Bulletin of the American Physical Society
20th Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 62, Number 9
Sunday–Friday, July 9–14, 2017; St. Louis, Missouri
Session U2: Energetic and Reactive Materials: Cook-Off II |
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Chair: Chris Stennett, Cranfield University Room: Grand Ballroom AB |
Thursday, July 13, 2017 2:15PM - 2:30PM |
U2.00001: Development of a Dual Windowed Test Vehicle for Live Streaming of Cook-Off in Energetic Materials. Phil Cheese, Tom Reeves, Nathan White, Christopher Stennett, Andrew Wood, Malcolm Cook A modular, axially connected test vehicle for researching the influence of various heating rates (cook-off) on energetic materials and how they fundamentally decompose, leading to a violent reaction has been developed and tested. The vehicle can accommodate samples measuring up to 50 mm in diameter, with thicknesses variable from 0.5 mm up to 50 mm long. A unique feature of this vehicle is the ability to have a live high speed camera view, without compromising confinement during the cook-off process. This is achieved via two special windows that allow artificial backlighting to be provided at one end for clear observation of the test sample; this has allowed unprecedented views of how explosives decompose and runaway to violent reactions, and has given insight into the reaction mechanisms operating, and challenges current theories. Using glass windows, a burst pressure of 20 MPa has been measured. The heating rate is fully adjustable from slow to fast rates, and its design allows for confinement to be varied to study the influence on the violence of reaction during cook-off. In addition to being able to view the test sample during cook-off, embedded thermocouples provide detailed temperature records and the ability to use PDV instrumentation is also incorporated. [Preview Abstract] |
Thursday, July 13, 2017 2:30PM - 2:45PM |
U2.00002: Investigation of the kinetics and microscopic mechanism of solid-solid phase transitions in HMX Pamela Bowlan, Natalya Suvorova, Dave Oschwald, John Bowlan, Kirk Rector, Bryan Henson, Laura Smilowitz Although studied intensely in the 2000's, a number of important questions about solid-solid phase transitions in the energetic organic material octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) remain. The mechanism by which one of the four isomorphs, known as \quad $\delta $, $\gamma $, $\alpha $ and $\beta $, transforms into another, and the conditions (i.e. temperature and pressure) and rates at which these transitions take place are still not fully known, yet important for predicting and controlling energy release phenomena in HMX such as detonation. The theory of virtual melting, by which a liquid forms at the interface of a nucleation site, is necessary to explain transformations between certain of the four different phases of HMX, such as the \quad $\beta $to $\delta $ transition. However the existence of this disordered intermediate state has never been directly proven due to the need for both spatial (\textless \textmu m), temporal (the lifetime of the transient melt state is unknown) and structural information. Also, while the $\beta $ to $\delta $ transition was more thoroughly studied, less is known about the other 10 possible phase transitions. We will report on our study of phase transitions in HMX using X-ray diffraction and confocal Raman and near-field infrared microscopy. [Preview Abstract] |
Thursday, July 13, 2017 2:45PM - 3:00PM |
U2.00003: Live Decomposition Imaging of HMX/HTPB Based Formulations During Cook-Off in the Dual Window Test Vehicle. Nathan White, Tom Reeves, Phil Cheese, Christopher Stennett, Andrew Wood, Malcolm Cook Thin, cylindrical samples of HMX/HTPB formulations with solids loadings from 85-95{\%} by mass have been heated at 1oC/minute until a reaction occurred in the new dual window cook-off test vehicle. The test vehicle has captured the response of these formulations, and shown the influence of variables such as confinement, heating rate and sample size. Live imaging of the heated samples revealed that as with pure nitramine samples, three distinct stages of change take place during heating; phase changes, melting and slow, flameless decomposition with production of gaseous intermediates and finally burning with a luminous flame of the gaseous intermediates. In addition, the binder appears to undergo decomposition before the HMX, darkening along the edge closest to the thermal input before the HMX melts. Prior to violent reaction, flame speeds were measured at approximately 30m/s for high confinement, which reduces by 2-3 orders of magnitude when confinement is lowered. The melting point of HMX has been observed below the widely reported value at 220oC, and requires further investigation. [Preview Abstract] |
Thursday, July 13, 2017 3:00PM - 3:15PM |
U2.00004: Reactive Behavior of Explosive Billets in Deflagration Tube of Varied Confinements Haibo Hu, Yingwen Guo, Tao Li, Hua Fu, Hailin Shang, Shanggang Wen, Tian Qiu The deflagration process of small size cylinder billets of pressed HMX-based explosive JO-9159 and the deflagration tube wall deformation is recorded by combined pressure£¬velocity-meter£¬high-speed frame photographic and radiographic diagnostic system. The influence of confinement structure strength on deflagration evolution behavior is compared with analysis of convective flame propagation along the slot between explosive billet and confinement wall.The follow-up reaction inside the cracks on the initiation site end surface£¬on the side surfaces and between the end surfaces of explosive billets is restored with the analysis results of post experimental explosive billet remains. [Preview Abstract] |
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