Critical velocities for deflagration and detonation triggered by voids in a REBO high explosive

TL;DR

This study uses molecular dynamics simulations to investigate how voids influence the shock sensitivity of a high explosive, revealing that larger voids significantly lower the velocity needed to trigger deflagration or detonation.

Contribution

It provides new insights into the role of void size on explosive sensitivity using a detailed reactive molecular dynamics model.

Findings

Larger voids cause a more deterministic reaction initiation.

Void radius as small as 10 nm reduces the minimum initiating velocity by a factor of 4.

Reaction probability increases sharply with piston velocity for larger voids.

Abstract

The effects of circular voids on the shock sensitivity of a two-dimensional model high explosive crystal are considered. We simulate a piston impact using molecular dynamics simulations with a Reactive Empirical Bond Order (REBO) model potential for a sub-micron, sub-ns exothermic reaction in a diatomic molecular solid. The probability of initiating chemical reactions is found to rise more suddenly with increasing piston velocity for larger voids that collapse more deterministically. A void with radius as small as 10 nm reduces the minimum initiating velocity by a factor of 4.