A computational framework to predict the deformation, flow, and compaction of an energetic material (EM) powder subjected to drop impact is discussed. Explicit dynamic finite element analysis was performed to simulate drop-weight impact tests for comparison with experimental results and to gain insight into the ignition sensitivity of RDX powder. The computations simulated the Thermo-Mechanical behavior of a thin layer of energetic powder subjected to drop impact to study the dependence of ignition sensitivity on the anvil material properties. By modeling high strength steel and a low strength copper anvil, a direct comparison is made on how energy dissipation within the EM is influenced by anvil properties. A hybrid finite element model is introduced that captures the mesoscale discrete particle nature of the powder response in regions of interest while using a continuum model elsewhere to reduce computational cost. To capture the mesoscale behavior, a multi-particle finite element method (MPFEM) approach was used in selected regions in the hybrid model. Powder temperatures were computed to understand how the striker impact energy is dissipated by plasticity and friction into localized heating of the EM that triggers the ignition. Munition designers can use such a framework to study the low-level impact sensitivity of munitions in a computationally efficient manner. Results of the simulation using the hybrid model suggest that copper anvil undergoes plastic deformation which absorbs a significant portion of the impact energy reducing the energy dissipated within the EM and suppressing ignition.

中文翻译：

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RDX粉末对跌落冲击的热机械响应的建模和仿真

讨论了一种计算框架，用于预测受到跌落冲击的含能材料 (EM) 粉末的变形、流动和压实。进行显式动态有限元分析以模拟落锤冲击试验，以便与实验结果进行比较，并深入了解 RDX 粉末的点火敏感性。计算模拟了受到跌落冲击的高能粉末薄层的热机械行为，以研究点火敏感性对砧材料特性的依赖性。通过模拟高强度钢和低强度铜砧，直接比较了 EM 内的能量耗散如何受砧特性的影响。引入了混合有限元模型，该模型捕获感兴趣区域中粉末响应的中尺度离散粒子性质，同时在其他地方使用连续模型来降低计算成本。为了捕捉中尺度行为，在混合模型的选定区域中使用了多粒子有限元方法 (MPFEM) 方法。计算粉末温度以了解撞击能量如何通过塑性和摩擦消散到 EM 的局部加热中，从而触发点火。弹药设计者可以使用这样的框架以计算效率高的方式研究弹药的低级撞击敏感性。