Bulletin of the American Physical Society
APS March Meeting 2020
Volume 65, Number 1
Monday–Friday, March 2–6, 2020; Denver, Colorado
Session R02: Materials in Extremes: Dynamic Compression I: StrengthFocus
|
Hide Abstracts |
Sponsoring Units: GSCCM Chair: Rachel Flanagan, University of California, San Diego Room: 105 |
Thursday, March 5, 2020 8:00AM - 8:36AM |
R02.00001: Experimental and numerical studies on phase change under dynamic loadings: application to Tin. Invited Speaker: Camille Chauvin Polymorphic (structural) phase transformations of metals under dynamic high pressures is an area of fundamental scientific research at CEA which are studied through both experimental and theoretical/computational means. Experiments have long suggested that non-equilibrium behavior (kinetics) is an important part of the dynamic compression response of materials undergoing phase transformations. Both this deeper understanding, and quantitative data on specific metals, are needed to improve material models used in state-of-the-art hydrocodes. Only in recent years have experimental capabilities advanced sufficiently enough, in terms of diagnostics as well as drivers, that kinetics effects in dynamic phase transformations can begin to be quantified in a more rigorous manner. Empirical kinetic models can in a lot of cases reproduce the experimental velocity profiles but without clearly identifying the nature of the transition. |
Thursday, March 5, 2020 8:36AM - 8:48AM |
R02.00002: Unusual strength in tin under dynamic compression Camelia Stan, Alex Zylstra, Matthew P Hill, Tom Lockard, Hye-Sook Park, Philip Powell, Damian C Swift, James M McNaney Tin is a soft metal that undergoes several phase transitions at high pressure and temperature (1). These structural changes should lead to significant changes in both material microstructure and physical properties upon compression. Here, we use the Rayleigh-Taylor instability to measure its strength within the high-pressure BCC phase. A pre-machined rippled pattern seeds the instability, wherein a low density fluid pushing against a high density fluid causes growth of surface perturbations. We use a CH layer as the low density material, and the “push” is provided by the Omega EP laser facility, University of Rochester, which generates a ramped compression drive of ~1.5 Mbar in the sample. Ripple growth is measured using face-on radiography, and strength is interpreted based on the rate of growth relative to the undriven portion of the sample. We find that the growth rate is much less than that predicted in hydrodynamic simulations using a Steinberg-Guinan model. This suggests that BCC tin has unusually high strength, interpreted here as a resistance to plastic deformation. |
Thursday, March 5, 2020 8:48AM - 9:00AM |
R02.00003: Coupled Experiment and Theory to Explore the Limits of Material Strength at High Strain Rates Mitchell Wood, James Stewart, Joseph D Olles Experiments to study materials at high pressure are challenging and time consumptive, therefore we turn to modeling tools to refine and predict outcomes beforehand. Efficient models balance absolute physical accuracy against approximate but computationally lightweight constitutive inputs. By using a relatively small number of high fidelity simulations we have be able to broaden the predictive power of the shock response in metals and polymers. Analysis of these simulations has produced parameterizations of material strength, which can be used as constitutive inputs for continuum hydrodynamics codes. For shocked Cu, MD simulations show a yield strength from Richmyer-Meshkov Instability(RMI) jet growth of approximately 450MPa that depends on the details of the free surface geometry. This value is close to the yield strength of 500MPa parameterized from experiments at the Dynamic Compression Sector at Argonne National Lab. The same analysis applied to MD simulations of PMMA jetting resulted in no clear determination of yield strength, implying a more complex RMI process in polymeric materials. Simulations of both materials demonstrate the need for explicit strain rate dependence for future improvements in strength models used in continuum codes. |
Thursday, March 5, 2020 9:00AM - 9:12AM |
R02.00004: Dynamic Strength in Polymers Jennifer Jordan, Rachel Huber, Dana Dattelbaum, Daniel T. Casem Dynamic strength in polymers has been related to the underlying polymer structure in studies by Bourne, Millett, and co-workers. However, the majority of this work focused on changing the polymer chemistry. In this study, the effect of polymer structure, e.g. crystallinity, on dynamic polymer strength is investigated. The current understanding of polymer strength will be reviewed and recent results will be presented. |
Thursday, March 5, 2020 9:12AM - 9:24AM |
R02.00005: Rayleigh-Taylor strength experiments in the high pressure and high strain rate regime on NIF Hye-Sook Park, Nathan R Barton, Andrew Krygier, Bruce Allen Remington, Robert E Rudd, Philip Powell, Shon T. Prisbrey, Damian C Swift, Christopher Wehrenberg, Alex Zylstra, James M McNaney, Matthew P Hill A solid material can be placed in the high energy density regime by compressing it to pressures >1 Mbar using a laser driven plasma piston drive. We create a ramped laser drive that keeps the material in the solid state during compression without shock melting. Understanding plastic deformation dynamics of materials under these extreme conditions is of high interest to a number of fields, including meteor impact dynamics and advanced inertial confinement fusion. We infer the strength of Ta, Pb [1,2] and Fe at high pressures (upto 8 Mbar), high strain rates (~107 s-1) and high strains (> 30%) by measuring the growth of Rayleigh-Taylor instabilities (RTI) under ramped compression. We find that the RTI growth for materials in the solid state, compressed under high pressure and high strain rates, is reduced compared to the no-strength case. We will describe the experimental results from NIF and compare them to various strength models. |
Thursday, March 5, 2020 9:24AM - 9:36AM |
R02.00006: Experimental studies of material strength in the high energy density regime Philip Powell, Andrew Krygier, Hye-Sook Park, Nathan R Barton, Channing M Huntington, Bruce Allen Remington, Robert Rudd, Shon T. Prisbrey, Damian Swift, Christopher Wehrenberg, Alex Zylstra, James M McNaney A solid material can be placed in the high energy density regime by compressing it to pressures > 1 Mbar using a laser driven plasma piston drive. We create a ramped laser drive that avoids shock melting, maintaining the material in the solid state during the full compression. Understanding plastic deformation dynamics of materials under these extreme conditions is of great interest in a number of fields, including meteor impact dynamics and advanced inertial confinement fusion. We infer the strength of Ta, Pb [1,2] and Fe at high pressures (up to 8 Mbar), high strain rates (~107 s−1) and high strains (> 30%) by measuring the growth of Rayleigh-Taylor instabilities (RTI) under ramped compression. We find that the RTI growth for materials in the solid state, compressed under high pressure and high strain rates, is reduced compared to the no-strength case. We describe recent experimental results from NIF and compare them to various strength models. [1] H. -S. Park et al., Phys. Rev. Lett. 114, 065502 (2015). [2] A. Krygier et al., Phys. Rev. Lett., accepted (2019). |
Thursday, March 5, 2020 9:36AM - 9:48AM |
R02.00007: Influence of Defects on the Shock Hugoniot of Tantalum Saryu Fensin, Eric N Hahn Using molecular dynamics simulations, we investigate the effect of vacancies and dislocations on the dynamic response of single crystal tantalum to shock loading. A Hugoniostat technique is employed, for which a series of states along the Hugoniot are sampled by many individual simulations. We show that defects have a limited effect on the shock/particle velocity relationship and that the shock pressure/volume relationship can be well predicted by taking into account the changes in the initial density and sound speeds of the samples. The principal effect of initial defects is the activation of heterogeneous dislocation nucleation and expedited dislocation multiplication during shock. The heat generated by plastic work, caused by defects moving through the lattice, is substantial. The result is significantly divergent final shock temperatures for different initial defect concentrations and pronounced changes in the resultant shock melting temperatures. The motion of dislocations also leaves behind a inconsequential concentration of vacancies that is quantified. |
Thursday, March 5, 2020 9:48AM - 10:00AM |
R02.00008: Experiments studying the flow strength of tantalum up to 30 GPa Frank Cherne, Matthew Hudspeth, Michael Prime, Brian Jensen In the recent years, there has been a number of experiments performed looking at different platforms or techniques to probe the strength of tantalum. The focus of this research has been to apply a shock/double shock drive conditions to determine the flow strength in tantalum up to about 30 GPa. The elastic/plastic response of tantalum and its interaction with typical lower impedance window materials complicates the design of these experiments. In this work, we present the results where we applied the shock/reloading technique to determine the flow strength of tantalum at initial loading stress states up to 30 GPa. Simulations with and without a PTW strength model are also compared to the experimental data. |
Thursday, March 5, 2020 10:00AM - 10:12AM |
R02.00009: Simulating Tantalum Strength Measurements on the National Ignition Facility, Z-Machine, and Gas Gun Platforms Corbett Battaile, Nathan R Barton, Justin Brown, J Matthew D Lane, Hojun Lim, Philip Powell, Michael Prime The yield strengths of body-centered-cubic refractory metals (e.g. molybdenum, niobium, tantalum, and tungsten) can depend strongly on temperature, pressure, and strain rate. A variety of constitutive models have been proposed to describe these effects, but most are calibrated and/or validated in specific regimes of interest. In this work we used three recently-developed strength models, namely the Livermore Multiscale Model, the Preston-Tonks-Wallace model, and the Kink Pair model, to describe the response of tantalum subjected to elevated temperatures, pressures, and strain rates. We applied these models to predict strength measurements from Lawrence Livermore's National Ignition Facility, Los Alamos' gas gun facilities, and Sandia's Z-Machine, in order to explore a wide range of loading regimes. In this presentation we will outline each approach, and discuss validation results for the models' predictions of the strength of tantalum across a wide range of temperatures, pressures, and strain rates on these high-energy-density platforms. |
Thursday, March 5, 2020 10:12AM - 10:24AM |
R02.00010: Nonisentropic Release of a Shocked Solid Patrick Heighway, Marcin Sliwa, David R McGonegle, Christopher Wehrenberg, Cynthia Bolme, Jon Henry Eggert, Andrew Higginbotham, Amy E Lazicki, Haeja Lee, Bob Nagler, Hye-Sook Park, Robert Rudd, Raymond Smith, Matthew Suggit, Damian Swift, Franz Tavella, Bruce Allen Remington, Justin Stephen Wark Shock release is the fundamental process that takes place when a material at high pressure undergoes rapid decompression. It is commonly accepted that rarefaction of this sort takes place isentropically, and is thus attended by substantial cooling due to the thermoelastic effect. However, this treatment fails to account for the fact that rapidly releasing material within the first few microns of the free surface typically exhibits material strength of order gigapascals, and therefore suffers copious plastic-work heating. Moreover, an isentropic treatment of release neglects the energy that can be recovered via the annihilation of crystal defects that ensues during rarefaction. Here, we present molecular dynamics simulations of shock and release in micron-scale tantalum crystals that exhibit release temperatures far exceeding those expected under the standard assumption of isentropic release. We show via an energy-budget analysis that this is due primarily to heating from material strength that largely counters thermoelastic cooling. The simulations are corroborated by experiments where the release temperatures of laser-shocked tantalum foils are deduced from their thermal strains via femtosecond x-ray diffraction, and are found to be close to those behind the shock itself. |
Thursday, March 5, 2020 10:24AM - 10:36AM |
R02.00011: A model for twinning and plasticity in tantalum under shock conditions Nicolas Bruzy, Aurélien Vattré, Christophe Denoual During deformation of tantalum at high strain rates, a competition takes place between plastic slip and twinning. The higher the strain rate, the harder it is to activate slip systems and twinning becomes predominant. In view of investigating this transition, a phase field model for phase changes including crystal plasticity, written in the finite strain format, is derived. It relies on the Reaction Pathway formalism, which is tailored for dynamic loadings since elastic and inelastic effects are properly split. First, all accessible variants are identified using point group symmetries of the parent phase. In the case of tantalum, two levels of transformation are considered (with 1+36 accessible variants in total), which makes it possible to reproduce secondary twinning. Then, the variants are taken as local minima of an energy landscape from which transformational energy and kinetic relations are obtained. A crystal plasticity model is further embedded at each variant to run polyphase plastic computations. Shock simulations on tantalum bars are performed using a 3D total Lagrangian code with an element-free Galerkin least-squares formulation. Results in terms of both variants repartition and plastic activity are consistent with past experimental works. |
Thursday, March 5, 2020 10:36AM - 10:48AM |
R02.00012: Study of Hugoniot Elastic Limit in Tantalum single crystal using elastic precursor decay at normal and elevated temperature:Molecular Dynamics study Anuradha Singla, Aditi Ray Crystalline solids subjected to extremely high strain rates, as happens in shock wave propagation, is an important branch of material science.Knowledge of HEL is of fundamental importance in shock wave studies.Among BCC metals, Ta has several technological advantages due to its excellent mechanical property and thermodynamic phase stabilty at extreme conditions.This makes it useful in designing high impedence flyers for equation of state studies. |
|
R02.00013: Anisotropic shock response of single-crystalline β-phase tin Robert Scharff Mesoscale simulations of the dynamic response of polycrystalline metals to shockwave compression can provide unique insight in to the nature of the various physical mechanisms responsible for material failure. This approach requires a constitutive description for individual grains and boundaries, including defects such as dislocations, within an explicit representation of the microstructure geometry and evolving deformation fields. Computational models of the single-crystal constituents cannot be unambiguously constrained by traditional measurements of the shock or stress-strain response of polycrystalline metals. Instead, these models require comprehensive measurements of the anisotropic shock response of single crystals for their calibration and validation. We present a coordinated experimental and simulation campaign on the shock response of single-crystalline β-phase tin demonstrating a remarkable anisotropic elastic-plastic response of the metal. |
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