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Mechanisms of shock-induced initiation at micro-scale defects in energetic crystal-binder systems
Journal article   Open access   Peer reviewed

Mechanisms of shock-induced initiation at micro-scale defects in energetic crystal-binder systems

P. Das and H. S. Udaykumar
Shock waves, Vol.32, pp.593-616
10/08/2022
DOI: 10.1007/s00193-022-01099-x
url
https://arxiv.org/pdf/2205.08688View
Open Access

Abstract

Crystals of energetic materials, such as 1,3,5,7-Tetranitro-1,3,5,7-tetrazocane (HMX), embedded in plastic binders are the building blocks of plastic-bonded explosives (PBX). Such heterogeneous energetic materials contain microstructural features such as sharp corners, interfaces between crystal and binder, intra- and extra-granular voids, and other defects. Energy localization or "hotspots" arise during shock interaction with the microstructural heterogeneities, leading to initiation of PBXs. In this paper, high-resolution numerical simulations are performed to elucidate the mechanistic details of shock-induced initiation in a PBX; we examine four different mechanisms: (1) shock-focusing at sharp corners or edges and its dependency on the shape of the crystal and the strength of the applied shock; (2) debonding between crystal and binder interfaces; (3) collapse of voids in the binder located near an HMX crystal; and (4) the collapse of voids within HMX crystals. Insights are obtained into the relative contributions of these mechanisms to the ignition and growth of hotspots. Understanding these mechanisms of energy localization and their relative importance for hotspot formation and initiation sensitivity of PBXs will aid in the design of energetic material-driven systems with controlled sensitivity, to prevent accidental initiation and ensure reliable performance.
 Mechanics Technology Science & Technology

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