Bulletin of the American Physical Society
APS March Meeting 2020
Volume 65, Number 1
Monday–Friday, March 2–6, 2020; Denver, Colorado
Session S02: Dynamic Compression II: Experiments |
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Sponsoring Units: GSCCM Chair: Camille Chauvin Room: 105 |
Thursday, March 5, 2020 11:15AM - 11:27AM |
S02.00001: Complex loading experiments to study multiphase strength in Cerium Brian Jensen Understanding the mechanical properties of materials at extreme conditions is relevant to a wide range of dynamic phenomena related to geophysics and planetary science, general solid and fluid flow behavior, and applications for ballistics and armor development, for example. Efforts in recent years have used multiple-shock and release loading to examine material strength in metals including single crystal and polycrystalline aluminum. Despite these efforts, data that describes strength effects following a shock-induced, solid-solid phase transition is lacking. In this work, complex loading experiments were analyzed to examine the strength of cerium shocked to stress states that span the low-pressure phase transition up toward the melt boundary. The experimental results and data analysis will be presented along with a discussion on their implications and future work. |
Thursday, March 5, 2020 11:27AM - 11:39AM |
S02.00002: Direct Temperature Measurement of Laser-compressed Matter using inelastic X-ray Scattering Emma McBride
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Thursday, March 5, 2020 11:39AM - 11:51AM |
S02.00003: Toward predictive pulsed power loss estimates to ensure dynamic materials properties experiment success Andrew Porwitzky, Brian Hutsel Successful execution of dynamic materials properties experiments on large scale pulsed power machines can involve over-taxing the pulsed power driver. Under some circumstances, electrical loses can alter the isentropic compression path of the sample material at high pressure, resulting in shock formation or a failure to reach the desired peak pressure. Loss models based on space charge limited ion emission, enhanced by electron flow current, are beginning to demonstrate potential for predictive modeling of materials experiments. We present the state of this effort and some of the challenges inherent in the use of the ion loss model. |
Thursday, March 5, 2020 11:51AM - 12:03PM |
S02.00004: Electrical Conductivity of Tin Under Shock Conditions Ryan Crum, Minta C Akin, David Brantley, Ricky Chau Electrical conductivity of materials under extreme conditions may provide the necessary information to obtain bulk temperatures, the location of phase boundaries, and pertinent knowledge for ongoing electromagnetic responses for planetary interiors. We introduce a means to study the electrical conductivity of metals, in this study tin, with an easily accessed melt boundary between 45 and 70 GPa on the principal Hugoniot. A plate impact methodology is implemented to drive the tin sample to high pressure and temperature states while the electrical resistivity and conductivity of the sample are recorded. We observe a stark jump in the electrical resistivity and conductivity associated with the melt boundary, further constraining the tin melt boundary. Through the Wiedemann-Franz law, we will address implications of whether the law holds and what the predicted temperature and thermal conductivity are under shock conditions. |
Thursday, March 5, 2020 12:03PM - 12:15PM |
S02.00005: Shock Driven Dynamics on the Benchtop: Generation and Characterization with Imaging and Spectroscopy Dmitro Martynowych, Jet Lem, Keith Adam Nelson We have developed a benchtop platform to generate shockwaves in materials and monitor the ensuing material response and chemistry. A thin layer (20-100 µm) of material is pressed between two glass plates, confining it to a planar geometry. A nanosecond laser pulse is focused into a circular “ring” pattern of 180 µm radius, launching a shock wave that propagates within the plane of the sample and focuses toward the circle’s center. Using a high-speed multi-frame camera, we have been able to record up to sixteen images of a single shock event with time intervals as short as 5 ns. Employing a host of spectroscopic techniques, we can further interrogate the structural and chemical nature of the shocked sample. This single-shot method of imaging and characterizing shocked samples has allowed us to investigate a variety of chemical and physical phenomena including cavitation, structural phase transitions, and chemical reactivity/decomposition. |
Thursday, March 5, 2020 12:15PM - 12:27PM |
S02.00006: Determining an orientation relationship for the diffusionless hcp-bcc phase transition in Mg under dynamic loading Matthew Beason, Brian Jensen For years, crystallographers have sought to decompose phase transitions into a series of dilations, shears, or contractions based on fundamental symmetries between the parent and product phases. Burger’s mechanism describes the bcc-hcp phase transition through two steps: a strain in the [001]bcc direction followed by an internal shear of the (110)bcc planes along the [1-10]bcc direction displacing every alternate plane and resulting in the hcp structure. While such mechanisms may describe certain transitions under static conditions and provide a framework for theoretical studies, it is not clear that such an orderly process is relevant for a shock driven transformation. This presentation reports on experiments performed at the Dynamic Compression Sector (DCS) on the hcp-bcc phase transition of Mg. By performing in situ X-ray diffraction (XRD) on shock loaded Mg we have captured the orientation of the bcc phase at the shock state, allowing an orientation relationship to be established with the initial hcp lattice. This represents an important first step in ongoing efforts to develop a transition mechanism for the hcp-bcc phase transition under dynamic loading. |
Thursday, March 5, 2020 12:27PM - 12:39PM |
S02.00007: Cellular Structures Imaged in the Detonation Front of Pure Liquid Nitromethane Erin Nissen, Mithun Bhowmick, Dana D Dlott We developed a tabletop compression microscope, which uses laser driven flyer plates to generate 4-ns duration planar shocks in tiny cuvettes filled with the high explosive nitromethane. When the flyer velocity is 4.0 km/s, a detonation forms at a pressure of 19 GPa and a velocity of 6.25 µm/ns. We implemented a high-speed high-resolution camera in combination with photon Doppler velocimetry to watch how the reaction zone develops on the nanoscale. We captured, for the first time in pure liquid nitromethane, micron-scale structures, known as cellular structures in the detonation front. These cells are caused by a superdetonation, a shock traveling in a precompressed medium, that forms behind the shock front after a short delay. The superdetonation will collide with the original shock front and reflect transverse waves into the reacting material behind it. These waves bounce between the backwards traveling shock from the superdetonation and the shock front creating a complex reactive flow with a convoluted shock front. Applying the size of the cells measured in the front to known theory allows us to measure the reaction zone length. |
Thursday, March 5, 2020 12:39PM - 12:51PM |
S02.00008: Molecular Influence in Microparticle Impact Response of Elastomers David Veysset, Yuchen Sun, You-Chi Mason Wu, Steven E Kooi, Timothy M. Swager, Keith Adam Nelson, Alex J. Hsieh Segmented elastomers have gained attention for their performance against high-velocity impacts through tailored segmental dynamics. The influence of molecular moieties has also been reported to be important on the dynamic behavior of polymers. In this work, we present impact measurements of laser-launched supersonic micro-particle impacts on polyurea and polyurethane elastomers. In a laser-induced projectile impact test (LIPIT), we accelerate solid microparticles to supersonic velocities up to 1 km/s through a laser-ablation process. The impact events are observed in situ using an ultra-high-speed multi-frame camera that can record up to 16 images with time resolution of each frame as short as 5 ns. We study the high-strain rate deformation response of elastomers to unravel the relation between microstructure and high-rate properties. In particular, we are interested in the influence of the nature and the extent of hydrogen bonding and the role of intermolecular interaction in the dynamic response of these polymers. We demonstrate that LIPIT is capable of quantifying the variation in dynamic stiffening observed among these elastomers upon impact at strain rate ~108 s-1. |
Thursday, March 5, 2020 12:51PM - 1:03PM |
S02.00009: Hot Spot and Reaction Temperature of Insensitive High Explosives using Time-Resolved Optical Pyrometry Meysam Akhtar, Dana D Dlott The capability of time-resolved optical pyrometry of our dynamic shock microscope system enables us to explore the evolution of the hot spot and combustion temperatures of shocked insensitive high explosives with nanosecond time resolution. Primarily, we analyze plastic-bonded explosive (PBX) formulations of triaminotrinitrobenzene (TATB), 1,1-diamino-2,2-dinitroethene (FOX-7), and 2,6-Diamino-3,5-Dinitropyrazine-1-Oxide (LLM-105). These explosives are particularly interesting because they are powerful but insensitive to accidental initiation. These three insensitive explosives have a yellow color, which causes a significant absorption in the blue region of the visible spectrum. This deviation from thermal radiation complicates the pyrometry experiment and should be accounted for in the determination of the temperature. |
Thursday, March 5, 2020 1:03PM - 1:15PM |
S02.00010: High-speed X-ray Phase Contrast Imaging Analysis of Microscale Shock Response of a Mock Additively Manufactured Energetic Material Karla Wagner, Andrew Boddorff, Amirreza Keyhani, Gregory B. Kennedy, Didier Montaigne, Min Zhou, Naresh N Thadhani X-ray phase contrast imaging (XPCI) is used to probe the interior of a mock additively manufactured energetic material (AMEM) under dynamic loading and determine the equation of state (EOS). AMEMs have a range of structural characteristics with a hierarchy of length scales and process-inherent heterogeneities. Many of these features are difficult to precisely control or avoid and it is important to understand how they affect the dynamic response of the AMEM. To this effect, XPCI is a technique that grants insight into micro- and meso- scale processes during a shock event. We use XPCI results to analyze the shock response of a mock AMEM loaded in different directions at several impact conditions. By tracking displacement of the shock front and features behind it, we can determine shock velocity and particle velocity. PDV was also used to measure the free surface velocity of the specimens and from that the particle velocities, which correlate well with those obtained from XPCI. The shock and particle velocity EOS is found to approximately follow Us = 1.63Up+ 2619 with R2 = 0.8. The experiments presented were performed at the DCS in the APS at Argonne National Lab, in collaboration with Brian Jensen at Los Alamos National Lab. |
Thursday, March 5, 2020 1:15PM - 1:27PM |
S02.00011: Quantitative Assessment of the Interior Deformation of an Additively Manufactured Energetic Material Simulant under Shock Loading Amirreza Keyhani, Karla Wagner, Andrew Boddorff, Naresh N Thadhani, Min Zhou The performance of energetic materials subjected to dynamic loading depends on the morphology of their microstructures. The geometric flexibility and versatility offered by additive manufacturing open new pathways to control the performance of these materials and functionally tailor them for given applications. Additively manufactured energetic materials (AMEM) have a wide range of microstructures with a hierarchy of length scales and heterogeneities which are difficult to control or avoid. To understand how they affect the response of such materials under shock loading, X-ray phase contrast imaging (XPCI) is used to probe the interior and quantify the deformation fields in the impacted samples. Two to four XPCI images were captured revealing the shock front and deformation. DIC analysis was then used to provide the first-ever assessment of the average strain fields inside the material under shock loading. The results show that the average axial strain in the samples depends on the intensity of shock loading and reaches as high as ~0.23 for impact velocities up to 1.5 m/k. The experiments presented were performed at the DCS in the APS at Argonne National Lab, in collaboration with Brian Jensen at Los Alamos National Laboratory. |
Thursday, March 5, 2020 1:27PM - 1:39PM |
S02.00012: Inferring 3D Behavior of Dynamically Compressed Granular Materials from X-ray Tomography and Dynamic Radiography Measurements Adyota Gupta, Kaliat T Ramesh, Ryan Hurley Dynamically compressed granular materials have primarily been studied using macroscopic measurements (e.g., VISAR, PDV). However, simulations and x-ray imaging measurements have revealed the rich, heterogeneous behavior occurring at the microscale during dynamic compression of granular materials: force chains, non-planar shock fronts, porosity-dependent shock velocities. |
Thursday, March 5, 2020 1:39PM - 1:51PM |
S02.00013: Deviation from classical laws in shock-driven gas mixtures at moderate Mach numbers. Peter Vorobieff, Humberto Silva, Caleb White, Patrick J Wayne We conducted a series of experiments where planar shocks propagated through mixtures of helium and sulfur hexafluoride. Even at modest Mach numbers, the bulk temperatures and pressures measured in the shocked mixture deviated significantly from the predictions of both Dalton's and Amagat's laws. As early as in the 1960s, it was already known that the behavior of gas mixtures in the immediate vicinity of a shock front was highly non-classical, however, our measurements show that the observed non-classical behaviors may persist far beyond the temporal and spatial scales associated with the shock passage. Simple molecular physics considerations can help explain some of the observed discrepancy. Numerical simulation of the experiments helps elucidate the observed disagreement between observations and models. |
Thursday, March 5, 2020 1:51PM - 2:03PM |
S02.00014: Single shot metrology of shocked dynamic parameters for transparent materials Zhicheng Zhong, Hao Jiang, Shiyuan Liu Laser-driven shock compression is a common method to study the equations of states (EOS) of materials under extreme conditions. The shock etalon method is an effective method to extract the shocked dynamic parameters of transparent materials. However, the sample surface reflection should be eliminated when using this method, which results in more time and efforts on the sample preparation. |
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