Science and Technology of Energetic Materials

Vol.79, No.5 (2018)

Research paper

A computational study of the effect of grain size distribution on shock initiation of pressed HMX powder
YaochiWei,Yasuyuki Horie, Christopher Molek, EricWelle, and Min Zhou


CODEX code is used to study the impact sensitivity of bimodally distributed HMX powders by mixing two monomodally distributed systems having the mean diameters of 70μm and 220μm. The sensitivity is examined through the coefficients of the James function for initiation threshold. Predicted thresholds of bimodally distributed systems are bounded mostly by those of the monomodally distributed systems. The coefficient of trigger energy is found to correlate well with equivalent diameter. However, the coefficient of specific energy appears to be independent of mixing ratio and relates to that of the 70μm monomodal system. This tendency is supported by a close correlation found between the density of dissipated energy and the percentage of grains as a function of equivalent grain diameter, signifying that fine particles predominate the initiation characteristics in mixtures.

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shock initiation, HMX powder, bimodally distributed powders, CODEX, James initiation threshold

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