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 O2: Energetic and Reactive Materials VII: Sensitivity |
Hide Abstracts |
Chair: Cynthia Bolme, Los Alamos National Laboratory, Brian Little, Air Force Research Laboratory, Eglin Room: Grand F |
Wednesday, June 17, 2015 9:15AM - 9:30AM |
O2.00001: Mechanisms of pressurization and insensitivity in TATB Bryan Henson, Laura Smilowitz We have studied thermal ignition and subsequent internal deflagration in explosive formulations based on 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) with the goal of understanding the underlying mechanisms which combine to either enable or preclude the deflagration to detonation transition (DDT). We measure spatially resolved temperature, density change using new dynamic x-ray radiography techniques, and pressure inferred from observations of case deformation and direct measurement during ignition and burning in samples of variable initial density. We compare these observations with previous measurements on formulations of the more sensitive explosive octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX). TATB deflagration is characterized by a measured ignition temperate approximately half that of HMX and very low pressures and rates of deflagration compared to HMX. Very stable and slow laminar internal burning is observed at lower densities as well as cracking, deconsolidation and a transition to faster deflagration rates under some conditions. We examine mechanism of pressure generation in the context of the combustion chemistry of TATB and discuss possible explanations of the lower observed rates and pressures when compared to HMX. [Preview Abstract] |
Wednesday, June 17, 2015 9:30AM - 9:45AM |
O2.00002: Tailoring the Sensitivity of Explosives via Elemental Substitution Virginia Manner, Daniel Preston, Bryce Tappan PETN is a very common nitrate ester explosive that has been widely studied due to its use in military and commercial explosives. Recently, it was shown by Klapotke, et al. that the central carbon atom in PETN could be replaced with silicon, resulting in an extremely sensitive contact explosive. Calculations have shown that the central Si atom forms a strong bond with the oxygen of the nitro group in the intermediate step. This information can be used to tailor PETN into a less sensitive explosive. Derivatives of PETN have been prepared by substituting the central carbon atom with atoms such as phosphorous and nitrogen, since they form weak bonds with oxygen. With a fully characterized suite of PETN derivatives in hand, the sensitivity and performance properties of each material can be measured. We will discuss the sensitivity/performance properties of each derivative relative to its structure, and relate the new results to the previously calculated mechanism of decomposition of PETN. Derivatives of other common explosives will also be discussed. [Preview Abstract] |
Wednesday, June 17, 2015 9:45AM - 10:00AM |
O2.00003: Impact sensitivity test of liquid explosives Andrei Tiutiaev, Valeri Trebunskih, Andrei Dolzhikov, Irina Zvereva The sensitivity of liquid explosive in the presence of gas bubbles increases many times as compared with the liquid without gas bubbles. If we consider that in the liquid as a result of convection, wave motion, shock, etc. gas bubbles are easily generated, the need to develop a method for determining sensitivity of liquid explosives to impact and a detailed study of the ignition explosives with bubbles is obvious. On a mathematical model of a single steam bubbles in the fluid theoretically considered the process of initiating explosive liquid systems to impact. For the experimental investigation, the well-known K-44 -II and the so-called appliance No. 1 were used. Instead of the metal cap in the standard method in this paper there was polyurethane foam cylindrical container with LHE, which is easily deforms by impact. A large number of tests with different liquid explosives were made. It was found that the test LHE to impact in appliance No. 1 with polyurethane foam to a large extent reflect the real mechanical sensitivity due to the small loss of impact energy on the deformation of the metal cap, as well as the best differentiation LHE sensitivity due to the higher resolution method . [Preview Abstract] |
Wednesday, June 17, 2015 10:00AM - 10:15AM |
O2.00004: The Thermal Response of HMX-TATB Charges Rod Drake The use of formulations containing two explosives is one approach to achieving charge safety and performance requirements. The intention of this approach is to produce a formulation that only has the desirable features of the constituent materials. HMX and TATB have very different properties {\&} have been used in a study to understand how the characteristics of the constituent materials affect the thermal response of a mixed formulation. A range of formulations were prepared in which the proportion and particle size distributions of the HMX and TATB were varied. Times to explosion of spherical charges were measured in the One-Dimensional Time-To-Explosion apparatus and compared to those of formulations based only on HMX and TATB. The response of the mixed formulations was found to be largely determined by the HMX. Small contributions to the responses were made by the binder type and the particle size of the TATB. Numerical models were developed and used to rationalise the results. [Preview Abstract] |
Wednesday, June 17, 2015 10:15AM - 10:30AM |
O2.00005: Observation and modeling of deflagration-to-detonation (DDT) transition in low-density HMX Joseph Tringe, Kevin Vandersall, Jack Reaugh, Harold Levie, Bryan Henson, Laura Smilowitz, Gary Parker We employ simultaneous flash x-ray radiography and streak imaging, together with a multi-phase finite element model, to understand deflagration-to-detonation transition (DDT) phenomena in low-density ($\sim$ 1.2 gm/cm$^{3})$ powder of the explosive cyclotetramethylene-tetranitramine (HMX). HMX powder was lightly hand-tamped in a 12.7 mm diameter column, relatively lightly-confined in an optically-transparent polycarbonate cylinder with wall thickness 25.4 mm. We observe apparent compaction of the powder in advance of the detonation transition, both by x-ray contrast and by the motion of small steel spheres pre-emplaced throughout the length of explosive. High-speed imaging along the explosive cylinder length provides a temporally continuous record of the transition that is correlated with the high-resolution x-ray image record. Preliminary simulation of these experiments with the HERMES model implemented in the ALE3D code enables improved understanding of the explosive particle burning, compaction and detonation phenomena which are implied by the observed reaction rate and transition location within the cylinder. [Preview Abstract] |
Wednesday, June 17, 2015 10:30AM - 10:45AM |
O2.00006: Experiments and modelling of dynamic powder compaction in the scope of deflagration to detonation transition studies Sebastien Bodard, Emmanuel Lapebie, Richard Saurel, Eric Daniel, Robert Tosello, Eric Lafontaine Understanding DDT in granular media is of prime interest for ammunition safety. However, the mechanisms involved are multiphasic, granular and multi-scale. To progress in DDT understanding it is thus necessary to focus on some mechanisms. As compaction plays a prominent role in DDT it is important to accurately model this phenomenon. In this communication, dynamic compaction of inert powder is studied to focus on the mechanical effects taking place in early stages of DDT. Both experimental and modelling aspects are considered. A novel experimental setup is designed to generate a dynamic 1D compaction. It consists in a container filled with powder and closed by a piston. A projectile launched with a gas gun impacts the piston rod to compress the powder. High-speed cameras with grain-scale resolution record the test. The velocity field is determined with image correlation. A multiphase compaction model (Saurel et al., 2010) has been implemented. Granular effects are taken into account with a granular equation of state, determined by quasi-static compaction. With additional features such as wall friction, good agreement between experiments and computations is found. The experimental apparatus is then used to study reactive powders. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700