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 M9: Poster Session II (6:00-8:00pm)Poster
|
Hide Abstracts |
Room: Regency Ballroom CD |
|
M9.00001: DETONATION AND SHOCK-INDUCED CHEMISTRY |
|
M9.00002: Development of a TDLAS sensor for temperature and concentration of H$_{2}$O in high speed and high temperature flows Suzanne Sheehe, Sean O'Byrne The development of a sensor for simultaneous temperature concentration of H$_{2}$O and temperature in high speed flows is presented. H$_{2}$O is a desirable target sensing species because it is a primary product in combustion systems; both temperature and concentration profiles can be used to assess both the extent of the combustion and the flow field characteristics. Accurate measurements are therefore highly desirable. The sensor uses a vertical-cavity surface emitting laser (VCSEL) scanned at 50 kHz from 7172 to 7186 cm$^{-1}$. Temperatures and concentrations are extracted from the spectra by fitting theoretical spectra to the experimental data. The theoretical spectra are generated using GENSPECT in conjunction with line parameters from the HITRAN 2012 database. To validate the theoretical spectra, experimental spectra of H$_{2}$O were obtained at known temperatures (290-550 K) and pressures (~ 30 torr) in a heated static gas cell. The results show that some theoretical lines deviate from the experimental lines. New line-strengths are calculated assuming that the line assignments and broadening parameters in HITRAN are correct. This data is essential for accurate H$_{2}$O concentration and temperature measurements at low pressure and high temperature conditions. [Preview Abstract] |
|
M9.00003: Effect of Vertical Concentration Gradient on Globally Planar Detonation with Detailed Reaction Mechanism Qingguana Song, Cheng Wang, Yong Han, Dayuan Gao, Yingliang Duan Since detonation often initiates and propagates in the non-homogeneous mixtures, investigating its behavior in non-uniform mixtures is significant not only for the industrial explosion in the leakage combustible gas, but also for the experimental investigations with a vertical concentration gradient caused by the difference in the molecular weight of gas mixture. Objective of this work is to show the detonation behavior in the mixture with different concentration gradients with detailed chemical reaction mechanism. A globally planar detonation in H2-O2 system is simulated by a high-resolution code based on the fifth-order weighted essentially non-oscillatory (WENO) scheme in spatial discretization and the third-order Additive Runge-Kutta schemes in time discretization. The different shocked combustion modes appear in the rich-fuel and poor-fuel layers due to the concentration gradient effect. Globally, for the cases with the lower gradient detonation can be sustained in a way of the alternation of the multi-heads mode and single-head mode, whereas for the cases with the higher gradient detonation propagates with a single-head mode. [Preview Abstract] |
|
M9.00004: Molecular Probing of Shocked Water. Erin Nissen, Dana Dlott I have developed a method for generating powerful shock waves in liquid samples. The sample array consists of 50 miniature cuvettes each holding 125 nL, enabling a throughput of roughly 100 independent tabletop experiments per day. Planar shock waves were generated in liquid samples on impact from a laser driven flyer plate, whose velocity was measured with photon Doppler velocimetry and used to determine the pressure inside the liquid cell. This work focuses on the fascinating and unknown properties of water in extreme conditions. We established an advanced spectroscopy system that employs a nanosecond laser and streak camera, as well as a femtosecond visible and IR laser to understand the photophysics of various molecular probes in shock compressed water. The dye probes measure changes in viscosity, while the hydrogen bonding and dissociation of water itself can be analyzed with the femtosecond IR laser. [Preview Abstract] |
|
M9.00005: Kinetics of carbon clustering in detonation of high explosives: Does theory match experiment? Kirill Velizhanin, Erik Watkins, Dana Dattelbaum, Richard Gustavsen, Tariq Aslam, David Podlesak, Millicent Firestone, Rachel Huber, Bryan Ringstrand, Trevor Willey, Michael Bagge-Hansen, Ralph Hodgin, Lisa Lauderbach, Tony van Buuren, Nicholas Sinclair, Paulo Rigg, Soenke Seifert, Thomas Gog Chemical reactions in detonation of carbon-rich high explosives yield carbon clusters as major constituents of the products. Efforts to model carbon clustering as a diffusion-limited irreversible coagulation of carbon clusters go back to the seminal paper by Shaw and Johnson. However, first direct experimental observations of the kinetics of clustering yielded cluster growth one to two orders of magnitude slower than theoretical predictions. Multiple efforts were undertaken to test and revise the basic assumptions of the model in order to achieve better agreement with experiment. We discuss our very recent direct experimental observations of carbon clustering dynamics and demonstrate that these new results are in much better agreement with the modified Shaw-Johnson model. The implications of this much better agreement on our present understanding of detonation carbon clustering processes and possible ways to increase the agreement between theory and experiment even further are discussed. [Preview Abstract] |
|
M9.00006: Study of particle evolution from Composition B-3 detonation by time-resolved small angle x-ray scattering R Huber, D Podlesak, D Dattelbaum, M Firestone, R Gustavsen, B Jensen, B Ringstrand, E Watkins, M Bagge-Hansen, R Hodgin, L Lauderbach, T Willey, T van Buuren, T Graber, P Rigg, N Sinclair, S Seifert High explosive (HE) detonations produce an assortment of gases (CO, CO$_{\mathrm{2}}$, N$_{\mathrm{2}})$ and solid carbon products (nanodiamond, graphite). The evolution of solid carbon particles, within the chemical reaction zone, help to propel the detonation wave forward. Due to the violent nature and short reaction times during HE detonations, experimental observation are limited. Through time-resolved small angle x-ray scattering (TRSAXS) we are able to observed nanocarbon formation on nanosecond time scales. This TRSAXS setup is the first of its kind in the United States at Argonne National Laboratory at the Advanced Photon Source in the Dynamic Compression Sector. From the empirical and analytical analysis of the x-ray scattering of an in-line detonation we are able to temporally follow morphology and size. Two detonation geometries were studied for the HE Comp B-3 (40{\%} TNT/60{\%} RDX), producing steady and overdriven conditions. Steady wave particle evolution plateaued by 2 microseconds, where overdriven condition particle size decreases at the collision of the two shock fronts then plateaus. Post detonation soot is also analyzed to confirm size and shape of nanocarbon formation from Comp B-3 detonations. LA-UR-17-21443 [Preview Abstract] |
|
M9.00007: Isotope-Labeled Composition B for Tracing Detonation Signatures Virginia Manner, David Podlesak, Rachel Huber, Ronald Amato, Anna Giambra, Patrick Bowden, Ernest Hartline, Dana Dattelbaum To better understand how solid carbon forms and evolves during detonation, we have prepared Composition B with $^{\mathrm{13}}$C and $^{\mathrm{15}}$N-labeled 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX) and 2,4,6-trinitrotoluene (TNT) in order to trace the formation of soot from the carbon and nitrogen atoms in these explosives. Isotope-labeling of explosives has been performed in the recent past for a variety of reasons, including environmental remediation and reaction mechanism studies. Because it is expensive and time consuming to prepare these materials, and our detection equipment only requires trace amounts of isotopes, we have prepared fully-labeled materials and substituted them into unlabeled RDX and TNT at less than the 1{\%} level. We will discuss the preparation and full characterization of this labeled Composition B, the detonation tests performed, along with the results of the post-detonation soot analysis. Various detonation models predict differing amounts and forms of carbon and nitrogen; these isotopically-labeled precursors have allowed these models to be tested. [Preview Abstract] |
|
M9.00008: Characterization of Detonator Performance as a Function of Porosity via the Hayes Effect via Rogowski Coil Teagan Nakamoto, Kristina Parrack, Dalton Smith, Chris Trujillo, Zak Wilde, John Gibson, Rylie Lodes, Hayden Malcolm Researchers experimented with a novel diagnostic to study the effects of porosity on detonator performance. The new diagnostic takes advantage of the detonation electric effect observed by Hayes (1966). Detonation-produced electrical charges induce a current in the detonator wire that may be detected by use of a Rogowski coil developed and tailored for the purpose. Data collected by the Rogowski coil were then used to characterize detonations. Researchers tested PETN charges of various porosity levels (as characterized by measured particle size and surface area) to study the effect of porosity on detonation characteristics. This novel method was compared with and verified by the well-established technique of using PVDF gauges for detonator response characterization. [Preview Abstract] |
|
M9.00009: High Performance Modeling of Novel Diagnostics Configuration Dalton Smith, John Gibson, Rylie Lodes, Hayden Malcolm, Teagan Nakamoto, Kristina Parrack, Christopher Trujillo, Zak Wilde A novel diagnostics method to measure the Hayes Electric Effect was tested and verified against computerized models. Where standard PVDF diagnostics utilize piezoelectric materials to measure detonation pressure through strain-induced electrical signals, the PVDF was used in a novel technique by also detecting the detonation’s induced electric field. The ALE-3D Hydro Codes predicted the performance by calculating detonation velocities, pressures, and arrival times. These theoretical results then validated the experimental use of the PVDF repurposed to specifically track the Hayes Electric Effect. [Preview Abstract] |
|
M9.00010: Shock Waves Generated by Exploding Bridgewires in Condensed Media William Neal, Nathaniel Sanchez, Brian Jensen, John Gibson, Mike Martinez, Charles Owens, Jonathon Ramero, Dennis Jaramillo, Adam Iverson, Carl Carlson, Alex Derry, Paulo Rigg An exploding bridgewire (EBW) detonator functions due to the electrical explosion of a metal wire in contact with a low-density explosive powder. The exact mechanism that transfers the energy from the wire to the explosive that leads to initiation is not well understood. One energy transfer theory is a shock-to-detonation transition. Due to difficulties involved due to the small length scales and the unsteady shock-wave, the shock-wave emanating from a exploding wire in a representative medium has not been measured. This study uses non-invasive ultrafast x-ray phase contrast imaging, taken using Los Alamos National Laboratory's IMPULSE system, and magneto-hydrocode simulations to characterise the shock-wave produced by an exploding bridge-wire in a non-reactive analogue porous medium. This effort will be used to determine if the shock-wave has sufficient magnitude and duration to initiate typical EBW detonator explosives. [Preview Abstract] |
|
M9.00011: Deflagration of Energetic Materials Initiated by Electrostatic Discharges and Laser-Induced Plasmas Eric Collins, Jennifer Gottfried A laser-induced plasma and an electrostatic discharge were used for the ignition of small quantities (5-10 mg) of energetic materials. The laser-induced plasma was generated from a ns-pulsed Nd:YAG laser with energy output of 0.8 J per pulse and the electrostatic discharge was generated from a 0.035 $\mu $F capacitor that was charged to energy levels of up to 10 J. Although the durations and energy outputs of these two ignition mechanisms are very different, similarities in the initiation of the energetic materials include particle ejection from the target, heating of particles in the air from the plasma and spark, and a shockwave formation. The shock wave was measured and analyzed at various energy levels using schlieren imaging with a high speed camera. Diagnostics used to measure time-resolved temperatures, energy generation, and emission signatures of the deflagrations were high speed camera pyrometry, visible and infrared photo receivers, and a high-resolution spectrometer, respectively. [Preview Abstract] |
|
M9.00012: Laser-Driven Flyer Plate Impact of CL-20 Steven Dean, Frank De Lucia Jr., Jennifer Gottfried A recently constructed and characterized laser-driven flyer plate system has been used to impact CL-20 (Hexanitrohexaazaisowurtzitane), a highly energetic and relatively impact sensitive material. Flyer plates are generated by focusing a ns-pulsed Nd:YAG laser on the interface of a metal foil and glass substrate to which the foil has been adhered. Flyer plates are composed of 25 $\mu $m thick Al and have diameters of approximately 700 $\mu $m. The flyer plate's velocity can be controlled by varying the energy of the launch laser, and can exceed 1.5 mm/$\mu $s. Dozens of flyer plate impacts can be conducted in a single day and require only a few mg of energetic material. The impact event is characterized through high speed videography, visible and infrared high speed photodiodes, and spectral emission. At a critical flyer plate velocity a large spike in the photodiode signal is taken to indicate the shock initiated decomposition of CL-20. This impact event is compared with more traditional measurements of impact sensitivity. [Preview Abstract] |
|
M9.00013: Optimization of Parameters for Aged EBW Detonators Ty Brooks, Peter Schulze, Casey Spawn, Matt Biss, Daniel Preston Working towards an optimal exploding bridgewire (EBW) detonator design, three parameters were varied among two detonator platforms. These three parameters were bridgewire dimension, high explosive (HE) density, and component material. These parameters were chosen due to their potential to benefit initiation characteristics. The performance of each parameter was characterized at pristine conditions and after accelerated aging. The overall performance as well as the severity of performance loss observed after aging were considered. The results of this parameter study are presented and trends related to parameter variation are examined. [Preview Abstract] |
|
M9.00014: Fireset and Cable Design for Support of Detonator Diagnostic Development Christopher Trujillo, Elizabeth Francois, John Gibson, Rylie Lodes, Teagan Nakamoto, Dalton Smith, Douglas Tasker, Kristina Parrack, Zakary Wilde The performance of detonators can be affected by porosity effects in high explosive (HE) materials. In an effort to understand how these effects characterize performance, experiments are to be performed implementing new approaches with advanced diagnostics. This presentation will include the design choices and implementation of diagnostics within two primary components in the experimental test set up, the fire-set and cables. The fire-set contains a current viewing resistor (CVR) which characterizes the electrical performance of the detonator. The cable between the fire-set and detonator includes a Rogowski coil to measure the induced current passing to the detonator. We will present the experimental results and discuss the relevance of these data in the context of the overall experiments. [Preview Abstract] |
|
M9.00015: The Correlation of Electrical Fields and Detonator Behavior Zakary Wilde, Elizabeth Francois, John Gibson, Rylie Lodes, Teagan Nakamoto, Kristina Parrack, Dalton Smith, Douglas Tasker, Christopher Trujillo It is well established that behavior of the shock is affected by the microstructure of the explosive. Diagnostics are being developed to utilize Polyvinylidene fluoride (PVDF) gauges for shock wave detection and observing transient electric fields generated by shocked Pentaerythritol Tetranitrate (PETN), which is a piezoelectric explosive. This study has the goal of determining whether PVDF gauges can detect the electrical signature generated by the shock compression of PETN crystals and correlate it with the explosive material microstructure and shock to detonation transition (SDT) process in slapper detonators. Slapper detonators function by inputting current to an exploding foil initiator. The metal foil converts to a plasma causing a thin polymer layer to separate at high velocity and impact the explosive resulting in the SDT. Experiments will observe correlations between changes in the electrical signals and explosive microstructure. [Preview Abstract] |
|
M9.00016: Measurement and reactive burn modeling of the shock to detonation transition for the HMX based explosive LX-14 J. D. Jones, Xia Ma, B. E. Clements, L. L. Gibson, R. L. Gustavsen Gas-gun driven plate-impact techniques were used to study the shock to detonation transition in LX-14 (95.5 weight {\%} HMX, 4.5 weight {\%} estane binder). The transition was recorded using embedded electromagnetic particle velocity gauges. Initial shock pressures, $P$, ranged from 2.5 to 8 GPa and the resulting distances to detonation, $x_{D}$, were in the range 1.9 to 14 mm. Numerical simulations using the SURF reactive burn scheme coupled with a linear $U_{S} - u_{p}$ / Mie-Grueneisen equation of state for the reactant and a JWL equation of state for the products, match the experimental data well. Comparison of simulation with experiment as well as the ``best fit'' parameter set for the simulations is presented. [Preview Abstract] |
|
M9.00017: Detonation States without a Transition in the Super Large Scale Gap Test Harold Sandusky, Samantha Church, Joshua Felts At or above the critical pressure for shock-to-detonation transition (SDT), there is a run up in shock velocity before a distinct change to high-velocity detonation (HVD). If below that critical pressure a slower supersonic wave, referred to as low-velocity detonation (LVD), sometimes steadily propagates with enough energy to punch a witness plate. This was observed for sample diameters ranging from 36.5 mm in the large scale gap test to 177.8 mm in the super large scale gap test (SLSGT). Recent SLSGTs on an extremely insensitive explosive with a critical diameter \textgreater 100 mm exhibited HVD without SDT for no gap and LVD with decreasing velocity for longer gaps. These reactive shocks commenced from the donor input and continued steadily. This unique response suggests behavior more like a mass-deflagrating propellant. It is speculated that the large SLSGT diameter in conjunction with the confinement of a steel tube permits more time for shock reaction to occur before quenching by lateral rarefactions. Traditional GO/NOGO determinations do not apply for shock insensitive materials that require evaluation with the largest of the standardized tests, which has implications for both hazard classification and booster requirements. [Preview Abstract] |
|
M9.00018: Cylinder Tests with LX-17 and PBX 9502 as a Function of Temperature Lisa M. Lauderbach, P. Clark Souers Recent 125$^{\circ}$C cylinder test (CYLEX) data on PBX 9502 and LX-17 shows a larger change from ambient than can be obtained from the usual -55$^{\circ}$ to 75$^{\circ}$C range. Also, the large thermal expansion of the explosive relative to the copper closes the air gap and reduces the error. Comparison errors of detonation energy densities can be as low as +1/3\% as long as differences between samples of the same lot are considered. The measured energy density difference from ambient agrees with 1) the thermal energy of the explosive less that of the gaseous products is added or subtracted, and 2) this thermal energy difference and the original chemical energy are modified by the thermal expansion or contraction of the explosive. Also, the data at a relative volume of 2.4 and above is extrapolated back to C-J and the analysis shows that the detonation velocity is not expected to change by much, which is also seen. The C-J volume is also expected to remain almost constant. The results all depend on accurate corrections for the air gap in the test, and the most recent results, which vary with relative volume, are shown. [Preview Abstract] |
|
M9.00019: Improved Reactive Flow Modeling of the LX-17 Double Shock Experiments Thomas J. Rehagen, Peter Vitello Over driven double shock experiments provide a measurement of the properties of the reaction product states of the insensitive high explosive LX-17 (92.5{\%} TATB and 7.5{\%} Kel-F by weight). These experiments used two flyer materials mounted on the end of a projectile to send an initial shock through the LX-17, followed by a second shock of a higher magnitude into the detonation products. In the experiments, the explosive was initially driven by the flyer plate to pressures above the Chapman-Jouguet state. The particle velocity history was recorded by Photonic Doppler Velocimetry (PDV) probes pointing at an aluminum foil coated LiF window. The PDV data shows a sharp initial shock and decay, followed by a rounded second shock. Here, the experimental results are compared to 2D and 3D Cheetah reactive flow modeling. Our default Cheetah reactive flow model fails to accurately reproduce the decay of the first shock or the curvature or strength of the second shock. A new model is proposed in which the carbon condensate produced in the reaction zone is controlled by a kinetic rate. This allows the carbon condensate to be initially out of chemical equilibrium with the product gas. This new model reproduces the initial detonation peak and decay, and matches the curvature of the second shock, however, it still over-predicts the strength of the second shock. [Preview Abstract] |
|
M9.00020: ENERGETIC AND REACGTIVE MATERIALS |
|
M9.00021: Influence of surface contamination on the microstructure and morphology of vapor-deposited pentaerythritol tetranitrate (PETN) films Eric Forrest, Robert Knepper, Michael Brumbach, Kim Archuleta, Michael Marquez, Hy Tran, Alexander Tappan The field of Microenergetics relies on novel techniques to produce small-scale explosive samples for study of ignition, combustion, and detonation phenomena. Physical vapor deposition is one method to achieve precise control of explosive morphology and microstructure at length scales of interest. However, interfacial effects on morphology resulting from deposition processes are poorly understood, and can result in drastically different detonation behavior. In this study, we investigate the influence of substrate surface contamination on morphology and microstructure of vapor-deposited PETN films. Surface conditions are altered with various cleaning treatments, resulting in a range of oxide and contaminant profiles. Surface energy is quantified using a four-liquid contact angle measurement approach. Surface science techniques such as angle-resolved XPS enable study of surface constituents at {\AA}ngstrom length scales. Following deposition, PETN films are characterized using optical microscopy, scanning electron microscopy, and profilometry. Results demonstrate that substrate contamination at {\AA}ngstrom length scales has a profound effect on PETN microstructure and morphology, likely through influence over interface energy during the deposition process. [Preview Abstract] |
|
M9.00022: Abstract Withdrawn
|
|
M9.00023: Compaction of Ni-Al powders in a sharp interface framework Alexia De Brauer, H. S. Udaykumar Under high strain rate loading, structural energetic materials, such as Ni-Al powders, experience large deformation that causes high energy release which may lead to chemical reaction. In particular, the particle interfaces are the locations of energy deposition and reaction between the components. The present work proposes a level set-based numerical framework that models the particles and their interfaces as sharp objects on a Cartesian fixed grid. The current effort focuses on the compaction, heat generation and material melting at the interfaces of Ni and Al particles under high-velocity impact. The chemical reaction between Ni and melted Al is modeled by an Arrhenius type equation. The effect of friction on deformation and heat generation at the interfaces is examined. The material and interfacial modeling is applied on an idealized mixture powder composed of spherical particles and submitted to a flyer plate impact. [Preview Abstract] |
|
M9.00024: The Nuclear Barcode: a New Taggant for Identifying Explosives James Seman, Catherine Johnson, Carlos Castaño Creating an effective taggant system for explosives is a challenging problem since the taggant used must be designed to endure the detonation process. A new taggant for use in explosives has been recently developed and named the `nuclear barcode'. The nuclear barcode tags explosives by adding low concentrations of eight different elements to the explosive, and then reads the tag from the post-blast residue using neutron activation analysis (NAA) to identify the elements and their concentrations. The nuclear barcode can be used to identify explosives after detonation by sampling the post-blast residue that is deposited due to incomplete reaction of the explosives. This method of tagging explosives creates an identifying taggant that survives detonation as NAA detects atomic nuclei as opposed to using any chemical or physical properties of the taggant that don't always survive the detonation process. Additional advantages this taggant method offers is ease of recovery of the taggant after detonation, and a total of 25.6 billion possible taggants as currently conceived, which enables the nuclear barcode to be used to tag individual batches of explosives. This paper describes the development of the nuclear barcode taggant system and its potential use in the explosives industry. [Preview Abstract] |
|
M9.00025: Abstract Withdrawn
|
|
M9.00026: Abstract Withdrawn
|
|
M9.00027: Recent Advances on Thermal Safety Characterization of Energetic Materials Peter Hsu, Steve Strout, Micha Gresshoff, Evan Kahl, Greg Klunder Understanding the response of energetic material to thermal insults is very important for the storage and handling of energetic materials. The One-Dimensional Time to Explosion (ODTX) system at the Lawrence Livermore National Laboratory (LLNL) has been used for decades to characterize the thermal sensitivity of energetic materials and provide data for the construction of cook-off models. The system can measure times to explosion, the threshold temperature for thermal explosion and allow for the determination of kinetic parameters. In 2014, we added pressure diagnostics to the system, referred as P-ODTX. When energetic material is heated in a confined space, pressure increases slowly at low temperature. As the temperature increases, thermal decomposition accelerates resulting in higher gas pressure until thermal explosion occurs, at which time gas pressure increases very rapidly. In 2016 the data acquisition system was upgraded to allows for gas pressure measurement in micro-second intervals during thermal explosion. In this paper, we will share our recent times to explosion data on various energetic materials as well as gas pressure data during thermal explosion. We will also report recent progress in our C-ODTX development for the in-situ measurement of gas composition at elevated temperature and pressure as explosive is heated in a confined space. [Preview Abstract] |
|
M9.00028: One dimensional shock ring up of a TATB based explosive. Malcolm Burns Complex shock initiation of explosives is a gas gun technique that has been used for many years to explore shock sensitivity under various loading regimes. This body of work studies the shock initiation of a TATB-based explosive using a gas gun driven multiple shock technique somewhat between a double shock and ramp loading. In these experiments a shock wave rings up in a low impedance disc sandwiched between a high impedance flyer and anvil. The explosive sample under study has been placed in contact with the anvil and therefore each ring up is transmitted through the anvil into the explosive. This has created a stepped multiple shock input into the explosive, which can be tailored by varying both the dimensions within the ring up stage, and the flyer velocity. Typically the explosive sample will experience four to five stepped pulses before shock convergence. Two distinct shock initiation regimes have been studied; in the first the reactive growth in the explosive commences after shock coalescence and in the second the reactive growth commences within the first shocked state. In both cases the run distance to detonation, and growth of reaction has been measured using embedded particle velocity gauges. [Preview Abstract] |
|
M9.00029: Effects of void anisotropy on the ignition and growth rates of energetic materials. Nirmal Kumar Rai, Oishik Sen, H.S. Udaykumar Initiation of heterogeneous energetic materials is thought to occur at hot spots; reaction fronts propagate from sites of such hot spots into the surrounding material resulting in complete consumption of the material. Heterogeneous materials, such as plastic bonded explosives (PBXs) and pressed materials contain numerous voids, defects and interfaces at which hot spots can occur. Amongst the various mechanisms of hot spot formation, void collapse is considered to be the predominant one in the high strain rate loading conditions. It is established in the past the shape of the voids has a significant effect on the initiation behavior of energetic materials. In particular, void aspect ratio and orientations play an important role in this regard. This work aims to quantify the effects of void aspect ratio and orientation on the ignition and growth rates of chemical reaction from the hot spot. A wide range of aspect ratio and orientations is considered to establish a correlation between the ignition and growth rates and the void morphology. The ignition and growth rates are obtained from high fidelity reactive meso-scale simulations. The energetic material considered in this work is HMX and Tarver McGuire HMX decomposition model is considered to capture the reaction mechanism of HMX. The meso-scale simulations are performed using a Cartesian grid based Eulerian solver SCIMITAR3D. The void morphology is shown to have a significant effect on the ignition and growth rates of HMX. [Preview Abstract] |
|
M9.00030: Effect of local void morphology on the reaction initiation mechanism in the case of pressed HMX Sidhartha Roy, Nirmal Rai, H.S. Udaykumar The microstructural characteristics of pressed HMX has a significant effect on its sensitivity under shock loading. The microstructure of pressed HMX contains voids of various orientation and aspect ratio. Subject to shock loading, these voids can collapse forming hotspots and initiate chemical reaction. This work shows how the ignition and growth of chemical reaction is dependent on the local microstructural features of the voids. Morphological quantities like size, aspect ratio and orientations are extracted from the real microstructural images of Class III and Class V pressed HMX. These morphological quantities are correlated with the ignition and growth rates of the chemical reaction. The dependency of the sensitivity of a given HMX sample on the local morphological features shows that these local features can create a mocroscale physical response. [Preview Abstract] |
|
M9.00031: Ability of thermochemical calculation to treat organic peroxides Antoine Osmont, Gérard Baudin, Marc Genetier Since 3 years, the CEA Gramat is developing a new thermochemical code, called SIAME, funded by DGA to help French defense industry at conceiving new explosives compositions. It enables the calculation of CJ detonation and deflagration points and combustion of explosives. The accuracy of the code has been checked on several compositions containing PETN, RDX, HMX, TNT, NTO. The error on the velocity of detonation is 3 {\%}. To enlarge the domain of validity of the code, organic peroxides have been considered. It is known that thermochemical simulation is in failure regarding compounds as simple as hydrogen peroxide. The computed velocity of detonation is 5720 m/s when shock planar impact gives 6150 m/s. The same discrepancy is found for TATP, with a calculated value at 5870 m/s when 5290 has been measured. Detonation velocity of TATP has been measured at two different densities. These velocities agree with other published values. A closer look at the enthalpy of formation of TATP has revealed that it comes from an article of 1932. Ab initio computations have given a totally different value, leading to better agreement with experiment. [Preview Abstract] |
|
M9.00032: Calibration of a macroscopic impact ignition model from simulations of shear band formation on the mesoscale Yehuda Partom Relying on test results in [1] we propose in [2] a macroscopic impact ignition model in terms of the product PD (P$=$pressure, D$=$plastic deformation rate). Here we upgrade this model by taking into account the time duration of different PD levels. Our macroscopic impact ignition model is now based on, and calibrated from, 1D simulations of pure torsion on the mesoscale. We assume that impact ignition is invoked by shear localization and formation of shear bands. We denote by (PD)$_{\mathrm{Loc}}$ the macroscopic shear localization threshold. When PD\textgreater (PD)$_{\mathrm{Loc}}$ in a macroscopic cell, shear bands start to form there. The shear bands then develop and heat up towards the ignition temperature. We further assume that the time duration from localization to ignition $\Delta $t$=$t$_{\mathrm{ig}}$-t$_{\mathrm{Loc}}$ also depends on PD. Using 1D simulations of shear band formation in torsion, similar to [3], we calibrate (PD)$_{\mathrm{Loc}}$ and $\Delta $t(PD), which we can then use in macroscopic hydrocode simulations. Our mesoscale simulations depend on a realistic strength model for explosives. This model employs the overstress approach to dynamic viscoplasticity [4], and its main feature is pressure dependence of the plastic flow curve. 1. V. Boyle, R.B. Frey and O. Blake, 9$^{\mathrm{th}}$ Det. Symp., 3-17, 1989. 2. Y. Partom, 12$^{\mathrm{th}}$ Det. Symp., 831-834, 2002. 3. Y. Partom, SCCM 2015. 4. Y. Partom, DYMAT 2015, 94, 04003. [Preview Abstract] |
|
M9.00033: Investigating the Deflagration to Detonation Transition in LLM-105 and RX-55-DQ Using High Confinement as a Function of Density Shawn L. Strickland, Kevin S. Vandersall, Martin R. DeHaven The potential for deflagration-to-detonation transition (DDT) in LLM-105 and RX-55-DQ (94/6 LLM-105/Viton) has been investigated as a function of loading density using high confinement tubes. The high confinement arrangement uses a 76 mm outer diameter by 25 mm inner diameter mild steel tube 320 mm in length with 25 mm thick mild steel end caps ignited using a thermite igniter and was loaded with samples of varying densities. None of the experiments showed a transition to detonation over the entire length with non-violent burning or extinguishing of the burning observed. The hand packed RX-55-DQ molding powder or neat LLM-105 (\textasciitilde 1.1 g/cm$^{\mathrm{3}})$ burned nearly completely and vented non-violently by deforming or splitting the end caps. The RX-55-DQ was tested at higher densities with 1.35 g/cm$^{\mathrm{3}}$ resulting in a burning reaction on the 2$^{\mathrm{nd}}$ attempt that fractured the end cap while the 1.85 g/cm$^{\mathrm{3}}$ resulted in the burning reaction extinguishing in the first \textasciitilde 15 mm on the 2$^{\mathrm{nd}}$ attempt. This work will outline the testing details, present the results, and compare them to the relatively high binder content HMX-based LX-04 (85{\%} HMX and 15{\%} Viton) and ultra-fine TATB results tested under similar confinement. [Preview Abstract] |
|
M9.00034: Non-Gurney Scaling of Explosives Heavily Loaded with Dense Inert Additives Jason Loiseau, Andrew Higgins, David Frost For most high explosives, the ability to accelerate material to some terminal velocity scales with the ratio of material-mass to charge-mass (M/C) according to the Gurney equations. Generally, the Gurney equation for planar geometry accurately predicts the terminal velocity of the driven material until the M/C ratio is reduced to roughly 0.15 or lower; at which point gasdynamic departures from the assumptions in the model result in systematic underpredictions of the material velocity. The authors conducted a series of open-face sandwich flyer plate experiments to measure the scaling of flyer terminal velocity with M/C for a heterogeneous explosive composed of a packed bed of 280 $\mu $m steel particles saturated with amine-sensitized nitromethane (90{\%} NM, 10{\%} diethylenetriamine). The propulsive capability of this explosive did not scale according to a modified form of the Gurney equation. Rather, propulsive efficiency increased as the flyer plate became relatively thicker. In the present study the authors have conducted further experiments using this explosive in symmetric sandwiches as well as for normally-incident detonations initiated via a slapping foil to examine how flyer terminal velocity scales with M/C for alternative geometries and loading conditions. [Preview Abstract] |
|
M9.00035: Double Shock Experiments Performed at -55\textdegree C on LX-17 with Reactive Flow Modeling to Understand the Reacted Equation of State Martin R. DeHaven, Kevin S. Vandersall, Shawn L. Strickland, Laurence E. Fried, Craig M. Tarver Experiments were performed at -55\textdegree C to measure the reacted state of LX-17 (92.5{\%} TATB and 7.5{\%} Kel-F by weight) using a double shock technique using two flyer materials (with known properties) mounted on a projectile that send an initial shock through the material close to the Chapman-Jouguet (CJ) state followed by a second shock at a higher magnitude into the detonated material. Information on the reacted state is obtained by measuring the relative timing and magnitude of the first and second shock waves. The LX-17 detonation reaction zone profiles plus the arrival times and amplitudes of reflected shocks in LX-17 detonation reaction products were measured using Photonic Doppler Velocimetry (PDV) probes and an aluminum foil coated LiF window. A discussion of this work will include a comparison to prior work at ambient temperature, the experimental parameters, velocimetry profiles, data interpretation, reactive CHEETAH and Ignition and Growth modeling, as well as detail on possible future experiments. [Preview Abstract] |
|
M9.00036: Molecular Dynamics calculation of solid/liquid surface tension: a methodological study Nicolas Pineau, Thibaud Dreher, Laurent Soulard, Emeric Bourasseau, Patrice Malfreyt The influence of polymer/molecular crystal interfaces on the mechanical properties of Polymer \underline {Binded} Explosives under high strains is an open topic which can be explored through surface tension calculations. While such calculations are being performed for liquid/liquid and liquid/vapor interfaces intensively (A. Ghoufi et al., Chem. Soc. Rev. 45 (2016), 1387), little is known for the solid/liquid and solid/solid interfaces. The aim of this work is to fill that gap by computing the solid/liquid surface tension of a simple model system consisting of a graphene sheet embedded in liquid methane. We show that, unlike the liquid/vapour and liquid/liquid systems, the presence of a solid substrate has a strong impact on the structure of the fluid phase and that the simulation parameters should be chosen carefully to compute accurate surface tensions. [Preview Abstract] |
|
M9.00037: Compression and Decompression of RDX [100] via Large-scale Simulation Brian Barnes, Sergei Izvekov, N. Scott Weingarten Response of single-crystal cyclotrimethylene trinitramine (RDX) to insult in the [100] direction has been a lively topic of investigation due to the shock sensitivity of RDX in that direction. Simulations of [100] shock response have yet to reproduce an experimentally observed phase transition, and experiments have yet to observe shear bands predicted by simulation. It remains an open question as to whether the shear bands are artifacts of the computational model/method, with reality corresponding to another relaxation mechanism such as dislocation-mediated plasticity. RDX response to uniaxial compression is expected to have a transition from brittle failure to plastic response at strain rates approaching shock compression, but this transition has not been identified in molecular simulation. Prediction of explosive initiation is challenging, and ``unraveling this unpredictability starts with knowing about plasticity and failure in these materials.'' We attempt to make progress toward understanding those observations through large-scale classical atomistic molecular dynamics simulations of RDX. We investigate effects of time scale, boundary conditions, system size, and strain rate on RDX response. We discuss possible comparisons of simulation to experiment. [Preview Abstract] |
|
M9.00038: Surface energy of explosive nanoparticles Nicolas Pineau, Xavier Bidault, Laurent Soulard Recent experimental studies show that nanostructuration has a substantial impact on the detonation of high explosives: a nanostructured one leads to smaller nanodiamonds than a microstructured one (Pichot et al, Sc. Rep, 3 (2013), 2159). Whether it comes from a higher surface energy or from porosity, the origin of these different behaviors must be investigated. The surface energy of TATB nanoparticles with a radius from 2 nm upto 60 nm has been determined by means of ReaxFF-based simulations. Then, using the Rankine-Hugoniot relations and the equation of states of the bulk material, the contribution of this excess energy to the heating of a shock-compressed nanostructured (and porous) material is evaluated and compared to the thermal effect due to its porosity collapse. A maximum temperature increase of 50 K is found for 4-nm nanoparticles, which remains negligible when compared to the few hundred degrees induced by the compaction work. [Preview Abstract] |
|
M9.00039: PARTICULATE, POROUS, AND COMPOSITE MATERIALS |
|
M9.00040: Real-time measurements of shock and release in granular materials with synchrotron X-ray radiography Michael E. Rutherford, David J. Chapman, Alexander Rack, Daniel E. Eakins Real-time mesoscale measurements of shock-induced densification in granular materials are required to further our understanding of how potential design parameters such as porosity and crystalline phase influence macroscale material performance. Synchrotron light sources provide periodic, high-flux, penetrating X-ray beams, making them an ideal tool with which to make dynamic, early-time (ns-$\mu$s), mesoscale measurements of compaction and release front evolution in shocked powders. This poster discusses the development and application of a high-spatiotemporal resolution (150 ps, 10’s $\mu$m) phase-contrast X-ray radiography method for studying shock-compressed porous materials at the European Synchrotron Radiation Facility (France). Representative results recorded on single and multi-component granular samples are presented. Emphasis is placed upon the greatly enhanced scope of data available with the radiographic method in comparison with surface-based studies. Analysis of spatially-resolved wave speeds, wavefront thickness and density will be presented. [Preview Abstract] |
|
M9.00041: The experimental study of shock wave compressibility of fiberglass and carbon fiber. Valentina Mochalova, Alexander Utkin By the using of a laser interferometer VISAR the experiments on investigation of shock compressibility of heterogeneous anisotropic materials fiberglass and carbon fiber were conducted. The shock wave profile and the shock wave velocity of that materials were obtained in each experiment. For fiberglass the two-wave configuration almost in the entire pressure range was recorded for both orientations of the fibers. But the amplitude of precursor along the fibers is much higher than the amplitude for the transverse direction. In carbon fiber the structure of shock waves significantly depends on the fibers orientation - the two-wave configuration is recorded only for longitudinal direction in the investigated range of pressures. From the obtained experimental data Hugoniots of these anisotropic materials for two orientations of fibers were plotted. Hugoniot of carbon fiber is different for two orientations of fibers. There is a tendency to their convergence with the pressure increasing. For fiberglass -- they are the same for both orientations. Also a study of spall strength was conducted. It was shown for both materials that the value of spall strength for parallel orientation of the fibers is much higher than for perpendicular orientation. [Preview Abstract] |
(Author Not Attending)
|
M9.00042: Use of SHPB tests for incorporating a compaction constitutive equation within a two-phase model S.A. Weckert, A.D. Resnyansky The well-known Split Hopkinson Pressure Bar (SHPB) set-up is used for analysis of compaction of calcite sand samples within a gauge instrumented confinement. A two-phase material model, used previously for simulation of sand behaviour under extreme shock loading, requires a constitutive equation for a parameter responsible for the compaction response within a non-equilibrium loading path tending to the solid Hugoniot. A mathematical formulation approximating the present experimental set-up is suggested and used for inverse adjustment of parameters in the constitutive equation. This equation determined from the SHPB tests and incorporated in the two-phase model is used for description of the behaviour of explosively driven sand with the help of the CTH shock physics code. Comparison with available independent experiments shows a good agreement. [Preview Abstract] |
|
M9.00043: Characterization of the Dynamic Consolidation Behavior of Cerium Dioxide Powders as a Function of Green Density Travis Voorhees, Gregory Kennedy, David Fredenburg, Naresh Thadhani The uniaxial strain dynamic consolidation behavior of cerium dioxide powders as a function of particle morphology and powder compact green density is investigated in this work. Cerium dioxide is a lanthanide metal oxide powder. It is often used for the study of brittle powders exposed to extreme conditions, such as high velocity impact and shock loading. In this study, cerium dioxide powders of two particle sizes (nominally 1 and 10 $\mu $m) and two green densities (55{\%} and 63{\%} TMD) are shock compressed using gas gun impact and their particle and shock wave velocities are measured using optical velocimetry techniques. The velocity data collected is used to describe the Hugoniot of the shocked cerium dioxide powders and develop an improved P-$\alpha $ compaction model, building upon prior studies at Los Alamos National Laboratory [D. A. Fredenburg, et al, J. Appl. Phys. 115, 123511 (2014)]. In this presentation, the preliminary results regarding the suitability of the P-$\alpha $ compaction model to describe the experimentally determined Hugoniot response of cerium dioxide powders will be discussed. [Preview Abstract] |
|
M9.00044: Shock compression response of model polymer/metal composites David Bober, Yoshi Toyoda, Brian Maddox, Matthew Barham, Eric Herbold, Yogendra Gupta, Mukul Kumar Heterogeneous materials do not respond mechanically to an impulse in the manner of homogeneous metals and alloys. The propagation of a wave in a microstructure with chemically distinct identities, that are only in incidental contact with each other, is a complex process and also poorly understood. Here we will report on a series of gas gun plate-impact experiments on a polymer-metal composite, where the volume fraction of the metallic phase is systematically varied from 0 to 40{\%}, while other parameters like the sample thickness is kept a constant. A range of impact velocities was employed and the free surface velocity was interrogated to get a continuum measure of the internal materials processes. These results were then compared to the results of highly resolved mesoscale calculations to understand the wave propagation and visco-plastic effects that were observed in the experimental observations. The unfilled Si-polymer demonstrated a steady single wave shock response; whereas the wave profiles obtained from mixture samples showed structures at the onset of wave that depended on the volume fractio of the fill. [Preview Abstract] |
|
M9.00045: Meso-scale modelling of the heat conductivity effect on the shock response of a porous material A.D. Resnyansky Understanding of deformation mechanisms of porous materials under shock compression is important for tailoring material properties at the shock manufacturing of advanced materials from substrate powders and for studying the response of porous materials under shock loading. Numerical set-up of the present work considers a set of solid particles separated by air representing a volume of porous material. Condensed material in the meso-scale set-up is simulated with a viscoelastic rate sensitive material model with heat conduction formulated from the principles of irreversible thermodynamics. The model is implemented in the CTH shock physics code. The meso-scale CTH simulation of the shock loading of the representative volume reveals the mechanism of pore collapse and shows in detail the transition from a high porosity case typical for abnormal Hugoniot response to a moderate porosity case typical for conventional Hugoniot response. Results of the analysis agree with previous analytical considerations and support hypotheses used in the two-phase approach. [Preview Abstract] |
|
M9.00046: Blast Wave Mitigation in Granular Materials Quentin Pontalier, Maxime Lhoumeau, David Frost A common technique to mitigate the blast wave from a high explosive is to surround the explosive with a layer of inert particles or liquid. In the case of a powder layer in spherical geometry, the spherically expanding shock wave that propagates first within the porous powder bed has a complex structure and induces the formation of force chains through particles in contact, shock propagation in the interstitial gas, and leads to shock compaction and deformation of the particle bed. Overall, the shock accelerates the particles and heats the gas in the pores and the partition of the total energy between kinetic and internal energy is primarily a function of the layer porosity and mass ratio of material to explosive. This energy partition is explored computationally with a multiphase hydrocode as a function of the bed parameters and compared with the case of a homogeneous liquid. The results are compared with experiments which track the strength of the blast wave emerging from the material layer as well as the material velocity using high-speed photography. For a given mass ratio, the strength of the blast wave transmitted into the air and the material velocity are significantly lower for particle beds than liquid layers due to energy dissipation during compaction of the bed. [Preview Abstract] |
|
M9.00047: A numerical study of unsteady heat-transfer between fluid and solid particles in shocked particle-laden flows Pratik Das, Oishik Sen, Gustaaf Jacobs, H.S. Udaykumar Shock-particle interaction is a commonly observed phenomenon in many natural and engineering processes, such as, volcanic eruptions, nozzle of solid propellant rockets, explosions, pneumatic conveyance of particles etc. Shock interaction with particle is inherently unsteady in nature. The unsteady momentum and heat-transfer between and the particle and the fluid phase significantly contribute to the overall acceleration and heating of the particle immersed in the fluid. In the current work, the unsteady heat transfer between the particles and fluid in shock-particle interactions is studied through particle resolved direct numerical simulations. Resolved simulations of shock-particle interactions are performed using a Cartesian grid based sharp interface framework. The solid-fluid interfaces are represented using level-sets. A heat-flux conserving boundary condition in conjunction with no-slip boundary condition is enforced at the immersed solid-fluid interfaces using a modified ghost fluid method. The current method is validated against similarity solution of compressible boundary layer over a heated flat-plate. Resolved simulations of shock-particle interaction are performed to quantify the unsteady heat transfer rate between the particles and the fluid. [Preview Abstract] |
|
M9.00048: Construction of Closure Models for Pseudo-turbulent Stresses in Shock-Particle Interactions Oishik Sen, Gustaaf Jacobs, Kyung K Choi, H.S. Udaykumar In multiphase flows involving shock-particles interactions, velocity fluctuations in the fluid field arise because of the interaction between the solid and the fluid phases. Macroscale models treat the velocity-fluctuations as subgrid scale phenomenon; the fluctuations are modeled using Reynolds stress equivalence terms (also known as pseudo-turbulent terms) in the homogenized macroscale system of equations. To solve the macroscale systems, the pseudo-turbulent terms require closure. This work shows a method of generating closure laws for the pseudo-turbulent terms from resolved mesoscale computations of shock-particle interaction. Closures are derived from ensembles of high-fidelity mesoscale simulations different Mach number (Ma) and Volume-Fraction ($\phi )$. The pseudo-turbulent stresses computed from the simulations are used as inputs to a metamodeling technique -- a Modified Bayesian Kriging Method (MBKG) - for creating surrogate models. The surrogates show that the pseudo-turbulent kinetic energy (P-TKE) is comparable to the kinetic energy of the mean flow for higher Ma and higher $\phi $ flows. In summary, this work evaluates the importance of velocity-fluctuations and creates closure for the pseudo-turbulent stresses in shock-particle interactions. [Preview Abstract] |
|
M9.00049: High amplitude pulses in a periodic composite with Al matrix and W cylindrical inclusions Pedro Franco Navarro, David Benson, Vitali Nesterenko The nature of short and long high amplitude pulses in a periodic composite made of an Al matrix with W cylindrical inclusions is explored using numerical calculations. They were compared to the observed Korteweg-de Vries type solitary like waves, created by short high amplitude loading pulses, or quasi-steady oscillatory shock waves, generated by long high amplitude incoming pulses in Al-W laminates having the same volume content of components. The structure of the pulses in these two composites with different mesostructure was different, but in both cases the maximum strain rate on the leading front of the localized pulse or on the leading front of the oscillatory quasi-steady shock wave was determined by the nonlinearity and geometric dispersion and not by a dissipative properties of components. [Preview Abstract] |
|
M9.00050: Dynamical Effects in Metal-Organic Frameworks: The Microporous Materials as Shock Absorbers Kiettipong Banlusan, Alejandro Strachan Metal-organic frameworks (MOFs) are a class of nano-porous crystalline solids consisting of inorganic units coordinated to organic linkers. The unique molecular structures and outstanding properties with ultra-high porosity and tunable chemical functionality by various choices of metal clusters and organic ligands make this class of materials attractive for many applications. The complex and quite unique responses of these materials to mechanical loading including void collapse make them attractive for applications in energy absorption and storage. We will present using large-scale molecular dynamics simulations to investigate shock propagation in zeolitic imidazolate framework ZIF-8 and MOF-5. We find that for shock strengths above a threshold a two-wave structure develops with a leading elastic precursor followed by a second wave of structural collapse to relax the stress. Structural transition of MOFs in response to shock waves corresponds to the transition between two Hugoniot curves, and results in abrupt change in temperature. The pore-collapse wave propagates at slower velocity than the leading wave and weakens it, resulting in shock attenuation. Increasing piston speed results in faster propagation of pore-collapse wave, but the leading elastic wave remains unchanged below the overdriven regime. We discuss how the molecular structure of the MOFs and shock propagation direction affect the response of the materials and their ability to weaken shocks. [Preview Abstract] |
|
M9.00051: SOFT MATTER |
|
M9.00052: Plate impact experiments on the silicone elastomer DC745U cooled to -60 degrees C A. B. Goodbody, D. M. Dattelbaum, B. D. Bartram, R. L. Gustavsen Filled elastomers are used in a variety of engineering applications such as structural supports and vibrational damping components. Silica and quartz fillers are commonly used with rubbery elastomers, such as cross-linked polydimethylsiloxane, to provide improved mechanical and creep properties in such applications. However, the shockwave properties and dynamic response of this class of materials are poorly characterized. For example, it is expected that filled elastomers would exhibit viscoelastic effects under high strain rate (shock) loading, and that glass and melt transitions may play a role in their dynamic compressibility. Using gas-gun-driven plate impact techniques, we have measured the Hugoniot of the filled silicone elastomer DC745U at ambient temperature, and cooled to -60 $+$/- 2 degrees C. At - 50 degrees C, DC745U crystallizes with 40{\%} crystallinity, accompanied by a density change from 1.31 g/cm$^{\mathrm{3}}$ at 23 degrees C to 1.45 g/cm$^{\mathrm{3}}$ at -60 degrees C. Below the crystallization transition, a measurable increase in the bulk shock velocity was observed which is coincident with a decrease in compressibility due to crystallization of the polydimethylsiloxane repeat units. The linear $U_{s}- u_{p}$ Hugoniot changed from $U_{s} \quad =$ 1.62 $+$ 1.74 $u_{p}$ mm/\textmu s at 23 degrees C to $U_{s} \quad =$ 2.03 $+$ 2.03 $u_{p}$ mm/\textmu s at -60 degrees C. Thus, cooling to -60 degrees C results in considerable stiffening. This is the first time, to our knowledge, that a polymer crystallization transition has been shown to affect shockwave properties in this way. Viscoelasticity was also observed in the room temperature experiments. [Preview Abstract] |
|
M9.00053: Test of the ``radical-like polymerization" scheme in molecular dynamics on the behavior of polymers under shock loading Claire Lemarchand, David Bousquet, Benoît Schnell, Nicolas Pineau The behavior of polymer melts under shock loading is a question attracting more and more attention because of applications such as polymer-bonded explosives, light-weight armor and civilian protective equipment, like sports and car equipment. Molecular dynamics (MD) simulations are a very good tool to characterize the microscopic response of the polymer to a shock wave. To do so, the initial configuration of the polymer melt needs to be realistic. The ``radical-like polymerization" scheme [Perez \textit{et al}, J. Chem. Phys. \textbf{128}, 234904 (2008), Wu \textit{et al}, Polymer \textbf{47}, 6004 (2006)] is a method to obtain near equilibrium configurations of a melt of long polymer chains. It consists in adding one neighboring monomer at a time to each growing chain. Between each polymerization step an MD run is performed to relax the new configuration. We test how details of our implementation of the ``radical-like polymerization" scheme can impact or not Hugoniot curves and changes of chain configuration under shock. We compare our results to other simulation and experimental results on reference polymers. [Preview Abstract] |
|
M9.00054: The Response of a Commercial Fluorinated Tripolymer to One-Dimensional Shock Loading Glenn Whiteman, Jeremy Millett, Eric Brown, Neil Bourne, George Gray The response of simple polymers to shock loading is governed by a number of factors, such as the complexity of the polymer chain and the nature of the atoms attached to the main carbon-carbon backbone. In the case of polyethylene based materials such as polyethylene, polypropylene or polytetrafluoroethylene, the competing effects of inter chain tangling (tacticity) and electrostatic repulsion between adjacent polymer chains has been shown to have a profound effect on shock velocity, release velocity and shear strength development. In this work, we apply this knowledge to a commercially available fluorinated tripolymer, Viton-B, where all these molecular features are present. [Preview Abstract] |
|
M9.00055: Tensile characterisation of the aorta across quasi-static to blast loading strain rates Danyal Magnus, William Proud, Antoine Haller, Apolline Jouffroy The dynamic tensile failure mechanisms of the aorta during Traumatic Aortic Injury (TAI) are poorly understood. In automotive incidents, where the aorta may be under strains of the order of 100/s, TAI is the second largest cause of mortality. In these studies, the proximal descending aorta is the most common site where rupture is observed. In particular, the transverse direction is most commonly affected due to the circumferential orientation of elastin, and hence the literature generally concentrates upon axial samples. This project extends these dynamic studies to the blast loading regime where strain-rates are of the order of 1000/s. A campaign of uniaxial tensile experiments are conducted at quasi-static, intermediate (drop-weight) and high (tensile Split-Hopkinson Pressure Bar) strain rates. In each case, murine and porcine aorta models are considered and the extent of damage assessed post-loading using histology. Experimental data will be compared against current viscoelastic models of the aorta under axial stress. Their applicability across strain rates will be discussed. Using a multi-disciplinary approach, the conditions applied to the samples replicate \textit{in vivo} conditions, employing a blood simulant-filled tubular specimen surrounded by a physiological solution. [Preview Abstract] |
|
M9.00056: BALLSTIC STUDIES |
|
M9.00057: Gas gun ballistic testing of moving prestressed targets A.D. Resnyansky, S.L. Parry, S.A. Weckert Analyzing the response of modern mobile platforms to ballistic impact is a challenge due to target mobility and inherent structural loads. The present work presents an experimental and numerical analysis of ballistic impact against simulated moving targets with the target plate samples under prestressed load. Representation of the target movement is achieved with an experimental set-up of impact against a plate target where an elongated projectile colliding with the target at the corresponding angle providing a normal impact, but with a transverse velocity component. The present experimental analysis considers the impact by a 50 calibre projectile against an aluminium target and shows the influence of the sample prestress on the damage of the material. The modelling agrees well with the experiments. [Preview Abstract] |
|
M9.00058: Concurrent Radiography, Velocimetry and High Speed Imaging During Ballistic Impact Brian Schuster, Phillip Jannotti, David Andrews, Brady Aydelotte, Nicholas Lorenzo We present applications of the High voltage In-situ Diagnostic Radiography Apparatus (HIDRA) at the US Army Research Laboratory to terminal ballistic impact in ductile and brittle material systems. HIDRA consists of an array of fourteen 150 kV flash X-ray sources that are coincident on the impact site, a four channel Photon Doppler Velocimetry (PDV) system and two synchronized high speed cameras operating at up to 10 million frames per second. We will present examples of laboratory penetrators fired from smooth bore powder cannons at velocities up to 2.3 km/s. This system has been applied in single events to measure the striking velocity, deceleration during penetration and residual velocity. Measurements of the penetrator/target interface position yield have been used to track the dwell time in ceramics, rod consumption velocity and penetration velocity as a function of time. PDV has been combined with edge-on and stereo imaging to map back face deformation. Direct comparisons to computational models of impact and penetration will be shown. [Preview Abstract] |
|
M9.00059: Ballistics Trajectory and Impact Analysis for Insensitive Munitions and Hazard Classification Project Criteria Ernest Baker, Martijn van der Voort Ballistics trajectory and impact conditions calculations were conducted in order to investigate the origin of the projection criteria for Insensitive Munitions (IM) and Hazard Classification (HC). The results show that the existing IM and HC projection criteria distance-mass relations are based on launch energy rather than impact conditions. The distance-mass relations were reproduced using TRAJCAN trajectory analysis by using launch energies of 8, 20 and 79J and calculating the maximum impact distance reached by a natural fragment (steel) launched from 1 m height. The analysis shows that at the maximum throw distances, the impact energy is generally much smaller than the launch energy. Using maximum distance projections, new distance-mass relations were developed that match the criteria based on impact energy at 15m and beyond rather than launch energy. Injury analysis was conducted using penetration injury and blunt injury models. The smallest projectile masses in the distance-mass relations are in the transition region from penetration injury to blunt injury. For this reason, blunt injury dominates the assessment of injury or lethality. State of the art blunt injury models predict only minor injury for a 20J impact. For a 79J blunt impact, major injury is likely to occur. MSIAC recommends changing the distance-mass relation that distinguishes a munitions burning response to a 20 J impact energy criterion at 15 m and updating of the UN Orange Book. [Preview Abstract] |
|
M9.00060: SPECTROSCOPY AND OPTICAL STUDIES |
|
M9.00061: Far-infrared Beamline at the Canadian Light Source. Jianbao Zhao, Brant Billinghurst Far-infrared is a particularly useful technique for studies on lattice modes as they generally appear in the Far-infrared region. Far-infrared is also an important tool for gathering information on the electrical transport properties of metallic materials and the band gap of semiconductors. This poster will describe the horizontal microscope that has recently been built in the Far-infrared beamline at the Canadian Light Source Inc. (CLS). This microscope is specially designed for high-pressure Far-infrared absorbance and reflectance spectroscopic studies. The numerical aperture (0.5) and the long working distance (82.1 mm) in the microscope are good fits for Diamond Anvil Cell (DAC). The spectra are recorded using liquid helium cooled Si bolometer or Ge:Cu detector. The pressure in the DAC can be determined by using the fluorescence spectrometer available onsite. The Far-infrared beamline at CLS is a state-of-the-art synchrotron facility, offering significantly more brightness than conventional sources. Because of the high brightness of the synchrotron radiation, we can obtain the Far-infrared reflectance/absorbance spectra on the small samples with more throughput than with a conventional source. The Far-infrared beamline is open to users through peer review. [Preview Abstract] |
|
M9.00062: The initial response of energetic materials to femto-second indirect laser heating Nhan Dang, Jennifer Gottfried, Frank De Lucia In this presentation, we show the capability of monitoring the initial evolution of heat transfer from femto-second laser-heated metal layers into thin films of solid explosives using time-resolved visible transient absorption (TA) spectroscopy. Reported here are visible TA data in the spectral region from 500 to 750 nm for indirect laser-heated, 5 micron thick films composed of cyclotrimethylene trinitramine (RDX), oxidized polyethylene (OPE), and RDX with 1, 2.5, 5 or 10{\%} OPE prior to decomposition. It was found that the heat generated by a 35 fs laser pulse with an energy density of 15 mJ cm$^{\mathrm{-2}}$ on a 100 nm thick Au layer was transferred into the thin film of RDX and was sufficient to induce changes in the electronic structure of RDX molecules, and that the heat transfer rate in RDX depends on its homogeneity and degree of purity. Also in this presentation, investigations of the temperature at metal surfaces (Au, Pt), and the temperature transferred from the metal surfaces into the samples will be discussed. TA of energetic materials induced by different temperature regimes will be reported. [Preview Abstract] |
|
M9.00063: 1D-Numerical investigation of the interaction of counter propagating laser ablative shock waves in air. Prem Kiran Paturi, Sai Shiva S, Nagaraju Guthikonda, Venkata Ramana Ikkurthi, Sijoy C. D., Chaturvedi Shashank A 1D-numerical model has been developed to investigate the interaction of counter propagating shock waves generated using 7 ns (FWHM) laser pulses and with 532 nm wavelength is presented. The simulations have been carried out using Lagrangian one dimensional radiation hydrodynamic code. The model takes into consideration the electron-ion inverse bremsstrahlung absorption coefficient for the laser energy deposition process. Similarly, the plasma behavior is assumed to follow the ideal gas equation of state with the charge state effects taken into account. The two shock waves are created by focusing the laser energy at two different focal points in the counter propagating direction. The distance between the two points is varied from 0.5 -- 10 mm. The input laser energy at one source is fixed to 25 mJ, whereas the other side is varied from 25- 96 mJ. The plasma and shock wave interaction dynamics were observed to vary with varying energy deposition and distance between the two sources. The numerical results were compared with the experimental observations along the laser axis over the time scales of 0.4 - 4 $\mu $s. [Preview Abstract] |
|
M9.00064: FOCUS SESSION: EJECTA PHYSICS |
|
M9.00065: Investigation of the static and dynamic fragmentation of metallic liquid sheets induced by random surface fluctuations Olivier Durand, Laurent Soulard, Emeric Bourasseau, Gaelle Filippini When a metal with a roughened free surface is shock-loaded above its fusion point, it can eject liquid sheets which will break up. We investigate the role of random surface fluctuations when the fragmentation of such sheets is simulated using molecular dynamics (MD). Static and dynamic regimes of fragmentation are considered. The static fragmentation is analyzed by simulating sheets of various thicknesses, and the dynamic fragmentation is ensured by applying along the longitudinal direction of a sheet an instantaneous expansion rate. The simulations show that the static/dynamic fragmentation becomes possible when the fluctuations of the upper and lower surfaces of the sheets can either overlap or make the local volume density of the system go down below a critical value. These two mechanisms cause locally in the sheet the random nucleation of pores of void which develop afterwards following distinct stages of growth, coalescence, and percolation. A model derived from the simulations suggests that both dynamic and static regimes of fragmentation are similar for expansion rates below typically $1\times 10^{7}$ s$^{\mathrm{-1}}$. This study could provide a help in the investigation of the fragmentation of dynamic sheets at higher scales than those of MD. [Preview Abstract] |
|
M9.00066: Development of a multiple wavelength extinction diagnostic for measuring ejecta particle size distributions. Paul Steele, Steve Compton, Barry Jacoby, Catalin Filip, Matthias Frank, Danial Phillips, Jose O. Sinibaldi Mie's solution of Maxwell's equations for the interaction of light with spherical particles shows that particle diameter has a dramatic impact on the amount of light scattered or absorbed by a particle. The ratio of particle size to wavelength is particularly important. By measuring the transmission through a sheet of ejecta at multiple wavelengths and making certain assumptions, it is possible to estimate the ejecta particle size distribution. The Multiple Wavelength Extinction (MWE) diagnostic is being developed at Lawrence Livermore National Laboratory (LLNL) to do just that. Various potential system configurations were initially evaluated using a computer model developed in MATLAB. Inexpensive hardware (MWE Beta) was acquired for a basic proof-of-concept experiment using calibrated test particles. Encouraging results enabled procurement of better hardware. Characterization and testing of this MWE 1.0 system is ongoing. MWE 2.0 is now being designed. Ejecta experiments require a high explosive drive, an array of ejecta diagnostics and containment vessels, all of which are readily available at LLNL's High Explosives Application Facility. LLNL-ABS-723858 [Preview Abstract] |
|
M9.00067: Using mid-Infrared External Reflectance Spectroscopy to Distinguish Between Different Commercially Produced Poly[Methyl MethAcrylate] (PMMA) Samples $-$ A Null Result. Mario Fajardo, Christopher Neel, David Lacina We report (null) results of experiments testing the hypothesis that mid-infrared (mid-IR) spectroscopy can be used to distinguish samples of poly[methyl methacrylate] (PMMA) obtained from different commercial suppliers. This work was motivated by the desire for a simple non-destructive and non-invasive test for pre-sorting PMMA samples prior to use in shock and high-strain-rate experiments, where PMMA is commonly used as a standard material. We discuss: our choice of mid-IR external reflectance spectroscopy, our approach to recording reflectance spectra at near-normal ($\theta \quad =$ 0 $+$/- 5 degree) incidence and for extracting the wavelength-weighted absorption spectrum from the raw reflectance data \textit{via} a Kramers-Kr\"{o}nig analysis. We employ extensive signal, which necessitates adopting a special experimental protocol to mitigate the effects of instrumental drift. Finally, we report spectra of three PMMA samples with different commercial pedigrees, and show that they are virtually identical ($+$/- 1 {\%} error, 95 {\%} confidence); obviating the use of mid-IR reflectance spectroscopy to tell the samples apart. [Preview Abstract] |
|
M9.00068: Ultrafast phase-contrast imaging of laser driven shocks using LWFA Betatron X-rays David Chapman, Michael Rutherford, Daniel Eakins, Jonathan Wood, Kristjan Poder, Nelson Lopes, Stuart Mangles In recent years Betatron X-rays produced within a laser-plasma wakefield accelerator (LWFA) have emerged as a potential alternative to advanced photon sources, such as Synchrotrons and X-ray free-electron lasers. LWFA Betatron X-rays offer the attractive combination of high brilliance, short pulse duration, and high-energy polychromatic X-rays, which make them particularly suitable for imaging highly transient events such as shock wave evolution in solids. We describe pioneering experiments on the 400 TW Astra Gemini laser at the Rutherford Appleton Laboratory, UK, imaging laser driven targets using Betatron X-rays. Shock waves were driven into thick aluminum foils using a 30J IR long-pulse (30ns), and stroboscopically radiographed perpendicular to the shock propagation direction using a $\approx$ 40 fs Betatron X-ray pulse (10-30 keV). The resulting high resolution (4 $\mu m$) radiograph time-sequence captured the shock wave propagation, and ultimate evolution of jets and spallation formed on the rear grooved surface of the aluminum targets. The measured dynamic radiographs are compared to 2D Hyades simulations, demonstrating a new capability to benchmark radiation-hydrocode modeling of laser-target interaction. [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