Manner Virginia W, Yeager John D, Patterson Brian M, Walters David J, Stull Jamie A, Cordes Nikolaus L, Luscher Darby J, Henderson Kevin C, Schmalzer Andrew M, Tappan Bryce C
Explosive Science and Shock Physics Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
Materials (Basel). 2017 Jun 10;10(6):638. doi: 10.3390/ma10060638.
The microstructure of plastic bonded explosives (PBXs) is known to influence behavior during mechanical deformation, but characterizing the microstructure can be challenging. For example, the explosive crystals and binder in formulations such as PBX 9501 do not have sufficient X-ray contrast to obtain three-dimensional data by in situ, absorption contrast imaging. To address this difficulty, we have formulated a series of PBXs using octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) crystals and low-density binder systems. The binders were hydroxyl-terminated polybutadiene (HTPB) or glycidyl azide polymer (GAP) cured with a commercial blend of acrylic monomers/oligomers. The binder density is approximately half of the HMX, allowing for excellent contrast using in situ X-ray computed tomography (CT) imaging. The samples were imaged during unaxial compression using micro-scale CT in an interrupted in situ modality. The rigidity of the binder was observed to significantly influence fracture, crystal-binder delamination, and flow. Additionally, 2D slices from the segmented 3D images were meshed for finite element simulation of the mesoscale response. At low stiffness, the binder and crystal do not delaminate and the crystals move with the material flow; at high stiffness, marked delamination is noted between the crystals and the binder, leading to very different mechanical properties. Initial model results exhibit qualitatively similar delamination.
已知塑料粘结炸药（PBXs）的微观结构会影响其在机械变形过程中的行为，但表征这种微观结构可能具有挑战性。例如，PBX 9501等配方中的炸药晶体和粘结剂没有足够的X射线对比度，无法通过原位吸收对比成像获得三维数据。为了解决这一难题，我们使用八氢-1,3,5,7-四硝基-1,3,5,7-四氮杂环辛烷（HMX）晶体和低密度粘结剂体系配制了一系列PBXs。粘结剂为用丙烯酸单体/低聚物的商业混合物固化的端羟基聚丁二烯（HTPB）或缩水甘油叠氮聚合物（GAP）。粘结剂的密度约为HMX的一半，使用原位X射线计算机断层扫描（CT）成像可获得出色的对比度。在中断的原位模式下，使用微型CT对样品在单轴压缩过程中进行成像。观察到粘结剂的刚性会显著影响断裂、晶体-粘结剂分层和流动。此外，对分割后的3D图像的二维切片进行网格化，以对中尺度响应进行有限元模拟。在低刚度下，粘结剂和晶体不会分层，晶体随材料流动而移动；在高刚度下，晶体和粘结剂之间会出现明显的分层，导致机械性能差异很大。初始模型结果显示出定性相似的分层现象。
