低速冲击载荷下高聚物粘结炸药绝热温升效应研究

The initiating mechanism of Polymer Bonded Explosive (PBX) under low velocity impact load has been a puzzle for PBX safety research. Although the hot spot initiating viewpoint has been generally acceptable, because of being lack in researches on how the mechanical energy dissipating to temperature rise and what the conversion charateristic to be, the researches based on the hot spot initiation theory often assume that all or part of the mechanical energy dissipating to heat led to PBX adiabatic temperature rise and are generally confined to give some qualitative interpretations. These problems are urgent to be solved to meet the develoment of the hot spot initiating theory. By analyzing the adiabatic temperature rise of PBX under low velocity compression impact load as an access, this project will investigate the conversion behavior of mechanical energy in PBX. Firstly, by virtue of the advanced temperature sensor technologies, we will establish a test method which can record the rapid temperature rise behavior in microsecond. Then combining with Split Hopkinson Pressure Bar (SHPB), and following the order of "single explosive crystal to polymer binder to PBX", these problems of energy dissipation behavior under low velocity imoact load, the conversion charateristics and the model will be studied to disclosure the mechanism of PBX adiabatic temperature rise. Finally, we will explore the adiabatic temperature rising, press and microstructure changing of PBX before initiating under higher impact load energy than that of SHPB. Based on numerical simulation analysis the mechanism of PBX adiabatic temperature rising will also be investigeted. This project, from a energy conversion viewpoint, will provide research foundation on the safety of PBX which is of great concern to the development of adcanced weapons.

高聚物粘结炸药(PBX)低速冲击起爆机理一直困扰其安全性研究，由于缺乏机械载荷在PBX中能量耗散方面的研究基础，在已被普遍接受的热点起爆理论研究中常假设"机械能全部或部分转变成热能导致PBX绝热温升"而局限于定性解释，热点起爆理论发展亟待深入认识机械能在PBX中如何转换及其转换特性。 本项目以低速冲击压缩载荷下PBX绝热温升效应为切入点，开展对该问题研究。首先基于新型温度传感器技术建立PBX微秒级绝热温升测试方法；将该方法与霍普金森压杆(SHPB)相结合，从"炸药单晶→粘结剂→PBX"途径，认识PBX的能量耗散行为及功热转换特性，建立其功热转换模型；开展比SHPB更高能量加载试验，研究PBX温升、压力及微结构变化，结合数值模拟，掌握PBX临界起爆前的绝热温升历程及其机制。通过本项目完成，将从能量转换角度，为先进武器十分关注的低速冲击起爆机理研究提供基础。

在高聚物粘结炸药（PBX）的热点起爆理论研究中常常假设“机械能全部或部分转变成热能导致PBX绝热温升”，热点起爆理论发展亟待深入认识机械能在PBX中的能量耗散行为。本项目以低速冲击压缩载荷下PBX绝热温升效应为切入点开展此项研究。在技术路线上，除了开展基于Hopkinson压杆、气炮、火炮的中低速冲击载荷下PBX响应研究外，还开展了基于材料试验机的静态载荷下PBX的响应特性研究，以更好地认识机械载荷在PBX中能量转换问题。首先开展了不同加载速度PBX能量耗散试验技术研究，建立了基于材料试验机、Hopkinson压杆、气炮、火炮等加载手段的PBX能量耗散试验装置及其响应检测方法，自主研制成功了一种微细热电偶，其测试精度达到Ⅱ级、响应时间优于1μs，突破了一直以来机械载荷作用下PBX的瞬态温升过程无法准确测试的难题。开展了不同速度载荷条件下以RDX/HTPB为基PBX、RDX晶体、HTPB粘结剂等材料的能量耗散试验研究，掌握了其不同的能量耗散特点，获得了低速冲击载荷作用下PBX因应力波的多次作用而导致累积温升直至反应爆炸、中等速度冲击载荷下PBX反应过程存在“快速温升→恒温反应→爆炸”三个阶段等多个试验现象。基于对机械载荷在PBX中主要能量耗散形式分析，提出了机械载荷在PBX中的能量耗散表达形式，开展其中本构关系、弹塑性应变能之比、功热转换模型等关键项研究，所建立的本构关系具有较高的描述精度，计算了RDX/HTPB为基PBX的弹塑性应变能之比β在0.2~0.4之间，计算获得了PBX功热转换系数η在0.9~1之间。开展了PBX能量耗散行为的细观数值模拟分析，数值模拟计算结果与试验较为吻合，结合PBX内部微结构变化研究，提出了不同载荷条件下PBX能量耗散机制，深化了对低速冲击载荷下PBX起爆行为的认识。