Bulletin of the American Physical Society
22nd Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 67, Number 8
Monday–Friday, July 11–15, 2022; Anaheim, California
Session P01: Grain Scale-to-Continuum Modeling of MetalsFocus Recordings Available
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Chair: Jonathan Belof, Lawrence Livermore Natl Lab Room: Anaheim Marriott Platinum 5 |
Wednesday, July 13, 2022 11:00AM - 11:30AM |
P01.00001: Modeling Dislocation Density Evolution During Microparticle Impacts Invited Speaker: Abigail Hunter A continuum-scale material model that is applicable over a wide range of loading conditions will be presented. The model is comprised of three coupled ordinary differential equations: a kinetic equation, which relates the strain-rate to the stress, mobile and immobile dislocation densities, mass density, and temperature, and two equations describing the evolution of the mobile and immobile (network, forest) dislocation densities. The dislocation density evolution equations account for a variety of known storage, dynamic recovery, and dislocation multiplication mechanisms in face-centered cubic metals. The model will then be applied to model copper-on- copper microparticle impacts with impact velocities ranging from ~100-1100 m/s. Simulated results are compared to experimental data reported in literature to validate the model. |
Wednesday, July 13, 2022 11:30AM - 11:45AM |
P01.00002: Modeling of laser interactions with metals using a hybrid atomistic-continuum approach Ching Chen, Sergey Galitskiy, Avanish Mishra, Avinash Dongare The modeling of interaction of metallic materials with lasers requires an accurate description of laser energy absorption, heat generation/transfer, and energy dissipation that can result in ablation, spallation, melting and shock compression. Such a capability is available through a hybrid atomistic-continuum method that combines classical molecular dynamics (MD) with the two-temperature model (TTM) to model the ultra-fast heating, melting, and shock generation in metals. The MD-TTM framework is extended to FCC Al and BCC Ta systems, wherein the electronic-temperature-dependent electron heat capacity, electron thermal conductivity, and electron-phonon coupling factor are parameterized via first-principles simulations. The capability is demonstrated by investigating the spall failure behaviors of Al and Ta systems under femtosecond laser shock loading. The talk will discuss the details of MD-TTM simulations, including the implementation of the framework, the parameterization of the TTM, and the interaction of lasers with microstructures of Al and Ta systems. |
Wednesday, July 13, 2022 11:45AM - 12:00PM |
P01.00003: The Slip-Twinning Competition in HCP Metals William Schill, Ryan Austin, Kathleen Schmidt, Nathan R Barton Experimental observations suggest that complex history-dependent behavior arises in metals with hexagonal crystal symmetry, and that the prominence of various deformation mechanisms varies with strain rate. The material response across a range of conditions appears to be challenging to capture using many standard J2-type plasticity models. The slip planes in HCP metals with the lowest resistance to flow – typically the basal and prismatic slip planes – do not accommodate every deviatoric deformation. Thus, out of necessity, slip and twinning are expected to play an important role in the deformation. This gives rise to a competition of mechanisms to maintain compatibility and equilibrium. We study this competition between twinning and slip. Under a set of reasonable simplifying assumptions, we perform an explicit homogenization procedure deriving an expression relating the macroscopic flow strength to a dimensionless variable relating the strength of the different slip systems. Utilizing this expression, we pose a simple model for inelastic deformation in hexagonal close-packed metals. We apply the model to examine Kolsky bar type data in beryllium and discuss agreement and improvement relative to existing models. |
Wednesday, July 13, 2022 12:00PM - 12:15PM |
P01.00004: Nonequilibrium Equation of State for Shock Compressed Particulate Composites Eric B Herbold, Roger W Minich, David B Bober, David Quint, Jonathan Lind, Moono Rhee, Mukul Kumar The dynamic compression of particulate composites results in long shock-fronts and transient states. The transient state of the material measured by particle velocity alone belies the complex nature of particle flow in a soft matrix. We will present the dynamic response of composites comprised of tungsten particles in a polymer matrix. The dynamic strength of the composite is not large enough to account for the transient response. Here we will discuss modifications of an equation of state accounting for particle size, volume fraction and properties of the polymer that capture observations in single and double-shock experiments. |
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