Modeling and Simulation of RDX Powder Thermo‐Mechanical Response to Drop Impact

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.