SHPB实验加载方式对PBX炸药力学响应的影响研究

高聚物粘结剂炸药(PBX)炸药的损伤本构关系是炸药安全性研究的重要基础课题之一。研究PBX炸药的损伤本构关系需要建立在准确获取和认识PBX炸药的动态力学响应基础之上。为此,针对某PBX炸药的SHPB实验,详细探讨加载方式的细节设计对PBX炸药力学响应的影响。通过采用不同应变加速度、不同加载脉宽以及重复加载等方法,分析了不同加载条件对PBX炸药力学响应的影响,并获得了一系列不同加载脉宽、不同加载应变率的应力应变曲线。采用扫描电镜观察回收试样最终损伤形态,分析了PBX炸药动态单轴压缩下的损伤发展过程及其在应力应变关系上的表现。结果表明:应变加速度过大仍会对PBX炸药形成一定的冲击加载,造成额外损伤;经历动态单轴压缩后破坏的试样表现为晶体多次穿晶断裂甚至碎裂;典型PBX炸药的损伤本构关系可从微裂纹的产生、稳定扩展,穿越晶界失稳扩展来描述。

Investigation into the Influences of SHPB Loading Ways on the Mechanical Response of PBX

The constitutive relationship of polymer bonded explosive (PBX) including damage is one of the key fundamental issues of the safety research of PBX. To study the damage constitutive relationship of PBX explosive, it is necessary to accurately acquire and understand the dynamic mechanical response of PBX explosive.. Therefore, in allusion to the SHPB tests on PBX, it is particularly discussed that the influence of loading ways on the mechanical response of PBX. Through different shapers, loading wave length, and repeated loading, the influences of different loading ways on the mechanical response including damage of PBX have been analyzed, and a series of stress-strain curves were obtained. The ultimate damage morphology of recycled samples was observed by scanning electron microscopy, and the damage development process of PBX explosive under dynamic uniaxial compression and its performance in stress-strain relationship were analyzed.. Results show that loading with brass shaper leads to large strain acceleration and still has an impact on PBX, resulting in additional damage. The failure of specimens subjected to dynamic uniaxial compression is characterized by multiple transgranular fracture or even fragmentation of crystals. The constitutive relationship considering damage can be described by the nucleation, stable growth, and unstable propagation through crystals of micro-cracks.