Bulletin of the American Physical Society
APS March Meeting 2020
Volume 65, Number 1
Monday–Friday, March 2–6, 2020; Denver, Colorado
Session B03: Materials in Extremes: Energetic and Reactive Materials: Novel ApproachesFocus
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Sponsoring Units: GSCCM Chair: Pamela Bowlan, Los Alamos National Laboratory Room: 107 |
Monday, March 2, 2020 11:15AM - 11:51AM |
B03.00001: Safety and performance characteristics of thermite systems: from powders to 3D printed lattices Invited Speaker: Kyle Sullivan The reaction in thermite powders is a highly complex process. Developing a true understanding of this process involves an understanding of the various length and time scales, as well as the non-equilibrium and equilibrium processes as fuel and oxide particles react to form mixed-phase products on a rapid time scale. In this work, we present an overview of our work, which ranges from loose-powder combustion testing to 3D printed lattices of thermite. Specifically, we explored the dynamic formation of mesoparticles and the resultant multi-phase expansion of these particles as they are entrained in a gas stream. Additive manufacturing (AM) was then used to probe how the printed architecture can be used to manipulate the reactivity, by affecting the forward energy transport through design of the structure. A materials design plot (i.e., an "Ashby Diagram") was constructed to quantify the control AM offers for these materials. |
Monday, March 2, 2020 11:51AM - 12:03PM |
B03.00002: High Velocity Impact Testing of Structural Reactive Projectiles Alan Williams, Colt Cagle, Michelle Pantoya This study examined the dynamic response of structural reactive projectiles penetrating through an aluminum target then impacting an inert steel anvil at speeds up to 1500 m/s. The impact testing is performed using a High-velocity Impact-ignition Testing System (HITS). The projectiles consist of a thermite with a high loading ductile metallic binder, consolidated into a cylindrical pellet contained in a .410 caliber shot gun case. The thermite includes aluminum fuel particles that were stress altered prior to their consolidation. This study considers the effect of stress altering aluminum particles on the overall penetration dynamics and reactivity of the projectile. Results demonstrate the range of plate deformation mechanics and overall transient pressure data that can be used to interpret reactivity. A threshold impact velocity was observed that corresponds with fragmentation of the projectile and is a function of stress-altered particles. The differences in reactivity between stress altered and untreated aluminum powder likely stem from the fragmentation field created upon penetration of the plate. Results provide a fundamental understanding of penetration and impact events with structural reactive formulations. |
Monday, March 2, 2020 12:03PM - 12:15PM |
B03.00003: Modeling PBX 9501 High Explosive Cylinder Experiments and an Evaluation of WSD and AWSD Parameter Sets Marvin Zocher, Tariq D Aslam Cylindrical assemblies are often used in experiments aimed at calibrating and validating continuum level models of reactive burn, and of the so-called equation of state model (constitutive model for the spherical part of the Cauchy tensor). Such is the case in work to be discussed here. In particular, work will be described involving the modeling of a series of experiments involving PBX 9501 encased in a copper cylinder. The objective of the work is to test and perhaps refine a set of phenomenological parameters for the Wescott-Stewart-Davis (WSD) and Arrhenius-WSD (AWSD) reactive burn models. |
Monday, March 2, 2020 12:15PM - 12:27PM |
B03.00004: High Explosive Shock Initiation Model Based on Hot Spot Temperature Laurence Fried, Matthew P Kroonblawd We describe a new shock initiation model based on the Cheetah thermochemical code. The model is based on a multiple stage picture of the shock initiation process and uses hot spot temperature as an auxiliary variable to control the initial stages of reaction. Unlike using rates controlled by other thermodynamic variables, this approach captures physical sub-zonal differences between the bulk temperature and the substantially higher local hot spot temperature that actually governs ignition chemistry. In the model, a single representative hot spot diameter is chosen and the hot spot temperature is controlled by shock pressure and thermal conductivity. The practical utility of a sub-zonal hot spot temperature model will be discussed, as well as evidence for co-existing hot spot and shear band ignition mechanisms in high explosive shock initiation. |
Monday, March 2, 2020 12:27PM - 12:39PM |
B03.00005: Multi criteria decision model for design of advanced energetic materials with tailored properties Maija M Kukla, Roman Tsyshevskiy The search for new high energy density materials (HEDMs) with targeted high performance, low toxicity, and reliable stability remains challenging. New materials are typically developed by Edisonian trial and error approach that involves sophisticated synthesis protocols combined with extensive sensitivity characterization tests. Such efforts are time consuming and resource exhaustive while the successful outcomes are seldom guaranteed. A combination of ab initio, group additive methods, and statistical analysis represents a powerful tool for computational design and discovery of new advanced high energetic density materials. Here, we report a sophisticated approach for design of new HEDMs with tailored properties based on extensive state-of-the-art study of structure-property-function relationships of various classes of energetic and explosive materials. We also show how we use this approach for discovery and characterization of new linear and fused heterocyclic HDEMs with performance and stability parameters considerably superior to conventional O-, N- and C-nitro compounds such as PETN, RDX and TNT. |
Monday, March 2, 2020 12:39PM - 12:51PM |
B03.00006: Transition and Optimization of Particle Impact Mitigation Sleeve Design between Munitions of Different Physical Parameters Daniel Pudlak, Kevin Miers Military munitions that fall within the NATO portfolio must be tested in accordance with Insensitive Munitions AOP-4496 Fragment Impact (FI) Testing. Under this test, a conical, steel cylinder is launched at the munition at 8300fps, and the response of the munition is evaluated for reactions ranging from violent detonation, to benign burning reaction. Standard practice to mitigate a violent detonation reaction from occurring is to develop barrier technologies (e.g. armor) that can reduce the velocity, and overall kinetic energy of the fragment to a level that will not produce a violent response of the munition. Previously, a technology known as Particle Impact Mitigation Sleeve (PIMS) that was developed for a specific munition, successfully reduced the munition’s response from a detonation, to a benign burn. This PIMS design is currently being evaluated for application to a different munition. While these different munitions produce similar responses without the PIMS, their energetic content, munition physical parameters, and packaging materiel are different, which can substantially affect the response of the munition to FI. This paper will describe the transition and optimization of the PIMS design to successfully mitigate the new munition’s response to the FI threat. |
Monday, March 2, 2020 12:51PM - 1:03PM |
B03.00007: Dynamic Compression of RDX Single Crystal and High Explosives Cheng Liu, Carl M Cady, Kyle Ramos, Benjamin M Morrow, Christopher Meredith Dynamic compression and failure of energetic RDX single crystals and high explosive PBX 9501 are studied experimentally using a miniature Split Hopkinson Pressure Bar (SHPB) combined with high-speed photography and optical digital image correlation (DIC) technique. In addition to the strain gages mounted at the center of the incident and transmitted bars, high-speed camera, running at the rate of 5 million frames per second, was used to capture the deformation process of the RDX single crystal and the PBX 9501. A random speckle pattern was also printed on the sample surface and optical DIC technique was applied to map out the displacement and the strain fields over the sample surface, as well as to capture the crack initiation and extension process. A technique was developed for quantitatively identifying crack, the motion of the crack tip, and extracting the fracture toughness of a brittle material in compression. Combined with the dynamic compression setup, we will be able to study the deformation and failure processes in much detailed and quantitative fashion. |
Monday, March 2, 2020 1:03PM - 1:15PM |
B03.00008: Performance Evaluation Methodology for Materials Subjected to Explosively-Driven Highly Non-Radial Implosive Motion Lawrence Hull, Steve M Gilbertson, Jonathan A Hudston, Thomas A Beery Non-radial implosive motion is experienced during the early stages of various important device formation processes, such a shaped charge jet. If the response of the material can be characterized during this initial stage of motion, then often the subsequent motion will be predictable. Diagnostics are either available or are under development, such as Modulation Based Ranging (MBR), to address this initial stage of motion. The use of velocimetry to evaluate material response when non-radial flow occurs is complicated by the non-colinearity of the velocity the surface normal, and non-colinearity with the laser beam. The result is that ordinary velocimetry results in an incomplete measurement, that of the component of velocty in the direction of the laser beam. We introduce a method, MBR, that measures the position that any object that intersects the laser line as a function of time, approximately closing the measurement system and enabling the application of the velocity-based evaluation methodologies. We describe our use of simultaneous Photon Doppler Velocimetry (PDV) and MBR along with radiography to characterize and compare the response two geometrically identical hemispherical shells that were manufactured differently. |
Monday, March 2, 2020 1:15PM - 1:27PM |
B03.00009: Shock-induced paracrystallinity in PPTA Paulo Branicio, Subodh Tiwari, Sungwook Hong, Daniel Shebib, Rajiv Kalia, Aiichiro Nakano, Priya Vashishta The outstanding strength-to-weight ratio of para-aramid fibers, such as Kevlar and Twaron, is largely attributed to their high content of crystalline p-phenylene terephthalamide (PPTA). Atomistic simulations of shock loading on PPTA are performed along the [100] and [010] crystallographic directions, using reactive molecular-dynamics simulations. The reactive forcefield utilized is fitted to PPTA properties using first principles data and the results are validated by ab-initio molecular dynamics (QMD) simulations. Simulation results reveal an anisotropic shock response displaying elastic, crosslinking, and phase transformation from crystalline to para-crystalline phases. While QMD simulations show elastic to amorphous planar transformation for shocks along [010] direction, long time simulations accessible by reactive molecular dynamics indicate the formation of a para-crystalline phase initiated by an amorphous planar transformation, which displays H-bond scission and rotation of chains. The rotation process reorients the polymer chains such that vdW interactions dominate chain-chain interactions leading to the formation of local domains where new H-bond interaction forms leading to the para-crystalline phase. |
Monday, March 2, 2020 1:27PM - 1:39PM |
B03.00010: Experiment and Numerical Simulation Study on Near-field Underwater Explosion of Aluminized Explosive Yuanxiang Sun Aluminized explosive can improve the energy output structure and power of detonation products. The application of aluminized explosive to underwater explosion enhances the brisance and damage capability of underwater weapons significantly. The near-field underwater explosion experiments of aluminized explosive RL_F and TNT were carried out using PVDF pressure sensor based on electrical measurement method, and Coupled Eulerian-Lagrangian (CEL) method was used for simulation. The numerical results agreed well with experimental and empirical ones. The results show that CEL method can be used to simulate the propagation process of near-field underwater explosion shock wave of TNT and aluminized explosive accurately if reasonable boundary conditions, calculation parameters and finite element model are adapted. Near-field underwater shock wave pressure attenuation of aluminized explosive is slower than TNT. Then, the approximate regression formulas of near field underwater explosion shock wave peak pressure of TNT within 6 times of charge radius and aluminized explosive in a certain distance range are obtained by fitting the simulation results. |
Monday, March 2, 2020 1:39PM - 1:51PM |
B03.00011: Thermal transport across diamond/copper interface functionalized by self-assemble monolayer BIN XU, Shih-Wei Hung, Junho Choi, Junichiro Shiomi
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B03.00012: Pressure- and Temperature-Dependent Structural Stability and Photoluminescence properties of LLM-105 Crystal Zengming Zhang, zilong xu, junke wang Energetic material LLM-105 maintains its structure stability under high pressure below 30 GPa at room temperature or in the temperature range from 513 K to 5 K with ambient pressure. One structural phase transition occurs at about 30 GPa and is confirmed by pressure-dependent Raman and infrared spectra. |
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