Bulletin of the American Physical Society
17th Biennial International Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 56, Number 6
Sunday–Friday, June 26–July 1 2011; Chicago, Illinois
Session Y4: Experimental Developments VII |
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Chair: Richard Gustavsen, Los Alamos National Laboratory Room: Renaissance Ballroom C |
Friday, July 1, 2011 9:15AM - 9:30AM |
Y4.00001: The Use of The ITraC Test to Characterise Main Charge Materials Mark Wright, Andrew Stoodley, Matthew Maisey AWE has developed a novel Initiation Train Characterisation (ITraC) tests to support the development of new explosives, formulations and systems. The ITraC is a flexible vehicle which enables indicative initiation characteristics to be determined from small (50g) samples. The test utilises fibre optic time of arrival probes to monitor the characteristic breakout at the surface of a cylinder and has the capability to incorporate additional diagnostics such as framing cameras, streak and laser velocimetry. A series of experiments have been undertaken on a HMX based PBX formulation to commission the test, quantify the test variability and provide a performance baseline for future trials. ITraC experiments have been performed on three novel TATB/Fluoropolymer based PBX formulations. This paper gives an overview of the test design and describes the performance characterisation of these explosive formulations, demonstrating the tests versatility. As part of this the relative sensitivity of the TATB/Fluoropolymer formulations has been ranked using the ITraC test in a Gap Test configuration. [Preview Abstract] |
Friday, July 1, 2011 9:30AM - 9:45AM |
Y4.00002: Developing Impact Marking Projectiles Using Triboluminescent Materials William Hollerman, Ross Fontenot, Brady Broussard, Shawn Goedeke, Corey Guidry In 1888, Wiedemann and Schmidt defined triboluminescence as the emission of light produced by mechanical action. In 1999, Sage and Geddes patented a design for a sensor capable of discerning the locations of impacts. Their design involved embedding a sensor inside a material coated with a triboluminescent crystal. Using this idea, the authors have been investigating the triboluminescent properties of several materials (like ZnS:Mn) for their possible use as the active element in ballistic projectiles. These new and improved rounds would be very useful because triboluminescence would mark the landing point of the projectile. This light would be ``cold'' in the sense it was not generated as a result of burning gunpowder or similar pyrotechnics. This light emission would also have a relatively short duration compared to other new projectiles, which generate long-term phosphorescence when two chemicals are mixed at impact (chemiluminescence). This presentation will give a status report in our efforts to develop practical impact marking ballistic projectiles using a triboluminescent charge. [Preview Abstract] |
Friday, July 1, 2011 9:45AM - 10:00AM |
Y4.00003: The effects of gas on ejecta particle size distributions for shock loaded Sn Danny Sorenson, Peter Pazuchanics, Robert Malone, Aric Tibbitts, Morris Kaufman, Tom Tunnell, Gene Capelle, Mike Grover, Guy Leach, Bruce Marshall, Gerald Stevens, William Turley A strong shock wave reflecting from a metal surface can lead to ``ejected matter'' which are metal/liquid particles emitted from the metal gas/vacuum interface. The mass, size and velocity distributions will depend on a variety of conditions including the material properties of the metal under investigation as well as the shock loading conditions. Furthermore, if the particles are produced in a gas environment the particles can undergo further fragmentation due to the interactions the particles have with the gas. This can result in a size distribution that can vary significantly from that measured in a vacuum environment. We will present particle size distributions from shock loaded Sn samples that were measured in a vacuum and He gas environments. The measurements were conducted using a new high-resolution in-line Fraunhofer holography measurement technique. [Preview Abstract] |
Friday, July 1, 2011 10:00AM - 10:15AM |
Y4.00004: Determining the Source of Oxygen in Post-Detonation Combustion of Aluminum Jeremy Monat, Joel Carney, James Lightstone, Nobumichi Shimizu Aluminum is often added to explosive formulations in the form of micron-sized particles to increase the energy released. Aluminum particles combust by reacting with oxidizers from the detonation products (such as CO) and the surrounding atmosphere (O$_{2})$. Quantifying the oxygen contribution from these sources is important for improved modeling and formulation. This work will determine the ratio of oxygen from detonation products to oxygen from the atmosphere using isotopic labeling. We detonated a 10-20 g aluminum-containing explosive formulation in a simulated air atmosphere where the oxygen was $^{18}$O$_{2}$. We collected the solid detonation products after detonation and analyzed them using secondary ion mass spectrometry (SIMS) to measure the ratio of $^{18}$O to $^{16}$O and thus the percentage of oxygen of aluminum combustion from the detonation products versus from the atmosphere. Preliminary results of detonations performed in a rigid chamber showed $\sim $60{\%} of the oxygen came from the atmosphere. In further experiments, we will create a free-field condition by performing detonations in flexible, thin-walled plastic spheres of known radius containing an $^{18}$O$_{2}$-enriched air atmosphere. We will then isolate the post-detonation aluminum oxide and determine the oxygen isotope ratio using SIMS analysis. [Preview Abstract] |
Friday, July 1, 2011 10:15AM - 10:30AM |
Y4.00005: Influence of the donor charge initiation on the fragment clouds of a metal plate pushed by High Explosives Alexandre Lefrancois, Jacques Petit, Sebastien Dumant, Frederic Sinatti, Patrick Rey Fragment clouds are observed when the free surface of a metal plate reflects a release wave generated by HE. The influence of the shock front propagation, the side release and the shock wave collide are investigated using multipoint initiation and several HE donor diameter on a screening small scale plate push test. These phenomena have been explored with different thicknesses of several metals (Al, Cu, Sn) using three soft 150 kV flash X ray radiography by shot, and using X-ray tomography on recovered samples. The radiography resolution of the low apparent density areas has been increased. A ``spall'' threshold is characterized by the clearing of the higher apparent density region ahead of the fragment clouds. The mean velocity of the different regions is also measured. The fragment clouds are recovered in foam. The particle size distribution is analysed and correlated with the shock conditions. [Preview Abstract] |
Friday, July 1, 2011 10:30AM - 10:45AM |
Y4.00006: Response of HMX-based HE to low-velocity loading by steel cylindrical impactor Victor Pushkov Studies of explosive transformations have been actively performed under low-velocity mechanical effect since the previous century. The studies were performed with HE subjection to effect by a bullet, a spherical fragment, planar and others impactors. Obtained results were numerically simulated with good agreement of numerical and experimental data. However, because of complicity of the explosive transformation process, there are presently no comprehensive data on conditions of its initiation. Among various low-velocity mechanical effects on HE, effects of elements as a bar or an extended impactor are possible. This paper presents a technique and some results of experimental study how hemispherical samples (with external diameter of about 100 mm) made of retarded HMX response to low-velocity mechanical effect of steel impactor at impact velocities V=55-75 m/s. In the experiments, radiointerferometer was used to record the process of impactor penetration into HE sample. Basing on the experimental results, quantitative data were determined on the conditions of explosive transformation beginning for retarded HMX and kinematics of motion of explosive transformation products. [Preview Abstract] |
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