In order to improve understanding of how aluminum contributes in non‐ideal explosive mixtures, cast‐cured formulations have been analyzed in a series of cylinder tests and plate‐pushing experiments. This study describes the contribution of 15 % aluminum (median size of 3.2 μm) vs. lithium fluoride (an inert substitute for aluminum; <5 μm) in cast‐cured HMX formulations in different temporal regimes. Small cylinder tests were performed to analyze the detonation and wall velocities (1–20 μs) for these formulations. Near‐field blast effects of 58 mm diameter spherical charges were measured at 152 mm and 254 mm using steel plate acceleration. Pressure measurements at 1.52 m gave information about free‐field pressure at several milliseconds. While the observed detonation velocities for all formulations were within uncertainty, significantly higher cylinder wall velocities, plate velocities, and pressures were observed for the aluminum formulations at ≥2 μs. Additionally, hydrocode calculations were performed to determine how non‐ideal behavior affected the plate test results. Collectively, this work gives a clearer picture of how aluminum contributes to detonation on timescales from 1 μs to about 2 ms, and how the post‐detonation energy release contributes to wall velocities and blast effects. The experiments indicate that significant aluminum reactions occur after the CJ plane, and continue to contribute to expansion at late times.

Impact response characteristics of a cyclotetramethylene tetranitramine based polymer-bonded explosives under different temperatures Line-imaging velocimetry for observing spatially heterogeneous mechanical and chemical responses in plastic bonded explosives during impact Rev. Sci. Instrum. 84, 083903 (2013); 10.1063/1.4817307 Energy localization in HMX-Estane polymer-bonded explosives during impact loading J. Appl. Phys. 111, 054902 (2012); 10.1063/1.3688350 Impact-induced initiation and energy release behavior of reactive materials

In order to more fully understand the factors that influence the thermal “hot-spot” initiation of high explosives, we have chosen a model system for study that uses the internal and localized dissipation of long wavelength electromagnetic energy (microwaves). High purity organic crystals generally interact weakly with microwave energy. Therefore, the addition of electromagnetically absorbing inclusions of silicon carbide provides a tractable system for the study of hot-spot ignition phenomena. Previously, we developed a simple analytic model that illuminates the important physical factors. In this work, we verify the relationships of the analytic model using a series of experiments and a numerical model.

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Abstract. A quadrature interferometer used in a free-field measurement mode has, with the aid of a high directivity horn antenna, been successfully used to measure the detonation front of PBX-9501 within a dielectric can. Using the known length of explosive, a relative dielectric permittivity of 3.84 has been calculated for the 34 GHz frequency used. Using this value, the displacement vs. time of the detonation front can be found and hence the velocity of detonation may be calculated. This technique shows good promise as a method of measuring the run-to-detonation distance in explosives using a totally non-contacting technique.