不同载荷下力-热-相变-化学反应，首次给出斜加载的四波结构，能够在细观尺度上解释宏观的各项异性非弹性响应，可以加深对单晶的变形机理理解，讨论RDX相变速度与加热速率和晶体本构的关系，满足炸药制备合成以及含能材料安全性评估的现实迫切需求。⑤探究HMX晶体的热致相变对材料内部损伤演化的影响机制，发展了考虑 HMX 晶体热膨胀和相变等变形机制的热力耦合晶体本构模型，从力学角度揭示了黏结剂包覆 HMX 晶体相变对体积变形、应力状态以及裂纹成核演化过程的影响机理，量化分析了升温速率对材料相变和裂纹损伤状态的影响规律。