Bulletin of the American Physical Society
19th Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 60, Number 8
Sunday–Friday, June 14–19, 2015; Tampa, Florida
Session E1: Experimental Developments II: Energetic Materials I |
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Chair: William Bassett, University of Illinois at Urbana-Champaign, Brandon Terry, Purdue University Room: Grand E |
Monday, June 15, 2015 3:30PM - 3:45PM |
E1.00001: Alternate Methods to Experimentally Investigate Shock Initiation Properties of Explosives Forrest Svingala, Richard Lee, Gerrit Sutherland, Philip Samuels Reactive flow models are desired for many new explosives early in the formulation development stage. Traditionally, these models are parameterized by carefully-controlled 1-D shock experiments, including gas-gun testing with embedded gauges and wedge testing with explosive plane wave lenses (PWL). These experiments are easy to interpret, due to their 1-D nature, but are generally expensive to perform, and cannot be performed at all explosive test facilities. We investigate alternative methods to probe shock-initiation behavior of new explosives using widely-available pentolite gap test donors and simple time-of-arrival type diagnostics. These methods can be performed at a low cost at virtually any explosives testing facility, which allows experimental data to parameterize reactive flow models to be collected much earlier in the development of an explosive formulation. However, the fundamentally 2-D nature of these tests may increase the modeling burden in parameterizing these models, and reduce general applicability. Several variations of the so-called modified gap test were investigated and evaluated for suitability as an alternative to established 1-D gas gun and PWL techniques. At least partial agreement with 1-D test methods was observed for the explosives tested, and future work is planned to scope the applicability and limitations of these experimental techniques. [Preview Abstract] |
Monday, June 15, 2015 3:45PM - 4:00PM |
E1.00002: Near-Field Optical Characterization of Explosions Kevin McNesby, Matthew Biss, Barrie Homan, Vincent Boyle, Richard Benjamin High-speed framing cameras, emission spectroscopy, and laser illumination are combined to allow for simultaneous, real-time mapping of temperature, pressure, chemical species and blast energy during and following explosions. This work provides quantitative, simultaneous measurement in the explosive near and far-field (0-500 charge diameters) of surface temperatures, peak air-shock pressures, chemical species signatures and shock energy deposition that characterize explosions. Information on these events is used to evaluate the performance, lethality, and survivability of Army munitions. [Preview Abstract] |
Monday, June 15, 2015 4:00PM - 4:15PM |
E1.00003: Estimating explosive performance from laser-induced shock waves Jennifer Gottfried A laboratory-scale method for predicting explosive performance (e.g., detonation velocity and pressure) based on milligram quantities of material is currently being developed. This technique is based on schlieren imaging of the shock wave generated in air by the formation of a laser-induced plasma on the surface of an energetic material. A large suite of pure and composite conventional energetic materials has been tested. Based on the observed linear correlation between the laser-induced shock velocity and the measured performance from full-scale detonation testing, this method is a potential screening tool for the development of new energetic materials and formulations prior to detonation testing. Recent results on the extension of this method to metal-containing energetic materials will be presented. [Preview Abstract] |
Monday, June 15, 2015 4:15PM - 4:30PM |
E1.00004: Partitioning of Initial Energy Release in a Tunnel Environment Joshua Felts, Richard Lee, Kyle Mychajlonka, Andy Davis After the detonation of an explosive charge in the closed end of a tunnel, the products and excess fuels mix and partially combust with the available air before expanding down the tunnel. Both the energy of the detonation and from the combustion of the products and excess fuels drive the blast wave. The energy of the blast wave was calculated for several explosives in a small-scale tunnel. The calculations were performed using the methodology of Hutchens, which is an adaptation of the classical approach of Taylor and Sedov. For similarly sized explosives, the detonation energy was measured using a detonation calorimeter. The difference in the initial energy release of the tunnel with that of the calorimeter is the energy from the initial partial combustion of the detonation products and excess fuels in the explosive formulation. This difference is related to the explosive formulations and can be interpolated for new formulations. This relationship can guide new formulation development for use in a tunnel environment. Knowledge of the initial energy release partitioning can lead to better computer models for fuel-rich explosives. [Preview Abstract] |
Monday, June 15, 2015 4:30PM - 4:45PM |
E1.00005: Dynamic Initiator Experiments using IMPULSE (Impact system for Ultrafast Synchrotron Experiments) at the Advanced Photon Source Nathaniel Sanchez, Brian Jensen, Kyle Ramos, Adam Iverson, Michael Martinez, Gary Liechty, Kamel Fezzaa, Steven Clarke We have successfully imaged, for the first time, the operation of copper slapper initiators that are used to initiate high explosive detonators. These data will aid in model development and calibration in order to provide a robust predictive capability and as a design tool in future applications. The initiation system consists of a copper bridge fixed to a parylene flyer. The copper bridge functions when a capacitor is discharged causing current to flow through the narrow bridge. As this happens, a plasma forms due to the high current densities and ohmic heating, which launches the parylene flyer that impacts a high explosive pellet producing detonation. Unlike traditional measurements, x-ray phase contrast imaging can see ``inside'' the process providing unique information with nanosecond time resolution and micrometer spatial resolution. The team performed experiments on the IMPULSE system at the Advanced Photon Source to obtain high resolution, in situ images of this process in real-time. From these images, researchers can examine the formation of the plasma instabilities and their interaction with the flyer, determine the flyer velocity, and obtain crucial information on the spatial distribution of mass and density gradients in the plasma and flyer. [Preview Abstract] |
Monday, June 15, 2015 4:45PM - 5:00PM |
E1.00006: Multi-parametric studies of electrically-driven flyer plates William Neal, Michael Bowden Exploding foil initiator (EFI) detonators function by the acceleration of a flyer plate, by the electrical explosion of a metallic bridge, into an explosive pellet. The length, and therefore time, scales of this shock initation process is dominated by the magnitude and duration of the imparted shock pulse. To predict the dynamics of this initiation, it is critical to further understand the velocity, shape and thickness of this flyer plate. This study uses multi-parametric diagnostics to investigate the geometry and velocity of the flyer plate upon impact including the imparted electrical energy: photon Doppler velocimetry (PDV), dual axis imaging, time-resolved impact imaging, voltage and current. The investigation challenges the validity of traditional assumptions about the state of the flyer plate at impact and discusses the improved understanding of the process. [Preview Abstract] |
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