Modifications and Applications of the HERMES model: June - October 2010

A Computer Model to Study the Response of Energetic Materials to a Range of Dynamic Loads

“…Computer simulations of those tests have shown that the value of the ignition criterion is quite sensitive to the coefficient of friction used. A separate parameter study, using a simplified geometry where a disk of explosive is crushed between two platens, illustrated both the sensitivity to friction, and how the localization of plastic strain depends on the pressure-and strain-rate-sensitivity of the flow stress [27]. If the flow stress is assumed constant, the maximum strain developed, and the maximum value of the ignition criterion, is inversely proportional to the mesh size.…”

HERMES: A Model to Describe Deformation, Burning, Explosion, and Detonation

“…We noted in [18] that when the mass fraction of gas is small, the change in specific volume of the gas in response to a small total volume change can be quite large. Conservation of energy by a differential method becomes so inaccurate that the gas gets on an unphysical adiabat.…”

“…If the flow stress is assumed constant, the maximum strain developed, and the maximum value of the ignition criterion, is inversely proportional to the mesh size. With the pressure-and strain-rate dependence illustrated in Figs 2 and 3, the strain and ignition criteria decrease exponentially from the surface, where the e-folding distance is about 0.8 mm [18,19].…”

“…The HERMES model [15][16][17][18][19][20] combines features from these prior models. It describes burning and explosion in damaged reactant, and also will develop a detonation if the gradual rise in pressure from burning steepens into a strong-enough shock.…”

HERMES Model Modifications and Applications 2012

“…HERMES was developed to meet requirements for a model to describe explosive response to impacts that do not produce prompt detonation [1,[2][3][4][5][6][7], but can include delayed detonations such as DDT and XDT. Such response is termed High Explosive Violent Response (HEVR).…”