Influence of the shape of RDX grains on the creation of hot spots by mesoscale modeling

TL;DR

This study uses mesoscale modeling to analyze how the shape of RDX grains influences hot spot formation during shock initiation, revealing that sharp-edged particles generate more hot spots than spherical ones.

Contribution

It introduces a mesoscale modeling approach combining real and virtual microstructure models to study the effect of particle shape on hot spot creation in energetic materials.

Findings

Sharp-edged particles produce more hot spots than spherical particles.

Microstructure heterogeneities are closely related to pressure and temperature hot spots.

Modeling microstructure effects helps understand explosive sensitivity.

Abstract

CEA-Gramat studies the sensitivity of energetic materials to enhance their security and reliability. The conditions leading to the initiation of an explosive must be understood to control its sensitivity. According to the hot spots theory, the shock initiation of heterogeneous explosives is related to their microstructure: the shock interacts with the heterogeneities of the microstructure (pores and inclusions, morphology of grains and fragments, debonding, etc.) and creates local deposits of energy. To describe these hot spots, energetic materials have to be modeled at a scale allowing the discretization of their microstructure: the mesoscale. Micro-computed tomographies of energetic materials are done at CEA-Gramat and analyzed to build geometric models used in finite element simulations. Two kinds of models are studied:-Real models are directly built on the real microstructures extracted from micro-computed tomographies.-Virtual models are based on the same microstructures but simplified to study independently the effects of microstructural parameters (granulometry, porosity, filler content{\ldots}) on the creation of hot spots. Compositions based on different kind of RDX particles in an inert binder are studied through numerical simulation. The influence of particle shape on the inert shock response is investigated at the mesoscale. Local heterogeneities of pressure and temperature fields appear intimately related to the morphological properties of the microstructures. Particles with sharp edges create more hot spots than spherical particles.