Bulletin of the American Physical Society
18th Biennial Intl. Conference of the APS Topical Group on Shock Compression of Condensed Matter held in conjunction with the 24th Biennial Intl. Conference of the Intl. Association for the Advancement of High Pressure Science and Technology (AIRAPT)
Volume 58, Number 7
Sunday–Friday, July 7–12, 2013; Seattle, Washington
Session P7: Nonconventional Energetics: Shock Loading and Fragmentation |
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Chair: Darla Thompson, Los Alamos National Laboratory Room: Grand Crescent |
Wednesday, July 10, 2013 11:00AM - 11:15AM |
P7.00001: Shock Response and Explosive Launch of Compacted Reactive Material John D. Molitoris, Alexander E. Gash, Raul G. Garza, Franco J. Gagliardi, Joseph W. Tringe, Jan D. Batteux, P. Clark Souers We have performed a series of experiments investigating the detailed dynamic response of compacted reactive material to shock and blast. Here a granular reactive formulation (Fe$_{2}$O$_{3}$/Al based thermite) was pressed into a solid cylinder of material and mated to a high-explosive charge of the same diameter. Detonation of the charge transmitted a shock wave to the thermite cylinder and imparted momentum launching it in the direction of the detonation. High-resolution time sequence radiography was used to image the dynamic response of the thermite. This technique allowed a detailed investigation of material deformation in addition to changes in the internal structure and indications of reactivity. The effect of variations in the initial density of the pressed thermite was also examined. We find that these pressed thermites behave much like solid metals during shock transit, then respond much differently. [Preview Abstract] |
Wednesday, July 10, 2013 11:15AM - 11:30AM |
P7.00002: Mechanisms of high strain, high strain rate plastic flow in the explosively driven collapse of Ni-Al laminate cylinders Karl Olney, Po-Hsun Chiu, Andrew Higgins, Matthew Serge, Gregory Fritz, Adam Stover, David Benson, Vitali Nesterenko Laminate materials composed of thin Ni and Al foils have shown promise as material systems used in reactive material applications due to the ability of the material to support a self-sustaining reaction between the Al and Ni layers. In addition to the traditional ignition methods, ignition may occur in the shear bands developed during mechanical loading. The thick-walled cylinder (TWC) technique was performed on samples of Ni-Al laminate materials with two different mesostructues; concentric and corrugated both constructed using alternating layers of Ni and Al thin foils on the order of 20-30 micron foil thickness. These TWC experiments were performed to examine how these materials accommodated large plastic strain during the collapse which may be used to tailor reactivity in the material system. Large scale numerical simulations of these specimens with mesostuctures digitized from the experimental samples were conducted to provide an insight into the mesoscale mechanisms of plastic flow during collapse of the thick walled laminate material during the explosive loading. Funding was provided by ONR MURI N00014-07-1-0740 (Program Officer Dr. Clifford Bedford) [Preview Abstract] |
Wednesday, July 10, 2013 11:30AM - 11:45AM |
P7.00003: Fragmentation of Structural Energetic Materials: Implications for Performance Brady Aydelotte, Christopher Braithwaite, Naresh Thadhani Fragmentation results for structural energetic materials based on intermetallic forming mixtures are reviewed and the implications of the fragment populations are discussed. Cold Sprayed Ni+Al and explosively compacted mixtures of Ni+Al+W and Ni+Al+W+Zr powders were fabricated into ring shaped samples and subjected to fragmentation tests. Ring velocity was monitored and fragments were soft captured in order to study the fragmentation process. It was determined that the fragments produced by these structural energetic materials are much smaller than those typically produced by ductile metals such as steel or aluminum. This has implications for combustion processes that may occur subsequent to the fragmentation process. [Preview Abstract] |
Wednesday, July 10, 2013 11:45AM - 12:00PM |
P7.00004: Fragmentation and Constitutive Response of Tailored Mesostructured Aluminum-Based Inert and Reactive Compacts Andrew Marquez, Chris Braithwaite, Timothy Weihs, Nick Krywopusk, David Gibbins, Marc Meyers The fragmentation and constitutive response of tailored aluminum-based compacts is examined under dynamic conditions. Mesostructured compacts with tailored interfaces between the powders (with sizes of 40, 100, and 400 $\mu $m) were produced by swaging. In addition to these, reactive Ni-Al mixtures were prepared by the same technique; the Ni/Al layer thicknesses within the powders were varied to control the reaction rate between Ni and Al. The fragmentation produced in the explosively-driven rings expanded at a velocity of approximately 100 m/s was captured by high-speed photography. The fragment size distributions obtained varied widely and correlated with the interfacial strength of the compacts as well as with powder size. Experimental results are compared with fragmentation theories to characterize the behavior of reactive powders based on material mesostructure. [Preview Abstract] |
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