Publications

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Microenergetic research involving a coupled experimental and computational approach to evaluate microstructural effects on detonation and combustion at sub-millimeter geometries

Proceedings of the 13th International Detonation Symposium, IDS 2006

Tappan, Alexander S.; Brundage, Aaron B.; Long, Gregory L.; Renlund, Anita M.; Kravitz, Stanley H.; Nogan, John J.; Wroblewski, Brian; Palmer, Jeremy A.; Baer, Melvin B.

A new approach to explosive sample preparation is described in which microelectronics-related processing techniques are utilized. Fused silica and alumina substrates were prepared utilizing laser machining. Films of PETN were deposited into channels within the substrates by physical vapor deposition. Four distinct explosive behaviors were observed with high-speed framing photography by driving the films with a donor explosive. Initiation at hot spots was directly observed, followed by either energy dissipation leading to failure, or growth to a detonation. Unsteady behavior in velocity and structure was observed as reactive waves failed due to decreasing channel width. Mesoscale simulations were performed to assist in experiment development and understanding. We have demonstrated the ability to pattern these films of explosives and preliminary mesoscale simulations of arrays of voids showed effects dependent on void size and that detonation would not develop with voids below a certain size. Future work involves experimentation on deposited films with regular patterned porosity to elucidate mesoscale explosive behavior.

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TYPE Conference YEAR 2006
ScopusOSTI

Development of scalable cook-off models using real-time in situ measurements

Kaneshige, Michael J.; Kaneshige, Michael J.; Renlund, Anita M.; Schmitt, Robert G.; Erikson, William W.

Scalable thermal runaway models for cook-off of energetic materials (EMs) require realistic temperature- and pressure-dependent chemical reaction rates. The Sandia Instrumented Thermal Ignition apparatus was developed to provide in situ small-scale test data that address this model requirement. Spatially and temporally resolved internal temperature measurements have provided new insight into the energetic reactions occurring in PBX 9501, LX-10-2, and PBXN-109. The data have shown previously postulated reaction steps to be incorrect and suggest previously unknown reaction steps. Model adjustments based on these data have resulted in better predictions at a range of scales.

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TYPE Conference YEAR 2003
OSTI

Preliminary Investigation of the Thermal Decomposition of Ablefoam and EF-AR20 Foam (Ablefoam Replacement)

Ulibarri, Tamara A.; Erickson, Kenneth L.; Wiemann, Dora K.; Erickson, Kenneth L.; Castaneda, Jaime N.; Borek, Theodore T.; Renlund, Anita M.; Miller, Jill C.

Preliminary thermal decomposition experiments with Ablefoam and EF-AR20 foam (Ablefoam replacement) were done to determine the important chemical and associated physical phenomena that should be investigated to develop the foam decomposition chemistry sub-models that are required in numerical simulations of the fire-induced response of foam-filled engineered systems for nuclear safety applications. Although the two epoxy foams are physically and chemically similar, the thermal decomposition of each foam involves different chemical mechanisms, and the associated physical behavior of the foams, particularly ''foaming'' and ''liquefaction,'' have significant implications for modeling. A simplified decomposition chemistry sub-model is suggested that, subject to certain caveats, may be appropriate for ''scoping-type'' calculations.

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TYPE Report YEAR 2002
OSTIDOI

LDRD final report : raman spectroscopic measurements to monitor the HMX beta-delta phase transition

Tappan, Alexander S.; Renlund, Anita M.; Miller, Jill C.

The HMX {beta}-{delta} solid-solid phase transition, which occurs as HMX is heated near 170 C, is linked to increased reactivity and sensitivity to initiation. Thermally damaged energetic materials (EMs) containing HMX therefore may present a safety concern. Information about the phase transition is vital to predictive safety models for HMX and HMX-containing EMs. We report work on monitoring the phase transition with real-time Raman spectroscopy aimed towards obtaining a better understanding of physical properties of HMX through the phase transition. HMX samples were confined in a cell of minimal free volume in a displacement-controlled or load-controlled arrangement. The cell was heated and then cooled at controlled rates while real-time Raman spectroscopic measurements were performed. Raman spectroscopy provides a clear distinction between the phases of HMX because the vibrational transitions of the molecule change with conformational changes associated with the phase transition. Temperature of phase transition versus load data are presented for both the heating and cooling cycles in the load-controlled apparatus, and general trends are discussed. A weak dependence of the temperature of phase transition on load was discovered during the heating cycle, with higher loads causing the phase transition to occur at a higher temperature. This was especially true in the temperature of completion of phase transition data as opposed to the temperature of onset of phase transition data. A stronger dependence on load was observed in the cooling cycle, with higher loads causing the reverse phase transitions to occur at a higher cooling temperature. Also, higher loads tended to cause the phase transition to occur over a longer period of time in the heating cycle and over a shorter period of time in the cooling cycle. All three of the pure HMX phases ({alpha}, {beta} and {delta}) were detected on cooling of the heated samples, either in pure form or as a mixture.

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TYPE Report YEAR 2000
OSTIDOI
19 Results
19 Results