Hybrid Continuum and Multi‐Particle Simulation of RDX Powder Subjected to Drop Impact

Abstract

A variety of energetic material (EM) devices could be designed more efficiently with a more rapid protocol of modeling and testing if computational tools are more predictive. Drop weight impact tester (DWIT) is widely used to experimentally study energetic material response to impact. Drop weight impact on a thin layer of RDX powder is studied here and computationally modeled to compute the likelihood of EM powder ignition from low‐speed impact. The overall objective is to develop a thermomechanical‐based FEM methodology that can qualitatively predict ignition‐likelihood to study iginition mechanics in EM powders and understand how anvil properties and striker impact conditions influence it. The mechanical confinement conditions offered by an anvil and striker type, influence energy transmission and heat localization within the energetic powder. Efficiently modeling both the bulk behavior and the mesoscopic behavior, such as, localized shear and particle‐to‐particle frictional heating, is necessary to design insensitive EM‐devices. A 3D finite element modeling (FEM) approach is described that more accurately models the impact conditions than previously developed 2D models. The results are compared with the experimental results and the 2D simulations. A continuum‐based explicit FEM can only simulate the bulk‐behavior of the powder. To accurately predict hot‐spot ignition mechanisms, meso‐scale multi‐particle models of the EM is needed. For computational efficiency, hybrid models that combines continuum and multi‐particle FEM (MPFEM) were utilized. The computed temperature profiles are compared for two anvil types and demonstrates that an assessment of ignition likelihood is viable with the hybrid methodologies proposed.