Bulletin of the American Physical Society
21st Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 64, Number 8
Sunday–Friday, June 16–21, 2019; Portland, Oregon
Session Z1: DSIC: Detonation Tests |
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Chair: Kevin McNesby, ARL Room: Grand Ballroom I |
Friday, June 21, 2019 11:00AM - 11:15AM |
Z1.00001: Disc Acceleration Experiments for Blends of High Explosive Composites Robert Reeves, Bradley White, Eric Bukovsky, Marcos Chaos, Denis Richard A basic goal of high explosive (HE) formulation is the development of a composite materials that combines the properties of its constituents to meet a specific need. Typically, this is done with a single HE and a binder system to create a mechanically-stable, energetic material. However, it may be useful to blend higher and lower performance HEs to finely tune the detonative, thermal, and safety properties of the composite. In this study, disc acceleration experiments (DAX) were performed on HMX-based explosives, TATB-based explosives, and several mixtures of the two. Experiments were performed at two sizes, as well, to investigate possible size effects on the detonative behavior of the lower-energy content mixtures. The detonation velocity and velocity of the produced flyer are presented as a function of composition. Experimental results are compared to simulations using models developed using CHEETAH. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-768458 [Preview Abstract] |
Friday, June 21, 2019 11:15AM - 11:30AM |
Z1.00002: The Effect of Confiner Concentricity on Cylinder Test Results Eric Anderson, Scott Jackson, Von Whitley The cylinder test is an established experiment where an explosive accelerates a copper confiner tube so that the tube velocity profile may be measured. Analysis of the results allows the explosive product equation of state to be inferred. In this work, we describe a method to measure the wall thickness of the confiner tube as a function of axial and angular position on the tube. We also describe additional assembly steps necessary to ensure maximum fidelity of wall velocity profiles measured by multiple photonic Doppler velocimetry (PDV) probes. The confiner measurements indicate that variations in confiner wall-thickness as a function of angular position on the tube are possible due to slightly off-center inner and outer tube surfaces. The results of four tests with probes positioned at the minimum, maximum, and average wall thickness for each axial probe position are reported. These results show that concentricity errors on the order of 0.0001 in. have a measurable effect on the resulting wall velocities and inferred product equation of state. Results of these tests are compared to prior tests for the same explosive. [Preview Abstract] |
Friday, June 21, 2019 11:30AM - 11:45AM |
Z1.00003: Measurement of Composition B Detonation Performance above the TNT Melting Point Ritchie Chicas, Eric Anderson, Scott Jackson Composition B (Comp B) is an explosive composed of RDX and TNT, typically in a 60/40 wt. % ratio. When heated above the TNT melting point, the suspended RDX crystals can settle, resulting in a composition gradient. While it is possible to measure the detonation performance of such a material, the resulting data is difficult to apply to computer models since the composition at any given location is not known experimentally. To ensure a uniform composition at these temperatures, we have designed an experimental apparatus to rotate the explosive during heating. Details of the apparatus are described and experimental results are reported which demonstrate its effectiveness. In particular, measured cylinder expansion test wall velocity profiles, front shapes, and steady detonation velocities are compared for nominally identical experiments with the exception of whether rotation was used during heating. Results show that the detonation front-shape is especially sensitive to the effect of rotation, suggesting that RDX particle settling is significant at 120 °C. [Preview Abstract] |
Friday, June 21, 2019 11:45AM - 12:00PM |
Z1.00004: Evaluating Mixing Length Scale using Coaxial Explosive Composites Michael Grapes, Bradley White, Keo Springer, Denis Richard, Robert Reeves Blends of explosive formulations with different characteristics may provide the means for a formulator to balance safety and performance; however, the level of mixing necessary to treat the materials as a single, homogeneous material is not known. To evaluate the intimacy of mixing necessary to propagate a homogenous detonation front in mixtures of an HMX-based formulation and a TATB-based formulation, binary periodic composites of the two explosive formulations have been fabricated and tested. The composites consist of alternating cylindrical shells of the formulations, arranged coaxially and with the overall materials ratio set to 50/50 by volume. To evaluate the importance of mixing, five different periodicity wavelengths were tested, ranging from 12.7 mm to 2.54 mm. Initial results from detonation velocity and front curvature experiments on these articles will be presented, with conclusions drawn regarding their implications for a “critical mixing length” in the context of the estimated reaction zone sizes for these formulations. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-768210 [Preview Abstract] |
Friday, June 21, 2019 12:00PM - 12:15PM |
Z1.00005: Progress made on measuring the temperature of four different detonating explosives. James Ferguson, James Richley, Ben Sutton, Simon Finnegan, Mike Goff, Dan Thomas We report on progress made in the measuring of the temperature of different detonating explosives using pyrometry. These measurements were made on four different types of PBX; HMX based, TATB based, RDX based and a TNT-HMX mix. Additionally, spectroscopy measurements were performed on an HMX based explosive in different geometries. The explosive geometries used for these measurements were cylinder tests, rate sticks and plate impact gas gun experiments. The measurements themselves have been taken both end on to the approaching detonation wave and tangentially as the detonation wave sweeps past. The gas gun experiments investigated partially reacted states rather than full detonation. The measured temperatures from all four explosive types are compared with maximum temperatures ranging from 3500 k to 4500 k. [Preview Abstract] |
Friday, June 21, 2019 12:15PM - 12:30PM |
Z1.00006: Time resolving the loss of crystallinity during detonation Pamela Bowlan, Dennis Remelius, Dave Oschwald, Natalya Suvorova, Bryan Henson, Laura Smilowitz There are still significant uncertainties in our ability to predict and control when and how secondary solid explosives release energy, and the initiation of a detonation. This has serious implications for the safety and performance of explosives. One reason is for this uncertainty is that while chemical kinetics are well understood in gases and liquids, much less is known about how chemistry proceeds within a crystalline lattice. Secondly, events like detonation, where a bulk material can go from ambient conditions to pressures of Gigapascals (GPa) and temperatures of about 4000 kelvin (K) within a nanosecond (ns) are extremely difficult to directly observe. To better understand initiation in solid explosives, we developed a technique using visible laser scattering to probe how the morphology of the initial solid changes on a picosecond time scale before and during detonation. We will present our results applying this to commercial exploding bridge wire detonators. These measurements reveal when, during a detonation wave, that the initial crystals change into a less scattering dense fluid. [Preview Abstract] |
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